Strong to Severe Weather Ahead

Attention Weather Enthusiasts
This is a very important blog update, so please take the time to read through it entirely. At the time of writing, there's a growing likelihood of a Severe Weather Outbreak on Wednesday 4/8/15 and Thursday 4/9/15. As always this information is subject to change, but this threat has already been on the Storm Prediction Center's (SPC) and National Weather Service (NWS) Kansas City's minds the last few days, which says something about this particular Weather setup. Please be sure to stay vigilant about these 2 days coming up.

Some Technical Details
Typically on this blog, we work to make the information more generalized for easy reading, but I feel compelled to quote a few things directly so that you, the people we're trying to help protect, get a feeling for exactly the kind of strong tone that the SPC and NWS offices are using to describe Wednesday & Thursday.

Storm Prediction Center - Mesoscale Discussion Quote
"DESPITE TIMING DIFFERENCES WITH RESPECT TO THE MAIN UPPER
   LOW/TROUGH...CONFIDENCE HAS INCREASED THIS FORECAST WITH RESPECT TO
   SEVERE RISK FOR DAY 4 /WED 4-8/ ACROSS CENTRAL AND ERN OK/ERN KS/MO.
    ALL MODELS INDICATE MID-LEVEL HEIGHT FALLS ACROSS THIS AREA...AND
   AT LEAST HINTS OF A SUBTLE/EMBEDDED WAVE CROSSING THE REGION NEAR
   PEAK HEATING.  ATTM...EXPECT RESULTING UVV TO BE SUFFICIENT ATOP THE
   EWD-MIXING DRYLINE TO PERMIT CAP WEAKENING SUFFICIENT TO YIELD
   ISOLATED TO SCATTERED STORM DEVELOPMENT BY LATE AFTERNOON.  WITH A
   VERY MOIST BOUNDARY LAYER AHEAD OF THE DRYLINE TOPPED BY STEEP LAPSE
   RATES...AND A KINEMATIC ENVIRONMENT FEATURING FLOW THAT VEERS
   SUBSTANTIALLY AND INCREASES STEADILY WITH HEIGHT...SHEAR WILL FAVOR
   LONG-LIVED SUPERCELLS AND ATTENDANT RISK FOR VERY LARGE
   HAIL...DAMAGING WINDS...AND TORNADOES.  GIVEN UNCERTAINTY DUE TO
   STORM COVERAGE...WILL MAINTAIN ONLY 15% PROBABILITY AREA ATTM --
   DESPITE SIGNIFICANT SEVERE WEATHER POTENTIAL WITH ANY STORM THAT
   DOES DEVELOP.

   THE LIKELIHOOD FOR MORE WIDESPREAD STORMS -- BUT WITH GREATER
   UNCERTAINTY IN TERMS OF TIMING AND AREA -- EXISTS DAY 5 /THU 4-9/.
   DEEPENING OF THE SURFACE LOW IN THE KS/NEB/IA VICINITY AND ADVANCE
   OF A TRAILING COLD FRONT INTO THE CENTRAL/SRN PLAINS WILL FACILITATE
   A BROAD ZONE OF STORM INITIATION...GIVEN THE MOIST/FAVORABLY
   UNSTABLE AIRMASS EXPECTED.  WITH STRONGER FLOW ALOFT AS COMPARED TO
   DAY 4 GIVEN PROGRESSION OF THE MAIN MID-LEVEL JET STREAK INTO THE
   CENTRAL STATES...SUPERCELL STORMS AND ASSOCIATED RISK FOR VERY LARGE
   HAIL...DAMAGING WINDS...AND TORNADOES CAN BE EXPECTED."

NWS Kansas City - Mesoscale Discussion Quote
"Wednesday: Both the Wed and Thu period present the greatest concern for severe weather at this time as a potent upper trough moves into the Central Plains, with height falls across the area. The frontal boundary will stall early Wednesday morning and lift northward as a warm front during the day. Moderate instability is expected to develop within the warm sector by late afternoon, with strengthening wind fields as the upper trough approaches. This spells a potentially volatile  environment for the area, if in fact this multi-day convective event evolves in this fashion. Models are somewhat consistent with the overall upper pattern and location of surface features, aiding in some confidence to the forecast. Also concerning is the strong convective signals generated by many model members during the late afternoon and evening across the CWA. With said environment, convection that develops would rapidly become severe, with all types of severe weather threats possible. This period will be critical to watch how the pattern and yet unresolved mesoscale details evolve in
the coming days.

Thursday: The upper trough finally moves into the Plains, with the Pacific front progressive in an eastward march. While deep layer shear will certainly support storm organization, uncertainty remains to the degree of destabilization that will be realized with anticipated overnight convection and/or convection forming early along the front in the highly forced/weakly-capped environment. Additionally, low-level direction shear will be much less on Thursday, with storm mode likely to be in a linear fashion with updraft seeding and strong forcing. Again, there are simply too mnay unknown mesoscale features to provide many intelligent details, but again some risk of severe weather will be possible, especially in the southeast half of the CWA that would see the front move through during the afternoon. Obviously any change in speed to the system will subsequently alter the frontal passage and area of concern. Coverage of convection on Thu is expected to be more widespread."

Hopefully,after reading the SPC and NWS Mesoscale discussions, though somewhat complicated, you can pick out the serious tone that both organizations already have (and have had!) for at least a couple of days now.

But Let's Not Forget the Graphics
So let's take a look at some pictures, because those always "say" a lot more than words.

These are some early runs of the chances of seeing significant Supercell development on Wednesday afternoon. The point here is to show how dynamic of an atmospheric setup we're looking at that day. There will be a lot of energy available for Supercell growth.

HIRES GFS (left) + HAZGFS | Supercell Composite model valid at 4PM on Wednesday, 04/08/2015

While this graphic doesn't look as threatening as the one above, it's important to note that this one denotes the forecasted area that may see a Significant Tornado (SIGTOR). A SIGTOR is typically anything expected to be in the EF2 or greater range.

HIRES GFS + HAZGFS | SIGTOR model valid on Wednesday at 4PM, 04/08/2015

Lastly, the graphic below has 2 different looks. The left shows the Type of Supercell forecasted to develop; in this case High Precipitation (HP), meaning Tornadoes could very well be rain-wrapped and hard to visually detect. The right frame depicts Bulk Shear from 0-6KM up in the atmosphere. Shear helps dictate the strength of Storms, and this shows a wide area of 50 Knot and above Shear for our area. Again, this helps reiterate the idea of how dynamic this setup appears to be at this time.

HIRES GFS | Supercell Type Index + HAZGFS 0-6KM Bulk Shear, valid at 4PM Wednesday, 04/08/2015

Stay Tuned
Please be sure to stay on top of this with us. Have a Weather Plan for you and your family in place and practice it in the next couple of days. These types of Weather Systems can change very quickly, and when they become violent & damaging, there is very little time to react. Make sure you have a Weather Radio programmed, and that it has fresh batteries. Even with a Warning message, the average time people have to take shelter is only 10 minutes.

Whether you're reading this as Twisted Skies fan, or a follower of the Kansas City Regional SKYWARN, we just want everyone to be aware of this risk and to take it seriously. Keep your eyes on our pages, as well as the NWS KC pages. We'll do our best to keep everyone informed.

Stay safe out there,

Twisted Skies Chase Team
Ground Truth | To Protect Life & Property
Established October 2014

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