Sunday, June 26, 2011

MESO: Mesoscale Discussion 1403

ACUS11 KWNS 262010
SWOMCD
SPC MCD 262009
IAZ000-MOZ000-NEZ000-262215-

MESOSCALE DISCUSSION 1403
NWS STORM PREDICTION CENTER NORMAN OK
0309 PM CDT SUN JUN 26 2011

AREAS AFFECTED...PORTIONS SERN NEB...SWRN IA...NWRN CORNER MO.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 262009Z - 262215Z

CONDITIONAL BUT POTENTIALLY SIGNIFICANT SVR THREAT EXISTS ACROSS
DISCUSSION AREA INITIALLY INVOLVING SUPERCELLS...AS ENVIRONMENT
APPEARS TO BE GETTING MORE FAVORABLE INVOF EXISTING CONVECTION AND
AHEAD OF NRN NEB MCS. WW MAY BE REQUIRED WITHIN NEXT HOUR OR TWO.

INITIAL SFC WARM FRONT IS STILL DRAWN S OF AREA...FROM LOW NEAR DDC
NEWD ACROSS HLC AREA THEN ARCHING TO BETWEEN SLN-CNK AND SEWD OVER
SERN KS. VERY HOT/WELL-MIXED AIR MASS WILL CONTINUE TO ITS S.
SECONDARY WARM-FRONTAL ZONE IS DEVELOPING INVOF KS/NEB BORDER AND
WILL MOVE NWD ACROSS SRN NEB...AND IS EVIDENT BOTH IN SFC OBS AND IN
PRONOUNCED CHANGE IN LOW-CLOUD CHARACTER PER VIS IMAGERY.
DIFFERENTIAL HEATING...AS WELL AS RAIN-COOLED AIR FROM CONVECTION TO
ITS N OVER SERN NEB...MAY REINFORCE THIS BAROCLINIC ZONE.

NON-SVR ELEVATED TSTMS HAVE BEEN DEVELOPING AND MOVING EWD ACROSS
SERN NEB BETWEEN OMA-GRI...WITHIN BAND OF MIDLEVEL ASCENT AND NEAR
ZONE OF RELATIVELY MAXIMIZED 700-MB MOISTURE. LOW-LEVEL AIR MASS IN
THIS AREA IS EXPECTED TO DESTABILIZE FROM S-N AS NRN WARM-FRONTAL
SEGMENT APCHS...LEADING TO STG SFC HEATING OF AIR MASS CONTAINING
LOW-MID 70S F SFC DEW POINTS. THIS WILL BOOST MLCAPE TO 4000-5000
J/KG RANGE...JUXTAPOSED WITH NEAR-FRONTAL MAXIMA IN LOW-LEVEL
VORTICITY AND HODOGRAPH SIZE. BACKED SFC WINDS WILL CONTRIBUTE BOTH
TO EFFECTIVE SRH 200-400 J/KG AND EFFECTIVE SHEAR MAGNITUDES 50-60
KT. EXISTING CONVECTION MAY BECOME SFC-BASED AND SVR AS MORE
FAVORABLE AIR MASS BUILDS INTO ITS VICNITY...AND/OR NEW DEVELOPMENT
MAY OCCUR ALONG WARM FRONT...AND/OR NRN NEB MCS ENTERS NRN PARTS OF
AREA. HOWEVER...THREAT FOR NEW TSTMS IS CONDITIONAL GIVEN 18Z OAX
RAOB SHOWING CAPPING THAT ACTUALLY STRENGTHENED SINCE 12Z. ANY
SUSTAINED/SFC-BASED TSTM IN NEAR-FRONTAL ENVIRONMENT OFFERS RISK OF
VERY LARGE/DAMAGING HAIL...SVR GUSTS AND TORNADOES.

..EDWARDS.. 06/26/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...OAX...GID...

LAT...LON 42069799 41879649 41429559 41199516 40819504 40409535
40399718 40539882 40749898 42069799

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