FXUS65 KPUB 071145
AFDPUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
445 AM MST MON DEC 7 2009
.SHORT TERM...
(TODAY AND TONIGHT)
SHORT TERM CONCERNS CONTINUE TO BE EFFECTS OF INCOMING MAJOR WINTER
STORM SYSTEM.
CURRENT WATER VAPOR IMAGERY AND RUC ANALYSIS INDICATING MODERATE
TO STRONG WEST TO SOUTHWEST FLOW ALOFT ACROSS THE STATE AS A BROAD
ELONGATED TROUGH PERSISTING ACROSS THE NORTHERN TIER OF STATES
THROUGH THE NORTHERN GREAT BASIN AND PAC NW ATTM. WATER VAPOR
IMAGERY ALSO INDICATING STRONG JET CORE DIGGING DOWN THE BACKSIDE OF
THE SYSTEM ACROSS PAC NW COAST ALONG WITH AMPLE PACIFIC MOISTURE AND
SEVERAL SHORT WAVES EMBEDDED WITHIN THE FLOW MOVING ACROSS THE
SOUTHERN CALIF COAST THROUGH THE DESERT SW AND INTO THE ROCKIES
ATTM. AT THE SFC...CANADIAN HIGH PRESSURE CONTINUES TO BUILD ACROSS
THE CENTRAL AND SOUTHERN HIGH PLAINS KEEPING A CLOUDY AND COLD
CONDITIONS IN PLACE ACROSS THE EASTERN PLAINS WITH EASTERLY LOW
LEVEL FLOW ATTM.
TODAY AND TONIGHT...NO BIG CHANGES TO THE ONGOING FORECAST WITH
EXPECTED INCREASED SOUTHWEST FLOW ALOFT LATE THIS MORNING WHICH
CONTINUES THROUGH TONIGHT AS ELONGATED TROUGH BEGINS TO MOVE ACROSS
THE GREAT BASIN AS BACKSIDE ENERGY ROUNDS THE BASE OF THE SYSTEM
THIS AFTERNOON WITH TROUGH AXIS PROGGED TO BE ACROSS CENTRAL UTAH BY
12Z TUESDAY. WITH PAC MOISTURE EMBEDDED WITHIN THE FLOW ALONG WITH
STRONG OROGRAPHICS AND INCREASING LAPSE RATES AND UVV AHEAD OF
SYSTEM...SHOULD SEE SNOWFALL INCREASING ACROSS THE CONTDVD THROUGH
THE MORNING...WITH SNOW HEAVY AT TIMES CONTINUING THIS AFTERNOON AND
TONIGHT...ESPECIALLY FOR THE SAN JUANS AND LA GARITA MOUNTAINS. HAVE
KEPT ALL CURRENT WARNINGS AND ADVISORIES IN PLACE...AND ISSUED AN
ADVISORY FOR THE SAN LUIS VALLEY BEGINNING AT 18Z AND RUNNING
THROUGH THE DAY TUESDAY. NOT EXPECTING MUCH SNOW FOR THE ALAMOSA
AND THE CENTER OF THE VALLEY...THOUGH THE WEST AND EAST ENDS OF THE
VALLEY COULD PICK UP 4 TO 8 INCHES OF STORM TOTAL ACCUMS.
WITH LOW LEVEL UPSLOPE IN PLACE ALONG WITH STREAMING MOISTURE...JET
DYNAMICS AND INCREASING WAA THROUGH TONIGHT EXPECTING OCCASIONAL
LIGHT SNOWFALL TO PERSIST ACROSS THE REST OF THE EASTERN MTS AND
IMMEDIATE ADJACENT PLAINS THIS MORNING AND SPREADING ACROSS THE REST
OF THE PLAINS THROUGH THE AFTERNOON AND EVENING...WITH ACCUMS OF 1
TO 2 INCHES OF LIGHT AND FLUFFY SNOW. -MW
.LONG TERM...
(TUESDAY THROUGH NEXT SUNDAY)
HEAVY SNOW AND STRONG WINDS WILL CONTINUE ALONG THE CONTINENTAL
DIVIDE TUE...WITH HEAVIEST PRECIP OVER THE SOUTHWEST MOUNTAINS
THROUGH 18Z SHIFTING TO THE CENTRAL MOUNTAINS BY MIDDAY AS MID
LEVEL FLOW BECOMES MORE WESTERLY WITH APPROACHING UPPER TROUGH.
GIVEN HOWLING UPPER JET AND STRONG UPWARD MOTION...EXPECT SNOW TO
SPILL OVER INTO AT LEAST THE EDGES OF THE SAN LUIS AND UPPER
ARKANSAS VALLEYS...WITH WINTER WEATHER ADVISORIES IN PLACE BOTH
AREAS. WEST FACING SLOPES OF THE SANGRES SHOULD SEE SEVERAL INCHES
OF WIND DRIVEN SNOW AS WELL...ESPECIALLY FIRST HALF OF THE DAY.
