SWODY1
SPC AC 111300
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 AM CDT FRI SEP 11 2009
VALID 111300Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A SMALL PART OF NJ...
...SYNOPSIS...
THE WLYS WILL REMAIN ACROSS SRN AND CNTRL CANADA THROUGH SAT. THIS
WILL LEAVE THE CONUS IN A REGION OF WEAK TO MODERATE FLOW ASSOCIATED
WITH /1/ A SWD-MOVING CLOSED LOW OVER THE NRN PLNS.../2/ A NEARLY
STATIONARY/DOUBLE-STRUCTURE CLOSED LOW OVER THE UPR OH VLY/MID
ATLANTIC STATES...AND /3/ A RDG OVER THE GRT BASIN. FARTHER
S...SATELLITE SHOWS WEAK UPR LVL CIRCULATIONS OVER SW NM...S TX AND
THE NWRN GULF. THESE FEATURES LIKELY WILL SHOW LITTLE OVERALL
MOVEMENT AS THEY PERSIST WITHIN A BROADER WEAK UPR TROUGH OVER THE S
CNTRL STATES.
...CNTRL PLNS/MID MO VLY...
TSTMS ON SE SIDE OF NRN PLNS UPR LOW EXPECTED TO DEVELOP GENERALLY
SW TOWARD/INTO THE CNTRL PLNS TODAY AS SFC HEATING DESTABILIZES
REGION ALONG AND AHEAD OF SYSTEM COLD FRONT. IN THE MEAN
TIME...STORMS NOW IN ERN SD/WRN MN SHOULD GRADUALLY DIMINISH AS THE
FRONT ENCOUNTERS INCREASINGLY DRY/MORE STABLE AIR WITH ERN EXTENT
INTO MN. TSTMS SHOULD DEVELOP/INTENSIFY OVER PARTS OF NEB AROUND
MIDDAY/EARLY AFTN...WITH THE ACTIVITY EXPANDING FARTHER SW INTO
NRN/WRN KS LATER THIS AFTN THROUGH EARLY TONIGHT.
WITH THE STRONGEST FLOW ALOFT ASSOCIATED WITH UPR LOW CONFINED TO
THE W SIDE OF THE SYSTEM...0-6 KM SHEAR ALONG/AHEAD OF COLD FRONT
WILL REMAIN WEAK /AOB 25 KTS/. THUS...POTENTIAL FOR SUSTAINED/
STRONGLY ORGANIZED STORMS WILL BE LOW. BUT WITH HEATING LIKELY TO
CONTRIBUTE TO SBCAPE OF 1500 TO LOCALLY 2000 J/KG FROM SE SD THROUGH
CNTRL NEB...SOME OF THE STORMS COULD PRODUCE HAIL AND/OR STRONG
WINDS. A FEW INSTANCES OF LARGER HAIL MAY OCCUR FROM WRN KS INTO
ERN CO AND THE OK PANHANDLE...WHERE STEEPER LOW TO MID LVL LAPSE
RATES WILL EXIST.
...NJ/CSTL LONG ISLAND...
SFC LOW ASSOCIATED WITH ERN MEMBER OF DOUBLE-STRUCTURED OH VLY/MID
ATLANTIC UPR LOW EXPECTED TO EDGE NWD ALONG OR JUST OFF THE NJ CST
LATER TODAY. THIS TRACK SHOULD KEEP WARM SECTOR/MORE SUBSTANTIAL
SFC-BASED INSTABILITY ALONG OF JUST OFF THE CST THROUGH THE
PERIOD...BUT ALSO KEEP MUCH OF THE STATE IN AN ENVIRONMENT OF
MODERATE LOW LVL DIRECTIONAL SHEAR. BAND OF STRONG OVERNIGHT STORMS
THAT EXHIBITED SCTD AREAS OF ENHANCED LOW LVL ROTATION HAS WEAKENED
AS THE LOW HAS BECOME SOMEWHAT OCCLUDED. A VERY MINIMAL BUT
NON-ZERO CHANCE WILL EXIST FOR THE DEVELOPMENT OF A NEW BAND OF
STORMS IN CNTRL/NRN NJ LATER TODAY AS BOUNDARY LAYER SLIGHTLY
DESTABILIZES BENEATH STRONG/PERSISTENT ESELY 925 MB FLOW. WERE SUCH
CONVECTION TO DEVELOP...A LOW CONDITIONAL THREAT FOR A TORNADO OR
TWO WOULD EXIST THROUGH EARLY THIS EVE.
..CORFIDI/HURLBUT.. 09/11/2009
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