+60 dBZ @ ~32Kft (bottom image) were observed.
Thursday, May 10, 2012
Mexico! CTC shows a rapidly developing thunderstorm
Forecaster comments from the EWP blog...
Top image – IR Satellite with CTC rates of -40C/15 min (dark looking region) ~25 minutes before
+60 dBZ @ ~32Kft (bottom image) were observed.
+60 dBZ @ ~32Kft (bottom image) were observed.
BRO Meso Analysis with Nearcast/Sythetic WRF at 2030Z
Forecaster comments from the EWP blog...
The below image at 22Z depicts nearcast theta-e at 780 mb in the upper left pane, synthetic WRF IR in the upper right, nearcast theta-e at 500 mb in the lower left, and nearcast vertical theta-e difference in the bottom right.
Looking at the 780 mb theta-e, it shows areas in yellow of best moisture/instability predicted for this afternoon which matches up with storms predict in synthetic IR imagery. Because the 2 products derived off of different model projections are in decent agreement, this lends more confidence to this convective scenario for this afternoon.
The below image at 22Z depicts nearcast theta-e at 780 mb in the upper left pane, synthetic WRF IR in the upper right, nearcast theta-e at 500 mb in the lower left, and nearcast vertical theta-e difference in the bottom right.
Looking at the 780 mb theta-e, it shows areas in yellow of best moisture/instability predicted for this afternoon which matches up with storms predict in synthetic IR imagery. Because the 2 products derived off of different model projections are in decent agreement, this lends more confidence to this convective scenario for this afternoon.
BRO MESO Desk @ 20Z
Forecaster comments from EWP blog...
The following four screen captures depict several favored areas of UAH-CI strength of signal along the outflow boundaries that exist immediately north of CWA and north-south along a line from Los Angeles-Realitos-Encino-Raymondville. Knowing were the boundaries were located, UAH strength of signal allowed us to focus on the most favored areas between 20Z-21Z. (Synthetic Sat showed the most likely CI would take place between 20-21Z, particularly with storms along the Rio Grande. It didn’t capture any activity over the northern extent of the outflow boundary.)
The following four screen captures depict several favored areas of UAH-CI strength of signal along the outflow boundaries that exist immediately north of CWA and north-south along a line from Los Angeles-Realitos-Encino-Raymondville. Knowing were the boundaries were located, UAH strength of signal allowed us to focus on the most favored areas between 20Z-21Z. (Synthetic Sat showed the most likely CI would take place between 20-21Z, particularly with storms along the Rio Grande. It didn’t capture any activity over the northern extent of the outflow boundary.)
BRO Afternoon Forecast 1920Z
Forecaster comments from the EWP blog...
Synthetic WRF imagery was useful in making a convective forecast for Brownsville this afternoon. At 13Z, the synthetic WRF depicted two areas of convection over TX with the south complex near Brownsville being slightly displaced to the south in location. This convection was occurring in an area of high shear ahead of an upper level low progress slowly across the southwest U.S. (seen in synthetic and observed imagery).
13Z Synthetic:
13Z Observed IR/WV (top 2 panes):
At 19Z synthetic and observed IR/WV imagery matched up well with the
southern complex, but over did convection to the south of the northern
complex in TX. Over Brownsville area, visible satellite imagery
depicted a low broken cu field at 1914Z which matches low clouds in the
synthetic IR imagery.
19Z Synthetic:
19Z Observed IR/WV (top 2 panes):
1914Z Visible Sat:
Conclusion: The Synthetic WRF model seems to be doing an OK job
overall so far today with a few issues. However, it depicts the upper
low driving convection today as well as 2 distinct areas of convection
over TX.
For Brownsville area for the rest of the afternoon, synthetic images below predict convective initiation around 20Z with convection strengthening through the afternoon hours (22Z image), and then beginning to decrease in strength at 0Z.
20Z Synthetic:
22Z Synthetic:
0Z Synthetic:
Synthetic WRF imagery was useful in making a convective forecast for Brownsville this afternoon. At 13Z, the synthetic WRF depicted two areas of convection over TX with the south complex near Brownsville being slightly displaced to the south in location. This convection was occurring in an area of high shear ahead of an upper level low progress slowly across the southwest U.S. (seen in synthetic and observed imagery).
13Z Synthetic:
19Z Synthetic:
For Brownsville area for the rest of the afternoon, synthetic images below predict convective initiation around 20Z with convection strengthening through the afternoon hours (22Z image), and then beginning to decrease in strength at 0Z.
20Z Synthetic:
BRO MESO desk @ 1834Z
Forecaster comments from EWP blog...
A few towering cu were present across BRO. CTC centriods were present in LaSalle county (CRP) an immediately south of Starr county. In fact, the LaSalle county CTC also showed a high strength of signal on the UAH-CI.
A few towering cu were present across BRO. CTC centriods were present in LaSalle county (CRP) an immediately south of Starr county. In fact, the LaSalle county CTC also showed a high strength of signal on the UAH-CI.
