FXUS64 KSJT 010455
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1055 PM CST MON NOV 30 2009

.DISCUSSION...
SEE 06Z AVIATION DISCUSSION BELOW.

&&

.AVIATION...
A STRONG UPPER LEVEL STORM SYSTEM WILL MOVE ACROSS NORTHERN MEXICO
TONIGHT AND EAST ACROSS TEXAS TUESDAY AND TUESDAY NIGHT. WIDESPREAD
MVFR CIGS WILL OVERSPREAD MUCH OF THE AREA LATE TONIGHT...BECOMING
MVFR/IFR CONDITIONS TUESDAY AFTERNOON. ALSO...AREAS OF -RA WILL
DEVELOP ACROSS WEST CENTRAL TEXAS LATE TONIGHT AND CONTINUE
TUESDAY. MID LEVEL DRY SLOT ON THE SOUTH SIDE OF THE UPPER LEVEL
SYSTEM WILL END PCPN ACROSS MUCH OF THE SOUTHERN HALF OF WEST
CENTRAL TEXAS TUESDAY EVENING.

21

&&

.PREV DISCUSSION... /ISSUED 924 PM CST MON NOV 30 2009/ 

DISCUSSION...

THERE ARE NO UPDATES PLANNED OTHER THAN TO INCREASE TUESDAY NIGHT
LOWS...AND THERE WILL BE NO HEADLINES ISSUED AS WELL. AFTER
LOOKING AT THE NEW 00Z NAM DATA...CONFIDENCE IS DECLINING THAT
THERE WILL BE ANY SIGNIFICANT WINTER PRECIP OVER WEST CENTRAL TX
OVER THE NEXT 24 TO 36 HOURS. THE 00Z NAM AGREES QUITE WELL WITH
THE MODEL CONSENSUS WITH REGARDS TO THE UPPER LOW...AND THUS I AM
CONFIDENT THAT ITS LOW LVL TEMP PROFILE CAN BE TRUSTED.

NOW TO THE FORECAST. THE FIRST AND MOST SIGNIFICANT ROUND OF
PRECIP WILL BEGIN LATE TONIGHT EARLY TUESDAY AS THE WARM CONVEYOR
AHEAD OF THE ADVANCING UPPER LOW SPREADS ACROSS THE REGION. THIS
FIRST ROUND SHOULD BE RAIN FOR ALL AREAS EXCEPT MY FAR WESTERN
TIER OF COUNTIES WHERE A RAIN/SNOW MIX IS POSSIBLE. AFTER 00Z
WEDNESDAY...THE SOUTHERN HALF OF THE CWA...WHICH IS EXPECTED TO BE
ALONG AND SOUTH OF THE 500MB LOW TRACK...WILL LIKELY GET DRY-
SLOTTED WITH A QUICK END TO THE PRECIP. THEN AS THE UPPER LOW
TRACKS ACROSS THE HEARTLAND AND THEN INTO EAST CENTRAL TX TUESDAY
NIGHT...A BAND OF WRAPAROUND PRECIP IN THE DEFORMATION ZONE TO THE
NORTH AND WEST OF THE CIRCULATION IS EXPECTED TO EXTEND INTO THE
BIG COUNTRY. THE 00Z NAM AGREES MORE WITH THE 12Z ECMWF AND UKMET
AND SUGGEST THAT THE AXIS OF HIGHEST PRECIP WILL LIKELY BE OVER
WESTERN NORTH TEXAS AND EXTEND SOUTH INTO THE NORTHERN BIG
COUNTRY. THE 00Z NAM LOW LEVEL PROFILES HAVE TRENDED WARMER THAN
IN PREVIOUS RUNS...SUGGESTING SFC TEMPS IN THE UPPER 30S TO NEAR
40 WHEN THIS PRECIP IS OCCURRING. THIS IS NOT FAVORABLE FOR SNOW
AND THUS THE CONFIDENCE IN ANY ACCUMULATION IS DECREASING. RIGHT
NOW IT APPEARS THAT THE AIRMASS IN PLACE FOR THIS SYSTEM IS JUST
NOT COLD ENOUGH FOR SIGNIFICANT WINTER PRECIP IN THE SAN ANGELO
FORECAST AREA. 

THE WRAPAROUND PRECIP WILL BE SHIFTING EAST RAPIDLY OUT OF WEST
CENTRAL TX AFTER 12Z WEDNESDAY AS THE UPPER LOW MOVES QUICKLY OFF
TO THE EAST.

THE NEXT FORECAST UPDATE WILL BE OUT AROUND 4 AM TUESDAY MORNING.

LACY

&&

.PRELIMINARY POINT TEMPS/POPS...
ABILENE  38  39  36  42  28 /  20  70  60  30   0 
SAN ANGELO  39  39  36  46  28 /  50  70  40  20   0 
JUNCTION  39  42  36  49  33 /  60  70  30  20  10 

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$