MESO: Mesoscale Discussion 2138

ACUS11 KWNS 261947
SWOMCD
SPC MCD 261947
VAZ000-NCZ000-262215-

MESOSCALE DISCUSSION 2138
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT FRI OCT 26 2007

AREAS AFFECTED...PORTIONS SERN VA/TIDEWATER...COASTAL NC...OUTER
BANKS AND INVOF ADJACENT SOUNDS.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 261947Z - 262215Z

SMALL TORNADO POTENTIAL MAY EXIST OVER DISCUSSION AREA...ESPECIALLY
NEAR FRONTAL ZONE DESCRIBED BELOW. THREAT APPEARS TOO TRANSIENT AND
MRGL FOR WW.

SFC MESOANALYSIS SHOWS LOW INVOF SC/NC LINE BETWEEN FLO-SOP...WITH
WARM FRONT NNEWD GENERALLY ALONG I-95 TO JUST S RIC...THEN EWD/ESEWD
OVER ORF AREA AND OFFSHORE. FRONT IS EXPECTED TO LIFT NWD AROUND 10
KT ACROSS SERN VA AND BECOME QUASISTATIONARY OVER MOST OF ITS NC
EXTENT...ITS MOVEMENT SLOWED PARTLY BY BAROCLINIC EFFECTS OF
ABUNDANT CLOUDS/PRECIP TO ITS N AND NW. WARM SECTOR IS SHUNTED
SOMEWHAT FARTHER E TOWARD SOUNDS BY E EDGE OF PRECIP PLUME.
PRESENCE OF WARM SECTOR OVER ERN NC AND OVER MORE OF SERN VA WITH
TIME WILL YIELD MRGLLY FAVORABLE BUOYANCY...MLCAPES UP TO 500 J/KG.
INSTABILITY WILL BE LIMITED BY WEAK MID-UPPER LEVEL LAPSE RATES AND
BY LACK OF ROBUST DIABATIC HEATING. STILL...BOUNDARY LAYER THETAE E
OF PRECIP PLUME AND S OF VA FRONTAL SEGMENT DOES SUPPORT SFC-BASED
EFFECTIVE LIFTED PARCELS. THIS REGIME COINCIDES WITH ENVIRONMENT OF
SOMEWHAT ENLARGED LOW LEVEL HODOGRAPHS...WITH EFFECTIVE SRH AROUND
100-200 J/KG LIKELY TO CONTINUE. WITH ROUGHLY 35 KT FLOW AROUND 6
KM AGL OR 500 MB...OBSERVED IN VWP AND NOWCAST IN RUC
GUIDANCE...STRONGEST DEEP-LAYER SHEAR SHOULD BE ALONG FRONT WHERE
SFC WINDS ARE WEAK BUT BACKED. RELATIVELY DISCRETE/HIGH
REFLECTIVITY TSTMS IN WARM SECTOR...OR CROSSING MORE ZONALLY ALIGNED
FRONTAL SEGMENT IN VA...MAY ROTATE FOR A SHORT PERIOD...AND
BRIEF/SMALL TORNADO CANNOT BE RULED OUT.

.EDWARDS.. 10/26/2007

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

ATTN...WFO...AKQ...MHX...ILM...

34357761 35247695 36547683 37217713 37857708 37917614
37787550 37147582 37127596 36927599 36297579 35707545
35197551 35227563 35147583 34927618 34577649 34637655
34687671 34657697 34557726

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