SWODY3
SPC AC 070809
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0209 AM CST SAT FEB 07 2009
VALID 091200Z - 101200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
WITHIN A STRONG SOUTHERN BRANCH OF SPLIT POLAR WESTERLIES...SHORT TO
MEDIUM RANGE FORECAST GUIDANCE INDICATES THAT A SIGNIFICANT SHORT
WAVE TROUGH WILL LIFT OUT OF THE PLATEAU REGION LATE THIS WEEKEND.
BY 12Z MONDAY...THIS FEATURE IS PROGGED TO REACH THE SOUTH CENTRAL
HIGH PLAINS...BEFORE CONTINUING NORTHEASTWARD INTO THE UPPER
MISSISSIPPI VALLEY BY EARLY TUESDAY...AS ANOTHER STRONG SHORT WAVE
TROUGH DIGS INTO THE FOUR CORNERS REGION. MODELS INDICATE THAT
STRONG CYCLOGENESIS WILL ACCOMPANY THE LEAD IMPULSE ...WITH
SUBSTANTIAL DEEPENING OF THE LOWER/MID TROPOSPHERIC CYCLONE AS IT
PROGRESSES ACROSS THE CENTRAL PLAINS/MID MISSOURI VALLEY REGION
DURING THE DAY MONDAY...TO THE SOUTH OF CENTRAL CANADIAN NORTHERN
STREAM SHORT WAVE RIDGING.
...PLAINS/MISSISSIPPI VALLEY...
DESPITE AN OTHERWISE FAVORABLE SYNOPTIC PATTERN...NEGLIGIBLE TO WEAK
WARM SECTOR INSTABILITY IS EXPECTED TO LIMIT THE RISK FOR SEVERE
STORMS DURING THIS PERIOD. CONSIDERABLE EARLY DAY CLOUD COVER AND
PRECIPITATION IS EXPECTED TO RESTRICT DAYTIME HEATING NEAR AND JUST
AHEAD OF THE DEVELOPING CYCLONE. AT THE SAME TIME... A RELATIVELY
WARM OR WARMING MID-LEVEL ENVIRONMENT ASSOCIATED WITH SHORT WAVE
RIDGING IN ITS WAKE LIKELY WILL CAP SLOWLY INCREASING LOW-LEVEL
MOISTURE...IN A RETURN FLOW ACROSS EAST TEXAS TOWARD THE MIDDLE
MISSISSIPPI/LOWER OHIO VALLEYS.
HOWEVER...A WINDOW OF OPPORTUNITY MAY EXIST FOR BOUNDARY LAYER
DESTABILIZATION WITHIN A DEVELOPING DRY SLOT...IN ADVANCE OF THE
MID-LEVEL COLD CORE...ACROSS PARTS OF NORTH CENTRAL/NORTHEAST KANSAS
INTO WESTERN/CENTRAL IOWA MONDAY AFTERNOON. SHORT RANGE ENSEMBLE
GUIDANCE INDICATES MIXED LAYER CAPE GENERALLY ON THE ORDER OF
250-500 J/KG IS POSSIBLE. WHILE RATHER WEAK...IN THE PRESENCE OF
STRONG SHEAR AND FAVORABLE FORCING...THIS MAY BE SUFFICIENT FOR THE
DEVELOPMENT OF LOW TOPPED STORMS...EITHER ISOLATED SUPERCELLS OR A
SHORT BROKEN SQUALL LINE. IF THIS OCCURS...LARGE CLOCKWISE CURVED
LOW-LEVEL HODOGRAPHS AND AMBIENT VERTICAL VORTICITY COULD SUPPORT
LOW-LEVEL MESOCYCLONES WITH THE RISK FOR TORNADOES/DAMAGING WIND
GUSTS...BEFORE STORMS DIMINISH BY THE EARLY EVENING HOURS.
..KERR.. 02/07/2009
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