FXUS64 KSJT 292332
AFDSJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
532 PM CST SUN NOV 29 2009
.DISCUSSION...
SEE THE 00Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
MVFR CIGS WILL BE COMMON ACROSS THE W CNTRL TX TERMINALS THRU
AROUND 06Z. IFR CIGS AT KABI SHOULD BECOME MVFR BY 02Z OR SO. A
TREND TOWARD VFR IS EXPTD AT ALL TAF SITES BY 12Z. A FEW RAIN
SHOWERS ARE ALSO POSSIBLE BEFORE 12Z ACROSS THE SOUTHERN TERMINALS
OF KJCT- KSOA- KBBD.
LACY
&&
.PREV DISCUSSION... /ISSUED 350 PM CST SUN NOV 29 2009/
SHORT TERM...
UPPER LOW WAS OVER THE NORTHERN BAJA PENINSULA...MOVING SLOWLY
SOUTH. COLD FRONT EXTENDED FROM SONORA TO NEAR SAN SABA AT 3 PM.
VERY LITTLE LIFT INDICATED IN THE GFS AND NAM MODELS OVER WC TEXAS
TONIGHT AND DAYTIME MONDAY. PUT HIGHEST CHANCES IN SW ZONES WHERE
UPPER LOW WILL BRING IN SOME WEAK LIFT. FARTHER NORTH...RAIN
CHANCES LOOK SLIGHT... ESPECIALLY OVER THE BIG COUNTRY...WHERE
DRIER AIR IN THE LOWER LEVELS WORKS IN FROM THE NORTH.
LONG TERM...
COMPLICATED FORECAST CONTINUES FOR THE EARLY PART OF THE EXTENDED
PERIOD. MINOR DIFFERENCES IN TRACK/STRENGTH OF THE CLOSED UPPER
LEVEL LOW CURRENTLY OVER BAHA WILL CONTINUE TO MAKE FOR A
DIFFICULT FORECAST WITH REGARD TO THE POTENTIAL FOR WINTER
PRECIPITATION OVER WEST CENTRAL TEXAS TUE INTO WED. 12Z GFS/ECMWF
SIMILAR IN TRACK AND STRENGTH WHICH TAKES THE UPPER LOW ACROSS
SOUTHWEST TEXAS ON TUE THEN EAST ACROSS THE I-10 CORRIDOR OVER
WEST CENTRAL TEXAS TUE NIGHT. CURSORY LOOK AT THE 18Z NAM IS
SIMILAR IN TRACK BUT ABOUT 6 HOURS SLOWER IN MOVING THE SYSTEM
EAST TUE NIGHT. THE SLOWER NAM WOULD DELAY THE ONSET OF WINTER
PRECIP UNTIL LATE TUE OR EVEN TUE NIGHT WHEN THE COLUMN IS ABLE
TO COOL SUFFICIENTLY TO SUPPORT THE FROZEN VARIETY. CURRENT
FORECAST IS CLOSER TO THE GFS BUT WITH A BIT SLOWER TRANSITION
TO SNOW THAN PREVIOUS FORECASTS.
DYNAMICS INCREASE DRAMATICALLY ACROSS THE AREA MON NIGHT INTO
EARLY TUE AS STRONG FORCING ALOFT DEVELOPS IN ADVANCE OF THE
UPPER LOW AND WAA/ISENTROPIC LIFT INCREASES OVER THE AREA. HAVE
INCREASED POPS TO LIKELY ON TUE WITH A RAIN/SLEET MIX OCCURRING
OVER THE EXTREME WESTERN PORTIONS OF THE CONCHO VALLEY AND NORTH
EDWARDS PLATEAU BY DAYBREAK TUE. A RAIN/SNOW MIX WILL BE POSSIBLE
ACROSS MAINLY THE WESTERN HALF OF THE CWFA INTO TUE AFTERNOON WITH
A CHANGEOVER TO ALL SNOW EXPECTED OVER EXTREME WESTERN SECTIONS.
THE POTENTIAL EXISTS FOR HEAVY PRECIPITATION ACROSS MUCH OF THE
AREA ON TUE WITH THE MOST LIKELY AREA FOR ANY ACCUMULATING
SNOWFALL OVER THE WESTERN PORTIONS OF THE BIG COUNTRY...CONCHO
VALLEY AND NORTH EDWARDS PLATEAU WHERE UP TO AN INCH IS POSSIBLE.
TEMPERATURES WILL BE COLD ON TUE WITH HIGHS ONLY IN THE 30S AND
LOWER 40S...WARMEST OVER EASTERN SECTIONS. UPPER LOW PASSES BY TO
THE SOUTH TUE NIGHT WITH PRECIP EXPECTED TO CHANGE OVER TO MOSTLY
LIGHT SNOW OVER THE WESTERN HALF OF THE CWFA WITH A MIX OF
RAIN/SNOW FURTHER EAST. WRAP AROUND PRECIP WILL LINGER INTO WED
BUT SHOULD SEE A CHANGEOVER TO RAIN BY AFTERNOON AS SFC TEMPS WARM
INTO THE 40S.
DRYING TREND WED NIGHT INTO THU AS UPPER SYSTEM MOVES EAST AND
NORTHWEST FLOW ALOFT DEVELOPS OVER THE AREA.TEMPS WILL REMAIN COOL
THROUGH THE PERIOD WITH HIGHS MAINLY IN THE 50S AND OVERNIGHT
LOWS IN THE 30S.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 35 54 34 38 34 / 20 20 20 60 50
SAN ANGELO 39 49 36 37 34 / 20 20 60 70 40
JUNCTION 42 50 41 43 34 / 40 50 60 70 30
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
