FXUS64 KMAF 282247
AFDMAF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX
447 PM CST SAT NOV 28 2009

.DISCUSSION...

SEE AVIATION DISCUSSION BELOW.

&&

.AVIATION...

NO MAJOR AVIATION CONCERNS...AS VFR CONDITIONS EXPECTED THRU THE 
FORECAST PERIOD.  CIGS PROGGED TO LOWER OVER THE NEXT 24 HRS AS 
BAROCLINIC LEAF INTENSIFIES AHEAD OF TROUGH OVER SOCAL...BUT STILL 
REMAIN VFR.

&&

.PREV DISCUSSION... /ISSUED 333 PM CST SAT NOV 28 2009/ 

DISCUSSION...
THE MAIN FOCUS FOR THIS FORECAST PACKAGE WILL CONTINUE TO CENTER ON 
A WINTER STORM THAT WILL LIKELY IMPACT WEST TEXAS AND SOUTHEAST NEW 
MEXICO LATE SUNDAY NIGHT...AND CONTINUING THROUGH MONDAY AND 
TUESDAY. 

LATE AFTERNOON WATER VAPOR IMAGERY SHOWS THE ADVERTISED UPPER LEVEL 
LOW DIGGING ACROSS SOUTHERN CALIFORNIA. THIS FEATURE WILL SLOWLY 
MOVE SOUTHWARD TO NEAR THE CA/AZ BORDER BY EARLY SUNDAY MORNING. THE 
FLOW ALOFT WILL BECOME SOUTHWESTERLY ACROSS OUR FORECAST AREA LATE 
TONIGHT...AS THE BROAD UPPER TROUGH CONTINUES TO CARVE ACROSS THE 
SOUTHWESTERN CONUS. A SHORTWAVE IMPULSE WITHIN THE SOUTHWEST FLOW 
ALOFT WILL LIFT NORTHEASTWARD ACROSS NORTHERN MEXICO AND FAR WEST 
TEXAS/SOUTHERN NEW MEXICO LATE TONIGHT. SCATTERED RAIN SHOWERS WILL 
DEVELOP ACROSS THE NORTHWESTERN HALF OF THE CWFA WITHIN THE FAVORED 
REGION OF LIFT TONIGHT...MAINLY AFTER MIDNIGHT. ELEVATED INSTABILITY 
WILL BE MARGINAL OVERNIGHT...BUT ENOUGH WILL BE PRESENT TO KEEP 
MENTION OF ISOLATED THUNDERSTORMS ACROSS THE GUADALUPE MOUNTAINS AND 
SOUTHEAST NEW MEXICO PLAINS. 

MODELS ARE THEN IN GOOD AGREEMENT THAT THE UPPER LOW WILL CONTINUE 
TO DIG/SLOWLY MOVE ACROSS NORTHERN BAJA/SONORA MX SUNDAY AND SUNDAY 
NIGHT. MEANWHILE...A FAST MOVING SHORTWAVE TROUGH WILL CLIP ACROSS 
THE CENTRAL PLAINS SUNDAY...AND WILL SEND A STRONG COLD FRONT 
SOUTHWARD THROUGH THE SOUTHERN PLAINS...INCLUDING MUCH OF OUR 
FORECAST AREA DURING THE DAY SUNDAY. MUCH COOLER TEMPERATURES WILL 
RETURN ACROSS THE NORTHERN CWFA BEHIND THIS FRONT SUNDAY AFTERNOON. 
TEMPERATURES WILL BE LUCKY TO REACH THE MID 50S TO NEAR 60 BEFORE 
THE FRONT PASSES ACROSS MOST LOCATIONS. ADDITIONAL LIFT WILL BE 
PROVIDED BY ADDITIONAL SHORTWAVE IMPULSES WITHIN THE SOUTHWEST FLOW 
AND ALSO ALONG THE FRONTAL BOUNDARY SUNDAY. THUS...A CHANCE OF RAIN 
SHOWERS WILL CONTINUE ACROSS THE FORECAST AREA THROUGH THE 
DAY...WITH A FEW THUNDERSTORMS ALSO POSSIBLE ACROSS SOUTHERN 
SECTIONS OF THE CWFA. COLDER AIR WILL CONTINUE TO FILTER ACROSS THE 
CWFA SUNDAY NIGHT. MID LEVEL FLOW WILL BECOME NEARLY SOUTHERLY 
ACROSS WESTERN PORTIONS OF THE REGION SUNDAY NIGHT...AS A DIFLUENT 
PATTERN DEVELOPS AHEAD OF THE UPPER LEVEL STORM SYSTEM. THIS WILL BE 
A FAVORABLE PATTERN FOR PRECIPITATION DEVELOPMENT...ESPECIALLY WEST 
OF THE PECOS RIVER...WHERE WE HAVE INCREASED GRIDDED POPS TO THE 
LIKELY CATEGORY. FORECAST SOUNDINGS ARE IN GENERAL AGREEMENT THAT 
PRECIPITATION SHOULD REMAIN IN THE FORM OF RAIN BEFORE MIDNIGHT... 
WITH THE EXCEPTION OF THE HIGHER ELEVATIONS OF THE GUADALUPE 
MOUNTAINS...WHERE A RAIN/SNOW MIX MAY OCCUR. AFTER MIDNIGHT... 
SOUNDINGS FAVOR A MIX OF RAIN/SLEET/SNOW ACROSS THE PERMIAN 
BASIN...UPPER TRANS PECOS...AND MARFA PLATEAU...WHILE ALL SNOW WILL 
BE POSSIBLE ACROSS THE SOUTHEAST NEW MEXICO PLAINS...AND THE 
GUADALUPE/DAVIS MOUNTAINS. SNOW ACCUMULATIONS OF 1-2 INCHES WILL BE 
POSSIBLE BY MONDAY MORNING...MAINLY IN THE MOUNTAINS AND THE 
ADJACENT SOUTHEAST NEW MEXICO PLAINS. 

