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The four panel image below shows composite reflectivity (upper left), MRMS MESH (upper right), reflectivity at -20C (lower left), and merged azimuthal shear (lower right). One can quickly compare the bowing segment on radar and quickly relate that to the azimuthal shear image. With somewhat high values along the leading edge of suspected winds, this may be useful in monitoring areas of damaging winds in bow echoes and squall lines.
Austin/Frank
The 4-panel image below shows 1km refl (upper left), Max column hail (upper right), Hourly max wind speed (lower left), and Max hourly updraft helicity (lower right). This run of the OUNWRF (16z) shows a high concentration of training supercells over far southern parts of the FWD CWA. This can be denoted via the updraft helicity and hail fields. Values of updraft helicity exceeding 80 would suggest at least some tornado potential with these cells. We will wait and see what unfolds later today across this area.
Austin/Frank
EWP STATUS FOR 9 MAY 2013: 12 – 8 PM SHIFT
For Thursday, we are focusing on Texas and Oklahoma for severe potential. An upper-level shortwave trough (associated with yesterday’s severe weather) will slowly progress east. Associated severe parameters will shift south and east, toward the I-35 corridor. Moisture quality should be higher than Wednesday’s event, given continued advection. As a result, moderate to strong instability should develop from central Texas to central Oklahoma. Additionally, deep-layer shear is forecast to range from 35 – 50 kts, which – given the forecast instability – should be more than sufficient for supercells. Damaging winds and large hail should be the main threats, given weak low-level shear. However, a few tornadoes cannot be ruled out.
In terms of timing, expect that severe thunderstorms will develop rather early, given the weak capping inversion. The lift associated with the upper-level shortwave trough will be present early in the day, so storms may be ongoing at the beginning of operations. Moreover, as the shortwave exits through the day, low-level winds will become more veered, reducing wind shear with time. Thus, an earlier shift seems reasonable, so will go with the 12 – 8 p.m. for operations.
WFOs Likely to See Operations: Norman and Fort Worth
-G. Garfield, Week 1 Coordinator
Winds are backing in two sections of the area that we are concerned about today. Both the OUNWRF and HRRR data indicate that 0-1km helicity is continuing to increase in two locations.
Near points D (OK/KS border) and J (OK/TX border), winds are backing at the surface. Looking at an OUNWRF MSLP, the front over southern Kansas is evident (as well as a change in air mass, as indicated by theta-e). Ahead of the dryline, there is another trough that digs south-southeast into Texas, with winds backing well ahead of the dryline.
RAP/HRRR/OUNWRF data indicates that LCL values will decrease with time over the next few hours. However, dewpoint depressions on surface obs remain quite large in both of these focused locations (about 20F in SW Oklahoma, and about 10-15 degrees ahead of the storms in southern Kansas).
We do not currently have the 1km LAPS forecast data available in AWIPS. However, what we are seeing on the internet appears to show that the line of supercells moving into the SW OUN CWA will continue to strengthen. This will be as it moves into the southern area highlighted above — perhaps an area that will be potentially favorable for a bit of an enhanced tornado threat.
–Hatzos
First, here is a look at the current MRMS data, which shows a line of very strong discrete cells along the dryline near and SW of southwestern Oklahoma. Additional convection (some cellular, some multi-cellular) curves up along the warm front and back toward the triple point into Kansas.
The 19Z LAPS forecast (1km OUN domain) appears to correctly capture some of the convection in Oklahoma and up into Kansas, but it did not accurately depict the mode of convection along the dryline. While the LAPS forecast shows several areas of convective clusters, the radar analysis shows a line of discrete supercells.
Obs from the Oklahoma Mesonet show that a bulge on the dryline has developed in NW Oklahoma near the panhandle, with a wind shift (SE to SW) also evident on several mesonet stations.
The 18Z and 20Z OUNWRF runs were examined to determine how the convection is expected to evolve tonight. Here are screen captures from 0130Z on the 18Z run, and 0200Z on the 20Z run.
Although most of the intense convection is currently moving into the OUN forecast area, both runs of the OUNWRF show that by this evening, the storms in Oklahoma will weaken. While both runs show an intensification in the Dallas/Fort Worth CWA, with concentrated areas of max column hail and max updraft helicity, the timing is quite a bit different. The 18Z run was much faster, while the 20Z run has the storms just getting into the CWA by 02Z. The storm mode appears to be somewhat of a congealing of the discrete cells, perhaps into an MCS or several clusters.
Here are some of the convective parameters in the same two model runs.
As the storms strengthen as they move through northern Texas, they will be in an environment with low LCLs (under 1km) and perhaps some enhanced -03km helicity (though this signal was a bit stronger on the 18Z run than the 20Z run). However, SBCAPE will be very low by this time of day. In general, these parameters do not look as favorable (by later in the evening) in Oklahoma as they do in Texas.
