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All posts for the month May, 2014

Cloud Top Cooling Product Utilized in Radar-Poor Region (5/28/14)

Posted by Bill Line on 05/29/2014
Posted in: CTC, SPC. Tagged: , , , . Leave a comment

The Cloud Top Cooling (CTC) product was utilized by an SPC forecaster in monitoring for severe weather development across northern Utah into western Wyoming on Wednesday, May 28 2014.  This region is characterized by especially poor radar coverage due to mountain beam-beam blocking and coarsely spaced radars (Fig. 1). For this reason, satellite-based products are especially useful to SPC forecasters in the western third of the the United States. In this particular case, the CTC product was helpful in highlighting when rapid convective development was beginning, as well as where the most rapid development was occurring (Fig. 2). Severe winds were eventually reported with these storms. The CTC product was mentioned in SPC Mesoscale Convective Discussion (MCD) 748 (Fig. 3): “THE GOES-R CLOUD TOP COOLING PRODUCT INDICATED COOLING TOPS OVER SWRN TO WEST-CENTRAL WY AND ONGOING CLOUD TOP COOLING IN NERN UT.”

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Fig. 1: United States radar coverage map.

 

 

 

 

 

 

 

 

 

 

Fig. 2: 140528/1715 - 2245 UTC GOES-West visible imagery, Cloud Top Cooling (color fill), storm reports.

Fig. 2: 140528/1715 – 2245 UTC GOES-West visible imagery, Cloud Top Cooling (color fill), storm reports.

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Fig. 3: Image from SPC MCD #0748. Please see link for full MCD: http://www.spc.noaa.gov/products/md/2014/md0748.html

 

– Bill Line, SPC/HWT Satellite Liaison

 

GOES-14 1-minute Imagery use in SPC with Texas Severe (5/21/14)

Posted by Bill Line on 05/22/2014
Posted in: SPC, SRSOR. Tagged: , , . 3 Comments

GOES-14 provided the Storm Prediction Center (SPC) with 1-minute Super Rapid Scan Operations for GOES-R (SRSOR) imagery May 8-25. This gave SPC forecasters an opportunity to use and comment on a capability that will be available with the next generation geostationary satellite system, GOES-R. The GOES-R Advanced Baseline Imager (ABI) will be capable of scanning one 1000×1000 km sector every 30 seconds, or two sectors every one minute. For more 1-minute imagery information and examples, please visit the following page:  http://cimss.ssec.wisc.edu/goes/srsor2014/GOES-14_SRSOR.html

The forecasters at SPC who had the opportunity really valued viewing this high temporal resolution imagery, and were sorry to see it go. Adding to the benefits of this imagery is the fact that the latency of each image is typically 2-4 minutes after the time stamp, something the forecasters value greatly. It seemed as though every day when I would peak into operations, at least one forecaster would have the 1-minute imagery looping on a workstation. I gathered informative, detailed feedback from SPC forecasters regarding features and processes they are able to see in this imagery that are otherwise not evident or more difficult to discern in regular 5-30 minute imagery.

One example of an SPC forecaster using the 1-minute visible imagery in his forecast decision-making came during the early evening hours of May 21. Convection was already ongoing across the western third of Texas by  2200 UTC. However, one of the mesoscale forecasters observed newly developing convection in the Texas panhandle as well as in SW Texas via the rapid updating, 1-minute imagery.This indicated to him that the severe threat would continue over the next couple of hours. The observation was noted in SPC MCD #0647: GOES 14 ONE-MINUTE IMAGERY SHOWS CONTINUED UPDRAFT GENERATION WITHIN A MORE MATURE CLUSTER JUST E OF AMA…AND ADDITIONAL TSTM DEVELOPMENT W OF MAF…SUGGESTIVE OF A CONTINUED SVR HAIL/WIND THREAT FOR AT LEAST THE NEXT 1-2 HRS.

Below is a loop of the 1-minute visible imagery over the region for the hour before this MCD was written (Fig 1), as well as the MCD graphic (Fig 2).



