MESO: Mesoscale Discussion 1764

ACUS11 KWNS 310221
SWOMCD
SPC MCD 310220
MNZ000-SDZ000-310315-

MESOSCALE DISCUSSION 1764
NWS STORM PREDICTION CENTER NORMAN OK
0920 PM CDT MON AUG 30 2010

AREAS AFFECTED...WRN THROUGH CNTRL MN

CONCERNING...TORNADO WATCH 635...636...

VALID 310220Z - 310315Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 635...636...CONTINUES.

STORMS WILL APPROACH ERN BORDER OF WW 635 AND 635 BY 03Z. STORM
INTENSITIES HAVE DECREASED...BUT RISK FOR ISOLATED DAMAGING WIND AND
PERHAPS A TORNADO OR TWO CONTINUES. A MODEST SEVERE THREAT MAY
PERSIST EAST OF THE CURRENT WATCHES...BUT UNCERTAINTY STILL EXISTS
REGARDING HOW QUICKLY THE THREAT WILL DIMINISH. THEREFORE REISSUANCE
FARTHER EAST WILL ULTIMATELY DEPEND ON CONVECTIVE TRENDS NEXT 20
MIN.

LINE OF STORMS WITH COUPLE OF EMBEDDED BOWING STRUCTURES EXTENDS
FROM NWRN MN SWWD INTO EXTREME ERN SD. THE LINE IS MOVING EAST AT
AROUND 20 KT WITH 30-35 KT ALONG BOWING SEGMENTS. THERMODYNAMIC
ENVIRONMENT BECOMES INCREASINGLY MARGINAL WITH EWD EXTENT INTO MN
WHERE MUCAPE DROPS BELOW 800 J/KG. THIS ALONG WITH A STABILIZING
BOUNDARY LAYER LOWERS OVERALL CONFIDENCE IN SEVERE THREAT EAST OF
CURRENT WW. LOW LEVEL JET IS FORECAST TO GRADUALLY VEER IN WAKE OF
UPPER IMPULSE AND ATTENDANT SURFACE LOW EJECTING THROUGH ND.
HOWEVER...A SECONDARY IMPULSE LIFTING NNEWD THROUGH E-CNTRL SD MAY
EXERT A GLANCING INFLUENCE ON THE LINE AND 50+ KT BOUNDARY LAYER
WINDS WILL LIKELY PERSIST OVERNIGHT OVER THE UPPER MS VALLEY. A
TRANSITION TO A HIGH SHEAR WITH LARGE HODOGRAPHS AND LOW CAPE
ENVIRONMENT MAKES THE FUTURE THREAT SOMEWHAT CONDITIONAL BUT WITH
SOME RISK FOR DAMAGING WIND AND AN ISOLATED TORNADO. GIVEN THE
UNCERTAINTY AND CONFLICTING SIGNALS...WW ISSUANCE EAST OF CURRENT
WATCHES WILL ULTIMATELY DEPEND ON TRENDS DURING THE NEXT 20-30 MIN.

..DIAL.. 08/31/2010

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

ATTN...WFO...DLH...MPX...FGF...FSD...ABR...

LAT...LON 44119655 46549553 48569484 48429300 46769354 44019538
44119655

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