HRRR and the Mid-Mississippi Valley Severe and Heavy rainfall event of October 2014

Size: px
Start display at page:

Download "HRRR and the Mid-Mississippi Valley Severe and Heavy rainfall event of October 2014"

Transcription

1 HRRR and the Mid-Mississippi Valley Severe and Heavy rainfall event of October 2014 By Richard H. Grumm National Weather Service State College, PA contributions by Charles Ross 1. Overview A deep 500 hpa trough (Fig. 1) moved across the central United States from October The flow between the deep trough and downstream ridge allowed a surge of warm moist air into the Mid-Mississippi Valley (MMV: Fig. 2) with a strong southerly 850 hpa low-level jet (LLJ: Fig. 3). The strong southerly flow resulted in a widespread rainfall event (Fig. 4) and severe weather from Illinois to the Gulf of Mexico (Fig. 5). The maximum rainfall was on the order of 100 mm in portions of Mississippi and Alabama. The strong southerly jet (Fig. 3) and implied strong shear is often associated with the Maddox Synoptic rainfall event type (Maddox et al. 1979) and is often associated with quasi-linear convective systems (QLCS: Atkin et. al 2004 & 2005). The composite radar (Fig. 6) shows that a QLCS did in fact traverse the region. How well this feature was forecast by the NCEP 3km HRRR will be explored. This case is used to show the larger scale pattern which contained strong southerly winds and high PW values. This resulted in relatively high CAPE (Fig. 7) from the lower to MMV producing heavy rainfall and severe weather with tornadoes as far north as Illinois (Fig. 5). It should be noted that the CFSR appears to under estimate CAPE relative to the HRRR and GFS 00-hour forecasts. This study will also show some forecast issues relative to the NCEP 16km SREF verse the convective allowing HRRR. The HRRR can show the mode of convection and where the more intense rainfall and convection may occur in short forecast ranges. Rapidly refreshed convective allowing models (Juanzhen et al. 2014: Fig. 1) can improve short-range QPFs verse traditional cold started models. 2. Methods and Data The NCEP 3km HRRR and 16km SREF were used to show the evolution of the rainfall and precipitation. The HRRR had the added value of showing the evolution of the radar and convection. The 0.5 degree CFSR was used to construct the larger scale pattern.

2 Radar data was retrieved from then multi-sensor (MRMS) site to evaluate and make loops of the evolving convection and rainfall The rainfall images in plain view were produced using the Stage-IV data and plotted using GrADS. 3. SREF The SREF and other NCEP models did relatively well predicting the pattern and the potential for both a heavy rainfall event and severe weather event. Six SREF forecasts of CAPE all valid near the height of the QLCS event at 2100 UTC 13 October 2014 (Fig. 8) bear out the surge of high PW air (Fig. 2) and are related to the SREF forecasts of the surge of high PW air (Fig. 9) and a strong LLJ (Fig. 10) with strong shear. The shear and CAPE were important ingredients to the convection and the development of the QLCS system and the tornadoes in Illinois. The resulting pattern produced locally heavy rainfall in the SREF (Fig ) in a general northsouth pattern along and ahead of the cold front with some hints of a wraparound rainband farther north in the cold air. The 12-hour probabilities of 25 mm showed a high probability along a north-south axis (Fig. 11). The 12-hour SREF mean (Fig. 12) showed a broader area of rainfall and some uncertainty with the regions susceptible to heavy rainfall. The ensemble mean in both the 12 and 24 hour periods showed the north-south band and an axis of heavy rainfall in the cold conveyor belt. The 24 hour totals showed some areas of over 50mm in both the convection ahead of the front and in the cold conveyor rain area (Fig. 13e-f). The short-term nature of these 50 mm forecasts implied a slow but steady convergence to get the higher amounts in extremely short forecast ranges. The SREF did reasonably well the pattern for heavy rainfall and convection. The next section examines how the NCEP 3km HRRR performed. 4. NCEP 3km HRRR The hourly convective evolution in the 1500 UTC 13 October 2014 HRRR is shown in Figure 14. These data showed the potential details of the rainfall evolution capturing the QLCS system in the MMV and the wrap-around rainband. Relative to the radar (Fig. 6-lower panel) the 15Z HRRR was slow to move the convective line across the Mississippi river. Six successive HRRR runs (Fig. 15) and the verifying 2100 UTC radar (Fig. 16) show the evolution of the QLCS system as forecast and observed. The salient point for this event was how well the HRRR captured the convective mode and how well the HRRR tracked the system to the east. At times the HRRR was slow relative to the observed radar.

3 Compared the SREF QPFs and probabilities of heavy rainfall (Fig ) it was apparent that the HRRR showed a faster evolution of the heavy rainfall to the east than implied in the SREF forecasts ending at 0000 UTC 14 October. The 1800 UTC HRRR (Fig. 17) near the mid-point of the forecasts in Figure 11, show that the heavy rainfall and convection was well into Mississippi from 2200 through 0000 UTC. The HRRR QPF in the periods was not shown. 5. Summary A strongly forced heavy rainfall and convective event impacted the central United States on October The strong LLJ and high CAPE lead to a severe weather event in the lower and MMV s. Tornadoes were observed as far north as Illinois, though most of the observed severe weather was in the form of strong winds from a QLCS. The larger scale pattern was a pattern often associated with both heavy rain and QLCS. The NCEP 16km SREF did relatively well predicted the pattern and thus the areas of heavy rainfall. The system is too coarse to predicted convective mode though along and ahead of the cold front the SREF predicted the ingredients for convection including strong low-level winds and shear and relatively high CAPE. The SREF also produced rainfall in the region implying ascent to realize the convection. The SREF 24 hour totals showed some areas of over 50mm in both the convection ahead of the front and in the cold conveyor rain area (Fig. 13e-f). The short-term nature of these 50 mm forecasts implied a slow but steady convergence to get the higher amounts in extremely short forecast ranges. Clearly, as forecast length decreases, new data improves the SREF short-term forecasts. But with a cold start and 6-hourly updates this effect is not as dramatic as that shown in the HRRR which is updated hourly. The rapidly updated HRRR with radar used to hot-start the model, provided relatively good guidance as the nature of the convective evolutions. The HRRR also produced the wrap-around band and handled a weak short-wave ahead of the QLCS which produced rain over portions of Florida, Alabama and Georgia. The power of rapidly updated forecasts and convective allowing models has been shown to provide skill in predicting convective mode. Several studies (Weisman et al. 2013) have shown the power the convective allowing models to simulate historic derechoes to include 8 May 2009 super derecho. A more recent study showed the ability of the HRR to simulate the historic eastern United States derecho of 30 June Clearly, the HRRR provides excellent guidance with regard to convective mode and system evolutions. However, relative to the radar there are considerable issues with timing and the convective details. The system is not perfect but represents an historic leap forward in short-term 1 Morris Weisman provided output from simulations of the historic 30 June 2012 derecho and his related talk is available on line from this AMS link:

