IOP-2 Summary of Operations 03 June UTC 04 June UTC Authors: Market, Kastman

Transcription

1 IOP-2 Summary of Operations 03 June UTC 04 June UTC Authors: Market, Kastman IOP-2 focused on the slow-moving warm front that extended east from a cyclone that was situated over eastern CO. Deployment was to southern Iowa and northern Missouri. A significant MCS developed over the cold air just to the north of this warm frontal boundary. a b c d Figure 1. Surface station models with RAP initial field isobars (solid, white; every 4 mb) and NCEP/WPC frontal zones valid at a) 1800 UTC 03 June 2014, b) 0000 UTC 04 June 2014, c) 0600 UTC 04 June 2014, and d) 1200 UTC 04 June 2014.

2 The forecast procedure for IOP-2 went quite well, and the forecasters chose the optimum site and the correct deployment times. Deployment details Stuart, IA Van 1 (known as PRECIP1) departed Columbia, MO, at 1500 UTC 01 April 2014, bound for Stuart, IA. PRECIP1 arrived at that site at ~2030 UTC. The south parking lot of the Super 8 in Stuart, IA, is where PRECIP1 operated from. PRECIP1 Crew: P. Market, A. Foscato, C. Richley, K. Wunsch Location: N W Elevation: 368 m MSL Panorama of photos from the work site: Looking N Looking E

3 Looking S Looking SW Looking W

4 Deployment details Bethany, MO Van 2 (known as PRECIP2) departed Columbia, MO, at ~1630 UTC 03 June 2014, bound for Bethany, MO. PRECIP2 arrived at that site at ~2030 UTC, and it was found to be suitable. An unfinished road and field across the street, west of the Comfort Inn Bethany, MO, is where PRECIP2 operated from. PRECIP2 Crew: J. Kastman, L. McCoy, M. S. Fairman, L. Victor, K. Flamm Location: N., W. Elevation: 301 m MSL Panorama of photos from the work site (pairs, from slightly different angles): Looking N Looking N

5 Looking W Looking W Looking S Looking S Looking E Looking E

6 Radiosonde data The soundings flown for this IOP are shown below for Stuart, IA (Figure 2) and Bethany, MO (Figure 3). All of these analyses are plotted showing the CAPE and CIN for the most unstable parcel in the lowest 400 mb. The most significant precipitation fell in a band in between the two sounding locations. PRECIP1 was well north of the weak surface warm front, and encountered more trailing stratiform precipitation under the MCS at Stuart, IA; this location undoubtedly affected the performance of several soundings. At Stuart, IA, PRECIP1 s surface weather station was not functioning for the first two flights (Fig. 2a, b), and so the temperature and humidity are unaltered from the sonde values. However, there was general agreement between those values and the ASOS obs at Atlantic, IA, and Des Moines, IA. The very first flight was launched immediately prior to the arrival of the MCS, and the convection, thought north of the warm front, was surface based (Fig. 2a). This flight vanished abruptly, its audio signal simply stopping and not returning. Most of the rest of the soundings show evidence of existing in some portion of the MCS. The 00Z sounding (Fig. 2b) reveals a ~100-mb deep MAUL layer between ~725 and ~625 mb. Similar MAUL layers show up at 02Z (Fig. 2c) and 04Z (Fig. 2d), but also some fairly weak and erratic winds are in evidence. However, both the 02Z and 04Z balloons show the convection to be elevated. Both were lost below 500 mb; attenuation due to being deep in significant trailing stratiform precipitation is thought to be the culprit. The final two flights were largely uneventful. PRECIP2 spent much of the night in Bethany, MO, along the warm frontal boundary and as a result, experienced more severe weather. At least one wall cloud was observed at the PRECIP2 site. The first two flights were to the south of the front (Fig.3a-b) and the remainder of the flights were to the north of the boundary (Fig. 3c-g). The 00Z flight (Fig. 3b) was launched ~25 miles southwest of a supercell. The radiosonde actually began to descend around ~315 mb before bursting around ~320 mb. Speculation on the balloon s descent and destruction was that the balloon was affected by the downdraft of the storm and finally destroyed by hail. Figure 4 shows the flight path of the 00Z flight in both horizontal and vertical directions as recorded by the radiosonde and displayed in Google Earth. This matches the location of the supercell, at the time the signal from the radiosonde was lost. The 04z flight (Fig. 3d) was launched directly into a severe warned squall line segment. This flight was almost immediately entrained into the storm and the data were affected above ~550 mb. After the launch, urban flash flooding was observed near the launch site as approximately one foot in depth by 6 feet wide of water flowed down the street between the hotel and launch site. This made it impossible to get to the vehicle from the hotel ~20 minutes before conditions improved. Around ~05z a meso-high pressure system formed behind the squall line to the west of the launch site, and was analyzed by NCEP. Conditions at the launch site became very gusty. Around 09z the hotel lost power. The speculation on the cause of the outage was a lightning strike. This was never confirmed, but did make sense as winds had calmed down by that juncture, but lightning flashes were still present.

