SWODY2
SPC AC 241728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT WED JUN 24 2009
VALID 251200Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE OH VALLEY AND PARTS
OF THE NERN U.S....
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL HIGH PLAINS...
...SYNOPSIS...
LARGE SCALE PATTERN WILL NOT CHANGE DRASTICALLY OVER THE NEXT FEW
DAYS AS DOMINANT UPPER RIDGE REMAINS ANCHORED OVER THE MIDDLE OF THE
CONUS. WITH THE LARGE ANTICYCLONE CENTERED OVER THE CNTRL PLAINS
ANY SHORTWAVE TROUGHS ENTERING THE PACIFIC NW WILL TOP THE RIDGE
ACROSS THE NRN PLAINS...THEN DIG SEWD INTO THE GREAT LAKES/OH
VALLEY. EACH OF THESE FEATURES WILL UNDOUBTEDLY AID CONVECTIVE
DEVELOPMENT...SOME OF IT LIKELY SEVERE.
...OH VALLEY/NERN U.S...
LATEST MODEL GUIDANCE SUGGESTS A FAIRLY STRONG SHORTWAVE TROUGH WILL
BEGIN TO DIG SEWD ACROSS THE GREAT LAKES AS WEAKENING MID LEVEL
SPEED MAX SPREADS ACROSS WI INTO UPSTATE NY BY EARLY EVENING. AT
THE SFC...A BROAD ZONE OF CONFLUENCE WILL EXIST ACROSS THE OH
VALLEY...WITH STRONGEST CONVERGENCE ALONG SHARPER FRONTAL ZONE OVER
QUEBEC/ONTARIO AT 26/00Z. FAIRLY BUOYANT AIRMASS ACROSS THE OH
VALLEY SHOULD SUPPORT SCATTERED CONVECTION BY MID AFTERNOON BENEATH
INCREASING NWLY FLOW REGIME. IT/S NOT ENTIRELY CLEAR WHETHER AN
EARLY MORNING MCS WILL BE ONGOING AT THE BEGINNING OF THE PERIOD
OVER THE MID MS VALLEY...IF SO THEN REDEVELOPMENT MAY OCCUR ALONG
LEADING EDGE OF THIS ACTIVITY BY MID DAY ACROSS PARTS OF MO/IL/IND.
OTHERWISE...SCATTERED THUNDERSTORMS SHOULD EVOLVE ALONG/AHEAD OF
ADVANCING COLD FRONT ACROSS SERN CANADA...EVENTUALLY SPREADING INTO
UPSTATE NY/NRN VT DURING THE AFTERNOON HOURS. DAMAGING WINDS AND
LARGE HAIL ARE THE PRIMARY THREATS.
...CNTRL HIGH PLAINS...
TRAILING FRONTAL ZONE WILL BEGIN TO RETREAT ACROSS THE CNTRL PLAINS
AS LLJ INCREASES LATE IN THE PERIOD...PARTLY IN RESPONSE TO MT
SHORTWAVE TROUGH. LOW LEVEL MOISTURE SHOULD SPREAD NWWD ACROSS NEB
INTO SD WHERE AIRMASS SHOULD BECOME QUITE UNSTABLE BY LATE
AFTERNOON. THUNDERSTORMS SHOULD EVOLVE ACROSS THE HIGHER TERRAIN OF
CO...THEN SPREAD NEWD INTO THE HIGH PLAINS LATE IN THE PERIOD.
OTHER STORMS MAY THEN EVOLVE WITHIN WARM ADVECTION ZONE NEAR/SHORTLY
AFTER DARK ACROSS SD/NEB. LARGE HAIL AND DAMAGING WINDS ARE
POSSIBLE.
...ELSEWHERE...
WEAK SFC BOUNDARY SHOULD BECOME ORIENTED ALONG AN AXIS FROM CNTRL
LA...NEWD INTO CNTRL AL. THIS BOUNDARY WILL LIKELY BE THE FOCUS FOR
CONVECTIVE DEVELOPMENT BY MID-LATE AFTERNOON AS TEMPERATURES WARM
INTO THE LOWER 90S. LOCALLY STRONG WINDS MAY ACCOMPANY
PULSE-MULTICELL UPDRAFTS.
..DARROW.. 06/24/2009
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