As mentioned above, as the environment continues to evolve through the evening, it was noted that surface winds have shown signs and will start to back along/ahead of the dryline, and especially along and north of the KS/OK border, as the sfc low track north/northeast. This has resulted in an increased signal in the 0-3 Helicities, evident on both the 21z run of the RAP and the 20z run of the OUNWRF. Forecast soundings from central and western/southwestern OK and southern KS continue to support modest LCLs, with dry/stable boundary layers. However with 0-3km helicities increasing from the 60s and 70s into pockets of 200-300 m^2/s^2 by 00z. We believe that if LCLs continue to lower with increasing moisture, we could see our environment become slightly more conducive to tornadic development. Especially across northern OK/southern KS and into central and southern OK.
–Hatzos/Kurtz
EWP STATUS FOR 8 MAY 2013: 2 – 10 PM SHIFT
For Wednesday, we are monitoring the potential for severe storms across the western High Plains. Model guidance suggests that a weak shortwave trough will begin to impact this area by mid-afternoon. Storms are forecast to develop by mid-afternoon in southeast Colorado, and expand eastward along the warm front / bent-back region. Moderate instability and shear will create the potential for supercells, with a transition to a mesocale convective system possible.
CWAs Likely to See Operations: Dodge City, Wichita
-G. Garfield, Week 1 Coordinator
On Tuesday, our day began at 1 p.m. in the Development Lab. We spent 20 minutes debriefing on Monday’s operations, after which we examined the Day 1 forecast. At the conclusion of the EWP forecast discussion, we joined the EFP in the HWT to discuss their forecast. Upon further review, we concluded that the Goodland and Dodge City, Kansas County Warning Areas would provide the best opportunities for initial storm development.
We waited for convection to form until 4 p.m., when robust development began in Kansas. The Goodland crew – consisting of Jonathan Kurtz and Jonathan Guseman – issued 12 severe thunderstorm warnings over the course of the evening. The Dodge City crew – consisting of Andrew Hatzos and Nick Hampshire – issued 10 severe thunderstorm warnings. The mesoscale desk – consisting of Hayden Frank and Marc Austin – monitored the mesoscale through late afternoon. At that time, it became apparent that storms were likely to develop in the West Texas Lightning Network, so Hayden Frank monitored the Lubbock storms. Geoff Stano (NASA/SPORT) noted that the storms produced less robust PGLM signatures than expected (compared to the Southeast networks). These assignments were carried through until 8:15, when the forecasters filled out daily surveys to end the day.
-G. Garfield, Week 1 Coordinator
On Monday, the first week of the 2013 Experimental Warning Program began. The visiting forecasters this week are Marc Austin (OUN), Hayden Frank (BOX), Jonathan Guseman (LUB), Nick Hampshire (FWD), Andrew Hatzos (ILN), and Jonathan Kurtz (OUN). After giving our guests a brief tour of the National Weather Center, Greg Stumpf (NSSL/MDL) gave an overview of the Experimental Warning Program. This was followed by a tutorial by Clark Payne (WDTB) for the Friday webinar.
After a brief break, we began work in the Hazardous Weather Testbed. The forecasters took a survey to test their existing knowledge of the Multi-Radar Multi-Sensor (MRMS) system. Shortly after, Jimmy Correia (CIMMS/SPC) of the Experimental Forecast Program delivered a forecast for the day. After a brief discussion, we began operations.
Severe parameters were limited, but a marginal severe threat existed in North Carolina, Virginia, and Kentucky. We asked the forecasters to use available products to hone down an operations area and to prepare a briefing. The consensus was that the Blacksburg, Virginia County Warning Area had the greatest threat of severe weather, so we began operations there.
While in Blacksburg, forecasters issued several severe thunderstorm warnings for marginally-severe hail. We received several verification reports, including reports of hail up to the size of nickels. After a couple hours of operations, Geoff Stano (NASA/SPORT) delivered a group tutorial on how to use a lightning trend product (developed by the University of Alabama-Huntsville group). After the conclusion of this tutorial, we took a break for dinner.
Upon our return, we split the forecasters between the Blacksburg , Viriginia and the Raleigh, North Carolina Weather Forecast Offices in order to avoid “warning collisions”. Unfortunately, the severe threat had diminished somewhat. Geoff Stano noticed that lightning was picking up close to the Lubbock CWA, so it was quickly decided that we localize to that WFO in order to take advantage. Unfortunately, though, storms began to dissipate as they approached the LUB CWA. After the conclusion of operations, the forecasters completed the daily survey and we finished for the day.