OVER THE EASTERN MOUNTAINS AND PLAINS...MAIN QUESTION IS STILL
TRACK OF THE SURFACE LOW AND DEPTH OF THE COLD AIR...ESPECIALLY
TUE MORNING. STILL SOME SUBTLE MODEL DIFFERENCES...WITH NAM/ECMWF
SLIGHTLY FARTHER NORTH...TRACKING THE LOW ALONG OR JUST NORTH OF
THE NM BORDER...WHILE GFS IS SLIGHTLY SOUTH...PLACING THE LOW IN
THE NRN TEX PANH BY 18Z TUE. IN EITHER CASE...ONLY AREA WHERE COLD
AIR MAY ERODE FOR A FEW HOURS TUE MORNING WILL BE ALONG THE
EASTERN MOUNTAIN SLOPES AND ACROSS THE RATON MESA...WHERE STRONG
WESTERLY DOWNSLOPE MAY CLEAR CLOUDS AND PUSH TEMPS INTO THE 30S
FOR A COUPLE HOURS BEFORE 18Z. COLD FRONT THEN RACES SOUTH TUE
AFTERNOON...WITH STRONG NORTH WINDS AND COLDER AIR REACHING THE NM
BORDER BY 21Z. WILL LIKELY SEE SOME LIGHT SNOW BREAK OUT OVER MUCH
OF THE EAST BY LATE TUE MORNING AS UPPER TROUGH AND STEEP LAPSE
RATES COMBINE TO WRING OUT AN INCH OR TWO OF ACCUMULATION...WITH
STRONG NORTH WINDS PRODUCING AREAS OF BLOWING AND DRIFTING SNOW
THROUGH THE DAY. HELD OFF ON ANY WINTER WEATHER HIGHLIGHT OVER THE
PLAINS AS SNOWFALL WILL BE LIGHT...BUT MANY AREAS ALONG AND EAST
OF I-25 COULD SEE AT LEAST A COUPLE HOURS OF LOW VIS AND POOR
TRAVEL CONDITIONS DUE TO BLOWING SNOW DURING THE LATE MORNING TUE.
MAIN UPPER TROUGH SHOOTS QUICKLY EAST INTO THE CENTRAL PLAINS TUE
NIGHT...THOUGH ENOUGH UPPER ENERGY HANGS BACK OVER THE WESTERN
U.S. TO KEEP AT LEAST LIGHT SNOW GOING THROUGH THE NIGHT...MAINLY
ALONG THE CONTINENTAL DIVIDE. GIVEN STRONG COLD ADVECTION THROUGH
TUE NIGHT...EXPECT VERY COLD MIN TEMPS WED MORNING...AND THUS
NUDGED TEMP GRIDS DOWNWARD A FEW DEGREES MOST AREAS. COLD DAY
EXPECTED WED WITH NORTHWEST UPPER FLOW OVER THE STATE PRODUCING A
FEW FLURRIES OVER THE CENTRAL MOUNTAINS.
LATEST RUNS OF THE GFS HAVE SLOWED THE WARMING TREND BY ANOTHER
DAY OR TWO...KEEPING COOL NORTHWEST FLOW OVER THE AREA UNTIL SAT.
STILL APPEARS ANY PRECIP WILL BE LIMITED TO THE CONTINENTAL
DIVIDE...AS A COUPLE OF WEAK SYSTEMS DROP SOUTH THROUGH THE FLOW.
NUDGED TEMPS DOWNWARD A COUPLE DEGREES BOTH THU AND
FRI...REMAINDER OF THE EXTENDED UNCHANGED. --PETERSEN
&&
.AVIATION...EXPECTING MAINLY MVFR AND OCCASIONAL IFR CONDITIONS TO
PERSIST FOR KCOS AND KPUB AND THE REST OF THE EASTERN PLAINS
WITH OCCASIONAL LIGHT SNOWFALL TODAY AND TONIGHT.
KALS WILL SEE OCCASIONAL SNOW SHOWERS DEVELOPING THROUGH THE MORNING
AND PERSISTING THROUGH TONIGHT AS BLOW-OVER FROM THE SAN JUANS
IMPINGES ON THE TAF SITE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 5 PM MST
TUESDAY FOR COZ062-069>075.
WINTER STORM WARNING UNTIL 5 PM MST TUESDAY FOR COZ058>061-064-
065-067.
BLIZZARD WARNING UNTIL 5 PM MST TUESDAY FOR COZ066-068.
&&
$$
23/10