4 forecasting and an opportunity to improve short-term forecasting. There are also issues to learn from such as the transition from coarse models such as the SREF to the HRRR. Comparing successive HRRR forecasts to the latest 6 SREF forecasts implied the SREF was too slow to move the heavy rainfall eastward. The 18Z HRRR was shown relative to the SREF 12 hour QPF in the 1200 to 0000 UTC window. The HRRR indicated that the more intense rainfall had moved east of the SREF area of heavy rainfall. Though not pointed out, the HRRR also showed little in terms of QPF and intense radar in the western area of heavy rainfall implied by the SREF. This implies an opportunity to use the HRRR and to study using the HRRR to improve upon these coarser cold-started model and ensemble forecast systems. The key point: rapid updates in the QPF and radar often create some conflict in the QPF and PoPs provided by models which are not rapidly updated and imply the potential to improve short-term forecasting. 6. Acknowledgements 7. References Atkins N. T., J. M. Arnott, R. W. Przybylinski, R. A. Wolf, and B. D. Ketcham, 2004: Vortex structure and evolution within bow echoes. Part I: Single-Doppler and damage analysis of the 29 June 1998 derecho. Mon. Wea. Rev., 132, Atkins, N.T., C.S. Bouchard, R.W. Przybylinski, R.J. Trapp, and G. Schmocker, 2005: Damaging Surface Wind Mechanisms within the 10 June 2003 Saint Louis Bow Echo during BAMEX. Mon. Wea. Rev., 133, Juanzhen Sun, Ming Xue, James W. Wilson, Isztar Zawadzki, Sue P. Ballard, Jeanette Onvlee- Hooimeyer, Paul Joe, Dale M. Barker, Ping-Wah Li, Brian Golding, Mei Xu, and James Pinto, 2014: Use of NWP for Nowcasting Convective Precipitation: Recent Progress and Challenges. Bull. Amer. Meteor. Soc., 95, doi: Maddox,R.A., C.F Chappell, and L.R. Hoxit. 1979: Synoptic and meso-alpha aspects of flash flood events. Bull. Amer. Meteor. Soc., 60, Morris L. Weisman, Clark Evans, and Lance Bosart, 2013: The 8 May 2009 Superderecho: Analysis of a Real-Time Explicit Convective Forecast. Wea. Forecasting, 28, doi:

5 kg/edit?usp=sharing

6 Figure 1. CFS 500 hpa height and standardized anomalies from a) 1200 UTC 8 October through f) 1200 UTC 14 October Contours every 60 m and anomalies as in color bar. Return to text.

7 Figure 2. As in Figure 1 except for precipitable water (mm) and precipitable water anomalies in 6-hour increments for a) 0000 UTC 13 to f) 0600 UTC 14 October Return to text.

8 Figure 3. As in Figure 2 except for 850 hpa winds (ms-1) and v-wind anomalies. Return to text..

9 Figure 4. Stage-IV rainfall in(mm) for the period of 0000 UTC 13 to 0000 UTC 14 October Return to text.

10 Figure 5. Storm reports by type for the 24 hour period ending at 1200 UTC 14 September Return to text.

11 Figure 6. NMQ site composite reflectivity showing the character of the convection as it moved across the Mid and lower Mississippi Valley at 1500 and 1900 UTC 13 October Return to text.

12 Figure 7. As in Figure 3 except for layered CAPE. Values greater than 400JK-1 shaded. Return to text.

13 Figure 8. NCEP SREF ensemble mean CAPE valid at 2100 UTC 13 October from 6 SREF runs initialized at a) 0900 UTC 12 October through f) 1500 UTC 13 October Return to text.

14 Figure 9. As in Figure 8 except for PWAT. Return to text. NWS State College Case Examples

15 Figure 10. As in Figure 8 except for v-wind in ms-1. Return to text.

16 Figure 11. The probability of 25mm or more QPF from 1200 UTC 13 October through 0000 UTC 14 October 2014 from NCEP SREF initialized at a) 2100 UTC 12 October through f) 0900 UTC 13 October Return to text.

17 Figure 12. As in Figure 11 except the SREF mean QPF and each members 25mm contour. Return to text.

18 Figure 13. As in Figure 12 except the 24 hour total and the 50 mm contours from each SREF member. Return to text.

19 Figure 14. NCEP 1500 UTC HRRR showing estimate composite reflectivity (dbz) in hourly increments from a) 1900 UTC through f) 0000 UTC October Return to text.

20 Figure 15. As in Figure 14 except for showing conditions from 6 HRRR from a) 1500 UTC through f) UTC 13 October valid at 2100 UTC 13 October Return to text.

21 Figure 16. As in Figure 6 except valid at 2100 UTC for comparison to Figure 15. Return to text.

22 Figure 17. As in Figure 15 except for the 1800 UTC HRRR showing forecasts in hourly increments from a) 1900 UTC through f) 0000 UTC October Return to text.

