MESO: Mesoscale Discussion 1825

ACUS11 KWNS 280627
SWOMCD
SPC MCD 280627
MNZ000-SDZ000-NDZ000-280900-

MESOSCALE DISCUSSION 1825
NWS STORM PREDICTION CENTER NORMAN OK
0127 AM CDT TUE AUG 28 2012

AREAS AFFECTED...PORTIONS SRN ND...WRN MN...NERN SD.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 280627Z - 280900Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...TSTM COVERAGE MAY INCREASE THROUGH ABOUT 09Z...AS ACTIVITY
SHIFTS/SPREADS ESEWD ACROSS DISCUSSION AREA. 1-INCH DIAMETER HAIL
WAS REPORTED IN MORTON COUNTY AT 615Z FROM A SMALL/LEFT-MOVING CELL.
ADDITIONAL/ISOLATED SVR HAIL OR GUSTS NEAR SVR LEVELS MAY OCCUR.
THREAT APPEARS TOO MRGL/DISORGANIZED TO WARRANT WW.

DISCUSSION...SEVERAL TSTMS HAVE DEVELOPED DURING PAST HOUR OVER
S-CENTRAL ND...IN AREA OF ELEVATED LOW-LEVEL WAA AND MOISTURE
TRANSPORT SUPPORTING ISENTROPIC ASCENT OF PARCELS TO LFC. 00Z
925/850-MB CHARTS...AND SHORT-FUSED GUIDANCE SINCE...SUGGEST THIS
AREA LIES ALONG NWRN RIM OF WNW-ESE ALIGNED GRADIENT IN MOISTURE AND
THETAE AT THOSE LEVELS...WHICH APPEAR TO CONSTITUTE PART OF INFLOW
LAYER FOR THIS CONVECTION. ACCORDINGLY MODIFIED RAOBS AND FCST
SOUNDINGS SUGGEST MUCAPE IN 500-1000 J/KG RANGE...WHICH SHOULD
SPREAD EWD ACROSS SERN ND...NERN SD AND ADJOINING PORTIONS MN AFTER
09Z IN STEP WITH EWD MOVEMENT OF 850-MB LOW ACROSS NRN SD...AND
MOISTURE ADVECTS INTO THAT REGION E OF LOW. RELATIVELY DRY AIR
BELOW INFLOW LAYER MAY AID DOWNDRAFT ACCELERATION AND ALLOW STG
GUSTS TO PENETRATE SHALLOW/DIABATICALLY STABILIZED NEAR-SFC LAYER.
VWP AND FCST SOUNDINGS ALSO SUGGEST MRGLLY FAVORABLE EFFECTIVE
SHEAR...WITH 35-50 KT MAGNITUDES LIKELY CONTRIBUTING TO
TRANSIENT/WEAK CYCLONIC SHEAR ALREADY OBSERVED ON STORM SCALE E
BIS...IN SUPPORT OF OCNL HAIL NEAR SVR LEVELS.

..EDWARDS/THOMPSON.. 08/28/2012

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

ATTN...WFO...DLH...MPX...FGF...ABR...BIS...

LAT...LON 45039695 45479847 46280089 46990197 47109820 46689460
44909518 45039695

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