-Gabe Garfield, Week 1 Coordinator
EWP2012 PROJECT OVERVIEW:
The National Oceanic and Atmospheric Administration (NOAA) Hazardous Weather Testbed (HWT) in Norman, Oklahoma, is a joint project of the National Weather Service (NWS) and the National Severe Storms Laboratory (NSSL). The HWT provides a conceptual framework and a physical space to foster collaboration between research and operations to test and evaluate emerging technologies and science for NWS operations. The Experimental Warning Program (EWP) at the HWT is hosting the 2012 Spring Program (EWP2012). This is the fifth year for EWP activities in the testbed. EWP2012 takes place across five weeks (Monday – Friday), from 7 May through 15 June. There are no operations during Memorial Day week (28 May – 1 June).
EWP2012 is designed to test and evaluate new applications, techniques, and products to support Weather Forecast Office (WFO) severe convective weather warning operations. There will be three primary projects geared toward WFO applications this spring, 1) evaluation of 3DVAR multi-radar real-time data assimilation fields being developed for the Warn-On-Forecast initiative, 2) evaluation of multiple CONUS GOES-R convective applications, including pseudo-geostationary lightning mapper products when operations are expected within the Lightning Mapping Array domains (OK/west-TX, AL, DC, FL), and 3) evaluation of model performance and forecast utility of the OUN WRF when operations are expected in the Southern Plains.
WEEK 5 SUMMARY:
We had six visiting NWS forecasters this week: Tim Tinsley (WFO, Brownsville, TX), Michael Dutter (WFO, Marquette, MI), Ty Judd (WFO, Norman, OK), Steve Nelson (WFO, Peachtree City, GA), Randy Skov (CWSU, Atlanta, GA), and Jeff Garmon (WFO, Mobile, AL). Once again, we were all over the map with our severe weather events. But continuing the trend of a quiet spring, there were no large severe weather outbreaks.
Photo: 1) Chris Siewert (CIMMS/SPC/GOES-R)c, 2) Travis Smith (CIMMS/NSSL), 3) Randy Skov (CWSU, Atlanta, GA), 4) Ty Judd (WFO, Norman, OK), 5) Steve Nelson (WFO, Peachtree City, GA), 6) Michael Dutter (WFO, Marquette, MI), 7) Tim Tinsley (WFO, Brownsville, TX), 8) Gabe Garfield (CIMMS/WFO Norman, OK), 9) Jeff Garmon (WFO, Mobile, AL), and 10) Jordan Gerth (UW-CIMSS). Photograph by Greg Stumpf (CIMMS/NWS-MDL).
REAL-TIME EVENT OVERVIEW:
11 June: Memphis (MEG), Huntsville (HUN), Tulsa (OK), San Angelo (SJT), Jackson (JAN), Birmingham (BMX)
12 June: Albuquerque (ABQ), Midland (MAF), Lubbock (LBB), Amarillo (AMA)
13 June: Albuquerque (ABQ), Midland (MAF), Sioux Falls (FSD), Fort Worth (FWD)
14 June: Minneapolis (MPX), Sioux Falls (FSD), Hastings (GID), Omaha (OAX), Amarillo (AMA)
FEEDBACK ON EXPERIMENTAL PRODUCTS:
3DVAR:
OUN WRF:
GOES-R NearCast:
GOES-R UAH SatCast/UW Cloud-Top Cooling:
GOES-R PGLM:
There are more GOES-R feedback details on the GOES-R HWT Blog Weekly Summary.
OVERALL COMMENTS:
CONTRIBUTORS:
Gabe Garfield, EWP2012 Week #5 Weekly Coordinator
Today, we started operations in the Minneapolis (MN), Sioux Falls (SD), and Hastings (NE) county warning areas. An early morning mesoscale convective system persisted in the Minneapolis CWA, which limited destabilization. Nevertheless, the Minneapolis forecasters (Ty Judd and Mike Dutter) issued several severe thunderstorm warnings, with half-dollar size hail the most significant report among those received. These forecasters primarily evaluated the 3DVAR products.
The Sioux Falls forecasters (Steve Nelson and Tim Tinsley) saw no organized convection, which prompted a move to Omaha (NE). There, they issued several severe thunderstorm warnings and one tornado warning. Again, the forecasters primarily evaluated the 3DVAR products.
The Hastings forecasters (Jeff Garmon and Randy Skov) issued several severe thunderstorm warnings in their CWA for severe multicellular storms. Hail up to the size of tennis balls was reported. The Hastings forecasters were able to evaluate the OUN WRF, in addition to the 3DVAR products.
Finally, after the severe weather event in Minnesota transitioned to a heavy rain event, forecasters Ty Judd and Mike Dutter transferred to the Amarillo CWA. They issued a few severe thunderstorm warnings; hail up to the size of quarters was reported. They evaluated both the 3DVAR and OUN WRF experimental products.
-G. Garfield, Week 5 Coordinator