The enduring Louisiana rain and flooding of August 2016 by Richard H. Grumm National Weather Service State College, PA 16803

The enduring Louisiana rain and flooding of August 2016 by Richard H. Grumm National Weather Service State College, PA 16803 1. Introduction The enduring Louisiana rain and flooding of August 2016 by Richard H. Grumm National Weather Service State College, PA 16803 Historic flooding impacted Louisiana on 12-15 August 2016 (TWC

More information

Southern Heavy rain and floods of 8-10 March 2016 by Richard H. Grumm National Weather Service State College, PA 16803

Southern Heavy rain and floods of 8-10 March 2016 by Richard H. Grumm National Weather Service State College, PA 16803 Southern Heavy rain and floods of 8-10 March 2016 by Richard H. Grumm National Weather Service State College, PA 16803 1. Introduction Heavy rains (Fig. 1) produced record flooding in northeastern Texas

More information

New Zealand Heavy Rainfall and Floods

New Zealand Heavy Rainfall and Floods New Zealand Heavy Rainfall and Floods 1. Introduction Three days of heavy rainfall associated with a deep upper-level low (Fig. 1) brought flooding to portions of New Zealand (Fig. 2). The flooding was

More information

Impacts of the April 2013 Mean trough over central North America

Impacts of the April 2013 Mean trough over central North America Impacts of the April 2013 Mean trough over central North America By Richard H. Grumm National Weather Service State College, PA Abstract: The mean 500 hpa flow over North America featured a trough over

More information

Indiana County Flash Flood of 22 June 2017

Indiana County Flash Flood of 22 June 2017 Indiana County Flash Flood of 22 June 2017 By Richard H. Grumm National Weather Service State College, PA 1. Overview Slow moving thunderstorms brought 3 to 4 inches of rainfall to Indiana County, PA during

More information

Eastern United States Wild Weather April 2014-Draft

Eastern United States Wild Weather April 2014-Draft 1. Overview Eastern United States Wild Weather 27-30 April 2014-Draft Significant quantitative precipitation bust By Richard H. Grumm National Weather Service State College, PA and Joel Maruschak Over

More information

Historic Ellicott City Flood of 30 July Introduction

Historic Ellicott City Flood of 30 July Introduction Historic Ellicott City Flood of 30 July 2016 by Richard H. Grumm and Norman W. Junker Satellite Contributions by Sheldon Kusselson National Weather Service State College, PA 16803 1. Introduction Intense

More information

Mid Atlantic Severe Event of 1 May 2017 Central Pennsylvania QLCS event By Richard H. Grumm National Weather Service, State College, PA 16803

Mid Atlantic Severe Event of 1 May 2017 Central Pennsylvania QLCS event By Richard H. Grumm National Weather Service, State College, PA 16803 1. Overview Mid Atlantic Severe Event of 1 May 2017 Central Pennsylvania QLCS event By Richard H. Grumm National Weather Service, State College, PA 16803 A strong upper-level wave (Fig.1) moving into a

More information

Multi-day severe event of May 2013

Multi-day severe event of May 2013 Abstract: Multi-day severe event of 18-22 May 2013 By Richard H. Grumm and Charles Ross National Weather Service State College, PA A relatively slow moving Trough over the western United States and a ridge

More information

Historic Central Pennsylvania Flash Floods of 21 October 2016 by Richard H. Grumm National Weather Service State College, PA 16803

Historic Central Pennsylvania Flash Floods of 21 October 2016 by Richard H. Grumm National Weather Service State College, PA 16803 1. Introduction Historic Central Pennsylvania Flash Floods of 21 October 2016 by Richard H. Grumm National Weather Service State College, PA 16803 A slow moving frontal system produced heavy rainfall in

More information

Heavy Rainfall Event of June 2013

Heavy Rainfall Event of June 2013 Heavy Rainfall Event of 10-11 June 2013 By Richard H. Grumm National Weather Service State College, PA 1. Overview A 500 hpa short-wave moved over the eastern United States (Fig. 1) brought a surge of

More information

Minor Winter Flooding Event in northwestern Pennsylvania January 2017

Minor Winter Flooding Event in northwestern Pennsylvania January 2017 1. Overview Minor Winter Flooding Event in northwestern Pennsylvania 12-13 January 2017 By Richard H. Grumm National Weather Service State College, PA A combination of snow melt, frozen ground, and areas

More information

Mid-West Heavy rains 18 April 2013

Mid-West Heavy rains 18 April 2013 Abstract: Mid-West Heavy rains 18 April 2013 By Richard H. Grumm and Charles Ross National Weather Service State College, PA The relatively wet conditions during the first 16 days of April 2013 set the

More information

Mid-Atlantic Severe Weather Event of 23 June 2015

Mid-Atlantic Severe Weather Event of 23 June 2015 Mid-Atlantic Severe Weather Event of 23 June 2015 By Richard H. Grumm National Weather Service State College, PA 1. Overview A widespread severe weather event occurred in the eastern United States on 23

More information

Flooding and Severe weather of 27 June 2013

Flooding and Severe weather of 27 June 2013 Flooding and Severe weather of 27 June 2013 By Richard H. Grumm National Weather Service State College, PA 1. Overview Flooding and severe weather affected Pennsylvania on 27 June 2013 (Fig 1). The severe

More information

Northeastern United States Snowstorm of 9 February 2017

Northeastern United States Snowstorm of 9 February 2017 Northeastern United States Snowstorm of 9 February 2017 By Richard H. Grumm and Charles Ross National Weather Service State College, PA 1. Overview A strong shortwave produced a stripe of precipitation

More information

Hurricane Harvey the Name says it all. by Richard H. Grumm and Charles Ross National Weather Service office State College, PA

Hurricane Harvey the Name says it all. by Richard H. Grumm and Charles Ross National Weather Service office State College, PA Hurricane Harvey the Name says it all by Richard H. Grumm and Charles Ross National Weather Service office State College, PA 16803. 1. Overview Hurricane Harvey crossed the Texas coast (Fig. 1) as a category

More information

Cold frontal Rainband and Mid-Atlantic Severe Weather Event 28 September 2006 by Richard H. Grumm And Ron Holmes

