Nearcast in warning operations...

Nearcast differential theta-e product 1-hour forecast valid at 2000 UTC on 24 May 2011
EWP forecasters have begun warning operations within the EWP. A few of them are examining the Nearcast differential theta-e product within the AWIPS D2D workstations. I overheard a comment about how the forecaster is watching the storms moving into an area of enhanced differential theta-e on the northern edge of the band extending from TX into western OK. He noted how he expects this storm to potentially intensify as it interacts with this area. While the Nearcast product is not necessarily a warning tool, it may be an interesting application of the data immediately following an hourly update.

SATCAST captures storm that produced estimated 1.75" hail

The SATCAST CI algorithm forecasted CI for an initial development on the dryline. Horizontal convective rolls were evident in satellite imagery which intersected with the dryline. Due to the busy nature of the day today, images were captured using NAWIPS rather than AWIPS. Therefore, the only comparison to be made is between the SATCAST (upper image) and base reflectivity (lower image).




Forecasters participating in the EWP estimated that SATCAST gave approximately 10-15 minute lead time on the intial appearance of 35 dBZ at -10 C. It gave a 33 minute lead time compared to base reflectivity. The storm has produced ~1.75" hail stones. As of writing, the storm is now producing a small rope tornado.

The storms are in a ripe environment to develop quickly, therefore it has been imperative GOES be in rapid scan mode as storms produce a cirrus shield within 15 minutes of development. Both CI algorithms have performed remarkably in such a volatile environment. Both continue to forecast CI along the southern end of the dryline.

EWP warning operations

Forecasters are currently issuing experimental warnings while monitoring the CI, PGLM and MRMS products during warning operations within the HWT. They also have a situational awareness display where we can stream live chase feeds from TV stations and websites.

Convective initiation along sw OK dryline

Forecaster comments reposted from EWP blog...

Convective inititation occured along the southwest OK dryline. According to UAHCI and CIMMS CI products, had about 10-15 minute lead time for storm near Altus. 30 minute lead time from UAHCI and 20 mintue lead time from CIMMS CI for storm near Sayer.

Horizontal convective rolls east of sw OK dryline suggest storms may form in the warm sector too…maybe!

Pablo, Rudoph, and Bobby

Both CI products capturing initial development of convection

Both CI products captured convective initiation in and near the Oklahoma panhandle this afternoon. Utilizing our 'ultimate_ci' procedure within AWIPS, I screen captured both the initial development of convection and further convective development farther east. See image above. The given images for CI products are valid for the 1645 UTC imagery, and you can see the general areas flagged by the algorithms. The bottom left panel of the four panel is reflectivity at -10C. The reflectivity product was not working earlier than 1745 UTC; therefore, what is shown is the first available image. As you can see this flagged convection has attained values around 55 dbZ showing that these CI hits were correctly flagged.

This second image shows both products correctly capturing CI within the 1710 UTC imagery. Querying the reflectivity at -10C, the cell at 1732 UTC had yet to attain greater than 35 dbZ with a max value of 28 dbZ. This cell would later attain greater than 35 dbZ approximately 30 minutes after initial CI flagging. As of the end of this blog post, these initial storms are still going strong.

Simulated GOES-R band differences

As part of the EFP CI desk's morning forecasts, they asked me to demonstrate the NSSL-WRF simulated 10-12 micron band difference provided to us by CIRA. Neither of these channels are currently available together on our operational GOES satellites and will be available on the GOES-R satellite once it launches. One of the advantages of simulating satellite data from a model is that we have the opportunity to produce channels that we don't have currently, and we take full advantage of this by producing all 9 of the non-solar GOES-R IR bands. The 10 micron channel is a very clean window, and thus is very sensitive to surface temperature. The 12 micron channel however is sensitive to low-level water vapor. As moisture moves into a clear pixel area, the 12 micron brightness temperature will decrease, whereas the 10 micron temperature should stay the same. When this occurs, the 10-12 micron channel difference will become strongly positive and indicates areas of moisture convergence or pooling, which can lead to destabilization and subsequent convective initiation. Below is a collection of today's notable images, with signals of moisture pooling and destabilization shown in yellow and orange colors...

NSSL-WRF simulated 10-12 micron band difference for 1600 UTC (top), 1900 UTC (middle) and 2000 UTC (bottom) on 24 May 2011.
At 1600 UTC (top image above), we can see that the channel difference is showing an area of low clouds (blue/green colors) beginning to dissipate over central Oklahoma. At 1900 UTC (middle image above) these low clouds are completely dissipated and we can start to see some development of pooling moisture along the dryline in W. OK and the triple point on the OK/KS border. By 2000 UTC (bottom image above), storms begin to initiate near the triple point and values in the channel difference become strongly positive just south along the dryline.

