Mesoscale Discussion 99

Issued

Feb 9, 2011, 2:33 AM CST (08:33 UTC)

Expired

Feb 9, 2011, 6:30 AM CST

In force

4 hr

Issued by

the Storm Prediction Center

The Dallas/Ft Worth radar (KFWS), 75 km from the middle of the area, began a volume at 08:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

524 
ACUS11 KWNS 090834
SWOMCD
SPC MCD 090833
TXZ000-OKZ000-091230-

MESOSCALE DISCUSSION 0099
NWS STORM PREDICTION CENTER NORMAN OK
0233 AM CST WED FEB 09 2011

AREAS AFFECTED...PORTIONS N-CENTRAL/NE TX AND SERN OK.

CONCERNING...WINTER MIXED PRECIPITATION

VALID 090833Z - 091230Z

RAIN ACCOMPANYING COLD FROPA IS FCST TO CHANGE QUICKLY TO FREEZING
RAIN WITH OCNL SLEET...BEFORE TURNING TO MOSTLY LIGHT-MDT SNOW AND
TAPERING FROM W-E.  ICING RATES .1-.2 INCH/HOUR ARE POSSIBLE
BRIEFLY...LOCALLY HIGHER IN EMBEDDED SHOWERS...WITH SIMILAR LIQUID
EQUIVALENTS OF SLEET POSSIBLE BEFORE PRECIP BECOMES SNOW.  LIGHTER
RATES ARE POSSIBLE FARTHER SW INTO HILL COUNTRY...HOWEVER MOST
SIGNIFICANT SHORT-TERM POTENTIAL SHOULD BE FROM METROPLEX EWD AND
NEWD.

08Z SFC ANALYSIS AND REFLECTIVITY IMAGERY INDICATE SFC COLD FRONT
MOVING EWD APPROXIMATELY 25 KT ACROSS N-CENTRAL TX...S OF WEAK
FRONTAL WAVE OVER NRN FRINGES DFW METROPLEX.  FCST SOUNDINGS SUGGEST
ADJUSTMENT OF LOW-LEVEL VERTICAL THERMAL PROFILE RELATED TO SHARP
DECLINE IN BOUNDARY-LAYER TEMPS BEHIND FRONT...AS WELL AS WAA/UVV
ATOP SLOPED FRONTAL SFC FOLLOWED BY LARGE-SCALE ASCENT/COOLING OF
ENTIRE COLUMN...WILL LEAD TO QUICK PRECIP PHASE CHANGE AND AN
INCREASING POTENTIAL FOR ACCUMULATING ICING AND BRIEF BURSTS OF
SLEET.  PRECIP AREA NOW FOLLOWING FRONT INTO WRN PORTIONS DFW
METROPLEX ALSO SHOULD EXPAND ACROSS RED RIVER REGION AND PERHAPS SWD
TO AREAS S/SE OF METROPLEX AS FRONT UNDERCUTS NRN SEGMENT OF 35-45
KT LLJ THAT WILL BECOME PROGRESSIVELY MORE MOIST WITH TIME.
VWP/PROFILER DATA SUGGEST LLJ AXIS CURRENTLY NEAR SAT-DFW
LINE...BENDING NWWD ACROSS SRN OK AND BEING LIFTED INTO SNOW REGIME
INITIALLY COVERED BY SPC MESOSCALE DISCUSSION 98.  GPS PW DATA
INDICATES INCREASING MOISTURE CONTENT OVER N-CENTRAL TX RELATED TO
MOIST ADVECTION/TRANSPORT IN LLJ...A PROCESS THAT SHOULD CONTINUE
AND SHIFT EWD AS
1. AXIS OF LLJ MOVES SLOWLY EWD AND FLOW IN IT VEERS SLIGHTLY...AND
2. COLD FRONT AND RELATED LOW-LEVEL ASCENT PROGRESS EWD AT FASTER
RATE THAN LLJ SHIFT.

..EDWARDS.. 02/09/2011

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

ATTN...WFO...SHV...TSA...FWD...OUN...

LAT...LON   31869782 32599770 33569715 33849673 34069632 34189600
            34109550 33899517 33339513 32509545 32019599 31629675
            31629742 31719771 31869782

Mesoscale Discussions in Texas, 2011Mesoscale Discussions in Oklahoma, 2011Every mesoscale discussion in 2011

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.