Cold frontal Rainband and Mid-Atlantic Severe Weather Event 28 September 2006 by Richard H. Grumm And Ron Holmes Cold frontal Rainband and Mid-Atlantic Severe Weather Event 28 September 2006 by Richard H. Grumm And Ron Holmes 1. INTRODUCTION A strong cold front moved across central Pennsylvania and the Mid-Atlantic

More information

Southern United States Heavy rain and flood event 6-8 April 2014

Southern United States Heavy rain and flood event 6-8 April 2014 Southern United States Heavy rain and flood event 6-8 April 2014 By Richard H. Grumm National Weather Service State College, PA 1. Overview Heavy rainfall (Fig. 1) affected the southern United States from

More information

Low-end derecho of 19 August 2017

Low-end derecho of 19 August 2017 Low-end derecho of 19 August 2017 By Richard H. Grumm and Charles Ross National Weather Service State College, PA 1. Overview A cluster of thunderstorms developed in eastern Ohio around 1800 UTC on 19

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Eastern United States Winter Storm and Severe Event of 28-29 February 2012 by Richard H. Grumm National Weather Service State College

More information

Southern Plains Heavy rain and Flooding

Southern Plains Heavy rain and Flooding Abstract: Southern Plains Heavy rain and Flooding By Richard H. Grumm National Weather Service State College, PA A severe weather event affected the southern Plains on 31 May 2013. The severe weather event

More information

Mid Atlantic Heavy rainfall event 1. Overview 2. Methods and Data 3. Pattern

Mid Atlantic Heavy rainfall event 1. Overview 2. Methods and Data 3. Pattern 1. Overview Mid Atlantic Heavy rainfall event With an inertial gravity wave? By Richard H. Grumm National Weather Service, State College, PA 16803 Contributions from the Albany MAP An unseasonably strong

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Heavy rainfall of 23 November 2011 by Richard H. Grumm National Weather Service State College PA 16803 Abstract:. A fast moving mid-tropospheric

More information

2 July 2013 Flash Flood Event

2 July 2013 Flash Flood Event 2 July 2013 Flash Flood Event By Richard H. Grumm and Charles Ross National Weather Service State College, PA 1. Overview A retrograding 500 hpa cyclone and anticyclone (Fig. 1) set up deep southerly flow

More information

Severe Weather Event of 13 July 2014

Severe Weather Event of 13 July 2014 Severe Weather Event of 13 July 2014 By Richard H. Grumm and Elyse M. Colbert National Weather Service State College, PA 1. Overview Severe weather affected the eastern United States (Fig. 1) from northwestern

More information

Early May Cut-off low and Mid-Atlantic rains

Early May Cut-off low and Mid-Atlantic rains Abstract: Early May Cut-off low and Mid-Atlantic rains By Richard H. Grumm National Weather Service State College, PA A deep 500 hpa cutoff developed in the southern Plains on 3 May 2013. It produced a

More information

Severe Weather with a strong cold front: 2-3 April 2006 By Richard H. Grumm National Weather Service Office State College, PA 16803

Severe Weather with a strong cold front: 2-3 April 2006 By Richard H. Grumm National Weather Service Office State College, PA 16803 Severe Weather with a strong cold front: 2-3 April 2006 By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION A strong cold front brought severe weather to much of

More information

Tropical Storm Hermine: Heavy rainfall in western Gulf By Richard H. Grumm National Weather Service Office State College, PA 16803

Tropical Storm Hermine: Heavy rainfall in western Gulf By Richard H. Grumm National Weather Service Office State College, PA 16803 Tropical Storm Hermine: Heavy rainfall in western Gulf By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION Tropical storm Hermine, the eighth named tropical system

More information

Winter Storm of 15 December 2005 By Richard H. Grumm National Weather Service Office State College, PA 16803

Winter Storm of 15 December 2005 By Richard H. Grumm National Weather Service Office State College, PA 16803 Winter Storm of 15 December 2005 By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION A complex winter storm brought snow, sleet, and freezing rain to central Pennsylvania.

More information

Heavy rains and precipitable water anomalies August 2010 By Richard H. Grumm And Jason Krekeler National Weather Service State College, PA 16803

Heavy rains and precipitable water anomalies August 2010 By Richard H. Grumm And Jason Krekeler National Weather Service State College, PA 16803 Heavy rains and precipitable water anomalies 17-19 August 2010 By Richard H. Grumm And Jason Krekeler National Weather Service State College, PA 16803 1. INTRODUCTION Heavy rain fell over the Gulf States,

More information

NWS-PSU Case Study Site 2010 Severe Weather Case

NWS-PSU Case Study Site 2010 Severe Weather Case NWS-PSU Case Study Site 2010 Severe Weather Case New Years Eve Severe Weather Event of 31 December 2010 by Richard H. Grumm National Weather Service State College PA 16083 Abstract: A surge of warm humid

More information

1. INTRODUCTION * Figure 1. National Weather Service Storm Prediction Center (SPC) storm reports for December 1, 2006.

1. INTRODUCTION * Figure 1. National Weather Service Storm Prediction Center (SPC) storm reports for December 1, 2006. P1.14 FORECAST ISSUES RELATED TO THE UNPRECEDENTED SEVERE AND HIGH WIND EVENT OF DECEMBER 2006 by Greg A. DeVoir* and Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION

More information

Pre-Christmas Warm-up December 2013-Draft

Pre-Christmas Warm-up December 2013-Draft Pre-Christmas Warm-up 21-23 December 2013-Draft By Richard H. Grumm National Weather Service State College, PA 1. Overview A large ridge over the west-central Atlantic (Fig.1) and trough moving into eastern

More information

Snow, freezing rain, and shallow arctic Air 8-10 February 2015: NCEP HRRR success story

Snow, freezing rain, and shallow arctic Air 8-10 February 2015: NCEP HRRR success story Snow, freezing rain, and shallow arctic Air 8-10 February 2015: NCEP HRRR success story By Richard H. Grumm National Weather Service State College, PA 1. Overview A short-wave (Fig. 1) moved over the strong

