FXUS64 KSJT 291700
AFDSJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1100 AM CST SUN NOV 29 2009
.UPDATE...
MADE CHANGES IN GRIDS...FOR DECREASING TEMPERATURES BEHIND FRONT.
&&
.DISCUSSION...
COLD FRONT WAS ALONG FORT STOCKTON...SAN ANGELO...MINERAL WELLS
LINE AT 11 AM. TEMPERATURES WERE FALLING INTO THE 40S AND 50S
BEHIND THE FRONT WITH STRONGER COLD ADVECTION. MADE ADJUSTMENTS TO
TAKE OUT SOME DIURNAL TRENDS...WITH FALLING TEMPS.
&&
.AVIATION...
COLD FRONT WAS ALONG FORT STOCKTON...SAN ANGELO...MINERAL WELLS
LINE AT 17Z. MVFR CIGS BECOME VFR...FROM NORTH TO SOUTH...AS DRIER
AIR MOVES IN BEHIND FRONT...THIS AFTERNOON AND EVENING. MAY SEE
SOME SHOWERS AT KSOA AND KJCT LATE TONIGHT AND EARLY MONDAY
MORNING...AS LIFT APPROACHES FROM UPPER LEVEL LOW IN N BAJA.
&&
.PREV DISCUSSION... /ISSUED 517 AM CST SUN NOV 29 2009/
DISCUSSION...
SEE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
LOW CLOUDS HAVE MOVED INTO THE SOUTHERN HALF OF WEST CENTRAL TEXAS
EARLY THIS MORNING AND EXPECT MVFR/IFR CONDITIONS ACROSS MOST
AIRPORTS ACROSS THE AREA THROUGH AT LEAST MID MORNING. LOWEST
CEILINGS WILL BE ACROSS SONORA/JUNCTION AREAS. ALSO SEEING SOME
REDUCED VISIBILITY WITH LIGHT FOG. COLD FRONT WILL MOVE ACROSS
KABI AROUND 14Z...SJT BY 18Z AND JCT AREA BY 22Z WITH A WIND SHIFT
TO THE NORTH. LIGHT DRIZZLE/LIGHT RAIN POSSIBLE THROUGHOUT THE DAY
AS WELL MAINLY SOUTHERN AREAS. WILL LIKELY SEE LOW CLOUDS DEVELOP
AGAIN AFTER MIDNIGHT TONIGHT MAINLY SOUTHERN TAF SITES.
PREV DISCUSSION... /ISSUED 418 AM CST SUN NOV 29 2009/
.MUCH COLDER WITH A POSSIBILITY OF WINTRY PRECIPITATION MAINLY
WEST FOR TUESDAY NIGHT INTO WEDNESDAY...
SHORT TERM...
EARLY THIS MORNING...WATER VAPOR SATELLITE IMAGERY SHOWED A POTENT
UPPER LOW CONTINUING TO TO DIG SOUTHEAST ACROSS FAR SOUTHERN
CALIFORNIA AND ARIZONA. ABUNDANT MID/HIGH LEVEL MOISTURE WAS
STREAMING INTO WEST TEXAS AHEAD OF THE UPPER LOW. A WEAK SHORTWAVE
TROUGH EMBEDDED IN THE SOUTHWESTERLY FLOW ALOFT WAS HEADING INTO
WEST TEXAS WITH RADARS SHOWING LIGHT RAIN SHOWERS ACROSS MUCH OF
WEST TEXAS. A RATHER STRONG COLD FRONT WAS PUSHING SOUTHWARD ACROSS
WEST TEXAS EARLY THIS MORNING AND WAS LOCATED ALONG A WICHITA FALLS
TO JAYTON TO SEMINOLE LINE AT 330 AM.
THE FRONT WILL CONTINUE TO HEAD SOUTHWARD ACROSS WEST CENTRAL TEXAS
TODAY...BRINGING COOLER TEMPERATURES TO THE AREA BY THIS AFTERNOON.
THE FRONT SHOULD CROSS THE CONCHO VALLEY IN THE LATE MORNING AND
REACH THE HILL COUNTRY BY MID TO LATE AFTERNOON. SHOWERS WILL
CONTINUE TO DEVELOP ALONG AND AHEAD OF THE FRONT AS THE WEAK
SHORTWAVE MOVES ACROSS WEST TEXAS...WITH THE BEST CHANCE OF
MEASURABLE PRECIPITATION ACROSS THE SOUTHERN THIRD OF THE AREA.
CLOUDY AND COOL WEATHER WILL CONTINUE INTO TONIGHT WITH LOWS
DROPPING INTO THE MID 30S BY MORNING MAINLY WEST.
