[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 131250
SWODY1
SPC AC 131248

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0748 AM CDT WED SEP 13 2006

VALID 131300Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
BROAD MID/UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT WILL
CONTINUE TO SLOWLY SHIFT EWD ACROSS THE APPALACHIANS THROUGH THE
PERIOD.  MODELS ARE CONSISTENT IN MOVING SURFACE LOW NOW OVER SRN
MI/NRN OH EWD ACROSS THE ERN GREAT LAKES...WITH SECONDARY LOW CENTER
CURRENTLY OVER SRN AL SPREADING EWD QUICKLY ACROSS THE SRN
APPALACHIANS AND ALONG THE SC COAST BY THE END OF THE PERIOD.

...NERN GULF COAST TO THE COASTAL CAROLINAS...
ACTIVE CLUSTER/LINE OF THUNDERSTORMS CONTINUES NEAR THE LOOP CURRENT
OVER THE NERN GOM THIS MORNING...WHERE A COUPLE OF SUPERCELLS HAVE
BEEN OBSERVED OFF THE FL BIG BEND COAST.  MORNING SURFACE ANALYSES
AND FORECAST SOUNDINGS ACROSS THIS REGION SUGGEST INSTABILITY WILL
REMAIN QUITE MARGINAL INLAND TODAY WITHIN RELATIVELY WEAK DEEP LAYER
SHEAR. HOWEVER...AREA VWPS AND OBSERVED HODOGRAPH AT TLH THIS
MORNING INDICATE STRONG LOW LEVEL SHEAR WITH 0-1 SRH IN EXCESS OF
150 M2/S2.  THE WEAK DEEP LAYER SHEAR /I.E. EFFECTIVE SHEAR AROUND
20 KT/ WILL LIMIT ANY SUSTAINED OR DEEP ROTATION.  HOWEVER...GIVEN
FEED OF RICH MOISTURE OFF THE GOM...AT LEAST LOW PROBABILITIES OF
DAMAGING WINDS AND POSSIBLY A BRIEF TORNADO/WATERSPOUT ARE
WARRANTED...ESPECIALLY NEAR THE NW-FL COAST TODAY.

TONIGHT...WEAK CYCLOGENESIS ALONG THE FRONT IS FORECAST TO OCCUR
INTO THE SC COASTAL PLAIN.  WITH INCREASING SLY FLOW OFF THE
ATLANTIC...LOW LEVELS SHOULD MOISTEN AND MAY ALLOW AIR MASS TO
BECOME MARGINALLY UNSTABLE LATER TONIGHT.  EFFECTIVE SHEAR AROUND 30
KT SHOULD SUPPORT SOME ORGANIZATION/LINES SHOULD MODEST INSTABILITY
DEVELOP.  WILL ADD LOW SEVERE PROBABILITIES INTO THIS REGION TO
ACCOUNT FOR THIS.

...OH INTO THE CENTRAL APPALACHIANS...
POCKET OF COLD MID LEVEL AIR /I.E. AOB -14C AT H5/ WILL OVERSPREAD
THIS REGION THIS AFTERNOON...ASSOCIATED WITH WELL-DEFINED MID/UPPER
LEVEL LOW NOW PROGRESSING EWD ACROSS IL/IND.  THOUGH LOW LEVELS WILL
BE RATHER COOL...STEEPENING MID LEVEL LAPSE RATES/COOLING ALOFT
APPEAR SUFFICIENT FOR WEAK INSTABILITY THIS AFTERNOON NEAR THIS LOW
CENTER.  SCATTERED THUNDERSTORMS SHOULD DEVELOP...WITH THE POTENTIAL
FOR HAIL WITH STRONGER STORMS THIS AFTERNOON.

...AZ...
SLOW MOVING MID AND UPPER LOW WILL SHIFT ENEWD INTO THE SRN ROCKIES
DURING THE PERIOD...WITH MID LEVEL DRYING LIKELY OVERSPREADING MUCH
OF SRN AZ.  ONGOING SHOWERS AND THUNDERSTORMS WILL LIKELY LIMIT
INSTABILITY ACROSS MUCH OF THE REGION TODAY.  HOWEVER...SUFFICIENT
LOW LEVEL MOISTURE AND STRONGER HEATING IN CLOUD-FREE AREAS SHOULD
SUPPORT MARGINAL TO MODERATE INSTABILITY THIS AFTERNOON.  WHERE AIR
MASS CAN DESTABILIZE...STORMS COULD PRODUCE MARGINALLY SEVERE HAIL.

..EVANS/CROSBIE.. 09/13/2006