DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 010551
SWODY1
SPC AC 010550

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1150 PM CST FRI FEB 28 2014

VALID 011200Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE MID/UPPER FLOW ACROSS THE U.S.CONTINUES TO TREND MORE
ZONAL...WITH THE COLD VORTEX NOW CENTERED NEAR HUDSON BAY GENERALLY
CONFINED TO THE EASTERN CANADIAN PROVINCES. HOWEVER...A VERY COLD
RIDGE OF SURFACE HIGH PRESSURE...WHICH CONTINUES TO BUILD TO THE LEE
OF THE CANADIAN AND NORTHERN U.S. ROCKIES...IS IN THE PROCESS OF
NOSING SOUTHEASTWARD...AND ITS SHALLOW LEADING EDGE IS EXPECTED TO
ADVANCE INTO THE LOWER OHIO VALLEY...OZARK PLATEAU AND TEXAS SOUTH
PLAINS BY 12Z SUNDAY. IT APPEARS THAT THIS WILL OCCUR COINCIDENT
WITH THE DEVELOPMENT OF AN INCREASINGLY SUBSTANTIVE RETURN FLOW OF
MOISTURE ON SOUTHERLY FLOW OFF THE WESTERN GULF OF MEXICO...IN THE
WAKE OF ANOTHER SURFACE HIGH CENTER SHIFTING OFF THE ATLANTIC COAST.


THE MOISTURE RETURN COULD CONTRIBUTE TO CONSIDERABLE DESTABILIZATION
BENEATH STEEPENING LOWER/MID TROPOSPHERIC LAPSE RATES ACROSS MUCH OF
THE SOUTHERN PLAINS AND OZARK PLATEAU...INTO THE MIDDLE MISSISSIPPI
AND LOWER OHIO VALLEYS. HOWEVER...UPPER RIDGING DOWNSTREAM OF A
SIGNIFICANT UPPER TROUGH MIGRATING INLAND ACROSS THE CALIFORNIA
COAST MAY SUPPRESS CONVECTIVE DEVELOPMENT THROUGH MUCH OF THE
PERIOD.

MODELS CONTINUE TO INDICATE CONSIDERABLE WEAKENING OF THE UPPER
TROUGH AND EMBEDDED LOWER/MID TROPOSPHERIC CYCLONE WILL OCCUR AS IT
ADVANCES INLAND ACROSS THE SOUTHWESTERN STATES TODAY. A RELATIVELY
COLD MID-LEVEL AIR MASS WILL SUPPORT SUFFICIENT DESTABILIZATION FOR
A CONTINUING RISK FOR THUNDERSTORM ACTIVITY NEAR SOUTHERN CALIFORNIA
COASTAL AREAS...AND ACROSS THE GREAT BASIN AND SOUTHERN PLATEAU INTO
THE SOUTHERN ROCKIES. BUT IT GENERALLY IS NOT EXPECTED TO BE ENOUGH
TO SUPPORT AN APPRECIABLE SEVERE STORM THREAT...AS DEEP LAYER WIND
FIELDS AND SHEAR WITH THE UPPER IMPULSE BECOME MORE MODEST.

...PARTS OF S CNTRL PLAINS INTO THE OZARK PLATEAU...
THE LATEST AVAILABLE HIGH RESOLUTION MODEL OUTPUT REMAINS UNCLEAR
CONCERNING THE DEVELOPMENT OF THUNDERSTORM ACTIVITY TONIGHT. BUT IT
DOES NOT APPEAR OUT OF THE QUESTION THAT STEEPENING ISENTROPIC
ASCENT WITHIN A MOISTENING ENVIRONMENT ALONG THE SOUTHWARD ADVANCING
LOWER/MID TROPOSPHERIC FRONTAL ZONE COULD INITIATE THUNDERSTORM
DEVELOPMENT TONIGHT. THIS SEEMS MOST PROBABLE AS THE LEADING EDGE
OF MID-LEVEL HEIGHT FALLS ASSOCIATED WITH THE APPROACHING UPPER
TROUGH BEGINS TO OVERSPREAD THE REGION AFTER 02/06Z. GIVEN THE
CONDITIONAL AND CONVECTIVE INSTABILITY EVIDENT IN FORECAST
SOUNDINGS...EVEN ABOVE/TO THE NORTH OF THE SHALLOW LEADING EDGE OF
THE COLD/STABLE SURFACE BASED AIR MASS...THERE STILL SEEMS AT LEAST
SOME POTENTIAL FOR SEVERE HAIL...AS THE CONVECTIVE LAYER SHOULD BE
CHARACTERIZED BY FAVORABLE VERTICAL SHEAR.

..KERR/ROGERS.. 03/01/2014

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