Friday, June 25, 2010

MESO: Mesoscale Discussion 1123

ACUS11 KWNS 251944
SWOMCD
SPC MCD 251944
MNZ000-IAZ000-SDZ000-252145-

MESOSCALE DISCUSSION 1123
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT FRI JUN 25 2010

AREAS AFFECTED...PORTIONS ERN SD...SRN MN...EXTREME NWRN IA.

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 251944Z - 252145Z

WW PROBABLY WILL BE NEEDED DURING NEXT COUPLE HOURS OVER THIS
REGION...COVERING INCREASING POTENTIAL FOR SVR BEGINNING INVOF ERN
LOBE OF CATEGORICAL MDT-RISK AREA IN DAY-1 OUTLOOK. INITIAL THREAT
IS FOR SUPERCELL MODES WITH POTENTIAL FOR TORNADOES...DAMAGING HAIL
AND SVR DOWNDRAFTS. HEAVY PRECIP WITH 2-3 INCH/HOUR RAIN RATES ALSO
IS LIKELY. UPSCALE GROWTH TO LARGER COMPLEX OF SVR TSTMS IS FCST
WITHIN A FEW HOURS THEREAFTER...WITH THREAT SHIFTING EWD ACROSS SRN
MN.

SFC MESOANALYSIS SHOWS LOW MOVING EWD ACROSS CENTRAL SD...ROUGHLY
BETWEEN PIR-HON...AND CORRESPONDING CLOSELY TO CENTROID OF CYCLONIC
CURVATURE EVIDENT IN VIS ANIMATIONS OF CUMULIFORM FIELD THAT HAS
THICKENED OVER SERN SD. RELATED MAX IN LOW-LEVEL CONVERGENCE...IN
TANDEM WITH SFC DEW POINTS UPPER 60S/LOW 70S F...AND SUSTAINED SFC
HEATING IN WRN PORTION OF LOW-CLOUD FIELD...SHOULD WEAKEN CINH AND
CONTRIBUTE TO TSTM DEVELOPMENT OVER THIS AREA. WITH MLCAPE APCHG
5000 J/KG...DEVELOPMENT MAY BE EXPLOSIVE WITH RAPID INTENSIFICATION
TO SVR LEVELS. WEAK WARM-FRONTAL ZONE...REINFORCED OVER NERN SD AND
SRN NM BY OUTFLOW FROM EARLY-MORNING COMPLEX...MAY MOVE NWD SLIGHTLY
AMIDST PERSISTENT AREA OF PRESSURE FALLS THAT HAS BEEN EVIDENT ALONG
AND TO ITS N OVER PAST 3-4 HOURS. RELATIVELY BACKED WINDS IN/NEAR
BAROCLINIC ZONE SHOULD ENHANCE LOW-LEVEL HODOGRAPHS...CONTRIBUTING
TO 100-300 J/KG EFFECTIVE SRH...AMIDST 40-50 KT EFFECTIVE SHEAR
MAGNITUDE.

..EDWARDS.. 06/25/2010

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

ATTN...WFO...MPX...DMX...FSD...ABR...

LAT...LON 43489812 43609906 44329995 44699991 45329910 45299587
44979330 43689345 43429480 43359627 43489812

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