Will Convection Initiate by 22z?

Forecaster comments from EWP blog...

5/22 00z NSSL WRF simulated IR & WV imagery (upper two panels) indicate deep moist convection initiating by 22z over west-central ND, along a strong cold front and ahead of shortwave energy approaching from the west/southwest.  This may be a tad optimistic given dense cirrus over the region, although the moderate/strong forcing may be able to compensate for this.  Additionally, despite some subtle differences, 20z simulated satellite (20 hour forecast) is very representative of realtime GOES IR/WV (bottom two panels), with regard to shortwave placement and magnitude, and overall spirit of dense high level clouds over the region.

EWP daily debrief 5/22

Today we had our first debrief with our new group of forecasters.  While most of yesterday was spent getting used to AWIPS II and building procedures, we did gather a few bits of feedback for some of the GOES-R products...

SATCAST / UW Cloud-top Cooling
- "I was impressed by the strength of signal over Western TX... it was low early in the day but then as things started to go in the evening, the values started rising with the increase of convection."
- It should be stressed that the UAH strength of signal is not necessarily a predictor of how strong the storms will be in the future, more of a measure of the confidence in the fact that the convection will initiate... that's where the UW CTC comes in, to tell you how strong this convection will be in the future and relate that to hail and radar features of severe weather.
- "I was looking at the CI products quite a bit yesterday because the OUN WRF kept insisting that convection was going to form... the UAH CI through the afternoon/evening stayed around 30 or so and we never got more than a couple of 20-30 min showers, so I think it did pretty good."

Simulated Satellite
- "I was really impressed with the simulated satellite... it was a 20 hour forecast and it got the timing and coverage of the convection spot on... It seemed to do an especially good job over orographic regions."
- "It didn't have any of the early convection that the OUN WRF kept insisting was going to happen but didn't."

Overall / Training
- The forecasters appreciated the one-on-one attention by the PIs to help explain the products on the first day.  They also mentioned that if the PIs see anything interesting that the forecasters are missing (which happens a lot because of the amount of data they are looking at)... PIs shouldn't hesitate to step in and show them something, they don't mind being interrupted.

Severe Hail in Extreme Western Nebraska

UW-CTC exhibited strong cooling in very western NE over Garden county at 2044 UTC with a value of approximately -23.5K/15min.

This flagged cloud growth would later go on to produce severe 1" hail an hour and 20 minutes later in Arthur, NE.  Below shows the GOES visible imagery from 2200 UTC.

Below is the graphic from SPC showing the hail report in Arthur, NE.

WFO Amarillo-Prelim 2130Z Verification

Forecaster comments from EWP blog...

Recall WFO Amarillo’s prior post referring to the OUNWRF’s convective initiation in the SW parts of the CWA by around 2130Z?  Let’s take a look at what actually happened.

 

4-panel Reflectivity from KAMA at 2205Z. A few weak showers have developed in the SW, but overall convective development has been slow and weak.

 

Looks like the OUNWRF was a bit too quick to develop convection over WFO AMA.  We did see some very weak Cloud Top Cooling (CTC) on the order of nearly ~4C/15min near the Oldham/Deaf Smith county line for a brief period but this diminished quickly.  Notice that the UAH Convective Initiation (CI) in the top left panel showed that the potential for development was elsewhere.  Note…these initial showers which triggered the weak CTC rates weakened pretty rapidly.

 

UAH CI (top left panel) and CIMSS CTC (top right panel) at 2145Z. The CTC indicated was very weak and the showers weakened quickly.

 

It appears the OUNWRF may have been a bit too bullish on convective development ahead of the activity moving out of New Mexico in the NW flow aloft this evening, but stay tuned.

CTC – Hot or cold

Forecaster comments from EWP blog...

Here’s a comparison of the UW-CTC product using the default AWIPS 2 color table (bottom right) vs. a warm to cold color table (upper right). In the upper right image the stronger cloud top cooling rates are displayed as a warmer color, similar to IR satellite color table enhancements that display the colder cloud top temperatures with warmer colors. This has the benefit of drawing the attention of forecasters who are conditions to associate warmer colors with more extreme values (ie, radar data).

GOES Simulated Satellite

Forecaster comments from EWP blog...

GOES 20z simulate satellite on 5/21 indicates deep moist convection breaking out over western OK and portions of northwest TX (above two images…20 hour forecast).  This is optimistic compared to 20z IR/WV (bottom two images).  However, convection over NM is verifying nicely.  Maybe simulated satellite handles orographically forced convection better?

West Texas CI

Forecaster comments from EWP blog...

Small area of cumulus developing over higher terrain in west Texas shows high strength of signal value on the UAH CI product at 1730z:

This area continued to develop into a mature CB, with the first cloud to ground lightning detected by NLDN at 1945z – a 2 hour lead time from the first CI signal to the initial cloud to ground lighting activity.

Simulated Satellite Imagery in EWP

Day 1 of the EWP this week is focusing on the AMA and LBB areas.  At the current time, no storms have yet formed in these regions, so the forecasters are looking at the various model solutions to determine which seem to be on track.  Simulated satellite imagery is an ideal tool for model evaluation because it shows where the model places clouds, boundaries, shortwaves, etc.  The image below shows the simulated imagery based on a 20-hour forecast from the NSSL WRF valid at 20Z today (top panels), along with the observed IR and WV imagery from GOES (bottom panels) also valid at 20Z.  Notice that the simulated IR image (top left) shows convective cloud formation in New Mexico that appears to match observations (bottom left) very well.  This gives forecasters confidence in the remaining NSSL-WRF forecast, including when storms will move into the Amarillo and Lubbock forecast areas.

UAH-CI provides 1 hour 20 minute lead time on 1 inch hail report

The UAH-CI product provided a strength of signal forecast of 75.0 at 1702 UTC on a cell developing in Lincoln County, New Mexico (see image below). At approximately 1820 UTC, the NWS received a report of 1" hail associated with this cell. This location in New Mexico is quite far from the GOES-East subsatellite point, yet the product still has very good utility at these distances. The University of Wisconsin CTR product followed up the UAH-CI forecast at 1745 UTC with a cooling rate of -24 to -25 C per 15 minutes.

Other cells have continued develop including the cell that featured a strength of signal over 90 in the image above!

CTC Captures Severe Convection in S. New Mexico

The UW-CTC product captured some severe convection in southern New Mexico, Lincoln County, and exhibited strong cooling rates well before the first report of severe hail.  Below is the screen capture from AWIPS-2 at 1745 UTC when the strongest CTC signal was evident valued at -25K/15min.

Following at 1820 UTC, the first report of severe hail at 1" was received by NWS.  Below is the screen capture of SPCs storm report page.

According to the reported time, UW-CTC provided a lead time of 45 minutes over this first hail report.