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Feb 20th Severe Event


Chicago Storm

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..KS/OK TO MO/NWRN AR

STRONG DYNAMICS/HEIGHT FALLS ARE EXPECTED ALONG THE TRACK OF THE

POTENT CO/NM SHORTWAVE TROUGH AND ATTENDANT CYCLONICALLY CURVED

70-90 KT MIDLEVEL JET. STRONG DPVA AND KINEMATICS WITH THIS SYSTEM

WOULD NORMALLY BE SUPPORTIVE OF GREATER COVERAGE OF SEVERE WEATHER.

HOWEVER...THE SHORT WAVELENGTH BETWEEN A TROUGH EXITING THE ERN

SEABOARD AND THE PLAINS SYSTEM TODAY WILL NOT ALLOW SUFFICIENT TIME

FOR ROBUST MOISTURE RETURN...AS AN INTRUSION OF CP AIR OCCURRED INTO

THE GULF ON SUNDAY. THUS...WEAK LOW LEVEL MOISTURE RETURN REMAINS

THE PRIMARY LIMITING FACTOR PRECLUDING THE INTRODUCTION OF A

CATEGORICAL SLIGHT RISK AREA AT THIS TIME. AT BEST...LOW-MID 40S

SURFACE DEWPOINTS WILL ADVECT NWD INTO CENTRAL/ERN OK BY AFTERNOON

WITH AROUND 40 F VALUES INTO ERN KS. THIS COMBINED WITH STEEP

MIDLEVEL LAPSE RATES /7-8 C PER KM/ ATTENDANT TO THE COMPACT TROUGH

AND DIABATIC HEATING WILL RESULT IN MUCAPE REMAINING BELOW 500 J/KG.

INITIAL TSTM DEVELOPMENT WILL BE POSSIBLE ACROSS WEST CENTRAL KS

INTO PARTS OF WRN OK BY EARLY AFTERNOON...WITH GREATER LIKELIHOOD

FOR TSTM DEVELOPMENT OCCURRING BETWEEN 21-00Z ALONG THE I-35

CORRIDOR IN OK AND NNWWD INTO CENTRAL KS AS THE COLD FRONT OVERTAKES

THE DRY LINE. MODELS SUGGEST THIS LATTER TIMING COINCIDES WITH

STRONGER FORCING FOR ASCENT WITHIN THE EXIT REGION OF THE MIDLEVEL

JET AND DPVA SPREADING ATOP THE CORRIDOR OF GREATER...THOUGH

WEAK...MOISTURE RETURN. FORECAST SOUNDINGS/HODOGRAPHS INDICATE

ACTIVITY WILL BE LOW-TOPPED AND FAST MOVING /ENEWD AT 45-50

KT/...WITH EFFECTIVE BULK SHEAR OF 35-40 KT RESULTING IN BOWING

STRUCTURES AND SUPERCELLS.

GIVEN THE STRENGTH OF THE WIND FIELDS...STEEP LAPSE RATES AND SPEED

OF THE STORMS...ISOLATED DAMAGING WINDS WILL BE THE PRIMARY THREAT

IN ADDITION TO ISOLATED HAIL. DESPITE THE WEAK MOISTURE...LOW LEVEL

SPEED/DIRECTIONAL SHEAR ALONG A 40-50 KT SLY LLJ SUGGESTS A NON-ZERO

THREAT FOR AN ISOLATED/BRIEF TORNADO WILL EXIST AS WELL.

DURING THIS EVENING...THERE IS SOME CONCERN FOR A GREATER THREAT FOR

DAMAGING WINDS AND THE EVENTUAL NEED FOR A CATEGORICAL SLIGHT

RISK/HIGHER PROBABILITIES ACROSS PARTS OF ERN OK/SERN KS INTO SWRN

MO/NWRN AR. RESIDUAL STEEP LOW LEVEL LAPSE RATES AHEAD OF THE COLD

FRONT WILL BE SUPPORTIVE OF DOWNWARD MOMENTUM TRANSFER OF

STRENGTHENING WIND FIELDS /WSWLY AT 55-65 KT AT 700 MB/ AS THE

PLAINS TROUGH BECOMES NEGATIVELY-TILTED AFTER 00Z. HOWEVER...THE

LACK OF GREATER INSTABILITY AGAIN PRECLUDES THE INCLUSION OF A

SLIGHT RISK AREA.

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I personally feel the tornado threat is (relatively) maximized a touch farther W/NW than indicated on the latest SWODY1, which seems to be a common bias on cold-core days. The first area of potential will be true cold core in NC KS, in the vicinity of RSL-HLC, during the early-mid afternoon. By mid-late afternoon, another threat could possibly materialize in NW/NC OK into S KS. Though farther displaced from the H5 low, the mid-level temperatures are still obscenely cold over this sliver of the warm sector, with surface-H5 lapse rates about as steep as you'll ever see. One can't help but have flashbacks to March 8, 2010, though I still suspect that was the kind of extreme result that only 1/25 similar events would yield in reality.

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I personally feel the tornado threat is (relatively) maximized a touch farther W/NW than indicated on the latest SWODY1, which seems to be a common bias on cold-core days. The first area of potential will be true cold core in NC KS, in the vicinity of RSL-HLC, during the early-mid afternoon. By mid-late afternoon, another threat could possibly materialize in NW/NC OK into S KS. Though farther displaced from the H5 low, the mid-level temperatures are still obscenely cold over this sliver of the warm sector, with surface-H5 lapse rates about as steep as you'll ever see. One can't help but have flashbacks to March 8, 2010, though I still suspect that was the kind of extreme result that only 1/25 similar events would yield in reality.

yeah, Dick McGowan and company are headed to the Russell area.

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Should be clearing out here by 2 p.m. or so; Mesonet data shows temperatures quickly rebounding into the 50s and lower 60s in places where it has cleared out already. Going to be a race against time to get storms to initiate before the dryline moves through here.

That weak dryline has pushed into western OK now. Low level lapse rates are responding and there is some Cu development already. Cold front isn't far behind though, pushing through the panhandles now.

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Seems like a warning should be in place in Wichita, but I don't see any yet. Also,

the southern part of the line has developed some rotation during the last few

minutes.

A little bit bewildered as to why no SVR for Wichita and surrounding areas. The

NWS office reported nickel size hail and the wind gusted to 55 mph, while the line

continued to strengthen as it entered the city. Quarter size hail and wind damage

were reported as well as some property damage in Andover. The SVR was then

issued as the line was east of Wichita. My guess is that warning for low-topped

lines is something that Wichita is not used to seeing, so that may have been

a factor here.

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