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

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1 Deep Cyclone and rapid moving severe weather event of 5-6 June 2010 By Richard H. Grumm National Weather Service Office State College, PA INTRODUCTION A rapidly deepening surface cyclone raced across the Midwest and into New England on 5-6 June 2010 (Fig.1). This storm system produced severe weather (Fig. 2). Tornadoes were observed on the 5 th from Iowa to Ohio. The severe weather, mainly in the form of wind damage, raced across Pennsylvania early Sunday morning then across New York and New England on 6 June It will be shown that most of the severe weather was in close proximity to a strong southwesterly low-level jet. Historically, deep cyclones have been associated with many severe weather events. Deep cyclone moving through the Great Lakes were present in both the 31 May 1985 and 02 June 1998 tornado events in Pennsylvania. The deep cyclone is often associated with strong low-level winds and thus strong shear. This event had the strong shear. Over western Pennsylvania and western New York the severe weather occurred at a climatologic minimum time for both severe weather and tornadoes. Despite this, one tornado was observed in far western Pennsylvania and there were numerous reports of wind damage in both Pennsylvania and New York during the overnight and early morning hours of Sunday 6 June The late evening tornadoes in Ohio, including the 06 June 3020 UTC Genoa, Ohio storm caused 2 fatalities. According to NWS storm reports and public information statements, the tornadoes in Indiana, Ohio and Michigan, close to the track of the cyclone, were observed between 0300 and There was on later tornado in Ohio around 0934 UTC. In local time these tornadoes occurred close to midnight. This is often a difficult time to reach people with warnings outside of communities with sirens or citizens with alarmed weather radios. This short note will document the vent 5-6 June The focus is on the pattern and the anomalies associated with this event. 2. METHODS Storm reports were retrieved from the Storm Prediction Center (SPC) website. These data are updated as they come in and are verified by National Weather Service offices and storm survey teams. The SPC data were decoded for use in a relational database and for use in GrADS (Doty and Kinter 1995). The data for 10 May were plotted on several images, such as Figure 1 to show the types color coded by type. The data were plotted based on the latitude and longitude of the data point. No time issues were addressed here thus all observed severe weather has been plotted.

2 Figure 1. NAM 00-hour forecasts of mean sea level pressure and mean sea level pressure anomalies valid at a) 1200 UTC 05 June, b) 1800 UTC 05 June, c) 0000 UTC 06 June, d) 0600 UTC 06 June, e) 1200 UTC 06 June and f) 1800 UTC 06 June Return to Introduction. The pattern was reconstructed used the NCEP GFS and NAM and were possible the JMA 1.25x1.25 data (Onogi et al. 2007). All data were plotted in GrADS (Doty and Kinter 1995). The severe weather data was overlaid on the JRA data. The higher resolution NCEP NAM is used to show the conditions during the event. The anomalies were computed from the NCEP/NCAR re-analysis data (Kalnay et al 1996) as describe by Hart and Grumm 2001 and Grumm and Hart Unless otherwise stated, the base data was the NAM and the means and standard deviations were computed by comparing the NAM to the NCEP/NCAR 30-year climatological values. For brevity times are referred to in the format of 06/0300 for 06 June UTC. Due to GMT verse local time issues some of the times will have a 06 June time stamp with hours mainly in the range of 0000 to 0400 UTC but

3 locally these events were in the late evening of 5 June RESULTS i. Large scale pattern The large scale pattern over the United States showed a large subtropical ridge over the western United States (Fig.3). A closed 5940m contour was present at times with significant 500 hpa height anomalies (Fig. 3f). The feature of interest in the Great Lakes and eastern Untied States was the fast moving short-wave which generated some minor -1SD below normal 500 hpa height anomalies. The 250 hpa winds and wind anomalies show the strong westerly jet coming over the subtropical ridge (Fig.4) and initially an implied jet exit region over the Great Lakes. These data imply a strong trough and energetic system. ii. Regional features Regionally, the surface frontal system was present in the mean sea-level field (Fig. 1) and in the precipitable water (PW) field (Fig. 5). In Fig. 5a there was extremely high PW air over Iowa at 05/1200 UTC which took on a more southwest to northeast character as the wave evolved (Fig. 5c). These feature the swept eastward and head the appearance of a surge or tongue of moist air ahead of a fast moving cold frontal boundary. There was an impressive transition from 1-3SD above normal PW to 0 to -1SD below normal PW air behind the evolving frontal boundary (Fig. 5c-5f). Figure 2. Reports of severe weather, color coded by type (see key) from the storm prediction center for 05 and 06 June. All reports are preliminary. Return to Introduction. Though not shown, the 850 hpa temperature pattern showed the frontal boundary too. These data showed 1 to 2SD above normal temperature anomalies ahead of the front and -1 to - 1.5SD below normal temperatures behind the front. The 850 hpa winds (Fig. 6) and wind anomalies show the strong low-level jet which developed ahead of the evolving frontal system. Initially over Iowa (Fig. 6a), this system intensified over northern