DIFLUENT FLOW WILL PERSIST MONDAY...AND PRECIPITATION WILL BE LIKELY 
AGAIN ALONG AND WEST OF THE PECOS RIVER. FORECAST SOUNDINGS 
GENERALLY FAVOR SNOW IN THE MOUNTAINS AND A WINTRY MIX OF 
RAIN...SLEET AND/OR SNOW ACROSS MUCH OF THE PLAINS MONDAY. A WINTER 
WEATHER ADVISORY MAY BECOME NECESSARY DURING THE SUNDAY NIGHT/MONDAY 
TIME FRAME ACROSS THE MOUNTAINS...AND POSSIBLY FARTHER EAST. THE 
UPPER LEVEL LOW WILL FINALLY APPROACH WEST TEXAS MONDAY NIGHT...AND 
CURRENT TRENDS ARE IN AGREEMENT THAT THIS FEATURE WILL PASS NEAR THE 
I-10 CORRIDOR TUESDAY. FORECAST SOUNDINGS/PROGS INDICATE THAT 
PRECIPITATION MONDAY NIGHT COULD BE A MESS OF SNOW AND POSSIBLY SOME 
SLEET ALONG AND NORTH OF INTERSTATE 10...WITH A MIX OF FREEZING RAIN 
AND SLEET...AND POSSIBLY SOME SNOW FLAKES ACROSS THE MARFA PLATEAU 
AND BIG BEND REGION. PRECIPITATION WILL LIKELY BECOME ALL SNOW 
TUESDAY NORTH OF THE PASSING UPPER LOW TUESDAY AND TUESDAY NIGHT. 
CONFIDENCE IS INCREASING THAT TOTAL SNOW ACCUMULATIONS OF 2 TO 4 
INCHES...WITH LOCALIZED HIGHER AMOUNTS MAY BE REALIZED ACROSS MUCH 
OF THE FORECAST AREA BY TUESDAY. ALL WILL BE DEPENDENT ON THE SPEED 
AND ACTUAL TRACK OF THE UPPER LOW. WE HAVE OPTED TO CONTINUE A 
STRONGLY WORDED SPECIAL WEATHER STATEMENT MENTIONING ACCUMULATIONS 
WITH THIS PACKAGE...AS THE HEAVIEST WINTER PRECIPITATION EVENT IS 
STILL 3 DAYS OUT. A WINTER STORM WATCH MAY BECOME NECESSARY ACROSS 
WESTERN PORTIONS OF THE CWFA WITHIN THE NEXT 12-24 HOURS. 

THE UPPER LOW WILL PASS EAST OF THE FORECAST AREA TUESDAY NIGHT. 
SOME WRAP-AROUND SNOW MAY CONTINUE ACROSS THE FORECAST AREA TUESDAY 
NIGHT...BEFORE TAPERING EARLY WEDNESDAY MORNING. NORTHWEST FLOW 
ALOFT AND COLD TEMPERATURES ARE EXPECTED WEDNESDAY IN THE WAKE OF 
THE SYSTEM. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE END OF 
THE WEEK...AS THE SURFACE RIDGE MAY BE HARD PRESSED TO MOVE EAST OF 
THE FORECAST AREA. 

&&

.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.

&&

$$

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