Mesocale and Area Forecast Discussions

Mesocale and Area Forecast Discussions
SPC Mesoscale Discussion	WFO OUN Norman
MESOSCALE DISCUSSION 0026 0711 PM CST TUE JAN 04 2005 AREAS AFFECTED ... TX AND OK PANHANDLES ... NW OK ... SWRN THROUGH E CNTRL KS CONCERNING ... FREEZING RAIN AND SLEET PRECIPITATION ... MOSTLY IN THE FORM OF FREEZING RAIN IS EXPECTED TO INCREASE IN COVERAGE AND INTENSITY FROM PARTS OF THE TX AND OK PANHANDLES NEWD THROUGH NW OK INTO SRN AND CNTRL KS. FREEZING RAIN RATES FROM .05 TO .1 INCHES PER HOUR WILL BE LIKELY. LOCALLY HIGHER RATES FROM .15 TO .2 INCHES PER HOUR WILL BE POSSIBLE. A SHALLOW LAYER OF COLD AIR ... GENERALLY AOB 1000 M DEEP ... REMAINS OVER MUCH OF CNTRL/S KS AND SWD INTO OK AND NW TX WITH THE FREEZING LINE FROM NERN KS SWWD THROUGH NW OK INTO THE NRN TX PANHANDLE. ABOVE THE SHALLOW COLD LAYER ... PERSISTENT WARM ADVECTION ALONG A 30-40 KT SLY LOW LEVEL JET HAS RESULTED IN A RATHER SUBSTANTIAL WARM NOSE ... AND THIS THERMODYNAMIC PROFILE WILL CONTINUE TO SUPPORT PRECIPITATION TYPE IN THE FORM OF MOSTLY FREEZING RAIN IN THE PREVIOUSLY MENTIONED AREAS. A TEMPORARY BREAK IN THE HEAVIER PRECIPITATION HAS OCCURRED ACROSS KS AS THE LEAD SHORTWAVE MIGRATES TOWARD THE MS VALLEY. THE BAROCLINIC ZONE OVER KS WILL BE REINFORCED BY A SWD MOVING ARCTIC BOUNDARY CURRENTLY EXTENDING FROM SW THROUGH NE KS. THIS WILL OCCUR AS AN UPSTREAM SHORTWAVE TROUGH EJECTS NEWD THROUGH W TX. THE PERSISTENT STRONG SLY LOW LEVEL JET AND APPROACHING SHORTWAVE TROUGH INTERACTING WITH THE STRENGTHENING LOW LEVEL BAROCLINIC ZONE WILL COMBINE TO ENHANCE VERTICAL MOTION AND PRECIPITATION RATES/COVERAGE FROM THE TX AND OK PANHANDLES NEWD INTO SRN AND CNTRL KS. A MIX WITH OR CHANGE TO SLEET AND SNOW MAY OCCUR FROM PARTS OF THE TX AND OK PANHANDLES THROUGH SW AND CNTRL KS LATER TONIGHT.	AREA FORECAST DISCUSSION 310 PM CST TUE JAN 4 2005 SIGNIFICANT ICE STORM EXPECTED ACROSS APPROX NW THIRD OF FA TONITE. ICE HAS ALREADY BEGUN TO AFFECT SOME OF THESE AREAS WITH POWER OUTAGES AND ICE ACCUMULATING ON ELEVATED SURFACES FROM MORNING AND AFTN FREEZING RAIN. THIS RAIN CONT TO LIFT NE INTO KS. ANOTHER ROUND OF PRECIP EXPECTED TONITE INTO WED AS SHORTWAVE ROTATES AROUND UPR LOW AND AS THIS UPR SYSTEM ... CURRENTLY MOVING INTO WESTERN U.S ... MOVES ACROSS THE PLAINS. STRONGER CAA EXPECTED TO DEVELOP TONITE/WED ACROSS THE FA WHICH WILL PUSH THE FREEZING LINE FURTHER SOUTH CAUSING MANY LOCATIONS ACROSS APPROX NW HALF OF OK TO SEE FROZEN PRECIP BEGINNING WITH FREEZING RAIN THAT COULD EVENTUALLY CHANGE TO FREEZING RAIN AND IP OR SNOW AND IP AS COLD AIR DEEPENS BEFORE ENDING. ICE ACCUMULATION TOTALS OF NEAR AN INCH IN NW OK TO LIGHT ACCUMULATIONS FROM SW TO CENTRAL OK POSSIBLE. PRECIP EXPECTED TO END WED FROM WEST TO EAST. WILL MAINTAIN CURRENT ICE STORM WARNING AND FREEZING RAIN ADVISORY. RAIN HAS ENDED ACROSS SOUTHERN HALF OF OK AND N TX THIS AFTN. HOWEVER ... MORE RAIN AND STORMS ARE EXPECTED IN THIS AREA TONITE. WITH ANTECEDENT WET CONDITIONS IN PARTS OF SOUTHEAST AND SOUTH CENTRAL OK AND WESTERN N TX ANY ADDITIONAL RAINFALL COULD CAUSE SOME MAINSTEM FLOODING PROBLEMS SO WILL MAINTAIN FLOOD WATCH FOR TONITE EXCEPT FOR THE NORTHERN TIER OF COUNTIES WHICH HAS NOT RECEIVED AS MUCH RAINFALL. TEMPS WILL BE DIFFICULT TO FORECAST NEXT 24 HOURS. WARM FRONT CONT TO LIFT N ACROSS TX AND COULD MOVE INTO EXTREME SOUTHERN PARTS OF FA WHICH WILL AFFECT OVERNIGHT LOWS. MAX TEMPS WED EXPECTED TO OCCUR IN THE MORNING IN MANY LOCATIONS WITH TEMPS FALLING DURING THE DAY.