DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 210547
SWODY2
SPC AC 210546

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT FRI MAR 21 2014

VALID 221200Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE MID/UPPER FLOW ACROSS MUCH OF THE U.S. MAY BECOME INCREASINGLY
CONFLUENT THROUGH THIS PERIOD...BETWEEN A LINGERING PROMINENT
SUBTROPICAL RIDGE...EXTENDING ACROSS CENTRAL AND SOUTHERN MEXICO
INTO THE CARIBBEAN...AND PERSISTENT DEEP UPPER TROUGHING ACROSS
CENTRAL AND EASTERN CANADA. MODELS SUGGEST THAT SOME SOUTHWARD
SHIFT OF THE STRONGER CYCLONIC FLOW BELT IS POSSIBLE SATURDAY ACROSS
THE UPPER MISSISSIPPI VALLEY INTO THE NORTH ATLANTIC SEABOARD...AS
THE UPPER TROUGH BEGINS TO AMPLIFY ONCE AGAIN IN RESPONSE TO A
SERIES OF DIGGING SHORT WAVE IMPULSES. PERHAPS THE MOST SIGNIFICANT
OF THESE MAY TURN SOUTHEASTWARD ACROSS THE NORTH CENTRAL
INTERNATIONAL BORDER...THROUGH MUCH OF THE UPPER MIDWEST...BY 12Z
SUNDAY...ACCOMPANIED BY A REINFORCING DEEPER COLD SURGE ASSOCIATED
WITH SURFACE HIGH PRESSURE NOSING SOUTHWARD TO THE LEE OF THE
ROCKIES. THE INITIAL SHALLOWER LEADING EDGE OF THIS COLD INTRUSION
PROBABLY WILL REACH PORTIONS OF THE TENNESSEE VALLEY/ OZARK PLATEAU
AND SOUTHERN PLAINS BY 12Z SATURDAY...BEFORE ADVANCING TO THE SOUTH
AND EAST OF THE SOUTHERN APPALACHIANS...AND INTO CENTRAL/WESTERN
GULF COASTAL AREAS...BY THE END OF THE PERIOD.

WHILE CONVECTIVE POTENTIAL IS EXPECTED TO REMAIN LOW ACROSS MUCH OF
THE NORTHERN TIER OF THE U.S...RELATIVELY STEEP MID-LEVEL LAPSE
RATES TO THE SOUTH OF THE BELT OF AMPLIFYING CYCLONIC
FLOW...PARTICULARLY ACROSS THE INTERMOUNTAIN WEST INTO THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY...ARE EXPECTED TO CONTRIBUTE TO
SCATTERED AREAS OF THUNDERSTORM ACTIVITY SATURDAY AND SATURDAY
NIGHT. THIS SHOULD BE AIDED BY FORCING FOR UPWARD VERTICAL MOTION
ASSOCIATED WITH A NUMBER OF SMALLER SCALE AND/OR GENERALLY WEAK
SHORT WAVE IMPULSES EMBEDDED WITHIN THE LARGE-SCALE PATTERN...AND AT
LEAST MODEST MOISTURE RETURN OFF THE GULF OF MEXICO AND WESTERN
ATLANTIC.

...SRN PLAINS EWD INTO TN VALLEY AND GULF COAST...
HIGHEST THUNDERSTORM PROBABILITIES SATURDAY APPEAR TO EXIST ACROSS
THE SOUTH CENTRAL STATES. ACTIVITY MAY BE ONGOING EARLY IN THE
PERIOD IN ASSOCIATION WITH LOWER/MID TROPOSPHERIC WARM ADVECTION
ACROSS THE RED RIVER VALLEY...BEFORE EVENTUALLY DEVELOPING EASTWARD
ACROSS THE OZARK PLATEAU INTO THE TENNESSEE VALLEY/NORTHERN GULF
STATES LATER IN THE PERIOD. MOST OF THIS IS EXPECTED TO BE ROOTED
ABOVE A STABLE SURFACE BASED LAYER TO THE COOL SIDE OF THE INITIAL
COLD FRONT...WITH WEAK ENOUGH CAPE...TO THE NORTHEAST OF THE RED
RIVER VALLEY...THAT THE RISK FOR SEVERE HAIL WILL BE MINIMAL.
HOWEVER...IN CLOSE PROXIMITY TO THE FRONT...ACROSS PARTS OF
NORTHEASTERN TEXAS AND SOUTHEASTERN OKLAHOMA THROUGH NORTHERN
LOUISIANA/SOUTHERN ARKANSAS INTO PARTS OF CENTRAL MISSISSIPPI...AT
LEAST A BIT MORE SUBSTANTIVE CAPE APPEARS POSSIBLE WITH BOUNDARY
LAYER BASED /OR NEAR BOUNDARY LAYER BASED/ INSTABILITY. BENEATH
40-50 KT WESTERLY 500 MB FLOW ...IT DOES NOT APPEAR OUT OF THE
QUESTION THAT THE ENVIRONMENT COULD BECOME AT LEAST MARGINALLY
CONDUCIVE TO ISOLATED SUPERCELLS SATURDAY AFTERNOON AND EVENING.

..KERR.. 03/21/2014

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