First glance:
A shortwave trough is moving across the Upper Midwest region causing scattered convection to develop over central and western IA. Earlier 12Z RAOBs showed a dry boundary layer between 700-890mb but steep low level lapse rates.
NUCAPS soundings: Noticed that NUCAPS doesn't have a current swath (17Z) over the central Plains. The latest availability sector is further east over the east coast and western Atlantic.
ALL Sky LAP products: Looking at Layer PWATs and CAPE products. Seeing a broad swath of instability and layer moisture moving from Ozarks to OAX. Also seeing a secondary area of increased instability gradients from the SW of the region from GID to ABR CWAs. Could be from those high low-level lapse rates within the conditionally unstable environment?
RAP13 is showing initiation around 20-23Z (especially the later part of this time period). Initiation is already occurring near an apparent warm front overlaid from FSD to the IA/MN border. Did see a fairly stout gradient in DCAPE from the southeast portion of the FSD area to the DMX area. DMX area is showing around 1000 J/kg while the southeast areas are showing a gradient between 700-1000 J/kg. With conditional surface based CAPE gradient (shown on NAM12/HRRR and GOES All Sky LAP products, from the western side of FSD CWA to the southeast side could see convective initiation but weak in nature until it approaches the far southern tip of the forecast area where a "surge" of instability is seen on all products though the All sky product maxima/tongue is displaced east compared to the other models.
Possible impacts: Damaging winds (isolated) mainly over southeast portion of FSD CWA. Could also see marginally severe hail threat.
Nowcasting:
NUCAPS soundings came in (18Z): Shows about 800-1000 J/kg of DCAPE and as much as 2500-3000 J/kg of MUCAPE. I am a little suspicious of this particular sounding data given the superadiabatic surface layer from the soundings. There is also a mid level cap that may be broken by the shortwave trough. Side note Suggestion: on the readouts, when we select the readout for a NSHARP sounding it would be nice to have a designation on the readout map either displayed on the NSHARP sounding display (top right in color circled area) or on the sounding availability map as maybe a white dot when selected.
The following NUCAPS sounding was more useful in diagnosing the environment. The sample was taken over NW area sampling the inflow airmass.
Wind profiles from HRRR suggest storm motions from the SW at around 20-25 kts which coincides with the current storm motions.
Tried to load NUCAPS Plan View data as a comparison to All Sky LAPS CAPE and HRRR CAPE but it is not available. Only lapse rates are available in Plan View. Even then the data was completely useless or hard to really resolve anything useful.
Looking at GLM Event Density, Average Flash area, and Total Energy decided to also load the NLDN and ENTLN Lightning Plot. The Event density coincides well with the land based systems. I would like to see more training on the average flash area in how to show how the lightning strike area coincides with the event density and Total Energy. Please do not just do another module, especially for something so new as GLM! It has taken me personally hours of handling the data WITH the presence of the GLM SMEs at the EWP to have even a modest understanding of the flash area, total energy, and flash extent. Perhaps average flash area is more of a IDSS application product than use in warning operations.
I do like the Total Energy product most as it is more intuitive (brighter color means higher energy). Showing cases from previous blog posts last week where less messy convection stronger severe convection) was taking place made it easier to see how the average flash area where a lightning strike was detected going into the anvil. Also, changing the color table of the event density definitely helped in visualizing the stronger updrafts (lightning events).
GOES East CI probability was useful due to its good time latency today (compared to yesterday). Seeing 10-30% probability across western portion of FSD area within bands of cumulus clouds. Severe CI did show some areas over the western portion of the FSD CWA. Seemed to have anomalously high probs (80%) of Severe CI for 1-2 time steps.
Prob Wind did increase on a storm moving from the FSD area into the northern portion of DMX area. Noticed it went up to 60%. Radar coverage is more limited as the storm moved outside the Rmax. Did look at SRM and there was about 40 knots at lowest tilt which was about 10kft AGL. There is another cell that is to the southwest of this one that is also showing a gradual (but lower) increase in ProbWind and ProbHail (insert image).
There were some other cells to the northwest over Aberdeen's area that actually started exhibiting higher Prob Severe values which could be due to deformation zone/cold conveyor belt development on the northwest flank of the upper low.
That's all for today folks!
Cheers!
Supercell
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