Forecast Courtesy of: KRZY
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Summary
A very potent all hazards day across E Kansas, NW Missouri, and SW Iowa is in store with a couple of stronger tornadoes, very large (2+ inch hail) and at least isolated (75+mph) wind possible with more widespread reports of 1-2 inch hail and 60-75mph wind being very probable.
Outlook
A severe weather outbreak will all hazards possible (including a the potential for a couple of stronger tornadoes) is possible today across E Kansas, NW Missouri and SW Iowa: Data from the Rocky Mountains region of the United States is sparse, and it has caused models to completely miss the ejection of a powerful 500mbar negative tilt trough with around 80kts of flow on it’s backside, with 60-70kts of flow in the exit region. The LLJ also has trended significantly stronger, with a broad zone of 40-50kts of slightly S-SWerly flow.
However, the only uncertainty with the environment currently is that moisture is still somewhat marginal (only 59-61 degree dewpoints in SW IA), though the ejection of a more powerful trough leading to much more powerful surface cyclogenesis should help to iron out this wrinkle in the forecast somewhat. It should also be mentioned that NE MO and E KS should have dewpoints more so in the mid to even upper 60s. When combined with the fact that temperatures should be in the mid 70s to low 80s, destabilization should be at least adequate to extreme in southern areas of the risk (1250-1750J/KG of MLCAPE in SW IA, with 2500-3500J/KG in E KS, somewhere between for NW MO)
Low-level shear should also be far more potent than expected given the much stronger low level flow mentioned earlier, combined with stronger cyclogenesis backing the low level winds further into the slightly more well established surface cyclone.
An issue with today (at least for tornado potential) is going to end up being storm mode. Storms should begin to cluster and eventually grow upscale relatively quickly as the extreme forcing from a powerful negative tilt trough ejection will undoubtedly force a lot of updrafts along the cold front. Despite this, the degree of perpendicularity between the shear vectors aloft and the initiating boundary is very high so it’ll be harder than typical for complete upscale growth to occur.
For damaging winds and very large hail, the environment should be primed no matter what. For damaging winds, there will be moderate DCAPE, somewhat higher spreads, and at least a somewhat rapid evolution towards upscale growth (~15 degrees), and steep (~7.5 degree C/KM) lapse rates throughout the entire column.
For destructive hail, there should at least be initially a mostly discrete storm mode. There will also be a somewhat large 3-6KM shear vector, a somewhat low freezing level, and at least moderate instability (not extreme though) in the hail growth layer, without extreme instability under the layer to throw the stones out of the updraft prior to being at their max size.