EWP: UW-CTC 45 minute lead-time on severe hail
Another day at HWT we are focusing on southern Texas. An upper level low over northern Mexico is finally beginning to move eastward, this combined with humid low-level flow off the Gulf of Mexico is setting the stage for severe thunderstorms over southern Texas today. There were numerous severe thunderstorms ongoing as of late morning. One of the most recent developing storms is showcased below. At 1632 UTC 10 May 2012, the UW-CTC product showed cloud-top cooling rates of ~ -6K / 15 min. The following satellite scan at 1645 UTC the UW-CTC increased substantially to over -20 K / 15 min. Later images of radar-based maximum expected hail size show estimated severe hail occurring at 1715 UTC and significant hail in excess of 3.00" at 1725 UTC.
Figure 1. Valid 1632 UTC 10 May 2012. The UW-CTC product indicates initial substantial vertical growth of a developing thunderstorm (red circle).
Figure 2. Valid 1645 UTC 10 May 2012. The UW-CTC rate on the developing storm explodes into the strong category with cooling rates near -23 K / 15 min (red circle).
Figure 3. Valid 1715 UTC 10 May 2012. The bottom right panel shows radar-based maximum expected hail size exceeding severe thresholds (1.00", red circle), 45 minutes after the initial UW-CTC signal.
Figure 4. Valid 1725 UTC 10 May 2012. The bottom right panel shows radar-based maximum expected hail size of over 3.00 (red circle)", 55 minutes after the initial UW-CTC signal and 40 minute after the maximum UW-CTC signal.
Wednesday, May 9, 2012
Another CI success story @ 2032z
Forecaster comments from the EWP blog...
At 2032z…storm was pushing offshore from St Johns County in Fl. The CTC product indicated strong cooling rates approaching -20 DegC/15 minutes associated with that storm. There was a short period of time when we did not receive any products. However…the radar showed a stronger storm with increased lightning activity by 2112z.
At 2032z…storm was pushing offshore from St Johns County in Fl. The CTC product indicated strong cooling rates approaching -20 DegC/15 minutes associated with that storm. There was a short period of time when we did not receive any products. However…the radar showed a stronger storm with increased lightning activity by 2112z.
EWP: GOES optical depth retrieval enhances UW-CTC
The inability for the UW-CTC algorithm to detect newly developing convection beneath thin cirrus clouds was the primary deficiency identified by forecasters in previous experiments. In response to forecaster feedback, a recent proposal was awarded to UW/CIMSS to include GOES optical depth retrievals into the UW-CTC algorithm for the purpose of detecting these type of developing thunderstorms. Thin cirrus clouds are frequently present related to anvil blow off of nearby storms, decayed convection from previous days, and related to jet streaks. Figure 1 below provides another example of detecting a newly developing convective cloud in areas of thin cirrus. The UW-CTC value is ~ -9K /15 min and the tower beneath the thin cirrus clouds can be seen in the upper right panel highlighted by the red circle. Since this storm was out of our focus domain, radar data is not available, but NLDN detected the first lightning strike about 10 minutes later.
Figure 1. Valid 2115 UTC 09 May 2012. Note the developing thunderstorm beneath cirrus blow-off from storms to the south (red circle, top left panel). The corresponding UW-CTC was ~ -9 K /15 min. The bottom right panel shows the UW-CTC ice mask, which shows areas where detection was not possible prior to the inclusion of GOES optical depth retrievals.
CHS Desk – UAH CI product/Visible-Radar 2014Z
Forecaster comments from EWP blog...
Two images are shown here. On the left, a line of storms extends along the South Carolina coast and into portions of southern Georgia at 2014Z. Earlier at 1945Z, on the right, the UAH Convective Initiation product showed 3 areas of 60%. Initiation was predicted along and just ahead of an outflow boundary, and just off the coast oriented west southwest to east northeast. The product performed very well, with around 30 minutes of lead team for the updrafts that exhibited +35dBZ.
Two images are shown here. On the left, a line of storms extends along the South Carolina coast and into portions of southern Georgia at 2014Z. Earlier at 1945Z, on the right, the UAH Convective Initiation product showed 3 areas of 60%. Initiation was predicted along and just ahead of an outflow boundary, and just off the coast oriented west southwest to east northeast. The product performed very well, with around 30 minutes of lead team for the updrafts that exhibited +35dBZ.
JAX Cloud To Cloud Lightning near MLB 2035Z
Forecaster comment from EWP blog...
Cloud to cloud lightning was observed in a very weak storm in Osceola County. pGLM flash rates are observed in the upper right and lower left images depicting the cloud to cloud lightning. Cloud to ground lightning was not observed with this storm as depicted by the absence of strikes in the lower right panel. This data proves that this weak storm had an updraft strong enough to produce cloud to cloud lightning but not cloud to ground lightning.
I feel that adding cloud to cloud lightning data will really help storm warnings, fire weather applications, aviation forecasts, etc. if added as a baseline product for WFOs because we’re obviously missing a lot of lightning data not only in weak convection as this example shows but in strong/severe storms as well.
Cloud to cloud lightning was observed in a very weak storm in Osceola County. pGLM flash rates are observed in the upper right and lower left images depicting the cloud to cloud lightning. Cloud to ground lightning was not observed with this storm as depicted by the absence of strikes in the lower right panel. This data proves that this weak storm had an updraft strong enough to produce cloud to cloud lightning but not cloud to ground lightning.
I feel that adding cloud to cloud lightning data will really help storm warnings, fire weather applications, aviation forecasts, etc. if added as a baseline product for WFOs because we’re obviously missing a lot of lightning data not only in weak convection as this example shows but in strong/severe storms as well.
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