Heavy Snow in TX
Posted by JAC on 2/23/2010, 1:17 pm
 MESOSCALE DISCUSSION 0141 NWS STORM PREDICTION CENTER NORMAN OK 1201 PM CST TUE FEB 23 2010 AREAS AFFECTED...PARTS OF N CNTRL/NE TX INTO NW LA CONCERNING...HEAVY SNOW VALID 231801Z - 232100Z MODERATE TO HEAVY SNOW LIKELY WILL IMPACT AREAS OF EAST TEXAS ALONG AND SOUTH OF THE INTERSTATE 20 CORRIDOR THROUGH THE BALANCE OF THE AFTERNOON HOURS. LATEST RUC GUIDANCE SUGGESTS THAT FRONTOGENETIC FORCING WITHIN A CONFLUENT MID-LEVEL FLOW REGIME REMAINS MAXIMIZED IN THE FAVORABLE DENDRITIC ICE CRYSTAL GROWTH LAYER...IN A BAND JUST SOUTH OF THE INTERSTATE 20 CORRIDOR...SOUTH THROUGH EAST OF THE DALLAS-FORT WORTH METROPLEX. THIS APPEARS LIKELY TO REMAIN THE CASE THROUGH AT LEAST THE 21-23Z TIME FRAME. HEAVIEST SNOW IS EXPECTED TO GRADUALLY DEVELOP EASTWARD...PERHAPS A BIT NORTHWARD...WITH A GREATER IMPACT ON INTERSTATE 20 INTO THE SHREVEPORT AREA BY 20-21Z ...AS LOWER LEVELS FARTHER EAST SATURATE AND COOL WITH THE ONSET OF PRECIPITATION. AIDED BY AVAILABLE PRECIPITABLE WATER ON THE ORDER OF .50-.75 INCHES...SUSTAINED SNOW RATES IN EXCESS OF 1 INCH PER HOUR APPEAR POSSIBLE...WHICH PROBABLY WILL CONTRIBUTE TO SIGNIFICANT ACCUMULATIONS ON ROAD SURFACES...DESPITE THE RELATIVELY WARM GROUND TEMPERATURES. ..KERR.. 02/23/2010  CONCERNING...HEAVY SNOW VALID 231238Z - 231815Z ALTHOUGH HEAVIEST PRECIP WILL REMAIN AS RAIN IN AREAS OF SUPERFREEZING SFC AIR...SNOW IS EXPECTED ACROSS PORTIONS CENTRAL/N-CENTRAL TX THROUGH 18Z. WITHIN BROADER AREA OF MDT SNOW...EPISODIC/CONVECTIVELY DERIVED BURSTS OF HEAVY SNOW ARE LIKELY...THE LATTER OFFERING SNOWFALL RATES 1-2 INCH/HOUR. MOISTURE CHANNEL IMAGERY AND AVAILABLE RAOB DATA INDICATE POSITIVELY-TILTED SHORTWAVE TROUGH OVER PORTIONS SRN NM...FAR W TX AND NRN CHIHUAHUA. THIS PERTURBATION...AND FOREGOING FIELD OF MID-UPPER LEVEL DPVA/ASCENT...WILL SHIFT ESEWD THROUGH REMAINDER MORNING...ERN EDGE OF MID-UPPER LIFT BEING JUXTAPOSED WITH WRN PART OF PLUME OF LOW LEVEL WAA. RELATED STEEPENING OF LOW-MIDLEVEL LAPSE RATES...ATOP ROUGHLY 3 KM DEEP STABLE LAYER...WILL RESULT IN WEAK ELEVATED BUOYANCY IN SOME LOCALES...UP TO ABOUT 100 /KG. THIS WILL SUPPORT EMBEDDED CONVECTIVE ENHANCEMENT TO PRECIP...AND ISOLATED THUNDER. STRONGEST LIFT IS EXPECTED ALONG AND N OF QUASISTATIONARY 850 MB FRONTAL/CONFLUENCE ZONE...EVIDENT IN 12Z RAOB/VWP/PROFILER DATA FROM BIG BEND AREA ENEWD TOWARD CLL. 12Z SFC ANALYSIS INDICATES WAVY FREEZING LINE...GENERALLY FROM SWRN AR NWWD TO S-CENTRAL OK THEN SWWD ACROSS WRN PORTIONS N-CENTRAL TX TO EDWARDS PLATEAU AND BIG BEND. FREEZING LINE IS EXPECTED TO UNDERGO NET SEWD MOTION ACROSS THIS REGION AS LOW LEVEL CAA AND EVAPORATIONAL/SUBLIMATIONAL COOLING OFFSET SECOND-ORDER EFFECT OF VERY WEAK DIABATIC HEATING. SNOW IS LIKELY BEHIND AND WITHIN ABOUT 50-75 NM AHEAD OF FREEZING LINE...GIVEN MODIFIED RAOBS AND RUC SOUNDINGS INDICATING COMBINATION OF MOSTLY BELOW-FREEZING THERMAL PROFILES ALOFT AND HIGH RH/UVV WITHIN DENDRITIC GROWTH ZONE. HOWEVER...NARROW AND SHORT-LIVED CORRIDOR OF FREEZING RAIN...LOCALLY MIXED WITH SLEET...ALSO IS POSSIBLE ALONG AND WITHIN 20-30 NM N OF SFC FREEZING LINE. THIS ZONE WILL MIGRATE SEWD WITH FREEZING LINE DURING REMAINDER MORNING. ..EDWARDS.. 02/23/2010 |
50
In this thread:
Post A Reply
This thread has been archived and can no longer receive replies.