Wednesday, July 24, 2013

MESO: Mesoscale Discussion 1504

ACUS11 KWNS 242136
SWOMCD
SPC MCD 242136
MNZ000-NDZ000-242330-

MESOSCALE DISCUSSION 1504
NWS STORM PREDICTION CENTER NORMAN OK
0436 PM CDT WED JUL 24 2013

AREAS AFFECTED...NWRN MN...ERN ND...FAR NERN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 242136Z - 242330Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE POTENTIAL FOR ISOLATED MARGINALLY SVR THUNDERSTORMS
WILL EXIST INTO THE EVENING HOURS...THOUGH THE ISSUANCE OF A WW IS
UNLIKELY.

DISCUSSION...THUNDERSTORMS CONTINUE MOVING SEWD INTO/ACROSS NWRN MN
INVOF A PRE-FRONTAL TROUGH THAT EXTENDS FARTHER SW INTO SERN ND AND
N-CNTRL SD. THE GREATEST CHANCE FOR SUSTAINED CONVECTION WILL EXIST
ACROSS NWRN MN IN CLOSEST PROXIMITY TO A ZONE OF MID-LEVEL ASCENT
ACCOMPANYING A LOW-AMPLITUDE SHORTWAVE TROUGH MOVING SEWD FROM SRN
MANITOBA INTO ADJACENT ONTARIO PER WATER VAPOR IMAGERY.

FARTHER SW ALONG THE PRE-FRONTAL TROUGH AND INVOF A COLD FRONT THAT
WILL ENTER NW PARTS OF THE DISCUSSION AREA DURING THE NEXT COUPLE OF
HOURS...CONVECTIVE DEVELOPMENT WILL BE POSSIBLE. HOWEVER...VIS
SATELLITE DATA SUGGEST THAT THE CUMULUS FIELD IN THESE AREAS IS
RELATIVELY FLAT WHERE DEEP FORCING FOR ASCENT IS RELATIVELY
WEAKER...AND ADDITIONAL SUBSTANTIAL CONVECTION MAY STRUGGLE TO
MATERIALIZE.

MODERATE MID-LEVEL FLOW -- E.G. 30-40-KT WNWLY/S BETWEEN 3.5 AND 5
KM AGL PER MVX VWP DATA -- WILL SUPPORT ENOUGH DEEP SHEAR FOR A FEW
ORGANIZED STORM STRUCTURES WITH MARGINALLY SVR HAIL/WINDS POSSIBLE.
HOWEVER...WITH SFC TEMPERATURES ONLY IN THE MID 70S TO AROUND 80
DEGREES AMIDST MIDDLE 50S DEWPOINTS...SFC-BASED BUOYANCY IS
RELATIVELY LIMITED WHICH SHOULD MITIGATE THE OVERALL SVR
THREAT...WHICH WILL LOWER EVEN MORE AFTER SUNSET.

..COHEN/CORFIDI.. 07/24/2013

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

ATTN...WFO...DLH...FGF...BIS...

LAT...LON 48949730 48999544 49349517 49359476 48819454 48509340
47319374 46339523 46099653 46249775 46879843 47969817
48949730

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