Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 230825
SWOMCD
SPC MCD 230824
TXZ000-231300-

MESOSCALE DISCUSSION 0092
NWS STORM PREDICTION CENTER NORMAN OK
0224 AM CST MON FEB 23 2015

AREAS AFFECTED...TX LOW ROLLING PLAINS / N-CNTRL TX

CONCERNING...WINTER MIXED PRECIPITATION

VALID 230824Z - 231300Z

SUMMARY...FREEZING RAIN WILL GRADUALLY EXPAND IN COVERAGE/RATE LATE
TONIGHT FROM PORTIONS OF THE EDWARDS PLATEAU AND TX LOW ROLLING
PLAINS EWD TOWARDS THE DFW METROPLEX.  A TRANSITION TO A MIX OF
SLEET/FREEZING RAIN IS EXPECTED AND P-TYPE FAVORING SLEET WILL
BECOME MORE PROBABLE ACROSS WRN N-CNTRL TX TOWARDS THE EARLY MORNING
HOURS.

DISCUSSION...RADAR MOSAIC AT 0820Z SHOWS A GRADUAL BLOSSOMING OF
CONVECTIVE RAIN SHOWERS OVER PARTS OF THE EDWARDS PLATEAU AND TX LOW
ROLLING PLAINS.  A FEW LIGHTNING FLASHES HAVE BEEN DETECTED WITH
SOME OF THIS ACTIVITY AND THIS WILL PROBABLY CONTINUE AS WEAK
ELEVATED BUOYANCY NOTED ON THE 23/00Z FWD RAOB WILL SUPPORT
CONVECTIVE SHOWERS/TSTMS.  SURFACE ANALYSIS SHOWS TEMPS RANGING FROM
NEAR 20 DEG F WEST TO AROUND 30 NEAR I-35 RESULTING IN FROZEN
PRECIPITATION.

SUITE OF MODEL GUIDANCE APPEARS TO HAVE UNDERESTIMATED EITHER 1)
TROPOSPHERIC DEPTH OF ABOVE FREEZING AIR IN THE H8-H65 LAYER OR 2)
TOO AGGRESSIVELY CHANGED P-TYPE TO SLEET ACROSS THIS REGION COMPARED
TO OBSERVATIONS IN THE 07-08Z TIMEFRAME.  MODELS SHOW UPWARD
VERTICAL MOTION INCREASING ACROSS THIS REGION THROUGH 12Z AS THE
WARM LAYER NEAR H7 SATURATES/COOLS.  AS THIS OCCURS OVER THE NEXT
SEVERAL HOURS...PRECIPITATION WILL SLOWLY BECOME MORE WIDESPREAD AND
FREEZING RAIN RATES AROUND 0.05 INCH PER 3 HOURS PROBABLE ARE IN
AREAS.  FORECAST SOUNDINGS INDICATE A FREEZING RAIN TO SLEET
TRANSITION WILL PROBABLY OCCUR OVER AT LEAST THE NWRN HALF OF THE
DISCUSSION AREA BY EARLY MORNING AS THE DEPTH OF THE COLD AIR
INCREASES BELOW THE MELTING LAYER ALOFT.

..SMITH.. 02/23/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

LAT...LON   31739924 31850036 32450105 33270096 33660035 33639715
            33299648 32809638 32299678 31739924



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