SPC AC 080600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SAT AUG 08 2009
VALID 091200Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH PLAINS
NEWD INTO THE UPPER GREAT LAKES REGION...AND THEN EWD INTO THE
NORTHEAST...
...SYNOPSIS...
UPPER TROUGH INITIALLY OVER THE ROCKIES SHOULD EJECT ENEWD ACROSS
THE N CENTRAL U.S. AS A SLOWLY DEAMPLIFYING FEATURE THIS
PERIOD...WHILE A RIDGE REMAINS OVER THE SOUTHEAST CONUS. A SURFACE
BAROCLINIC ZONE LYING WSW-ENE ACROSS THE PLAINS/UPPER GREAT LAKES
SHOULD FOCUS CONVECTIVE DEVELOPMENT THIS PERIOD...AS THE WRN TROUGH
SHIFTS ENEWD ACROSS THIS REGION.
...UPPER GREAT LAKES SWWD INTO THE CENTRAL HIGH PLAINS...
STORMS ONGOING OVER THE UPPER GREAT LAKES REGION AT THE START OF THE
PERIOD SHOULD SHIFT EWD/ENEWD INTO ONTARIO/QUEBEC. IN THE WAKE OF
THE DEPARTING STORMS...HEATING/DESTABILIZATION WILL OCCUR FROM MI/WI
WSWWD ACROSS THE MID MO VALLEY INTO THE CENTRAL HIGH PLAINS ALONG A
QUASI-STATIONARY BAROCLINIC ZONE.
AS A SHORT-WAVE TROUGH MOVES OUT OF THE ROCKIES AND INTO THE NRN AND
CENTRAL PLAINS THROUGH THE DAY...EXPECT THE BAROCLINIC ZONE --
STRETCHING FROM SWRN KS ENEWD ACROSS SERN NEB/IA AND INTO WI DURING
THE AFTERNOON -- TO BECOME A FOCUS FOR STORM DEVELOPMENT.
WHILE THE STRONGER BELT OF FLOW ALOFT WILL REMAIN TO THE COOL SIDE
OF THE FRONT...THE SRN FRINGE OF THE FASTER FLOW SHOULD RESIDE ATOP
THE NWRN EDGE OF THE SURFACE WARM SECTOR. THUS...A NARROW CORRIDOR
OF DEEP-LAYER SHEAR SUPPORTIVE OF ORGANIZED CONVECTION SHOULD BE
JUXTAPOSED WITH THE MODERATELY-UNSTABLE CONVECTIVE INITIATION ZONE.
THOUGH FLOW ALOFT WILL ALIGN ROUGHLY PARALLEL WITH THE SURFACE FRONT
THUS LIMITING WIND POTENTIAL TO SOME DEGREE...LARGE HAIL THREAT
JUSTIFIES INTRODUCING A NARROW AXIS OF GREATER /30%/ SEVERE
PROBABILITY THIS FORECAST. WITH A SWLY LOW-LEVEL JET PROGGED TO
DEVELOP OVER THE CENTRAL PLAINS...EXPECT STORMS/SEVERE POTENTIAL TO
CONTINUE/SPREAD ACROSS THE MID MO VALLEY OVERNIGHT.
FARTHER W...ISOLATED STORMS SHOULD DEVELOP OVER NERN CO AND
VICINITY...WITHIN A REGION OF POST-FRONTAL ENELY UPSLOPE FLOW. SOME
DESTABILIZATION AND FAVORABLE SHEAR PROFILES SHOULD SUPPORT SEVERE
POTENTIAL WITH STRONGER STORMS. LATER...STORMS/SEVERE THREAT SHOULD
MOVE SEWD OFF THE HIGHER TERRAIN AS LOW-LEVEL FLOW/WARM ADVECTION
INCREASES THROUGH THE EVENING.
...PARTS OF NY/NRN PA/NRN NJ AND VICINITY...
STORMS WILL LIKELY BE ONGOING AT THE START OF THE PERIOD ACROSS
PARTS OF THE NORTHEAST AND ADJACENT ERN CANADA...WITHIN A
BROAD/PERSISTENT ZONE OF LOWER-TROPOSPHERIC WARM ADVECTION
ASSOCIATED WITH THE NERN NOSE OF A PERSISTENT WLY/WSWLY LOW-LEVEL
JET.
WITH THE JET AND ASSOCIATED ZONE OF WARM ADVECTION EXPECTED TO
PERSIST THROUGH THE DAY...MULTIPLE BANDS OF STORMS WILL LIKELY
SPREAD ACROSS THIS REGION -- WHICH SHOULD LIMIT DESTABILIZATION
ACROSS MUCH OF THE AREA. HOWEVER...WHERE DESTABILIZATION CAN
OCCUR...SEVERE POTENTIAL WILL BECOME HEIGHTENED THROUGH THE
AFTERNOON...AIDED FURTHER BY MODERATE WNWLY FLOW ALOFT. THOUGH HAIL
POTENTIAL MAY REMAIN LIMITED...STRONGER CLUSTERS OF STORMS WILL
LIKELY BE CAPABLE OF PRODUCING ISOLATED DAMAGING GUSTS --
PARTICULARLY THROUGH PEAK HEATING WHEN AVAILABLE INSTABILITY WILL BE
MAXIMIZED.
..GOSS.. 08/08/2009
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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