4 Illinois at 05/1800 UTC (Fig. 5b-c). The maximum 850 hpa wind anomalies were observed in the NAM at 06/0000 UTC over Ohio. This strong jet then raced across Pennsylvania to New England (Fig. 5d-f). The severe weather in Figure 2 was clearly well aligned and concentrated with this feature. The NAM CAPE is shown in Figure 6. These data show the high CAPE ( JKG-1) over Illinois at 05/1200 UTC (Fig. 6a) which expanded into Iowa at 06/1800 UTC. The high CAPE moved into Ohio by 06/0000 UTC but diminished rapidly after 06/0000 UTC (Fig. 6c-e) before there was a modest resurgence of CAPE over the East Coast by 06/1800 UTC (Fig. 6f). Most of the severe weather and tornadoes were confined to areas of both high shear and high CAPE. iii. Forecasts Figures 8 & 9 show 05/0300 UTC SREF forecasts indicating the high CAPE in the Midwest and the strong winds. The forcing was well predicted by the NCEP SREF. The NAM forecasts from 6 initialization times also show how well the strong low-level jet was forecast (Fig ). Forecasts valid at 06/0300 and 06/0600 UTC are provided here. The key severe fields from the SREF valid at 0000 and 0300 UTC are shown in Figure 12 & 13. These data show the high confidence in high CAPE, shear, and helicity along with convective rainfall from Illinois to western Pennsylvania. Though not shown, later forecasts dropped the CAPE values to or below 600 JKg-1 as the front moved into Pennsylvania and New York. iv. Radar echoes An examination of KCLE and KCCX radar revealed the critical role the stability played in the storm evolution. Figure 14 shows the KCLE radar base reflectivity. At this time the radar showed a supercell storm and the storm relative velocity showed a strong mesocyclone which triggered a mesocyclone and at times a tornado vortex signature (not shown). But more importantly, the deep cores of 50dBZ or greater in the storm reached to and at times over 30KFT. Thus the storms in western Ohio and Michigan were vertical, rotating and long lived. In Pennsylvania, with low CAPE and high shear, the storms could not get 50 dbz cores much over 18KFT. This limited the storms development and life cycles. It was difficult to get long-lived, deep and persistent storms. The base radar data showed high winds, base winds were over 60KTS at 3-10KFT suggesting a storm could easily tap high winds. Despite this, there were relatively few reports of wind damage and the lone tornado occurred earlier in the event in extreme western Pennsylvania (Fig.2). 4. CONCLUSIONS The severe weather and tornadoes were well aligned if not concentrated along the axis of the anomalous 850 hpa jet. RUC or NARR data might show, in 3- hourly increments, the strengthening jet between 05/2100 and 06/0300 UTC. The 6-hourly NAM and GFS cannot resolved these features unless a 3-hour forecast is employed.

5 The NAM CAPE (Fig.6) compared to the 850 hpa winds (Fig. 5) suggest that the lack of surface based CAPE modulated the convection considerably. With both high CAPE and the strong low-level jet, deep convection was able to develop from Illinois to western Pennsylvania. These storms were able to persist and develop into more lasting supercell storms. Over Pennsylvania, despite the high shear, the storms could not organize and thus persistent thunderstorms were hard to evolve. Radar echoes over central Pennsylvania showed that the storms typically collapsed or fell apart when the 50 dbz cores reached 18 to 20KFT. The lack of surface based CAPE and the relative static stability limited the convective development. This in turn limited the evolution of persistent storms. The line and shear entered central Pennsylvania at a convective minimum time and though strong winds were present for the convection to tap and potentially bring to the surface, the lack of instability precluded the development of deep and persistent updrafts. The radar data from KCLE and KCCX revealed that the storms in Ohio, with high CAPE and strong shear were large persistent storms with well defined mesocyclone. The storms in Pennsylvania lacking large CAPE lacked big updrafts and thus could not persist nor develop persistent and deep mesocyclones. This limited the threat and observations of tornadoes in Pennsylvania and likely points farther to the east. 5. Acknowledgements 6. References Doty, B. E., and J. L. Kinter III, 1995: Geophysical data and visualization using GrADS. Visualization Techniques Space and Atmospheric Sciences, E. P. Szuszczewicz and Bredekamp, Eds., NASA, Doty, B. E., and J. L. Kinter III, 1995: Geophysical data and visualization using GrADS. Visualization Techniques Space and Atmospheric Sciences, E. P. Szuszczewicz and Bredekamp, Eds., NASA,