More information

Deep Cyclone and rapid moving severe weather event of 5-6 June 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803

Deep Cyclone and rapid moving severe weather event of 5-6 June 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 Deep Cyclone and rapid moving severe weather event of 5-6 June 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION A rapidly deepening surface cyclone raced

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Historic Ohio Valley January Severe weather and Tornado Event by Richard H. Grumm National Weather Service State College PA 16803 and

More information

The Long-lived eastern US tornadic supercell of 20 July 2017

The Long-lived eastern US tornadic supercell of 20 July 2017 1. Overview The Long-lived eastern US tornadic supercell of 20 July 2017 By Richard H. Grumm and Elissa A Smith National Weather Service State College, PA A long lived supercell developed near the eastern

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Abstract: Tropical Storm Debbie, standardized anomalies and heavy rainfall by Richard H. Grumm National Weather Service State College

More information

NCEP Short-Range Ensemble forecasts of an historic rainfall event: The June 2006 East Coast Floods 1. INTRODUCTION

NCEP Short-Range Ensemble forecasts of an historic rainfall event: The June 2006 East Coast Floods 1. INTRODUCTION NCEP Short-Range Ensemble forecasts of an historic rainfall event: The 23-27 June 2006 East Coast Floods By Richard H. Grumm National Weather Service Office, State College PA 16803 And Norman W. Junker

More information

Convective Heavy rainfall event of 23 July 2013

Convective Heavy rainfall event of 23 July 2013 Convective Heavy rainfall event of 23 July 2013 By Richard H. Grumm and Charles Ross National Weather Service State College, PA Abstract: A record rain event affected southern Lebanon County on 23 July

More information

Mid-Atlantic Severe Event of 1 June 2012

Mid-Atlantic Severe Event of 1 June 2012 Mid-Atlantic Severe Event of 1 June 2012 1. Introduction An unseasonably deep midtropospheric ridge (Fig. 1) brought a strong cold front into the Mid-Atlantic region on 1 June 2012. A surge of warm moist

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events The southern Express: High Impact Spring Storm of 14-17 April 2011 by Richard H. Grumm National Weather Service State College PA 16803

More information

Patterns of Heavy rainfall in the Mid-Atlantic Region 1. INTRODUCTION

Patterns of Heavy rainfall in the Mid-Atlantic Region 1. INTRODUCTION 5A.2 Patterns of Heavy rainfall in the Mid-Atlantic Region by Richard H. Grumm * And Ron Holmes National Weather Service Office State College, PA 16802 1. INTRODUCTION The patterns associated with heavy

More information

Southeastern Texas historic rain of 18 April 2016 by Richard H. Grumm and Charles Ross National Weather Service State College, PA 16803

Southeastern Texas historic rain of 18 April 2016 by Richard H. Grumm and Charles Ross National Weather Service State College, PA 16803 Southeastern Texas historic rain of 18 April 2016 by Richard H. Grumm and Charles Ross National Weather Service State College, PA 16803 1. Introduction Extremely heavy rainfall across southeastern Texas

More information

Mid-Atlantic Ice Storm 4 March 2015

Mid-Atlantic Ice Storm 4 March 2015 1. Overview Mid-Atlantic Ice Storm 4 March 2015 By Richard H. Grumm National Weather Service State College, PA A large 500 hpa ridge over the southern United States (Fig. 1a-e)) built into the Mid-Atlantic

More information

This paper will document the pattern which produced the record rainfall of 30 September The goal is to show the pattern the

This paper will document the pattern which produced the record rainfall of 30 September The goal is to show the pattern the The Historic Synoptic-Hybrid rainfall event 30 September 2010 By Richard Grumm And Michael Kozar National Weather Service State College, PA 16803 1. INTRODUCTION A slow moving north-south oriented frontal

More information

Heat wave ending severe events of July 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803

Heat wave ending severe events of July 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 Heat wave ending severe events of 23-25 July 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION A strong subtropical ridge (Fig. 1a) dominated the eastern

More information

Anticipating record events using patterns and pattern forecast: Mid-Mississippi Valley floods of April 2011

Anticipating record events using patterns and pattern forecast: Mid-Mississippi Valley floods of April 2011 Anticipating record events using patterns and pattern forecast: Mid-Mississippi Valley floods of April 2011 Richard H. Grumm National Weather Service State College, PA Abstract: A persistent pattern produced

More information

Mid-Atlantic Derecho event of 29 June 2012

Mid-Atlantic Derecho event of 29 June 2012 Mid-Atlantic Derecho event of 29 June 2012 Richard H. Grumm Charles H. Ross And Elyse Colbert National Weather Service Office State College, PA 16803 1. Overview An area of convection developed over eastern

More information

1. INTRODUCTION. In addition to the severe weather, the

1. INTRODUCTION. In addition to the severe weather, the Anomalous Low and its weather impacts 10-12 May 2008 By Richard Grumm National Weather Service Office State College, PA And Al Cope National Weather Service Office Mount Holly, NJ 1. INTRODUCTION An unusually

More information

1. INTRODUCTION. For brevity times are referred to in the format of 20/1800 for 20 August UTC. 3. RESULTS

1. INTRODUCTION. For brevity times are referred to in the format of 20/1800 for 20 August UTC. 3. RESULTS Heavy rains and precipitable water anomalies 20-23 August 2010-Draft By Jason Krekeler And Richard Grumm National Weather Service State College, PA 16803 1. INTRODUCTION Heavy rain fell across the central

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events March Madness: The 2 March 2012 super outbreak-draft by Richard H. Grumm National Weather Service State College PA 16803 and Kyle Imhoff

More information

Eastern Derecho June 2013-Draft

Eastern Derecho June 2013-Draft Abstract: Eastern Derecho 12-13 June 2013-Draft Richard H. Grumm National Weather Service Office State College, PA 16803 A strong mid-tropospheric short-wave coming over a sharp 500 hpa ridge produced

