The UAH-CI algorithm produced a strong CI signal (94) across southern Walker County in southeast Texas at 2215z. Over the next several images the Cu over this area continued to build and radar returns increased on the KHGX radar.
Tuesday, May 22, 2012
CI success over Walker County, TX
Forecaster comments from EWP blog...
The UAH-CI algorithm produced a strong CI signal (94) across southern Walker County in southeast Texas at 2215z. Over the next several images the Cu over this area continued to build and radar returns increased on the KHGX radar.
The UAH-CI algorithm produced a strong CI signal (94) across southern Walker County in southeast Texas at 2215z. Over the next several images the Cu over this area continued to build and radar returns increased on the KHGX radar.
BIS: Another UAH CI Victory
Forecaster comments from EWP blog...
A severe thunderstorm developed over northeast MT and straddled the Canada/ND border. The cirrus had finally cleared south/southeast of the storm, so we were waiting for one or both of the GOES CI products to kick in. Sure enough by 22z, the UAH-CI product indicated about 50% strength of signal along developing cumulus to the south of the severe storm. By 2224z, KMBX radar indicated convection certainly did “zipper down” the cold front/dryline as the UAH-CI product indictated at 22z, giving us a 24 minute lead time for the developing convection.
A severe thunderstorm developed over northeast MT and straddled the Canada/ND border. The cirrus had finally cleared south/southeast of the storm, so we were waiting for one or both of the GOES CI products to kick in. Sure enough by 22z, the UAH-CI product indicated about 50% strength of signal along developing cumulus to the south of the severe storm. By 2224z, KMBX radar indicated convection certainly did “zipper down” the cold front/dryline as the UAH-CI product indictated at 22z, giving us a 24 minute lead time for the developing convection.
2202 UTC
2225 UTC
Rapid storm development over far SW Texas
Forecaster comments from EWP blog...
Isolated thunderstorm development was possible over far SW Texas mainly due to intense diabatic heating (with temperature readings in the lower 90s). Roughly 30kt deep layer shear and 1 kJ/kg SBCAPE overlap were supportive for strong to severe pulsating storms. Rapid to explosive development occurred south of Pecos (isolated in nature) with UAH-CI product showing high probabilities for initiation at 1945Z (not shown) with cloud top cooling of -38K/15 min present at 2010Z. Cloud top cooling peaked at -46K/15 min at 2015Z. Would not be surprised to see an isolated large hail report with that storm (up to 60 dBz present).
Isolated thunderstorm development was possible over far SW Texas mainly due to intense diabatic heating (with temperature readings in the lower 90s). Roughly 30kt deep layer shear and 1 kJ/kg SBCAPE overlap were supportive for strong to severe pulsating storms. Rapid to explosive development occurred south of Pecos (isolated in nature) with UAH-CI product showing high probabilities for initiation at 1945Z (not shown) with cloud top cooling of -38K/15 min present at 2010Z. Cloud top cooling peaked at -46K/15 min at 2015Z. Would not be surprised to see an isolated large hail report with that storm (up to 60 dBz present).
BIS: UAH CI and UW CTC Victory, 5/22
Forecaster comments from EWP blog...
1745z image indicates developing cumulus over extreme northeast NM. In the 1830z image, UAH-CI product indicates a cluster of cumulus with a high confidence of convectively initiating. UW-CTC product also indicates rapid cloud-top cooling with the eastern-most convective element. Given the deeply mixed airmass with minimal cap, this would lend confidence to convective initiation soon. Sure enough, by 1915z the 15-minute lightning plot indicates some CG strikes with the eastern-most convective element, with a lead time to convective initiation of over one hour.
1745z image indicates developing cumulus over extreme northeast NM. In the 1830z image, UAH-CI product indicates a cluster of cumulus with a high confidence of convectively initiating. UW-CTC product also indicates rapid cloud-top cooling with the eastern-most convective element. Given the deeply mixed airmass with minimal cap, this would lend confidence to convective initiation soon. Sure enough, by 1915z the 15-minute lightning plot indicates some CG strikes with the eastern-most convective element, with a lead time to convective initiation of over one hour.
1745 UTC
1830 UTC
1910 UTC
Initiation along diffuse outflow boundary (far SW-KS)
Forecaster comments on EWP blog...
We watched a slowly SE-ward progressing outflow boundary with initiation already underway over far W-OK Panhandle. Northward building of deep convection is closely monitored as CI product indicates high potential with cloud top cooling around -11K/15 min present. Deep and well mixed profiles east of that boundary hint at enhanced downburst / isolated large hail potential as storms also enter a favorable air mass with MLCAPE AOA 2000 J/kg. Shear remains too weak but modest veering present, so a few better organized multicells are possible. Capture was done at 2032Z.
First signals seen in reflectivity fields in the area of interest about 20 min later (2052 Z), which gave a good lead time.
We watched a slowly SE-ward progressing outflow boundary with initiation already underway over far W-OK Panhandle. Northward building of deep convection is closely monitored as CI product indicates high potential with cloud top cooling around -11K/15 min present. Deep and well mixed profiles east of that boundary hint at enhanced downburst / isolated large hail potential as storms also enter a favorable air mass with MLCAPE AOA 2000 J/kg. Shear remains too weak but modest veering present, so a few better organized multicells are possible. Capture was done at 2032Z.
First signals seen in reflectivity fields in the area of interest about 20 min later (2052 Z), which gave a good lead time.
Simulated Satellite for Evaluation of CI Timing
The Tuesday 5/22 EWP focus will be over the northern Plains in the Bismarck (BIS) and Grand Forks (FGF) forecast regions. As of 20 Z storms had yet to form in the region, so the forecasters were looking at the simulated NSSL WRF imagery to get an idea of the timing of convective initiation. The 4-panel image below shows the simulated IR and WV bands (top) along with the corresponding GOES-13 IR and WV bands (bottom), valid at 20 Z. Cirrus is abundant in the region in both the simulated imagery and from GOES, complicating the forecast. But a qualitative comparison reveals that the model appears to have the cirrus in roughly the correct locations, and the shortwave trough and associated cold front in Montana seem to be placed properly at 20 Z. (This is even more evident when viewing the imagery in a loop in AWIPS-II.) This provides the forecasters with confidence in the subsequent NSSL WRF forecast imagery.
Below shows the simulated imagery valid 2 hours later, at 22 Z. It shows that the first storm has formed over west-central North Dakota. We will evaluate whether or not the model CI forecast was accurate a little later today.
Below shows the simulated imagery valid 2 hours later, at 22 Z. It shows that the first storm has formed over west-central North Dakota. We will evaluate whether or not the model CI forecast was accurate a little later today.
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.
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.
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.
Monday, May 21, 2012
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.
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.
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.
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.
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.
UAH CI (top left panel) and CIMSS CTC (top right panel) at 2145Z. The
CTC indicated was very weak and the showers weakened quickly.
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