LONG TERM...
THE MAIN CHALLENGE FOR THE LONG TERM CONTINUES TO BE THE POSSIBILITY
OF WINTRY PRECIPITATION ON TUESDAY AS AN UPPER LEVEL CLOSED LOW
APPROACHES AND MOVES ACROSS THE AREA.
THE GFS AND ECMWF CONTINUE TO BE IN GOOD AGREEMENT WITH THE TRACK OF
A CLOSED LOW THAT IS CURRENTLY OVER THE DESERT SOUTHWEST AND IS
FORECASTED TO EAST ACROSS NORTHERN MEXICO INTO WEST TEXAS TUESDAY
AND THEN EAST OF WEST CENTRAL TEXAS ON WEDNESDAY. THIS FORECASTED
TRACK WOULD PLACE PORTIONS OF WEST CENTRAL TEXAS IN A FAVORABLE
AREA FOR WINTRY PRECIPITATION.
AS THE UPPER LEVEL STORM SYSTEM
APPROACHES EXPECT SHOWERS TO DEVELOP MONDAY AND CONTINUE INTO
TUESDAY....WITH THE COLDER AIR ALOFT MOVING IN ACROSS THE WESTERN
PORTION OF WEST CENTRAL TEXAS TUESDAY MORNING AND SPREADING EAST
AND NORTH AS THE UPPER LEVEL STORM SYSTEM TRACKS EAST. THE BEST
CHANCE FOR WINTRY PRECIPITATION WILL OCCUR ACROSS THE WESTERN
PORTIONS OF THE BIG COUNTRY...CONCHO VALLEY AND NORTHERN EDWARDS
PLATEAU TUESDAY MORNING INTO TUESDAY EVENING. WITH CHANCES
CONTINUING INTO WEDNESDAY MORNING...ESPECIALLY ACROSS THE BIG
COUNTRY DUE WRAP AROUND MOISTURE ON THE BACKSIDE OF THE UPPER
LEVEL LOW. THE LATEST SOUNDING INDICATE THE POSSIBILITY OF
RAIN/SLEET MIX EARLY TUESDAY MORNING ACROSS THE FAR WESTERN CONCHO
VALLEY AND NORTHERN EDWARDS PLATEAU AND THEN AS THE DAY PROGRESSES
THE MIX CHANGES OVER TO A RAIN OR SNOW MIX AND PUSHES EAST INTO
THE CENTRAL PORTIONS OF THE CONCHO VALLEY AND NORTHERN EDWARDS
PLATEAU. THERE IS STILL SOME UNCERTAINTY ON HOW COLD TEMPERATURES
WILL BE ON TUESDAY...AS OF NOW HAVE MID 30S ALONG AND WEST OF A
SWEETWATER TO SAN ANGELO TO OZONA LINE BUT THIS WILL MOST LIKELY
CHANGE OVER THE NEXT DAY OR TWO. GIVEN THAT HAVE KEPT TEMPERATURES
IN THE MID 30S...MOST OF THE PRECIPITATION THAT FALLS WILL BE IN
THE FORM OF RAIN/SNOW MIX ...BUT STILL MAY BE A FEW DEGREES TOO
WARM WHICH IF IS THE CASE WOULD CHANGE PRECIPITATION TYPE TO
MAINLY SNOW. AS FAR AS SNOWFALL ACCUMULATIONS...ATTM THINK 1 TO 2
INCHES WILL BE POSSIBLE ACROSS THE WESTERN PORTIONS OF THE BIG
COUNTRY..CONCHO VALLEY AND NORTHERN EDWARDS PLATEAU...BUT THIS
COULD CHANGE WITH LATER FORECASTS...SO HAVE HELP OFF ISSUING ANY
WATCHES OR ADVISORIES.
FOR WEDNESDAY AND BEYOND...HAVE GONE ON THE COOL SIDE OF GUIDANCE
AS ECMWF HAS HANDLED THE PAST COUPLE OF WEEKS PRETTY WELL...AS THE
ECMWF KEEPS A BROAD UPPER LEVEL TROUGH ACROSS THE EASTERN
CONUS..WHICH KEEPS WEST CENTRAL TEXAS UNDER DRY NORTHWEST FLOW
ALOFT...KEEPING THE COOLER AIR PLACE LONGER.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 55 35 49 33 38 / 20 20 20 30 50
SAN ANGELO 62 39 46 33 35 / 30 30 50 50 60
JUNCTION 68 42 46 36 43 / 30 40 50 60 60
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99/04