7 Stuart, IA before QC a b c d e f Figure 2. Radiosonde data from Stuart, IA, at a) 22Z 03 June 2014, and, b) 00Z, c) 02Z, d) 04Z, e) 06Z, and f) 08Z 04 June 2014.

8 Bethany, MO before QC a b c d e f

9 g Figure 3. Radiosonde data from Bethany, MO, at a) 22Z 03 June 2014, and, b) 00Z, c) 02Z,d) 04Z, e) 06Z, f) 08Z and g) 10Z 04 June Figure 4. Google Earth image for the track of the 0000 UTC 04 June 2014 sounding from Bethany, MO (Fig. 3b), created by automatic kml file generated by the imetos-ii sounding control software. The image is titled slightly and looking towards the north so the viewer can estimate the vertical extent of the balloon rise.

10 Summary Operations began at both Stuart, IA (PRECIP1) and to the south in at Bethany, MO (PRECIP2) at 2200 UTC 03 June Sounding operations continued every 2 hours through the night, and finally ceased at PRECIP1 at 0800 UTC and at PRECIP2 at 1000 UTC 04 June Figure hour precipitation ending at 1200 UTC 04 June 2014 derived from observed point data provided by the National Weather Service Advanced Hydrologic Precipitation Service. Locations of PRECIP1 (black circle) and PRECIP2 (black triangle). The surface analyses in Figure 1 suggest that both PRECIP1 and PRECIP2 were well north of the surface warm/stationary frontal zone for the duration of all the precipitation (Fig. 5) at both locations. Indeed, less precipitation was observed at PRECIP1, as compared to PRECIP2. The following radar summaries span the time from 2200 UTC 03 June 2014 to 1000 UTC 04 June 2014 over northern Missouri and southern Iowa.

11 NCDC composite radar analysis at 2200 UTC 03 June NCDC composite radar analysis at 0000 UTC 04 June 2014.

12 NCDC composite radar analysis at 0200 UTC 04 June NCDC composite radar analysis at 0400 UTC 04 June 2014.

13 NCDC composite radar analysis at 0600 UTC 04 June NCDC composite radar analysis at 0800 UTC 04 June 2014.

14 NCDC composite radar analysis at 1000 UTC 04 June 2014.

15 KEY ISSUES 1) In the PRECIP1 deployment there appears to have been a setting changed in the ground station. The elevation of the sounding site was entered (368 m MSL), but was not recognized in the datastream, so for the first ~minute, we see negative elevations and ascent rates in the raw. It appears that this behavior persisted through IOP-3 as well. Pressures are fine, but the GPS elevations must be viewed as suspect until QC d/corrected. 2) Launching into severe warned storms became an issue prior to the 04z flight. Protocol needs to be discussed about what to do if severe weather will impact the launch site at the time of a scheduled launch. A decision regarding if a launch should be done before hand or after the severe weather moves through the area should be discussed. ACTION ITEMS 1) PRECIP1 needs to do a launch in fair weather and take the time to correct the ground station software. 2) PRECIP 2 needs to purchase a new power convertor that will support the laptops. We had to run the laptops in and out throughout the night in order to keep the batteries powered. LESSONS LEARNED 1) Massive trailing stratiform precipitation was not anticipated with this MCS. As such, we suspect that PRECIP1 lost 1-2 sondes simply due to attenuation through significant precipitation. If faced with similar situations in the future, no solution is obvious at this time.