SWODY1
SPC AC 101613
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1113 AM CDT MON SEP 10 2007
VALID 101630Z - 111200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
THE UPPER LEVEL PATTERN ACROSS THE CENTRAL/ERN CONUS WILL BECOME
AMPLIFIED THROUGH THE PERIOD...AS A STRONG SHORTWAVE TROUGH DIGS
SEWD FROM MB INTO THE NRN GREAT LAKES. GENERALLY WEAK MID LEVEL FLOW
/AOB 20 KTS/ AND WEAK LAPSE RATES WILL EXIST ALONG AND SOUTH OF
SEVERAL DIFFUSE CONVECTIVELY GENERATED BOUNDARIES EXTENDING FROM NRN
TX NEWD INTO OHIO VALLEY/CENTRAL APPALACHIANS. GIVEN THIS
ENVIRONMENT...TSTM DEVELOPMENT AHEAD OF THESE BOUNDARIES IS EXPECTED
TO BE SUB-SVR. HOWEVER...SOMEWHAT STRONGER MID LEVEL FLOW /AROUND
25-30 KTS/ WILL EXIST OVER THE MID-ATLANTIC REGION ASSOCIATED WITH A
LEAD SHORTWAVE TROUGH MOVING EWD OUT OF OHIO. FURTHER WEST...A
SECONDARY SHORTWAVE TROUGH MOVING ACROSS THE CENTRAL PLAINS WILL
SUPPORT SEWD MOVING COLD FRONT INTO THE SRN PLAINS AND MID MS VALLEY
LATER TODAY/TONIGHT.
..MID-ATLANTIC...
WV IMAGERY INDICATES THE PRESENCE OF A SHORTWAVE TROUGH OVER OHIO
THIS MORNING. AS THIS WAVE MOVES EWD...LOW LEVEL CONVERGENCE SHOULD
INCREASE INVOF OF A SFC LOW LOCATED OVER NRN NJ /NEAR NYC/ SWD ALONG
A BOUNDARY INTO NRN VA. ALTHOUGH MORNING SOUNDINGS INDICATE A FAIRLY
MOIST AIRMASS WITH MARGINAL LAPSE RATES /AROUND 6 DEG
C/KM/...SUFFICIENT HEATING COUPLED WITH THE PRESENCE OF DRY MID
LEVEL AIR WILL SUPPORT MLCAPE FROM 1000-1500 J/KG AND DCAPE VALUES
UP TO 1000 J/KG. AHEAD OF THE SHORTWAVE...UNIDIRECTIONAL MID LEVEL
FLOW WILL INCREASE TO BETWEEN 25-30 KTS /PER THE 12Z ILN SOUNDING/.
GIVEN THE EXPECTED SHEAR/INSTABILITY A FEW MARGINAL SVR TSTMS
CAPABLE OF PRODUCING DMGG WIND GUSTS WILL BE POSSIBLE. LACK OF
GREATER INSTABILITY/SHEAR WILL PRECLUDE HIGHER PROBABILITIES.
..SRN ROCKIES...
A MOIST AIRMASS WILL EXIST OVER THE REGION TODAY...WITH DWPTS IN THE
50S NOTED THIS MORNING ACROSS MOST OF CENTRAL/WRN NM. GENERALLY
LIGHT MID LVL FLOW WILL PRECLUDE A MORE ORGANIZED SVR THREAT OVER
CENTRAL/SRN NM...WHERE GREATER MOISTURE/INSTABILITY WILL EXIST
/MLCAPE UP TO 1000 J/KG/. STRONGER MID LEVEL FLOW OVER NRN NM/FAR
SWRN CO ASSOCIATED WITH TAIL END OF CENTRAL PLAINS SHORTWAVE TROUGH
AND AHEAD OF THE GREAT BASIN SHORTWAVE WILL OFFSET WEAKER
INSTABILITY /MLCAPES AROUND 500 J/KG/. THUS A FEW HIGH BASED
MARGINALLY SVR WIND GUSTS WILL BE POSSIBLE WITH THE STRONGEST TSTMS
IN THIS AREA AS WELL.
..SRN HIGH PLAINS...
AIRMASS OVER WRN TX WAS VERY MOIST WITH WEAK LAPSE RATES NOTED ON
THE 12Z AMA/MAF SOUNDINGS /5.5 TO 6 C/KM/. GIVEN RECENT TRENDS IN
CLOUD COVER OVER THE TX PANHANDLE...SUFFICIENT HEATING SHOULD OCCUR
THAT TSTMS WILL REDEVELOP ALONG A COLD FRONT THAT WILL PUSH SWD
THROUGH THE AREA THIS AFTERNOON/EVENING. ADDITIONAL TSTMS ARE
EXPECTED TO DEVELOP ALONG A CONVECTIVELY GENERATED BOUNDARY OVER
SWRN TX THIS AFTERNOON. WEAK SHEAR WILL COMBINE WITH THE WEAK LAPSE
RATES TO LIMIT ANY SVR WIND/HAIL THREAT WITH ANY STRONG TSTMS.
..SRN GREAT LAKES...
AHEAD OF A SHORTWAVE TROUGH MOVING THROUGH NEB...LOW-MID LEVEL
FRONTOGENESIS WILL INCREASE OVER THE SRN GREAT LAKES THIS
AFTERNOON/EVENING. LOW LEVEL MOISTURE WILL CONTINUE TO MOVE NWD
THROUGH THE AFTERNOON AHEAD OF AN ASSOCIATED DEVELOPING SFC LOW OVER
NRN IL. DESPITE STRENGTHENING MID LEVEL FLOW TO AROUND 50 KTS IN THE
WARM SECTOR BY 00Z...WEAK MID LEVEL COLD ADVECTION WILL PRECLUDE
GREATER INSTABILITY /GENERALLY AOB 500 J/KG/ AND STEEPER MID LEVEL
LAPSE RATES FROM DEVELOPING. THUS TSTMS ARE EXPECTED TO REMAIN BELOW
SVR LIMITS.
.CROSBIE/HALES.. 09/10/2007
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