NSSL-WRF simulated 10-12 micron band difference for 2200 UTC on 24 May 2011.
At 2200 UTC (image above) additional convection develops on the southern part of the dryline in central OK and into TX. It is interesting to note the presence of linear bands of enhanced moisture pooling where the convection develops ahead of the dryline. It is theorized by the EFP CI desk participants that this may be signals of horizontal convective rolls within the model leading to areas of enhanced convective potential. This demonstrates a very interesting tool to help aid forecasters in the prediction of convective initiation and also a unique combination of satellite and model information.

Examining NSSL-WRF simulated imagery/lightning

Observed (top) and simulated NSSL-WRF (bottom) WV imagery for 1300 UTC on 24 May 2011.
This morning EFP forecasters and scientists examined the simulated satellite imagery and lightning threat products from the NSSL-WRF. One of the most useful aspects of creating simulated satellite imagery from a model is the ability to compare the output directly to observed satellite imagery to determine model performance, as well as being able to have a one-stop 3-D representation of the model produced atmosphere. At 1300 UTC we matched the simulated GOES-R band 9 (6.95 micron) to the observed GOES-13 WV channel to determine model performance for the day. As you see from the images above, the model atmosphere and the observed atmosphere are very similar. The model correctly identifies an MCS over N. KS and on the KY/TN border. It should be noted that the model's simulated cloud tops generally appear to be smaller and less extensive with the cirrus shields. The position of the mid-level jet streak is also very similar, as seen in the deeper red colors extending from AZ/NM/TX panhandle.

NSSL-WRF simulated lightning threat for 2000 UTC (top) and 0000 UTC (bottom) for 24 May 2011
The NSSL-WRF initiates storms between 1900-2000 UTC along the OK/KS border. The simulated lightning threat imagery (seen above) provided by Bill McCaul (USRA) provides us with an estimation of total lightning flashes. At 2000 UTC (top most image), we see the first isolated storm along the border, with total flashes per square kilometer per 5 minutes reaching a value of 5. At 0000 UTC (bottom most image), we can see the extent of the storms across most of OK along the dryline. At this time we can see flash rate values reaching 12 and can start to get an idea of storm tracks.

NSSL-WRF simulated GOES-R low- (top), mid- (center), and high-level (bottom) WV imagery for 0000 UTC on 24 May 2011.
As we continue through time past initiation, we can take a look at the three GOES-R WV channels produced from the NSSL-WRF imagery. Each channel peaks at a different level in the atmosphere, essentially providing us with 3 layers of water vapor measurements. Currently unavailable on our operational GOES satellite, this will be available with GOES-R and we can simulated it using numerical models. What is particularly interesting in this imagery at this forecast time is the presence of a very strong dry signature (red colors) extending from the TX panhandle into central OK in the high-level water vapor (bottom image above). This is an indication of very strong mid-level jet streak. This signature is present in the lower level WV images as well.

High risk today....

Just wanted to quickly post about the weather situation today... attached below are the 1300 UTC day 1 probabilities from the SPC... One forecast sounding analogue for later today is 3 May 1999. May get a little hectic in here today, but we will do our best to keep up with things on the GOES-R front...

1300 UTC Day 1 Outlook
1300 UTC Day 1 Tornado Probabilities
1300 UTC Day 1 Wind Probabilities
1300 UTC Day 1 Hail Probabilities
For more information, please visit http://www.spc.noaa.gov/

SATCAST captures initial CI along dryline

At 1855 today, SATCAST flagged development occurring in Beckham county in Southwest OK (top left panel).



Forecasters have been waiting for the convection to develop along the dryline in West Oklahoma during the afternoon hours. Despite an environment characterized by MLCAPES greater than 3000 J/kg, SATCAST was able to have a lead time of approximately one hour before 35 dBZ reached the -10 C isotherm (bottom left) and lightning as detected by the PGLM (bottom right).


The early storms of the afternoon struggled initially develop, but have started developing rapidly in recent time frames. SATCAST has caught many of the storms which have developed along the dryline this afternoon as GOES is currently operating in rapid scan mode.

Ultimate CI

Visiting scientists and NWS forecasters visiting the EWP this week have begun looking at real-time data with the promise of some exciting weather over OK this evening. We are currently examining the SATCAST and UWCI products in combination with the multi-radar multi-sensor (MRMS) and PGLM products to anticipation convective initiation. The participants have worked together to develop what has been so lovingly called the "ultimate CI" 4-panel display within AWIPS. The 4-panel (shown above) includes the following products that are linked to the nowcast and detection of CI... Starting from top left and moving anti-cyclonic (clockwise) we have the visible with SATCAST, visible with UWCI, visible with MRMS reflectivity at -10 C, and finally visible with PGLM and NLDN lightning detections. The 4-panel has been saved as a procedure that forecasters can now load very quickly within their AWIPS D2D workstations throughout the rest of the week. Future visitors will have this available as well. This helps demonstrate the ability to combine these unique datasets from multiple sensors into one effective decision support tool.