More information

Winter Storm of February 2008 By Richard H. Grumm National Weather Service Office State College PA 16803

Winter Storm of February 2008 By Richard H. Grumm National Weather Service Office State College PA 16803 1. INTRODUCTION Winter Storm of 11-13 February 2008 By Richard H. Grumm National Weather Service Office State College PA 16803 A potent winter storm brought snow, sleet, freezing rain, and rain to the

More information

The Devastating Mid-Mississippi Valley Floods of 1-2 May 2010 By Richard H. Grumm National Weather Service

The Devastating Mid-Mississippi Valley Floods of 1-2 May 2010 By Richard H. Grumm National Weather Service The Devastating Mid-Mississippi Valley Floods of 1-2 May 2010 By Richard H. Grumm National Weather Service 1. INTRODUCTION A devastating heavy rainfall event affected the Mid-Mississippi Valley (MMV) from

More information

1. INTRODUCTION. The super storm of March 1993 produced severe weather and tornadoes as it s trailing cold front pushed through Florida (Kocin eta 1l

1. INTRODUCTION. The super storm of March 1993 produced severe weather and tornadoes as it s trailing cold front pushed through Florida (Kocin eta 1l 1. INTRODUCTION Super Tuesday and awful Wednesday: the 5-6 February 2008 Severe Weather Outbreak By Richard H. Grumm National Weather Service State College, PA And Seth Binau National Weather Service,

More information

Eastern United States Winter Storm of 1-2 February 2015-DRAFT Northeast Ground Hog Storm

Eastern United States Winter Storm of 1-2 February 2015-DRAFT Northeast Ground Hog Storm Eastern United States Winter Storm of 1-2 February 2015-DRAFT Northeast Ground Hog Storm By Richard H. Grumm National Weather Service State College, PA 1. Overview A major Winter Storm brought precipitation

More information

2. Methods and data. 1 NWS Reno, NV report circulated in the LA Times story maximum wind was observed at 0900 AM 8 January 2017.

2. Methods and data. 1 NWS Reno, NV report circulated in the LA Times story maximum wind was observed at 0900 AM 8 January 2017. The California Extreme Precipitation Event of 8-10 January 2017 By Richard H. Grumm and Charles Ross National Weather Service State College, PA 16803 1. Introduction A strong Pacific jet and a surge of

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Abstract: West Coast Heavy Precipitation Event of January 2012 by Richard H. Grumm National Weather Service State College PA 16803

More information

Orographically enhanced heavy rainfall of 23 May 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803

Orographically enhanced heavy rainfall of 23 May 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 Orographically enhanced heavy rainfall of 23 May 2010 By Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION During the overnight hours and into the early morning of

More information

The abrupt end of the Persistent Subtropical Ridge of the autumn of 2016

The abrupt end of the Persistent Subtropical Ridge of the autumn of 2016 The abrupt end of the Persistent Subtropical Ridge of the autumn of 2016 1. Introduction by Richard H. Grumm National Weather Service State College, PA 16803 Contributions by Elyse Hagner National Weather

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events Heavy Rain 7-8 December 2011 by Richard H. Grumm National Weather Service State College PA 16803 Abstract:. A mid-level short-wave

More information

Alaskan heat episode of June 2013-Draft

Alaskan heat episode of June 2013-Draft Alaskan heat episode of 16-19 June 2013-Draft Abstract: By Trevor Alcott National Weather Service Western Region, Salt Lake City UT And Richard H. Grumm National Weather Service State College, PA A strong

More information

1. INTRODUCTION. March. Local time used in text to define dates. 1 Due to UTC time the went passed 0000 UTC 31

1. INTRODUCTION. March. Local time used in text to define dates. 1 Due to UTC time the went passed 0000 UTC 31 New England Record Maker Rain Event of 29-30 March 2010 By Richard H. Grumm National Weather Service Contributions by Frank Nocera National Weather Service Office Taunton, MA 1. INTRODUCTION The second

More information

Pennsylvania Severe Weather of September 2016

Pennsylvania Severe Weather of September 2016 Pennsylvania Severe Weather of September 2016 By Richard H. Grumm National Weather Service State College, PA 1. Overview September 2016 was a relatively quiet month for severe weather across most of the

More information

09 December 2005 snow event by Richard H. Grumm National Weather Service Office State College, PA 16803

09 December 2005 snow event by Richard H. Grumm National Weather Service Office State College, PA 16803 09 December 2005 snow event by Richard H. Grumm National Weather Service Office State College, PA 16803 1. INTRODUCTION A winter storm produced heavy snow over a large portion of Pennsylvania on 8-9 December

More information

Southern United States Winter Storm of 28 January 2014-v1. High Impact Snow on Edge of Forecast Precipitation Shield

Southern United States Winter Storm of 28 January 2014-v1. High Impact Snow on Edge of Forecast Precipitation Shield Southern United States Winter Storm of 28 January 2014-v1 High Impact Snow on Edge of Forecast Precipitation Shield by Richard H. Grumm National Weather Service State College, PA 16803 and 1. Introduction

More information

Heavy Rainfall and Flooding of 23 July 2009 By Richard H. Grumm And Ron Holmes National Weather Service Office State College, PA 16803

Heavy Rainfall and Flooding of 23 July 2009 By Richard H. Grumm And Ron Holmes National Weather Service Office State College, PA 16803 Heavy Rainfall and Flooding of 23 July 2009 By Richard H. Grumm And Ron Holmes National Weather Service Office State College, PA 16803 1. INTRODUCTION Heavy rains fall over Pennsylvania and eastern New

More information

Eastern United States Synoptic Rain Event May 2014-Draft

Eastern United States Synoptic Rain Event May 2014-Draft 1. Overview Eastern United States Synoptic Rain Event 15-16 May 2014-Draft heavy rain and flooding event By Richard H. Grumm National Weather Service State College, PA A deep 500 hpa trough with -4σ height

