Idaho Storms Spudding Out - Low 700-300 Precipitable Water Values

Isolated to scattered high based storms are struggling to develop (with highest reflectivity cores 45-50 dBZ up to 25 kft MSL) as they move northeast across Idaho in a minima in 700-300 mb Precipitable Water Values (PW) according to CIMMS-NRW. Wonder if the storms will intensify if they moved into higher PW values.

Scotten

Using GOES-R CI in the NW U.S.

Not expecting a gangbusters severe day. The only area of real risk is across ID/MT today. We are starting out in the Missoula CWA and I have been checking out the GOES-R CI product. There have been some weak cells already showing some modest CTC signals…that one in the upper right panel is around -10C/15 min. The GOES-R CI product in the upper left has shown plenty of weak CI signals and a few stronger ones. Of particular note are all the pink areas on the GOES-R CI product. Those are “snow contaminated” areas…particularly widespread for this time of year! I find it neat that one can use the GOES-R CI in concert with the visible image to discern the real signals from the snowy noise. Continuing to wait for interesting storms.

CL

051313 2000 UTC CI (top left), CTC (top right), visible satellite (bottom left) and radar (bottom right)

Welcome to Week 2

Good afternoon and welcome to week 2 of the HWT Spring Experiment!

We've got a whole new batch of forecasters this week coming from all over the nation; Cheyenne, Grand Rapids, Charleston, New York, and Norman. Today will focus on getting these forecasters spun up with each of the products and slowly ease them into the warning process. We'll be centering on CWAs in the northwestern portion of the U.S. this afternoon as the rest of the country is fairly quiet. This rather docile weather pattern looks to stick around for at least the next several days, making it a quieter but hopefully still productive week.

As mentioned last week, the 'Tales from the Testbed' webinar this week will not be GOES-R focused; instead it will be looking at either EFP collaboration or HSDA and MRMS applications (depending on the weather). However, keep an eye on the blog throughout the week as forecasters will still be looking at and evaluating all of the experimental products at their disposal.

And now, without further ado, let week 2 begin...

EWP/EFP collaboration briefing - focusing on the NW U.S. for the first day of week 2

Week 1 debrief

We have reached the end of a very successful first week at HWT. Today was a shorter day dedicated to the GOES-R focused 'Tales from the Testbed' as well as a weekly debrief. This debrief covered our activities from yesterday as well as a wrap-up discussion from the entire including topics like which products were used, how they were used, what we can take away from the experience, and what is the next step for the experiment products within in an operational setting. Check it out...

PGLM
- 'We were able to successfully issue a warning in Lubbock based only the PGLM and golf ball sized hail resulted from the storm.'
- 'The one minute update for the total lightning data is a huge benefit over the traditional radar updates.'
- 'There was a storm that barely reached 40 flashes and ended up dropping penny sized hail, so [the PGLM] was fairly successful in this case.'

Cloud Top Cooling
- 'We had upwards of an hour and a half lead time given by the CTC in the Lubbock/Amarillo area.'
- 'The product wasn't useful in areas were there was cirrus contamination.'

GOES-R CI
- 'There was a 97% CI hit on the storms in Lubbock and it was successful.'
- 'The CI is too noisy. THe 10, 20, and 30% values are just a little too much. Maybe it would be better to use values of only 50% and greater.'
- 'The strength of signal concept was good.'
- 'The instantaneous concept of the CI made the product less intuitive, it jumped around. Perhaps it would be better if it focused more on the trend (i.e. a consistently increasing strength of signal on a particular area of cu).'
- 'You could see some of the trend in the CI, but then it faded again. If this happens, as a forecaster you think maybe [storm development] isn't going to happen.'
- 'Some additional continuity would be nice... for example, giving a probability of convective initiation over a specific area at a specific time.'

