FXUS64 KLUB 221740
AFDLUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1140 AM CST TUE DEC 22 2009
.UPDATE...
HAVE ISSUED A MINOR UPDATE TO REFLECT TEMPERATURE TRENDS. CURRENT
OBS SHOW THAT THE FRONTAL BOUNDARY HAS SAGGED WELL INTO THE FA IN
THE WAKE OF A DEPARTING SURFACE LOW EAST OF CHILDRESS...GENERALLY
FROM FARWELL...TO FLOYDADA...TO PADUCAH. ALSO...MID/HIGH CLOUDS
WILL ONLY BECOME INCREASINGLY THICK TODAY...PER IR IMAGERY THAT
DEPICTS SIGNIFICANT AMOUNTS OF ELEVATED MOISTURE ADVECTING
NORTHEASTWARD OVER THE AREA. THUS EXPECT TEMPERATURES OVER THE
NORTHERN FA WILL TOP OUT A FEW DEGREES COOLER THAN PREVIOUSLY
FORECAST...BUT OTHERWISE NO IMPACTS ON SENSIBLE WEATHER.
&&
.AVIATION...
VFR CONDITIONS SHOULD PERSIST AT BOTH KCDS AND KLBB THROUGH
23/18Z. HOWEVER SOME UNCERTAINTY EXIST WITH EXTENT OF CLOUD COVER
ABOVE 5KFT AND SURFACE WIND SPEEDS DURING THE 12-18Z TIMEFRAME AT
KLBB. NO TRUE AVIATION IMPACTS ARE EXPECTED THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 445 AM CST TUE DEC 22 2009/
SHORT TERM...
2 AM SFC ANALYSIS SHOWS A WEAK LOW CENTER ACROSS THE SRN TX
PANHANDLE...RESULTING IN SWERLY WINDS ACROSS MOST OF THE FA KEEPING
EARLY MORNING TEMPS ON THE MILD SIDE. IN ADDITION...MODEST MOISTURE
ADVECTION WAS UPPING DEWPOINT TEMPS INTO THE LOWER 40S ACROSS THE
SRN ROLLING PLAINS...WHILE IT REMAINED DRY IN THE NW ZONES.
ALOFT...EXTENSIVE MID TO HIGH LVL CLOUDS STRETCHED FROM SRN CALIF
THROUGH THE SRN PLAINS RIDING THE STRONG SUBTROPICAL JET NOSING INTO
TEXAS. THIS WHILE THE NRN BRANCH OF THE JET STREAM DOVE SOUTH ALONG
THE WEST COAST AND POURED ENERGY INTO THE UPPER LEVEL STORM SYSTEM
OF INTEREST TAKING SHAPE ACROSS CALIFORNIA.
FOR TODAY...WE EXPECT THAT SFC LOW TO SLIDE BACK TO THE SOUTHWEST A
BIT IN RESPONSE LEE-SIDE CYCLOGENESIS AND THIS WILL ALLOW A WEAK FRONT
TO SLIP INTO THE FAR SRN PANHANDLE AND NRN ROLLING PLAINS. WITH
GREATER CLOUD COVER AND THE LOSS OF THOSE STRONGER DOWNSLOPE WINDS
FROM YESTERDAY...WE SHOULD SEE AFTN HIGH TEMPS FALL BACK FROM THE
UPPER 60S/LOWER 70S YSTDY BACK INTO THE 50S AND AND LOWER 60S FOR
MOST LOCALES.
THE UPPER LEVEL STORM SYSTEM WILL TURN EASTWARD ACROSS THE DESERT SW
THIS EVENING...AND IT APPEARS THAT LARGE SCALE ASCENT WILL BEGIN TO
INCREASE ACROSS OUR WESTERN ZONES AS A LEAD SHTWV MOVES ACROSS AHEAD
OF THE CLOSED LOW. H7 TO H5 LAPSE RATE SHOULD ALSO STEEPEN A BIT.
DUE TO THIS WE EXPECT SOME MID-LVL SHOWERS TO DEVELOP ACROSS CENTRAL
NM AND SPREAD EASTWARD...APPROACHING THE TX/NM BORDER.
