DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 030537
SWODY1
SPC AC 030535

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1135 PM CST WED JAN 02 2013

VALID 031200Z - 041200Z

...NO TSTM AREAS FORECAST...

...SYNOPSIS...TX...
MODELS INDICATE THAT THE BLOCKING UPPER RIDGE OVER THE PACIFIC
NORTHWEST/NORTHERN INTERMOUNTAIN REGION WILL BREAK DOWN DURING THIS
FORECAST PERIOD...AS A CLOSED LOW/SHORT WAVE TROUGH IS FORCED INLAND
ACROSS THE PACIFIC NORTHWEST COAST...IN RESPONSE TO THE EASTWARD
PROGRESSION OF A MORE SIGNIFICANT UPSTREAM IMPULSE ACROSS THE
CENTRAL/EASTERN PACIFIC. AT THE SAME TIME...THE AMPLIFIED
DOWNSTREAM TROUGH OVER THE PLAINS IS EXPECTED TO BECOME INCREASINGLY
FRACTURED AND SHEARED. RESULTANT SMALLER SCALE IMPULSES ARE
EXPECTED TO BEGIN ACCELERATING EASTWARD THROUGH THE STRONG CONFLUENT
REGIME...BETWEEN THE DEEP POLAR VORTEX CENTERED NORTH OF HUDSON BAY
AND A STRONG HIGH CENTERED NEAR THE CARIBBEAN. HOWEVER...A PORTION
MAY DIG INTO THE SOUTHERN ROCKIES...AND CONSOLIDATE WITH THE
REMNANTS OF A CLOSED LOW...NOW TURNING EASTWARD ACROSS THE NORTHERN
MEXICAN PLATEAU...TO FORM A BROADER SCALE CIRCULATION OVER THE
SOUTHERN ROCKIES/HIGH PLAINS.

WHILE THE LARGE SCALE PATTERN WILL CONTINUE TO FAVOR COOL/COLD
SURFACE RIDGING...AND GENERALLY STABLE CONDITIONS...ACROSS MUCH OF
THE NATION...LOWER/MID TROPOSPHERIC THERMAL AND MOISTURE ADVECTION
DOWNSTREAM OF THE MEXICAN PLATEAU IMPULSE MAY CONTRIBUTE TO WEAK
DESTABILIZATION ACROSS MUCH OF SOUTHWESTERN/CENTRAL AND SOUTHERN
TEXAS. THE UNSTABLE LAYER LIKELY WILL BE BASED ABOVE A DEEP SURFACE
BASED STABLE LAYER...GENERALLY NEAR OR ABOVE 700 MB...WITH CAPE
MOSTLY VERY WEAK AND CONFINED TO A SUB-FREEZING ENVIRONMENT. THIS
MAY EXTEND THROUGH THE -10 TO -20C LAYER THOUGH...WITH FORECAST
SOUNDINGS ALSO SUGGESTIVE THAT MOST UNSTABLE PARCELS MAY EMANATE
FROM SATURATED LAYERS CLOSE TO THE FREEZING LEVEL...WITH THE
POSSIBILITY OF THE PRESENCE OF ENOUGH SUPERCOOLED CLOUD WATER TO
CONTRIBUTE TO POTENTIAL FOR CHARGE SEPARATION. SOME CONVECTION WITH
LIGHTNING DOES NOT SEEM COMPLETELY OUT OF THE QUESTION DURING THE
DAY ACROSS PARTS OF SOUTHWEST TEXAS...AND OVERNIGHT SOUTHEAST OF THE
BIG BEND INTO CENTRAL TEXAS. HOWEVER...THUNDERSTORM PROBABILITIES
STILL APPEAR BELOW THE MINIMUM 10 PERCENT THRESHOLD FOR A
CATEGORICAL OUTLOOK AT THE PRESENT TIME.

..KERR/DISPIGNA.. 01/03/2013

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