Forecaster thoughts... i.e. how would do we integrate these into an actual operational setting?
- 'A lot of the experimental products a very useful, but for a warning forecaster their first instinct would be to look back to the base data. It seems that this data would be more useful to a mesoscale analyst, who has time to look at each product in detail.'
- 'It may be hard for a warning forecaster to be looking at the experimental data because there's just so much of it, especially when things are rapidly developing.'
- 'As a warning forecaster I do use some of the experimental data when I can, but don't always have tie to look at all that stuff. That would definitely be useful for a mesosscale analyst and share with the warning forecaster.'
- 'Our mentality is, warning are the most important thing, even in an experimental setting... so it's good to view these new products with that mindset.'
- 'The training had me comfortable with the products when we came in... learning how the interpretation various and also finding out how to work with the products together was a challenge.'
- 'I could see myself using all the products we used this week in an operational setting.'
- 'You have to incorporate the products into an operational mindset. Once you get more used to them it becomes easier, but it's definitely not an immediate process. It take time to become comfortable with them and figure out how exactly it can be incorporated into your own procedures.'

The discussion today, particularly regarding integrating these new products into current forecast operations, was very enlightening. Forecasters have their own mindset when issuing warnings, etc., and  trying to integrate new products into this process is an interesting challenge faced by all in research to operations. However, testbeds like HWT are, I believe the stepping towards towards a successful R to O, and I look forward to continuing this effort next week.

See you then!

Convective Initiation in West Texas

Operations started earlier today, in part to give the chance to use some of the GOES-R products, such as convective initiation, before cirrus contamination.  The two initial locations were Ft. Worth and San Angelo.  The blog post “CI/CTC Identifying Developing Convection in a Favorable Environment” (http://goesrhwt.blogspot.com/2013/05/cictc-identifying-developing-convection.html) summarizes the use of CI earlier in the day in the San Angelo county warning area.

By mid-afternoon, one group shifted to the Lubbock county warning area to investigate the PGLM in that region.  The transfer to Lubbock occurred as storms were already firing, but we took a look back to see what had occurred previously.  

Flipping back we observed the GOES-R CI provide a probability of convection around 20 at 1930 UTC in northwestern Motley County (yellow arrow).

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 1930 UTC.

The GOES-R CI remained at this level until 1945 UTC when an upper 70 value was observed at the junction of Motley, Floyd, and Briscoe Counties (yellow arrow).  The visible satellite imagery shows that the features are nearly stationary.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 1945 UTC.

By the next scan, the GOES-R CI had topped 90 for the probability of convection at 2002 UTC (yellow arrow).  Up to this point, the radar was showing now activity in this area.  Also take note of the GOES-R CI in Briscoe County (red arrow) showing moderate strength of signal values around the county.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2002 UTC.

We then move ahead to 2022 UTC, where radar first observes reflectivities exceeding 35 dBZ and a developing cell can be seen in both the IR and visible imagery in Motley County (yellow arrow).  The GOES-R CI continues to trend upward in Briscoe County (red arrow, and there is no current radar observations of storms.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2022 UTC.

The situation continues to be interesting by 2045 UTC.  The Motley County storm (yellow arrow) continues to slowly grow.  Also, in Briscoe County (red arrow), where the GOES-R CI was suggesting possible initiation, we are observing several cells in the county on radar, although none have exceeded 35 dBZ just yet.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2045 UTC.

Finally, at 2115 UTC, the radar signature for the storms in Motley and Briscoe Counties is well defined.  Note that the GOES-R CI stops tracking mature cells.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2115 UTC.

The GOES-R CI provided the first indication of a potential cell in Motley County at 1930 UTC, giving it a 50 minute lead time.  Even with waiting for a stronger probability of convection, the GOES-R CI provided 35 minutes of lead time (signal of 70+), and 20 minutes (signal of 90+), respectively.  The GOES-R CI followed that with roughly 40 minutes of lead time for the Briscoe County storms.  Once the storms got rolling in this region, they became the focus of the PGLM total lightning blog post “Warning Issued with only PGLM Lightning Jump” (http://goesrhwt.blogspot.com/2013/05/warning-issued-with-only-pglm-lightning.html).

