[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 310043
SWOMCD
SPC MCD 310042
ALZ000-TNZ000-MSZ000-310145-

MESOSCALE DISCUSSION 1730
NWS STORM PREDICTION CENTER NORMAN OK
0742 PM CDT THU JUL 30 2009

AREAS AFFECTED...PORTIONS OF TN/AL

CONCERNING...TORNADO WATCH 640...642...

VALID 310042Z - 310145Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 640...642...CONTINUES.

THREAT FOR DMGG WINDS AND HEAVY RAINFALL WILL PERSIST ACROSS MUCH OF
TN/AL...WITH A TORNADO THREAT PRIMARILY CONFINED TO WRN/MIDDLE TN.

AN UPPER VORTICITY MAXIMUM NOTED ON WV IMAGERY NEAR THE AR/MS/TN
BORDERS AND AN ATTENDANT SURFACE LOW ROUGHLY NEAR JACKSON TN
CONTINUE TO PROVIDE FAVORABLE FORCING FOR ASCENT ACROSS THE WATCH
AREA. 00Z SOUNDINGS REFLECT MODERATE INSTABILITY IS
LINGERING...WHICH COMBINED WITH 40 TO 50 KT EFFECTIVE SHEAR WILL
CONTINUE TO SUPPORT OCCASIONAL ROTATION...ALTHOUGH RECENT ROTATION
NOTED ON RADAR HAS PRIMARILY BEEN CONFINED TO NRN PORTIONS OF BOWING
SEGMENTS. OCCURRENCE OF SUPERCELLULAR STRUCTURES APPEARS TO BE
WANING...AND MAY BE PARTLY DUE TO AN EXTENSIVE REGION OF LEADING
EDGE STRATIFORM PRECIPITATION THAT HAS LIKELY COOLED MUCH OF THE
AIRMASS AHEAD OF THE STRONGER CONVECTION...WITH A DECREASING NUMBER
OF LIGHTNING STRIKES SUGGESTING UPDRAFTS MAY NOT BE AS ROBUST AS A
FEW HOURS AGO. CONVECTION HAS DECREASED CONSIDERABLY ACROSS
CNTRL/NRN MS AND CNTRL AL AND WW MAY BE CANCELLED EARLY IN THESE
AREAS. HOWEVER...AS PREVIOUSLY MENTIONED...GIVEN THE UNSEASONABLY
STRONG UPPER WAVE/FORCING...A THREAT WILL REMAIN IN AREAS CLOSEST TO
THE SURFACE LOW. ABUNDANT MOISTURE/ABOVE NORMAL PWAT WILL ALSO
SUPPORT A HEAVY RAIN THREAT AS WELL.

..HURLBUT.. 07/31/2009

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

ATTN...WFO...OHX...BMX...HUN...MEG...

LAT...LON   34598593 34238776 35098938 35838903 35898765 35148639
            34598593



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