Chance For Severe Wx Tomorrow Night…

February 19th, 2013 at 6:54 am by under Weather

The experts in Norman, OK working at the NWS Storm Prediction Center have included the northern and western part of our viewing area in the “slight risk” area for severe weather.  This threat will arrive sometime Wednesday night into Thursday morning.  Of course, we will keep a very close eye on the radar as we inch closer to the threatening time period.  Our First Warning Weather Meteorologists will keep you posted on any severe weather threat that pops up.  Also, keep yourself ahead of the storms by monitoring our Interactive Radar on KXAN.com.  You can log on 24 hours a day, 7 days a week.  

Here is the latest write up about the storms from our friends at the SPC:

   SPC AC 190556

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1156 PM CST MON FEB 18 2013

   VALID 201200Z - 211200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS WEDNESDAY NIGHT ACROSS PARTS OF
   NORTHERN AND CENTRAL TEXAS...

   ...SYNOPSIS...
   A LARGE-SCALE UPPER TROUGH...CURRENTLY ADVANCING ACROSS AND EAST OF
   THE MISSISSIPPI VALLEY...APPEARS LIKELY TO PROGRESS OFF THE ATLANTIC
   COAST DURING THIS FORECAST PERIOD.  IN ITS WAKE...MID-LEVEL HEIGHTS
   SHOULD RISE IN ADVANCE OF ANOTHER LARGE-SCALE TROUGH...WHICH IS
   FORECAST TO CONTINUE TO EVOLVE ACROSS THE WESTERN AND CENTRAL
   U.S...WITHIN THE SOUTHERN BRANCH OF A SPLIT FLOW EMERGING FROM THE
   PACIFIC.  VARIABILITY IS SIZABLE AMONG THE MODELS AND MODEL
   ENSEMBLES CONCERNING SHORT WAVE IMPULSES ROUNDING THE CREST OF A
   BROAD AND AMPLIFIED EASTERN PACIFIC RIDGE...INTO THE TROUGH...AFTER
   EMANATING FROM A STRONG UPSTREAM MID-LATITUDE PACIFIC JET.  BUT
   GUIDANCE HAS REMAINED FAIRLY CONSISTENT WITH REGARD TO A VERY STRONG
   INITIAL SHORT WAVE TROUGH...WHICH IS FORECAST TO EMERGE FROM THE
   SOUTHERN INTERMOUNTAIN REGION.

   THIS LATTER FEATURE STILL APPEARS LIKELY TO TAKE ON AN INCREASING
   NEGATIVE TILT AND BEGIN LIFTING NORTHEASTWARD AS IT CROSSES THE
   SOUTHERN ROCKIES INTO THE CENTRAL AND SOUTHERN PLAINS LATE WEDNESDAY
   NIGHT...ACCOMPANIED BY A CYCLONIC 100 KT 500 MB JET STREAK.  PRIMARY
   SURFACE CYCLOGENESIS IS FORECAST TO TAKE PLACE ACROSS THE CENTRAL
   HIGH PLAINS...BUT SECONDARY WAVE DEVELOPMENT ALONG A FRONTAL ZONE
   ACROSS WESTERN INTO CENTRAL TEXAS IS STILL EXPECTED.  MODELS
   INDICATE THAT THIS WILL BE ACCOMPANIED BY THE DEVELOPMENT OF A 50-70
   KT SOUTHERLY 850 MB JET ACROSS THE SOUTHERN PLAINS...EVENTUALLY
   EXTENDING SOUTHWARD INTO THE WESTERN GULF OF MEXICO.  THIS WILL AID
   THE INLAND ADVECTION OF MOISTURE OFF A SLOWLY MOISTENING GULF OF
   MEXICO BOUNDARY LAYER...AS THE ADVECTION OF MIXED LAYER AIR OFF THE
   HIGHER TERRAIN TO THE WEST CONTRIBUTES TO STEEPENING MID-LEVEL LAPSE
   RATES.

   THOUGH A COOL TO COLD...AND STABLE...SURFACE BASED AIR MASS MAY
   REMAIN ENTRENCHED ACROSS MUCH OF THE CENTRAL AND SOUTHERN
   PLAINS...DEEPEST TO THE NORTH OF THE TEXAS FRONTAL
   ZONE...DESTABILIZATION ABOVE THIS LAYER IS EXPECTED TO BECOME
   SUFFICIENT FOR CONSIDERABLE THUNDERSTORM ACTIVITY WEDNESDAY AND
   WEDNESDAY NIGHT.  THE MOST SUBSTANTIVE DESTABILIZATION IS EXPECTED
   WITH THE BETTER RETURN FLOW OF GULF MOISTURE ACROSS PARTS OF
   NORTHERN AND CENTRAL TEXAS WEDNESDAY NIGHT...WHERE/WHEN SEVERE
   STORMS ARE POSSIBLE.

   ...NORTHERN AND CENTRAL TEXAS...
   STRONGEST MID/UPPER FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED
   WITH THE POLAR JET WILL SHIFT ACROSS THE ROCKIES INTO THE CENTRAL
   PLAINS...WELL TO THE NORTH OF THE REGION.  BUT UPPER FLOW WEDNESDAY
   NIGHT IS EXPECTED TO BECOME INCREASINGLY DIFLUENT...AND PERHAPS
   DIVERGENT...BETWEEN THE POLAR JET AXIS CURVING NORTHEASTWARD ACROSS
   THE TEXAS PANHANDLE...AND THE SUBTROPICAL JET AXIS EXTENDING EAST
   NORTHEAST OF THE TEXAS BIG BEND INTO THE LOWER MISSISSIPPI VALLEY. 
   AS WARMING MID-LEVELS CAP THE MOISTURE RETURN...PRIMARY STORM
   INITIATION IS EXPECTED TO AWAIT THE LEADING EDGE OF STRONGER
   MID-LEVEL COOLING...WHICH LATEST MODEL GUIDANCE APPEARS TO BE
   SUGGESTING A BIT SLOWER THAN EARLIER RUNS.  THIS SEEMS MOST LIKELY
   FROM 21/03-06Z...ALONG THE WARM FRONT JUST AHEAD OF THE SECONDARY
   SURFACE WAVE...NORTHEAST OF MIDLAND.  CONVECTION MAY EXPAND IN
   COVERAGE AND INTENSIFY AS IT SPREADS EASTWARD AND ENCOUNTERS BETTER
   MOISTURE...AND MORE SUBSTANTIVE CAPE...IN THE PRESENCE OF STRONG
   DEEP LAYER SHEAR.

   GENERALLY ELEVATED ABOVE THE WARM FRONTAL INVERSION...LARGE HAIL MAY
   BE THE PRIMARY SEVERE THREAT INITIALLY.  BUT THE SYNOPTIC
   SET-UP...STRONG LOW-LEVEL SHEAR...AND PRESENCE OF LOADED GUN TYPE
   SOUNDINGS ABOVE THE SURFACE BASED STABLE LAYER SUGGEST THE POTENTIAL
   FOR THE DEVELOPMENT OF A SIGNIFICANT SURFACE PRESSURE
   PERTURBATION...WITH THE RISK OF STRONG SURFACE GUSTS AS ACTIVITY
   SPREADS EASTWARD OVERNIGHT.

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