SWODY2
SPC AC 070603
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CST FRI JAN 07 2011
VALID 081200Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT BLOCKING WILL REMAIN PROMINENT WITHIN THE
EVOLVING LARGE-SCALE UPPER FLOW PATTERN THROUGH THIS FORECAST PERIOD
AND BEYOND...WITH A SIGNIFICANT NEW HIGH CENTER BEGINNING TO BUILD
ACROSS ALASKA. AS THIS OCCURS...DOWNSTREAM RIDGING ACROSS NORTH
CENTRAL AND NORTHEASTERN CANADA IS PROGGED TO WEAKEN...WHILE THE
DEEP CLOSED LOW TO ITS SOUTH GRADUALLY REDEVELOPS SOUTHEASTWARD AND
EASTWARD OUT OF THE GREAT LAKES REGION THROUGH THE NORTHEAST BY 12Z
SUNDAY. MEANWHILE...AS AN ELONGATED CLOSED LOW/TROUGH GRADUALLY
DIGS TO THE SOUTHEAST OF THE DEVELOPING HIGH...ACROSS THE
NORTHWESTERN U.S...ANOTHER CLOSED LOW EMERGING FROM THE SUBTROPICAL
EASTERN PACIFIC IS EXPECTED TO TRANSITION TO AN OPEN WAVE ACROSS THE
SOUTHERN ROCKIES AND NORTHERN MEXICAN PLATEAU...BEFORE TURNING INTO
TEXAS LATE SATURDAY NIGHT.
WHILE ONE COLD FRONT CONTINUES TO ADVANCE SOUTHWARD THROUGH PARTS OF
THE PACIFIC NORTHWEST/NORTHERN INTERMOUNTAIN REGION AND GREAT
BASIN...AND A MUCH MORE SIGNIFICANT COLD INTRUSION BEGINS TO NOSE
SOUTHWARD ALONG AND TO THE LEE OF THE CANADIAN ROCKIES... CONFLUENT
MID/UPPER FLOW TO THE LEE OF THE U.S. ROCKIES IS EXPECTED TO
MAINTAIN COLD SURFACE RIDGING ACROSS MUCH OF THE CENTRAL AND EASTERN
STATES. HOWEVER...A STALLED FRONTAL ZONE ON THE SOUTHWESTERN
PERIPHERY OF THIS AIR MASS MAY BECOME THE FOCUS FOR A DEVELOPING
SURFACE LOW...ACCOMPANIED BY DESTABILIZATION AND THE POTENTIAL FOR
THUNDERSTORM ACTIVITY ACROSS PARTS OF THE SOUTHERN PLAINS AND
WESTERN GULF COAST REGION.
...SOUTHERN PLAINS/WESTERN GULF COAST REGION...
MODELS SUGGEST SUFFICIENT BOUNDARY LAYER MODIFICATION OVER THE
WESTERN GULF OF MEXICO FOR A MODEST INLAND RETURN FLOW OF MOISTURE
ACROSS THE LOWER RIO GRANDE VALLEY AND LOWER TEXAS COAST DURING THIS
PERIOD. LOWER 60S SURFACE DEW POINTS MAY RETURN INLAND THROUGH THE
WARM SECTOR OF THE DEVELOPING SURFACE WAVE...AS FAR NORTH AS SAN
ANTONIO INTO THE MIDDLE TEXAS COASTAL AREA BY LATE SATURDAY NIGHT.
ALTHOUGH WEAK MID-LEVEL LAPSE RATES AND INHIBITION MAY SLOW
DESTABILIZATION AND CONVECTIVE DEVELOPMENT...GUIDANCE IS SUGGESTIVE
THAT THE APPROACHING UPPER TROUGH MAY TAKE ON AN INCREASING NEGATIVE
TILT ACROSS THE RIO GRANDE VALLEY AFTER 09/06Z...WITH A 50-70+ KT
SOUTHWESTERLY 500 MB JET STREAK NOSING ACROSS THE WESTERN GULF COAST
REGION. ASSOCIATED FORCING AND STEEPENING OF MID-LEVEL LAPSE RATES
PROBABLY WILL BECOME SUPPORTIVE OF INCREASING THUNDERSTORM ACTIVITY
WITHIN AN ELEVATED WARM ADVECTION REGIME TO THE NORTH OF THE SURFACE
FRONT...ACROSS CENTRAL AND NORTHEAST TEXAS INTO THE SABINE VALLEY.
IT ALSO MAY BECOME SUFFICIENT FOR NEAR SURFACE OR BOUNDARY LAYER
BASED STORMS ALONG AND SOUTH OF THE FRONT. ALTHOUGH CAPE IS
EXPECTED TO REMAIN GENERALLY BELOW 500 J/KG...IF THIS OCCURS...WIND
PROFILES CHARACTERIZED BY STRONG DEEP LAYER SHEAR AND SIZABLE
CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS SHOULD BECOME FAVORABLE FOR
ORGANIZED CONVECTION...INCLUDING AT LEAST SOME POTENTIAL FOR AN
ISOLATED SUPERCELL OR TWO.
..KERR.. 01/07/2011
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