More information

Memorial Day Weekend 2013: Snow and Cold

Memorial Day Weekend 2013: Snow and Cold Abstract: Memorial Day Weekend 2013: Snow and Cold By Richard H. Grumm National Weather Service State College, PA A slow moving 500 hpa low and associated unseasonably cold air in the lower troposphere

More information

The Deep South snowfall of February 2010 By Richard H. Grumm National Weather Service Office, State College, PA 16803

The Deep South snowfall of February 2010 By Richard H. Grumm National Weather Service Office, State College, PA 16803 The Deep South snowfall of 11-13 February 2010 By Richard H. Grumm National Weather Service Office, State College, PA 16803 1. INTRODUCTION A surface cyclone tracked across Mexico and the Gulf of Mexico

More information

The Spring Storm of April 2007 By Richard H. Grumm National Weather Service Office State College PA 16803

The Spring Storm of April 2007 By Richard H. Grumm National Weather Service Office State College PA 16803 The Spring Storm of 13-16 April 2007 By Richard H. Grumm National Weather Service Office State College PA 16803 1. INTRODUCTION A major spring storm struck the eastern United States from 13 through 16

More information

The Big Chill of November 2013

The Big Chill of November 2013 The Big Chill of November 2013 Value of anomalies for situational awareness By Richard H. Grumm National Weather Service State College, PA Trevor Alcott National Weather Service, Salt Lake City UT 1. Overview

More information

Ensemble Forecasts of the Blizzard of January 2005 By Richard H. Grumm National Weather Service State College Pennsylvania

Ensemble Forecasts of the Blizzard of January 2005 By Richard H. Grumm National Weather Service State College Pennsylvania Ensemble Forecasts of the Blizzard of 22-23 January 2005 By Richard H. Grumm National Weather Service State College Pennsylvania 1. Introduction A fast moving upper-level disturbance produced a wide area

More information

Multiscale Analyses of Inland Tropical Cyclone Midlatitude Jet Interactions: Camille (1969) and Danny (1997)

Multiscale Analyses of Inland Tropical Cyclone Midlatitude Jet Interactions: Camille (1969) and Danny (1997) Multiscale Analyses of Inland Tropical Cyclone Midlatitude Jet Interactions: Camille (1969) and Danny (1997) Matthew Potter, Lance Bosart, and Daniel Keyser Department of Atmospheric and Environmental

More information

End of heat-event severe event of 7 July 2012

End of heat-event severe event of 7 July 2012 End of heat-event severe event of 7 July 2012 Richard H. Grumm And Elyse Colbert National Weather Service Office State College, PA 16803 1. Overview A widespread severe weather event affected Pennsylvania

More information

New England Record Maker Rain Event of March 2010

New England Record Maker Rain Event of March 2010 National Weather Association, Electronic Journal of Operational Meteorology, 2011-EJ4 New England Record Maker Rain Event of 29-30 March 2010 RICHARD H. GRUMM National Weather Service, State College, PA

More information

Warm Episode of December 2015:

Warm Episode of December 2015: Warm Episode of 11-16 December 2015: Record Warmth over Mid-Atlantic Region By Richard H. Grumm National Weather Service State College, PA 1. Overview A strong 500 hpa ridge over the eastern United States

More information

A summary of the heat episodes of June 2017

A summary of the heat episodes of June 2017 A summary of the heat episodes of June 2017 By Richard H. Grumm and Elissa A. Smith National Weather Service State College, PA 1. Overview Over 1800 record high temperatures were set or tied during the

More information

Historic Eastern United States Winter Storm of January 2016: Record snow along the megalopolitan corridor 1. Introduction

Historic Eastern United States Winter Storm of January 2016: Record snow along the megalopolitan corridor 1. Introduction Historic Eastern United States Winter Storm of 22-24 January 2016: Record snow along the megalopolitan corridor by Richard H. Grumm National Weather Service State College, PA 16803 1. Introduction An historic

More information

The Historic Storm of October 2010 By Richard H. Grumm National Weather Service

The Historic Storm of October 2010 By Richard H. Grumm National Weather Service The Historic Storm of 24-26 October 2010 By Richard H. Grumm National Weather Service 1. INTRODUCTION An historic storm impacted much of the United States from 24-26 October 2010. Though the cyclone was

More information

Eastern United States Ice Storm of December 2008 By Richard H. Grumm National Weather Service State College, PA 16803

Eastern United States Ice Storm of December 2008 By Richard H. Grumm National Weather Service State College, PA 16803 Eastern United States Ice Storm of 11-12 December 2008 By Richard H. Grumm National Weather Service State College, PA 16803 1. INTRODUCTION A significant ice storm affected the eastern United States on

More information

5A.3 THE USE OF ENSEMBLE AND ANOMALY DATA TO ANTICIPATE EXTREME FLOOD EVENTS IN THE NORTHEASTERN U.S.

5A.3 THE USE OF ENSEMBLE AND ANOMALY DATA TO ANTICIPATE EXTREME FLOOD EVENTS IN THE NORTHEASTERN U.S. 5A.3 THE USE OF ENSEMBLE AND ANOMALY DATA TO ANTICIPATE EXTREME FLOOD EVENTS IN THE NORTHEASTERN U.S. Neil A. Stuart(1), Richard H. Grumm(2), John Cannon(3), and Walt Drag(4) (1)NOAA/National Weather Service,

More information

Thanksgiving Eve snow of November 2014

Thanksgiving Eve snow of November 2014 1. Overview Thanksgiving Eve snow of 26-27 November 2014 By Richard H. Grumm National Weather Service State College, PA An early season east coast winter storm (ECWS: DeGaetano et al. 2002) brought snow

More information

Devastating Tornadoes of 22 May 2011-Draft by Richard H. Grumm National Weather Service State College, PA

Devastating Tornadoes of 22 May 2011-Draft by Richard H. Grumm National Weather Service State College, PA Abstract: Devastating Tornadoes of 22 May 2011-Draft by Richard H. Grumm National Weather Service State College, PA A series of tornadoes struck the central United States on Sunday 22 May 2011. Tornadoes

More information

East Coast Heavy Rainfall of January 2010 By Richard H. Grumm National Weather Service

