DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 191732
SWODY2
SPC AC 191730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CST TUE NOV 19 2013

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A COUPLE OF DISTINCT BELTS OF STRONGER WESTERLIES EMERGING FROM THE
PACIFIC HAVE BECOME GENERALLY ZONAL ACROSS NORTH AMERICA...BUT THIS
MAY BE SHORT-LIVED AS MODELS INDICATE THAT THE SOUTHERN BRANCH WILL
UNDERGO AMPLIFICATION ACROSS THE EASTERN PACIFIC INTO THE
SOUTHWESTERN U.S. DURING THIS FORECAST PERIOD. AS MID/UPPER RIDGING
BUILDS OVER THE EASTERN PACIFIC...IT APPEARS THAT TROUGHING WILL
DEEPEN JUST WEST OF THE CALIFORNIA COAST INTO THE FOUR CORNERS
STATES. A SMALLER SCALE DOWNSTREAM IMPULSE PROBABLY WILL WEAKEN
WHILE SHIFTING NORTHEAST OF THE MID MISSOURI VALLEY THROUGH THE
GREAT LAKES REGION...ATOP A BUILDING RIDGE OVER THE SOUTHEAST...AND
AHEAD OF A MORE SIGNIFICANT NORTHERN STREAM SHORT WAVE TROUGH
ACCELERATING EAST NORTHEASTWARD THROUGH SASKATCHEWAN AND MANITOBA.

IN THE WAKE OF THE NORTHERN STREAM IMPULSE...A SIGNIFICANT INTRUSION
OF LOW-LEVEL COLD AIR LIKELY WILL CONTINUE NOSING SOUTHWARD TO THE
EAST OF THE NORTHERN AND CENTRAL U.S. ROCKIES...WHILE A LARGE
SURFACE RIDGE TO THE EAST CONTINUES TO SLOWLY SHIFT EASTWARD ACROSS
THE ATLANTIC COAST STATES. ON THE WESTERN PERIPHERY OF THIS LATTER
FEATURE...THE DEVELOPMENT OF A SOUTHERLY RETURN FLOW IS EXPECTED TO
PROCEED...INCREASINGLY OFF A MODIFYING/MOISTENING BOUNDARY LAYER
OVER THE WESTERN GULF OF MEXICO. WHILE SUBSTANTIVE INLAND BOUNDARY
LAYER MOISTENING ACROSS THE SOUTHERN PLAINS MAY LAG THAT OCCURRING
ALOFT...GUIDANCE...INCLUDING THE NCEP SREF...SUGGESTS SEASONABLY
HIGH PRECIPITABLE WATER /ON THE ORDER OF 1.25 INCHES/ RETURNING TO
MUCH OF THE SOUTHERN PLAINS BY LATE WEDNESDAY NIGHT.

...SOUTH CENTRAL PLAINS INTO LOWER MISSOURI VALLEY...
THIS MOISTENING...BENEATH MODESTLY STEEP MID-LEVEL LAPSE RATES...
WILL CONTRIBUTE TO INCREASING CONDITIONAL AND CONVECTIVE INSTABILITY
ABOVE A RESIDUAL NEAR SURFACE STABLE LAYER...NORTHEAST OF THE
SOUTHERN HIGH PLAINS INTO THE LOWER MISSOURI VALLEY. THIS SHOULD BE
SUFFICIENT TO SUPPORT INCREASING PROBABILITIES FOR THUNDERSTORM
ACTIVITY. BY WEDNESDAY EVENING...FORECAST SOUNDINGS SUGGEST THAT
LOW-LEVEL MOISTENING IN THE PRESENCE OF STEEPENING ISENTROPIC
ASCENT...ALONG A STRENGTHENING LOW-LEVEL JET...COULD CONTRIBUTE TO
SUFFICIENT MID-LEVEL CAPE TO SUPPORT AT LEAST SOME POTENTIAL FOR
MARGINALLY SEVERE HAIL ACROSS PARTS OF NORTHWEST OKLAHOMA AND
ADJACENT NORTHEAST TEXAS/SOUTHERN KANSAS.

...CALIFORNIA INTO FOUR CORNERS REGION...
WEAK DESTABILIZATION SUPPORTIVE OF AT LEAST LOW THUNDERSTORM
POTENTIAL...ASSOCIATED WITH MOISTENING AND DIFFERENTIAL THERMAL
ADVECTION...IS EXPECTED WEDNESDAY/WEDNESDAY NIGHT ACROSS CENTRAL
CALIFORNIA THROUGH MUCH OF THE GREAT BASIN. PROBABILITIES
SUFFICIENT FOR A CATEGORICAL THUNDER OUTLOOK SEEM TO EXIST ACROSS AT
LEAST THE INTERIOR VALLEY OF CALIFORNIA...WHERE MID-LEVEL FORCING
ASSOCIATED WITH AN INLAND ADVANCING SHORT WAVE IMPULSE MAY COINCIDE
WITH PEAK DAYTIME BOUNDARY LAYER INSTABILITY.

...FLORIDA PENINSULA...
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION IS EXPECTED TO REMAIN
GENERALLY WEAK. BUT...A RELATIVELY MOIST BOUNDARY LAYER MAY AGAIN
BECOME SUFFICIENTLY UNSTABLE WEDNESDAY TO SUPPORT A RISK FOR
ISOLATED TO WIDELY SCATTERED THUNDERSTORM ACTIVITY... MAINLY NEAR
COASTAL AREAS.

..KERR.. 11/19/2013

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