INITIALLY...THE LOW LVLS WILL BE DRY...BUT COOLING AND MOISTENING OF
THE AIR BY LIFT/EVAPORATION SHOULD RESULT IN A STEADILY LOWERING
CLOUD DECK. AFTER MIDNIGHT...IT IS POSSIBLE THAT WE COULD SEE SOME
LIGHT SHOWERS REACH THE GROUND ACROSS THE NW ZONES AND THUS HAVE
UPPED POPS TO SLGT CHC CAT IN THAT AREA FROM 6Z TO 12Z. FCST SNDGS
INDICATE THAT PRECIP COULD BEGIN AS RAIN AND THEN AS EVAPORATIVE
COOLING KICKS WE COULD SEE SOME SLEET MIX IN...BUT ACCUMULATIONS ARE
EXPECTED TO BE VERY LIGHT.
LONG TERM...
FOCUS FOR THE EXTENDED REMAINS FIXED ON THE UA STORM SYSTEM TO TRACK
ACROSS THE REGION LATE WEDNESDAY...BRINGING WITH IT POTENTIAL WINTRY
PROSPECTS ALONG WITH A STRONG COLD FRONT. HOWEVER...LATEST GUIDANCE
HAS CHANGED CONSIDERABLY FROM 24-HOURS AGO AS THE STORM SYSTEM AND
STRONG JET IS JUST MAKING ITS WAY DOWN THE WESTERN CONUS.
SPECIFICALLY...LATEST MODEL GUIDANCE HAS TRENDED FASTER AND FURTHER
NORTH WITH THE UA STORM...NOW TRACKING THE ELONGATED 500 MB
CIRCULATION FROM CENTRAL/NORTHERN AZ/NM AT 12Z WEDNESDAY TO THE
PANHANDLES/SW KS BY 00Z THU AND THEN QUICKLY UP INTO THE CENTRAL
PLAINS BEFORE IT SLOWS TO A CRAWL. THUS...BEST LIFT AND
PRECIPITATION CHANCES LOOK TO REMAIN MUCH FURTHER NORTH THAN
SOLUTIONS INDICATED JUST 12 TO 24 HOURS AGO. HAVE ADJUSTED FORECAST
POPS DOWNWARD SLIGHTLY IN THE WED/WED NIGHT TIME-FRAME
ACCORDINGLY...THOUGH SOME LIGHT WINTRY PRECIPITATION STILL CAN NOT
BE RULED OUT /FAVORING THE NORTHERN ZONES/.
EARLY WEDNESDAY...A WEAK QUASI-STATIONARY FRONT WILL LIKELY BE
SITUATED ACROSS THE NORTHEASTERN ZONES. MODELS SUGGEST THE FRONT
WILL BE ERODED NORTHWARD THROUGH THE EARLY AFTERNOON AS STOUT
SOUTHWESTERLY FLOW SPREADS ACROSS THE AREA IN ADVANCE OF THE
APPROACHING STORM. REMAIN A LITTLE HESITANT THAT THIS SHALLOW AIR
WILL BE SCOURED AS FAR NORTH AS DEPICTED...AND HAVE KEPT
TEMPERATURES COOLER THAN GUIDANCE ACROSS THE NORTH WITH THIS IN
MIND. AS ALLUDED TO IN THE SHORT TERM...A LEAD WAVE AND STOUT JET
MAY PROVIDE ENOUGH FORCING FOR SOME LIGHT PRECIPITATION...THOUGH
RELATIVELY DRY LOW LEVELS WILL TEND TO INHIBIT AMOUNTS. MOST OF
THE ACTIVITY WOULD LIKELY BE IN THE FORM OF LIGHT RAIN
SHOWERS...THOUGH THERE COULD BE ENOUGH WET-BULB COOLING FOR A LITTLE
SLEET TO MIX IN ACROSS THE NORTHWEST ZONES. A DEEPENING SFC LOW
WILL TRACK EASTWARD ACROSS THE SOUTHERN PANHANDLE THROUGH THE
AFTERNOON...WITH A PACIFIC COLD FRONT SWEEPING ACROSS THE SOUTH
