ACUS11 KWNS 202249
SWOMCD
MESOSCALE DISCUSSION 0625
NWS STORM PREDICTION CENTER NORMAN OK
0549 PM CDT TUE MAY 20 2014
AREAS AFFECTED...CNTRL IA...NRN IL AND ADJACENT SRN WI...SRN LAKE
MI...NWRN IND AND SWRN MI
CONCERNING...SEVERE THUNDERSTORM WATCH 161...
VALID 202249Z - 210015Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 161
CONTINUES.
SUMMARY...STRONG TO SEVERE STORM DEVELOPMENT IS EXPECTED TO
PERSIST...AND MAY STILL INCREASE SOME THROUGH 00-01Z. ACTIVITY IS
ALREADY FORMING AS FAR WEST AS AREAS NEAR/NORTH OF OMAHA NEB...WITH
ADDITIONAL ISOLATED DEVELOPMENT POSSIBLE INTO PORTIONS OF SOUTHERN
LOWER MICHIGAN AND NORTHERN INDIANA BY EARLY EVENING. WHILE IT IS
NOT CLEAR THAT THIS WILL REQUIRE ADDITIONAL WATCHES...TRENDS WILL
CONTINUE TO BE MONITORED FOR THIS POSSIBILITY.
DISCUSSION...VIGOROUS CONVECTIVE DEVELOPMENT IS NOW WELL
UNDERWAY...GENERALLY ALIGNED ALONG THE EDGE OF STEEPER MID-LEVEL
LAPSE RATES ASSOCIATED WITH THE WARMER...MORE STRONGLY CAPPING
ELEVATED MIXED-LAYER AIR ADVECTING NORTHEAST OF THE CENTRAL/SOUTHERN
PLAINS REGION. THIS ROUGHLY CORRESPONDS TO 700 MB THERMAL GRADIENT
ARCING ACROSS CENTRAL IOWA...NEAR THE INTERSTATE 80 CORRIDOR...INTO
NORTHERN ILLINOIS...NEAR/WEST THROUGH SOUTH OF THE CHICAGO
METRO...ALONG WHICH CONVECTION PROBABLY WILL PROPAGATE INTO EARLY
EVENING.
THOUGH SOMEWHAT MODEST IN MAGNITUDE...HIGHER PRECIPITABLE WATER
CONTENT IS ALSO FOCUSED ALONG THIS AXIS...SUPPORTING MODERATELY
LARGE CAPE ON THE ORDER OF 1500 TO 2000 J/KG. BENEATH 40-50 KT
WESTERLY 500 MB FLOW...THE ENVIRONMENT SHOULD REMAIN CONDUCIVE TO
SUPERCELL DEVELOPMENT CAPABLE OF PRODUCING LARGE HAIL AND LOCALLY
STRONG WIND GUSTS. LOW-LEVEL FLOW FIELDS AND SHEAR REMAIN RATHER
WEAK...AND ANY ORGANIZED DAMAGING WIND POTENTIAL WILL LARGELY HINGE
ON UPSCALE CONVECTIVE GROWTH AND CONSOLIDATING/MERGING COLD POOLS.
POTENTIAL FOR THIS REMAINS A BIT UNCLEAR...BUT SEEMS LOW AT THE
PRESENT TIME...DUE...ADDITIONALLY...TO THE APPARENT LACK OF STRONGER
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION.
..KERR.. 05/20/2014
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...LOT...MKX...DVN...ARX...DMX...OAX...
LAT...LON 41699579 42699147 42878973 42888774 41748583 41028723
41378865 41659066 41339352 41439553 41699579
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