UWCTC detected well before storm turns severe in AMA CWA

UWCTC hit a developing convective element within AMA WFOs CWA at 2045 UTC with a moderate value of -17K/15 min (Figure 1).

Figure 1.  UWCTC valid at 2045 UTC showing cooling rate values of -17K/15 min.

Continued cooling was detected at the following scan at 2115 UTC (of course during the period of the half hour full disk scan!) with a weak cooling rate observed at ~-8K/15 min (Figure 2).

Figure 2.  UWCTC valid at 2115 UTC showing a cooling rate of ~-8K/15 min.

Radar at this time (2119 UTC; Figure 3) showed moderate reflectivity values of ~40 dBZ associated with the detected convective element.

Figure 3.  AMA radar reflectivity valid at 2119 UTC showing moderate (~40 dBZ) reflectivity.

These convective elements did not attain severe levels for quite some time, but the element of interest eventually turned strong to marginally severe with an observed hail report at 2251 UTC of 0.88" (Figure 4).  If one is counting, the CTC signal had a lead time for this convective element of ~110 minutes.  Figure 5 is the radar imagery out of AMA valid at 2249 UTC.

Figure 4.  LSR for hail in AMA CWA

Figure 5.  Reflectivity from AMA radar valid at 2249 UTC during time of above hail report.

This is just one of several other good cases of CTC for today.  Not too bad of an event.

Warning Issued with only PGLM Lightning Jump

At 2226z a storm in the LUB CWA had 1 flash on the pGLM and 10 minutes later the number was up to near 40 flashes.

An experimental warning was issued based only on this and without any other data. About 5 minutes post warning, the HSDA algorithm hit for large hail.

Purple color is large hail

Several minutes later the MESH hit at 1.02″

The pGLM was the first hit of possible severe weather and gave 5-10 minutes more lead time to when the MRMS products hit for severe hail.

Hampshire

PGLM Flash Extent Density in Linear Convection

The PGLM flash extent density product was useful at picking out areas of more severe convection in a linear storm segment. While the lightning “jumps” were not all that impressive (~20 to 30 flashes/min), they were still significant enough in conjunction with MESH near an inch to issue a warning. This is evident in the four panel image below which shows FED, Comp Reflectivity and MESH.

Austin/Frank

PGLM Flash Extent Density Helps with Tracking Storm Intensification

We finally had storms develop within the West Texas LMA. The strongest updraft this evening showed marked ramp up of flashes to 40 just as the storms 50 dBZ core reached 26.25 kft briefly before coming back down about 10 minutes later with the flash density also subsiding back to 15 to 25 flashes. Although the storm didn’t reach severe criteria, it was beneficial that the Flash Extent Density updates in 1 minute intervals, which lets the warning forecaster monitor for rapid updraft development between radar volume scans. This storm resulted in a report of dime size hail.

0.5 reflectivity and Flash Extent Density

Kurtz

Simulated Satellite Imagery, CI, and CTC Forecast Convection Across West Texas

NSSL WRF simulated satellite imagery accurately depicted convection erupting across West Texas as an outflow boundary from a previous MCS across north-central Texas interacted with the dryline. The three following images show a westward propagating outflow boundary interacting with isolated cells along the dryline across portions of West Texas.

NSSL WRF simulated satellite imagery from 21Z. 

Simulated satellite imagery at 22Z.

Simulated satellite imagery at 23Z

The UAH CI and UW-CTC products were also very persistent in developing convection across the extreme southern Texas panhandle and adjacent portions of West Texas.

UAH CI product prior to convective development this afternoon. 

UW-CTC product showing persistent cloud top cooling of 15 to 25 C/15 min.

Satellite imagery verified convective development across West Texas. While impossible to forecast the exact location of initiation, the general area was well represented with lead times of up to around half an hour. Convection can be seen beginning near 2010Z and lasting well into the afternoon hours.

Visible satellite imagery overlaid with analyzed mean sea level pressure and surface observations at 2010Z. 

Same but for 2125Z

Guseman