PLAINS...AND THEN A STRONGER CANADIAN FRONT DIVING IN FROM THE
NORTH DURING THE EVENING HOURS. IN ADDITION TO LIGHT PRECIPITATION
CHANCES THROUGH THE DAY...COULD SEE SOME BREEZY TO WINDY WESTERLY
WINDS /PERHAPS THREATENING ADVISORY LEVELS/ DEVELOP ACROSS MUCH OF
THE CENTRAL/SOUTHERN ZONES AS STRONG WIND FIELDS MOVE ACROSS ON
THE SOUTHERN PERIPHERY OF THE STORM SYSTEM. THE WINDS COULD BE
FURTHER ENHANCED BY ANY HIGH BASED SHOWERS THAT ARE ABLE TO
DEVELOP. CANADIAN COLD FRONT WILL THEN QUICKLY SWEEP THROUGH
DURING THE EVENING HOURS WITH GUSTY NORTHWESTERLY WINDS AND MUCH
COLDER TEMPERATURES. IN THE WAKE OF THE FRONT...COLUMN OF AIR WILL
QUICKLY COOL...SWITCHING ANY RAIN OVER TO SNOW FROM NW TO SE
ACROSS THE AREA. HOWEVER...MODEL SOUNDINGS/CROSS-SECTIONS SHOW
MINIMAL LIFT WITH ONLY A QUICK ROUND OF FRONTAL FORCING...SO THINK
ANY PRECIPITATION WILL BE LIGHT...WITH LITTLE MORE THAN A
TRACE...EXCEPT PERHAPS ACROSS THE NORTHWEST WHERE LIGHT
ACCUMULATIONS MAY BE POSSIBLE. REGARDLESS...SYSTEM WILL QUICKLY
SHIFT NORTHEAST OF THE REGION BY EARLY THURSDAY SHUTTING OFF
REMAINING PRECIPITATION CHANCES. HOWEVER...THE STRENGTHEN SFC LOW
ACROSS THE CENTRAL PLAINS WILL KEEP GUSTY NORTHWESTERLY WINDS INTO
THURSDAY. ANOTHER VORT LOBE WILL DIVE DOWN THE BACK SIDE OF THE
SYSTEM THURSDAY...BUT INDICATIONS ARE THAT THE ATMOSPHERE WILL BE
TOO DRY TO SUPPORT ANY SUBSTANTIVE POPS.
BEYOND THURSDAY...THE LARGE UPPER STORM WILL REMAIN ACROSS THE UPPER
MIDWEST THROUGH MUCH OF THE WEEKEND...WITH A DRY BUT COLD NORTHERLY
FETCH FOR WEST TEXAS. CURRENTLY HAVE FORECAST HIGHS ONLY IN THE 30S
AND 40S THU-SAT. TEMPERATURES MAY SLOWLY MODERATE BY LATE WEEKEND AS
THE UA TROUGH FINAL EDGES EASTWARD. EYES WILL THEN TURN TO ANOTHER
POTENTIAL TROUGH TRACKING INTO THE DESERT SOUTHWEST BY EARLY NEXT
WEEK. FOR NOW...HAVE KEPT FORECAST DRY BEYOND EARLY THURSDAY...BUT
IT WILL BE SOMETHING TO KEEP AN EYE ON.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 54 32 41 17 35 / 10 20 50 40 10
TULIA 55 35 43 21 34 / 10 10 40 40 10
PLAINVIEW 56 36 48 22 35 / 10 10 40 40 10
LEVELLAND 58 36 53 21 41 / 10 10 40 30 10
LUBBOCK 59 38 53 24 40 / 10 10 40 30 10
DENVER CITY 61 36 55 23 43 / 10 10 40 20 10
BROWNFIELD 62 38 56 25 43 / 10 10 40 20 10
CHILDRESS 59 40 53 28 37 / 0 10 30 40 10
SPUR 62 41 59 27 41 / 0 10 20 30 10
ASPERMONT 66 44 66 29 42 / 0 10 20 40 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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