FXUS64 KSJT 231740
AFDSJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1140 AM CST WED DEC 23 2009
.DISCUSSION...
SEE 18Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
A STRONG UPPER LEVEL LOW OVER THE SOUTHERN ROCKIES WILL MOVE EAST
ACROSS NORTHERN TEXAS TONIGHT AND THURSDAY. ISOLD TSTMS WILL BE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY EAST OF A CROSS
PLAINS TO JUNCTION LINE...WITH SCT SHWRS POSSIBLE ELSEWHERE. UPPER
LEVEL DYNAMICS AND WRAP AROUND MOISTURE WILL BEING SOME SNOW TO
THE BIG COUNTRY LATE TONIGHT AND THURSDAY MORNING.
21
&&
PREV DISCUSSION... /ISSUED 348 AM CST WED DEC 23 2009/
SHORT TERM...
.POTENTIAL FOR LIGHT SNOW ACCUMULATIONS IN THE NORTHERN BIG
COUNTRY LATE TONIGHT...
UPPER LOW WAS DIGGING INTO NW NEW MEXICO AT 8Z. GFS...NAM...AND
ECMWF MODELS HAVE UPPER LOW MOVING EAST SOUTHEAST ACROSS THE BIG
COUNTRY TONIGHT. CENTER IS PRETTY MUCH ALONG THE I-20 CORRIDOR...
ALTHOUGH THE NAM IS A LITTLE FARTHER NORTH BY ABOUT 50 MILES.
THIS WILL BE A DYNAMIC UPPER SYSTEM...WITH GOOD LIFT AND DECENT
MOISTURE. BEST LIFT WILL BE AHEAD OF THE SYSTEM 6 PM TO MIDNIGHT.
THIS WILL BE ALL RAIN THIS EVENING. LATER...AS CENTER OF UPPER
LOW PASSES OVER THE THE BIG COUNTRY...3 AM INTO THE EARLY THURSDAY
MORNING...IT HAS THE POTENTIAL FOR SOME LIGHT SNOWFALL
ACCUMULATIONS...PARTICULARLY ACROSS HASKELL AND THROCKMORTON
COUNTIES...WHICH WILL BE APPROXIMATELY 50 MILES NORTH OF THE
CENTER OF THE UPPER LOW. IF THE UPPER LOW DOES TRACK ACCORDING TO
GFS MODEL...POTENTIAL EXISTS FOR ACCUMULATIONS OF AN INCH OR TWO
OF SNOW. NAM IS DRIER AS USUAL...1 OR 2 TENTHS. IF THE GFS TRACK
HOLDS ...THERE IS THE POSSIBILITY OF A WINTER WEATHER ADVISORY
LATER TODAY...FOR THE NORTHERN BIG COUNTRY FOR LATE TONIGHT INTO
EARLY THURSDAY MORNING. MITIGATING FACTORS FOR HEAVY SNOWFALL
POTENTIAL WILL BE THE SHORT TIME WINDOW AND DRIER AIR ON THE BACK
SIDE OF UPPER LOW.
OTHERWISE FOR THIS MORNING AND THIS THIS AFTERNOON...LOW CLOUDS
WILL BE BREAKING UP MID/LATE MORNING. A FEW AREAS OF PATCHY FOG
POSSIBLE THROUGH MID MORNING...ALONG EDGES OF HOLES IN STRATUS.
MID/UPPER CLOUDS ASSOCIATED WITH APPROACH OF UPPER LOW WILL MOVE
INTO THE REGION FROM THE WEST MID AFTERNOON...KEEPING TEMPERATURES
DOWN A LITTLE. DID GO A COUPLE DEGREES WARMER THAN GFS GUIDANCE
HOWEVER WITH DOWN SLOPE SW WINDS TODAY.
LONG TERM...
BY THURSDAY MORNING...THE UPPER LEVEL LOW IS EXPECTED TO BE OVER
NORTH TEXAS...MOVING NORTHEAST AWAY FROM WEST CENTRAL TEXAS. THE
SFC COLD FRONT WILL HAVE MOVED THROUGH MOST OF THE CWA BY 6 AM.
EXPECT TO SEE SOME LINGERING SNOW SHOWERS ACROSS THE BIG COUNTRY
THROUGH THE MORNING HOURS ON THE BACKSIDE OF THE UPPER LEVEL LOW.
HOWEVER...IF ACCUMULATION OCCURS...IT WILL LIKELY BE PRIOR TO THIS
TIME PERIOD.
BEHIND THE COLD FRONT...EXPECTING MUCH COLDER TEMPERATURES FOR
THURSDAY...AND HAVE KEPT HIGHS IN THE UPPER 30S FOR THE NORTHERN
BIG COUNTRY...WITH 40S AS FAR SOUTH AS THE HEARTLAND AND CONCHO
VALLEY AREAS AS 850MB TEMPERATURES WILL COOL THROUGHOUT THE DAY
ON THURSDAY.
ON FRIDAY...AS THIS FIRST LOW IS MOVING NORTHEAST AWAY FROM THE
AREA...ANOTHER UPPER LEVEL DISTURBANCE WILL BE PULLED SOUTH FROM
CANADA BEHIND IT. THIS WILL KEEP THE AREA COOL FRIDAY AS 850MB
TEMPS GET A REINFORCING SHOT OF COLD AIR. LOWS FRIDAY AND SATURDAY
MORNING WILL BE VERY COLD...IN THE 20S ACROSS THE AREA WITH A FEW
LOCAL AREAS POSSIBLY DROPPING INTO THE TEENS.
A LARGE AREA OF TROUGHING WILL COVER THE MIDSECTION OF THE U.S.
THROUGH SATURDAY...CONTINUING TO KEEP WEST CENTRAL TEXAS COOLER
THAN NORMAL. 850MB TEMPERATURES REMAIN COOL THROUGH EARLY NEXT
WEEK...SO EXPECT TO SEE COOLER THAN NORMAL TEMPERATURES THROUGH
THE FIRST HALF OF NEXT WEEK. WE WILL ALSO EXPERIENCE A FAIRLY WIDE
DIURNAL RANGE WITH PARTLY CLOUDY TO MOSTLY CLEAR SKIES...LIGHT
WINDS...AND DRY AIR IN PLACE.
WEAK RIDGING WILL ALLOW A SLOW WARM-UP TO CONTINUE INTO THE
MIDDLE OF NEXT WEEK. THERE IS A HINT OF AN UPPER LEVEL LOW AND
SOUTHWEST FLOW AFFECTING THE AREA NEAR THE END OF THE
FORECAST...AND HAVE KEPT SLIGHT CHANCE POPS GOING FOR EASTERN
AREAS. STILL A LOT OF UNCERTAINTY THAT FAR OUT THOUGH.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 65 34 40 21 43 / 20 70 30 0 0
SAN ANGELO 65 37 43 22 46 / 20 40 0 0 0
JUNCTION 68 41 48 22 48 / 20 40 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