East Coast Heavy Rainfall of January 2010 By Richard H. Grumm National Weather Service 1. INTRODUCTION A strong storm moved across the United States from 21 January through 25 January 2010 (Fig. 1). This storm produced record rainfall and snowfall in the western United States from 20-22

More information

Arkansas Flash Floods and heavy rainfall-draft By Richard H. Grumm National Weather Service State College PA 16803

Arkansas Flash Floods and heavy rainfall-draft By Richard H. Grumm National Weather Service State College PA 16803 Arkansas Flash Floods and heavy rainfall-draft By Richard H. Grumm National Weather Service State College PA 16803 1. INTRODUCTION Training convection associated with deep moisture and a strongly southerly

More information

The southern express: Winter storm of January 2010 By Richard H. Grumm National Weather Service

The southern express: Winter storm of January 2010 By Richard H. Grumm National Weather Service The southern express: Winter storm of 28-30 January 2010 By Richard H. Grumm National Weather Service 1. INTRODUCTION A storm system of Pacific origin tracked across the southern United States from 27-31

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events The record eastern United States Severe Weather event of 3-4 April 2011-Draft by Richard H. Grumm National Weather Service State College

More information

12.2 MESOVORTICES FORMED WITHIN BOW ECHOES: THEIR GENESIS AND SENSITIVITY TO THE ENVIRONMENT AND SYSTEM COLD POOL

12.2 MESOVORTICES FORMED WITHIN BOW ECHOES: THEIR GENESIS AND SENSITIVITY TO THE ENVIRONMENT AND SYSTEM COLD POOL 12.2 MESOVORTICES FORMED WITHIN BOW ECHOES: THEIR GENESIS AND SENSITIVITY TO THE ENVIRONMENT AND SYSTEM COLD POOL Nolan T. Atkins and Mike St. Laurent Lyndon State College, Lyndonville, Vermont 1. INTRODUCTION

More information

National Weather Service-Pennsylvania State University Weather Events

National Weather Service-Pennsylvania State University Weather Events National Weather Service-Pennsylvania State University Weather Events New Zealand heavy rain and flood event-draft by Richard H. Grumm National Weather Service State College PA 16803 Abstract:. A record

More information

Eastern United States Anafrontal Snow 4-5 March 2015-Draft

Eastern United States Anafrontal Snow 4-5 March 2015-Draft Eastern United States Anafrontal Snow 4-5 March 2015-Draft By Richard H. Grumm National Weather Service State College, PA 1. Overview A 500 hpa ridge over the western Atlantic (Fig. 1) and an approaching

More information

P9.6 RADAR OBSERVATIONS OF A TORNADIC SEVERE FRONTAL RAINBAND

P9.6 RADAR OBSERVATIONS OF A TORNADIC SEVERE FRONTAL RAINBAND P9.6 RADAR OBSERVATIONS OF A TORNADIC SEVERE FRONTAL RAINBAND Jenni Rauhala* and Ari-Juhani Punkka Finnish Meteorological Institute, Helsinki, Finland 1. INTRODUCTION On the afternoon of 26 August 2005,

More information

Warm Episode over Indian Sub-continent March 2010 By Richard Grumm National Weather Service State College Contributions by Lance Bosart SUNY Albany

Warm Episode over Indian Sub-continent March 2010 By Richard Grumm National Weather Service State College Contributions by Lance Bosart SUNY Albany Warm Episode over Indian Sub-continent March 2010 By Richard Grumm National Weather Service State College Contributions by Lance Bosart SUNY Albany 1. INTRODUCTION A massive subtropical ridge formed over

More information

The Severe Weather Event of 7 August 2013 By Richard H. Grumm and Bruce Budd National Weather Service State College, PA 1. INTRODUCTION and Overview

The Severe Weather Event of 7 August 2013 By Richard H. Grumm and Bruce Budd National Weather Service State College, PA 1. INTRODUCTION and Overview The Severe Weather Event of 7 August 2013 By Richard H. Grumm and Bruce Budd National Weather Service State College, PA 1. INTRODUCTION and Overview A fast moving short-wave (Fig. 1) with -1σ 500 hpa height

More information

Thanksgiving Snow and Arctic Front 25 November 2005 By Richard H. Grumm National Weather Service State College, PA 16801

Thanksgiving Snow and Arctic Front 25 November 2005 By Richard H. Grumm National Weather Service State College, PA 16801 Thanksgiving Snow and Arctic Front 25 November 2005 By Richard H. Grumm National Weather Service State College, PA 16801 1. INTRODUCTION An approaching arctic front brought light snow to most of western

More information

Justin Arnott and Michael Evans NOAA National Weather Service, Binghamton, NY. Richard Grumm NOAA National Weather Service, State College, PA

Justin Arnott and Michael Evans NOAA National Weather Service, Binghamton, NY. Richard Grumm NOAA National Weather Service, State College, PA 3A.5 REGIONAL SCALE ENSEMBLE FORECAST OF THE LAKE EFFECT SNOW EVENT OF 7 FEBRUARY 2007 Justin Arnott and Michael Evans NOAA National Weather Service, Binghamton, NY Richard Grumm NOAA National Weather

More information

Eastern United States Winter Storm of February Dealing with Divergent Model and Ensemble Forecast Systems

Eastern United States Winter Storm of February Dealing with Divergent Model and Ensemble Forecast Systems Eastern United States Winter Storm of 12-14 February 2014 Dealing with Divergent Model and Ensemble Forecast Systems By Richard H. Grumm National Weather Service State College, PA 16803 1. Introduction

More information

Name of University Researcher Preparing Report: Russ Schumacher (PI) and Charles Yost (Graduate research assistant)

Name of University Researcher Preparing Report: Russ Schumacher (PI) and Charles Yost (Graduate research assistant) FINAL REPORT University: Colorado State University Name of University Researcher Preparing Report: Russ Schumacher (PI) and Charles Yost (Graduate research assistant) NWS Office: Hydrometeorological Prediction

More information