6 Figure 3. As in Figure 1 except for 500 hpa height and height anomalies. Grumm, R.H. and R. Hart. 2001: Standardized Anomalies Applied to Significant Cold Season Weather Events: Preliminary Findings. Wea. and Fore., 16, Hart, R. E., and R. H. Grumm, 2001: Using normalized climatological anomalies to rank synoptic scale events objectively. Mon. Wea. Rev., 129, Junker, N. W., R. H. Grumm, R. Hart, L. F. Bosart, K. M. Bell, and F. J. Pereira, 2008: Use of standardized anomaly fields to anticipate extreme rainfall in the mountains of northern California. Wea. Forecasting,23, Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40- Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, Onogi, K., J. Tsutsui, H. Koide, M. Sakamoto, S. Kobayashi, H. Hatsushika, T. Matsumoto, N. Yamazaki, H. Kamahori, K. Takahashi, S. Kadokura, K. Wada, K. Kato, R. Oyama, T. Ose, N. Mannoji and R. Taira (2007) : The JRA-25 Reanalysis.

7 J. Meteor. Soc. Japan,85, Lin, Y. and K. E. Mitchell, 2005: The NCEP Stage II/IV hourly precipitation analyses: development and applications. Preprints, 19th Conf. on Hydrology, American Meteorological Society, San Diego, CA, 9-13 January 2005, Paper 1.2.

8 Figure 4. As in Figure 1 except for 250 hpa winds and wind anomalies.

9 As Figure 5 As in Figure 1 except for precipitable water (mm) and precipitable water anomalies.

10 Figure 6. As in Figure 1 except for 850 hpa winds and wind anomalies.

11 Figure 7. As in Figure 1 except for NAM surface based CAPE (JKG-1) in 600 JKG-1 intervals.

12 Figure 8. NCEP SREF initializied at 0300 UTC 5 June 2010 showing CAPE (JKG-1) valid at (left) 1800 UTC 5 June, (center) 2100 UTC 5 June and (right UTC 6 June Upper panels show the probability of 1200 JKG-1 or more CAPE and the ensemble mean CAPE with contours every 600JKg-1. Lower panels show the ensemble mean CAPE very 200JKG-1 and the spread about the mean.

13 Figure 9. NCEP SREF forecasts initialized at 0300 UTC 5 June 2010 valid at (left) 0000 UTC 06 June, (center) 0300 UTC 06 June, and (right) 0900 UTC 06 June Upper panels show 850 hpa winds and u-wind anomalies and lower panels show the 850 hpa winds and v- wind anomalies...

14 Figure 10. NAM forecasts of 850 hpa winds and u-wind anomalies valid at 0300 UTC 06 June 2010 from forecasts initialized at a) 1200 UTC 4 June, b) 1800 UTC 04 June, c) 0000 UTC 5 June, d) 0600 UTC 5 June, e) 1200 UTC 5 June and f) 1800 UTC 05 June 2010.

15 Figure 11. As in Figure 10 except valid at 0600 UTC 6 June.

16 Figure 12. SREF forecasts initialized at 0300 UTC 5 June 2010 valid at 0000 UTD 06 June 2010 showing a) the probability of 1 mm or more precipitation, b) the probability of surface based CAPE exceeding 1200JKg-1, c) probability of helicity greater and 200 s-2 and probability of layer mean shear greater than 0.012s-1.

17 Figure 13. As in Figure 12 except valid at 0300 UTC 06 June 2010.

18 Figure 14. KCLE radar at UTC showing base reflectivity and the mesocyclones symbol. Data from GR2Analyst.

19 Figure 15 Volumetric cross section of the storm from KCLE radar at 0307 UTC. Red colors show 50 dbz or greater cores

20 Figure 16. As in Figure 14 except for KCCX radar valid at 1030 UTC. The data show two organized storms. No cross section is taken as cores of 50 dbz or greater above 20KFT were hard to find.