I loaded the surfaced based CAPE product from the vLAPS and below is the 1-hr forecast. The interesting area is over lake MI where the water temperature is still very cold, generally in the 40s F, and the model is indicating SBCAPE values of 1500-2500 j/kg over the central and southern area of the lake. This seems to be overdone given the very cold surface temperatures.

-JB

I decided to look back at the NSSL-WRF Simulated Satellite Imagery (top left) and it is pretty close to the actual IR satellite (top right).  You can also see the MRMS radar (bottom left) that it had the idea of a cluster of storms breaking out in central Iowa to N. Illinois.  The only issue I would say is it may have been slightly slower (30 min-1hr) with initializing the convection.  Other than that it has it timed pretty well after. I like it! ~Vollmar

Visible satellite imagery indicates a few overshooting tops associated with the convection from central IL back west into central IA. The over-shooting top product did highlight the region over northern IL (where currently a golf ball size hail report was just received) but the ones to the west were not highlighted. The ones to the west must not have been large enough of an over-shooting top to trip the algorithm. Since the one indicated did product the big hail it tends to add confidence to use of the product.

-JB

Just another view of LAPs CAPE field here. Lake County appears to have its cell simulated by LAPs during the actual storm time. While the storm over Ogle county did not show up in the CAPE field. HOWEVER… I would like to note that LAPs did initiate with a very high CAPE maxima of almost 3000 J/kg in this area. Perhaps there was slightly stronger cap aloft in this simulation than what occurred in reality.

Grant H.

Building on the previous post the simulated IR/WV imagery did very well capturing the orientation/timing of the convection later in the day across eastern IA and into northern IL. In reality it did under-forecast the degree of convection over western IA.

-JB

Analysis of the simulated water vapor imagery compared to the actual water vapor imagery at 13Z indicated the simulated model had a good handle on the speed max that was located over western KS at 12Z. Although the simulated water vapor/IR was to agressive on TSRAs over western NEb at 13Z this leads to confidence in the position of the speed max later in the day on the simulated water vapor.

-JB

We have now switched CWA to LOT and have loaded in the MRMS composite reflectivity overlaid with ProbSVR. It is interesting to compare this area to what we were seeing to the west. In eastern WY the probabilities were lower despite rotation on velocity products and supportive 3-dementional reflectivity of a BWER. For the LOT CWA there is very high probabilities.

-JB

The prob. severe model has been a great way to grab attention to storms that need to be monitored for the developing convection over the northern DVN CWA. Taking a look at how well it verified with dual-pol products and spotter reports, this screen capture (below) shows the prob. severe model overlaid on ZDR (upper right) and then 0.5 base reflectivity in the upper left, KDP on the lower left, and CC on the lower right. Based on the severe prob (shows 94% at 2138Z), my partner issued a Severe Thunderstorm Warning ten minutes prior to this screen capture as the probability trend was increasing over time. Having the ability to look at the parameters detailing more specifics about what the model is analyzing is very helpful in maintaining awareness with a particular storm. The MUCAPE (2325 J/kg, shown) and effective bulk shear (50.3 kts., also shown) being consolidated into one quick click of a mouse is much faster and easier than going to pull up the RAP elsewhere and analyzing the local storm environment. One other parameter that might be helpful is effective SRH. As for the other current, existing parameters, the same could be said as the other two above: the MRMS MESH, while overdone, provides an opportunity to monitor trends; and the satellite progs with annotations indicating whether or not the vertical growth rate and glaciation rate is moderate, strong, etc. is helpful and allows for increased confidence when utilizing this tool with other, more traditional methods. Without knowing how the exact values with respect to the satellite-tracking rates translate to growth/decay, the annotations deciphering what the values mean is critical to understanding the storm’s trend.

Comparing the prob. severe outline with the storm in question, dual-pol showed KDP values that were blacked out (with surrounding pixels well above 1), CC values below 1 (~.8 to .9), and a small but still evident three-body scatter spike. DVN received a report on this storm just two minutes later that was close to severe criteria:

LSRDVN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
445 PM CDT TUE MAY 20 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     HAIL             2 W DUBUQUE REGIONAL AI 42.40N 90.75W
05/20/2014  M0.88 INCH       DUBUQUE            IA   EMERGENCY MNGR

            PEA TO NICKEL SIZE HAIL REPORTED ON HIGHWAY 151.

&&

Ten minutes later, another report of hail over severe criteria was issued from DVN, verifying my partner’s warning, the prob. severe model, and what was seen in radar trends:

LSRDVN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
457 PM CDT TUE MAY 20 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     HAIL             1 E DUBUQUE REGIONAL AI 42.40N 90.70W
05/20/2014  M1.50 INCH       DUBUQUE            IA   EMERGENCY MNGR

&&

Overall and so far, this tool is a great resource and would be good to have in the toolbox.

~Linda