Fig. 1: 2249-2257 UTC GOES-14 1-minute imagery. 
Fig. 1: 2249-2257 UTC GOES-14 1-minute imagery.


 


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Fig. 2: SPC MCD #0647. Full version can be found on the web at: http://www.spc.noaa.gov/products/md/2014/md0647.html


SPC forecasters have found the 1-min imagery to be quite useful when monitoring mature convective evolution, as is seen in the forecaster comments below:


“Post-storm initiation, the high-resolution data allowed for careful analysis of overshooting and collapsing tops, the character of the storm anvils (ie. health of the storm) and the identification of convectively generated outflows.”


“I found it very useful in… Assessing the trends of convection via evolution of cloud character in the storms themselves (overshooting tops, subjective visual assessment of storm-top divergence and flanking-line development, etc.)”


 


-Bill Line, SPC/HWT Satellite Liaison

	


	

							



	

					
May 10 Kansas Severe and Cloud Top Cooling Product
				

			Posted by Bill Line on 05/11/2014
					


		

						Posted in: CTC, SPC, Uncategorized.			
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The use of the UW-CIMSS Cloud Top Cooling (CTC) product in the Storm Prediction Center (SPC) has been highlighted in a several previous posts on this blog. Please view previous posts for a brief description of this product, along with its utility in operational environments. This post demonstrates yet another example of this product being utilized in the decision-making process of SPC forecasters.


On May 10, SPC highlighted a slight risk for severe weather across eastern Kansas into much of Nebraska. The threat included significant hail, damaging winds, and even a few tornadoes. One of the biggest challenges facing SPC forecasters is not only being able to identify where convective initiation is going to occur (or is concurring) in the near future, but also which of the developing storms will be the strongest and most likely ones to produce severe weather (information beyond just CI). The CTC product can be used for this purpose, as it tells the forecaster where you have convection developing, but also quantifies that vertical growth.


Looking at the animation below, convection began initiating in south-central Kansas on the 10th shortly after 1800 UTC along a dryline/warm front (Fig 1). At 1830 UTC, the CTC product indicated weak cooling, and by 1915 UTC very strong cooling (<-20K/15 min) was detected, indicating that convection was beginning to develop rapidly. The first severe weather with this storm was reported at 2021 UTC (1″ hail), over one hour after the first very strong CTC detection. Storms continued to exhibit rapid cooling over the next several hours as they initiated to the southwest and northeast along the boundary. These storms produced widespread severe hail, wind and even a couple of tornadoes across Kansas and into Missouri (Fig 2).


 


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Figure 1: GOES-East Visible Imagery, Cloud Top Cooling rates (K/15 min)


 


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Figure 2: SPC severe storm reports across Kansas and Missouri


 


The SPC forecaster on shift at the mesoscale desk was monitoring the CTC product during this event (FIg 3). In a Mesoscale Discussion (MD) issued at about 0100 UTC, the forecaster mentions the CTC product:  “…WITH THE GOES-R CLOUD TOP COOLING PRODUCT INDICATING THE GREATEST COOLING ATTENDANT TO THE STORMS IN THESE THREE KS COUNTIES.” This is an example of how the CTC product gave the forecaster additional confidence to where the strongest storms were developing within the watch box.  Full MD can be found at: http://www.spc.noaa.gov/products/md/md0555.html


 


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– Bill Line, SPC/HWT Satellite Liaison

	


	

							



	

					
Nearcast…Texas Convection
				

			Posted by Bill Line on 05/06/2014
					


		

						Posted in: HWT, NearCast.			
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Convective initiation has once again lined up pretty well with the instability depicted on the theta-e difference graphic in the nearcast. I have now seen this in a couple of cases. The nearcast forecast brings some instability north into Oklahoma later this evening. It will be interesting to see how this lines up with the convection at that time, as the HRRR model has shown some decent development across portions of North Central Texas and Southwestern Oklahoma.


Jared Maples


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