SWODY2
SPC AC 080532
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1132 PM CST SAT FEB 07 2009
VALID 091200Z - 101200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS CONTINUE TO INDICATE THAT A VIGOROUS IMPULSE...CURRENTLY
ROTATING AROUND A CLOSED LOW OVER SOUTHERN CALIFORNIA...WILL LIFT
OUT OF THE SOUTHWESTERN U.S./NORTHWESTERN MEXICAN PLATEAU REGION
THROUGH THE SOUTH CENTRAL HIGH PLAINS BY 12Z MONDAY. THIS IS
EXPECTED TO SUPPORT THE DEVELOPMENT OF A STRONG SURFACE CYCLONE TO
THE LEE OF THE CENTRAL ROCKIES...WHICH IS FORECAST TO DEEPEN THROUGH
THE LOWER/MID TROPOSPHERIC AS IT MIGRATES NORTHEASTWARD TOWARD THE
UPPER MISSISSIPPI VALLEY MONDAY/MONDAY NIGHT. AT THE SAME TIME...A
STRONG UPSTREAM IMPULSE IS PROGGED TO DIG ACROSS CALIFORNIA INTO THE
FOUR CORNERS STATES...AS YET ANOTHER STRONG SHORT WAVE TROUGH/CLOSED
LOW DIGS TOWARD THE NORTHERN PACIFIC COAST.
...PLAINS/MISSISSIPPI VALLEY...
DESPITE AN OTHERWISE FAVORABLE SYNOPTIC PATTERN...SLOW BOUNDARY
LAYER MOISTENING OVER THE GULF OF MEXICO...AND THE LACK OF A MORE
SUBSTANTIVE INLAND RETURN FLOW...COUPLED WITH WARM ANTECEDENT
LOWER/MID TROPOSPHERIC TEMPERATURES TO THE LEE OF THE ROCKIES...
STILL APPEAR LIKELY TO LIMIT THE RISK FOR SEVERE STORMS DURING THIS
PERIOD. A CONVECTIVE BAND...PERHAPS WITH EMBEDDED
THUNDERSTORMS...MAY BE ONGOING EARLY MONDAY MORNING ACROSS PARTS OF
CENTRAL KANSAS AND OKLAHOMA INTO NORTH CENTRAL TEXAS. AND...LIFT
JUST AHEAD OF THE MID-LEVEL TROUGH MAY BE SUFFICIENT TO MAINTAIN
CONVECTION IN THE PRESENCE OF STRONG WIND FIELDS/DEEP LAYER SHEAR
ASSOCIATED WITH A 70-90 KT 500 MB JET STREAK...AS IT SHIFTS
NORTHEAST OF THE CENTRAL PLAINS...TOWARD THE GREAT LAKES REGION.
HOWEVER...FORECAST SOUNDINGS SUGGEST THAT BY THE TIME THE MORE MOIST
LOW-LEVEL PARCELS ARE FORCED THROUGH A DEEP RELATIVELY WARM AND
UNSATURATED MID-LEVEL LAYER...THERE IS LITTLE IF ANY CAPE.
THUS...IT STILL SEEMS THAT IF AN APPRECIABLE SEVERE THREAT IS TO
DEVELOP MONDAY...IT WILL LIKELY BE IN THE WAKE OF THIS BAND... WHERE
A DEVELOPING DRY SLOT CONTRIBUTES TO CONVECTIVE DESTABILIZATION JUST
AHEAD OF THE MID-LEVEL COLD CORE. GUIDANCE CONTINUES TO INDICATE
THE EVOLUTION OF ONLY VERY WEAK CAPE WITHIN THIS ZONE...LIKELY LESS
THAN 500 J/KG...FROM PARTS OF NORTH CENTRAL/NORTHEAST KANSAS THROUGH
EASTERN NEBRASKA/WESTERN IOWA DURING THE AFTERNOON. BUT...IN THE
PRESENCE OF SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS...AND
FAVORABLE AMBIENT VERTICAL VORTICITY NEAR THE CYCLONE...THIS MAY BE
ENOUGH FOR LOW TOPPED SUPERCELLS WITH A RISK FOR TORNADOES/DAMAGING
WIND GUSTS. THE WINDOW OF OPPORTUNITY FOR THIS ACTIVITY PROBABLY
WILL DIMINISH BY EARLY MONDAY EVENING...WITH ONSET OF BOUNDARY LAYER
COOLING...AS THE CYCLONE PROGRESSES AWAY FROM THE MID MISSOURI
VALLEY.
..KERR.. 02/08/2009
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