FXUS65 KPUB 061149
AFDPUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
449 AM MST SUN DEC 6 2009
.SHORT TERM...
(TODAY AND TONIGHT)
SHORT TERM CONCERNS CONTINUE TO BE SNOW AND COLD TEMPERATURES.
CURRENT WATER VAPOR IMAGERY INDICATING MODERATE SOUTHWEST FLOW ALOFT
ACROSS THE STATE WITH A BROAD UPPER LOW ACROSS THE GREAT BASIN
REGION. WATER VAPOR IMAGERY ALSO INDICATING AN EMBEDDED SHORT WAVE
AND ASSOCIATED JET CORE ROUNDING BASE OF LOW ACROSS CENTRAL UTAH
ATTM. AT THE SFC...COLD FRONT HAS MOVED THROUGH ALL OF SE COLORADO
WITH COLD AIR CONTINUING TO FILTER INTO THE AREA WITH NORTH TO
NORTHEAST LOW LEVEL FLOW. REGIONAL RADARS INDICATING ECHOES ACROSS
THE CENTRAL MTS THROUGH THE MID ARKANSAS RIVER VALLEY WITH ECHOES
BLOSSOMING OVER PUEBLO AND EL PASO COUNTIES OVER THE PAST HOUR.
TODAY...MODELS REMAIN IN GOOD AGREEMENT OF CENTRAL UTAH SHORT WAVE
TROUGH MOVING INTO WESTERN COLORADO THIS MORNING AND CONTINUING TO
LIFT OUT ACROSS EASTERN WYOMING WITH ASSOCIATED JET CORE TRANSLATES
ACROSS CENTRAL COLORADO THROUGH THE AFTERNOON. MODELS CONTINUE TO
INDICATE ISENTROPIC LIFT WITH DEEPENING EASTERLY FLOW AT H7 ACROSS
THE MID AND UPPER ARKANSAS RIVER VALLEY THROUGH THE PIKES PEAK
REGION AND SHOULD SEE ECHOES CONTINUING TO DEVELOP AND PERSIST
ACROSS THIS AREA THROUGH THE LATE MORNING. PRECIP SHOULD CONTINUE TO
LIFT NORTH AND EAST THROUGH THE AFTERNOON AS TROUGH AXIS PASSES AND
H7 FLOW BECOMES INCREASINGLY DOWNSLOPE. HAVE INCREASED POPS ACROSS
ACROSS THE MID AND UPPER ARKANSAS RIVER VALLEY AND PIKES PEAK REGION
WITH FLUFFY ACCUMULATIONS OF 2 TO 4 INCHES EXPECTED. AS FOR
TEMPS...HAVE LIKELY ALREADY HAD THE HIGHS FOR THE DAY WITH STEADY OR
SLOWLY FALLING TEMPS THROUGH THE AFTERNOON AS LOW LEVEL EASTERLY
UPSLOPE FLOW DEVELOPS...SAVE PORTIONS OF THE SAN LUIS VALLEY WHERE
DOWNSLOPE FLOW WILL INCREASE WITH PASSING WAVE.
TONIGHT...STRONG WESTERLY FLOW ALOFT PROGGED ACROSS THE AREA JET
CORE CONTINUES TO TRANSLATE INTO THE HIGH PLAINS WITH INCREASING MID
AND UPPER LEVEL MOISTURE STREAMING INTO THE AREA AHEAD OF THE NEXT
SYSTEM MOVING INTO THE GREAT BASIN. SHOULD CONTINUE TO SEE COLD LOW
LEVEL UPSLOPE AND STRATUS PERSISTING ACROSS THE PLAINS AND ALONG
WITH STREAMING MOISTURE...CANT RULE OUT SOME LIGHT SNOW OR FLURRIES
ACROSS THE EASTERN MTS AND PLAINS. SHOULD SEE INCREASING CHANCES OF
SNOWFALL ACROSS THE SW AND CENTRAL MTS AS WELL...WITH THE INCREASING
MOISTURE AND GOOD OROGRAPHIC FLOWS. -MW
.LONG TERM...
(MONDAY THROUGH NEXT SATURDAY)
NO BIG SURPRISES IN THE MODELS EARLY THIS MORNING...AS MAJOR
WINTER STORM REMAINS ON TRACK FOR THE CONTINENTAL DIVIDE MONDAY
INTO TUESDAY. EXPECT SNOW TO INCREASE RAPIDLY IN
COVERAGE/INTENSITY MONDAY MORNING OVER THE SAN JUANS...WITH HEAVY
SNOW SPREADING NORTH TO THE LA GARITAS AND SAWATCH RANGE DURING
THE DAY. HEAVIEST SNOW WILL FALL OVER THE SAN JUANS LATE MON/MON
NIGHT...WITH FOCUS SHIFTING TO THE CENTRAL MOUNTAINS MON
NIGHT/EARLY TUE AS MID LEVEL FLOW SHIFTS FROM SOUTHWEST TO WEST AS
TROUGH MOVES ACROSS. BLIZZARD WARNING ISSUED EARLIER STILL LOOKS
ON TRACK FOR THE HIGHER ELEVATIONS OF THE SAN JUANS/LA
GARITAS...AS A PROLONGED PERIOD OF WIND/SNOW LOOKS LIKELY. FOR THE
CENTRAL MOUNTAINS...700 MB TRACKING ACROSS THE AREA LATE MON INTO
TUE KEEPS BEST GRADIENT SOUTH OF HIGHWAY 50...SO WHILE WIND AND
SNOW WILL STILL BE LIKELY...NOT SURE IF WINDS WILL BE STRONG
ENOUGH FOR WIDESPREAD/PROLONGED BLIZZARD CONDITIONS. THUS HOISTED
WINTER STORM WARNINGS FOR THE CENTRAL MOUNTAIN ZONES (AND LOWER
ELEVATION SAN JUAN/LA GARITA ZONES)...AND WILL LET LATER SHIFTS
TAKE A LOOK TO SEE IF AN UPGRADE TO A BLIZZARD WARNING FOR THE
CENTRAL MOUNTAINS IS JUSTIFIED. MAIN CHANGE TO THE GRIDS WAS TO
KNOCK ABOUT A FOOT OFF OF ACCUMS OVER THE SAN JUANS...AS MODELS
APPEAR TO BE HANGING ON TO HEAVY PRECIP TOO LONG AFTER WINDS
BECOME WLY TUE MORNING. STILL...WILL SEE 2 TO 4 FEET OVER THE SAN
JUANS BY LATE TUE...1 TO 3 FEET CENTRAL MOUNTAINS. UPPER ARKANSAS
VALLEY AND HIGHER ELEVATIONS OF THE SANGRES MAY NEED A SNOW
ADVISORY EVENTUALLY MON NIGHT...BUT A LITTLE EARLY FOR THAT AT
THIS POINT.
OVER THE EASTERN MOUNTAINS AND PLAINS...COLD AIR REMAINS
ENTRENCHED THROUGH THE DAY MONDAY...WITH CLOUDY SKIES AND A FEW
FLURRIES POSSIBLE...ESPECIALLY NEAR THE MOUNTAINS. FOR MONDAY
NIGHT...SOUTHWEST FLOW ALOFT INCREASES AS WESTERN TROUGH MOVES
CLOSER...WITH 700 MB WINDS INCREASING TO 40 KNOTS BY EARLY TUE
MORNING. WILL LIKELY SEE SOME GUSTY WINDS AND STEADY OR SLOWLY
WARMING TEMPS OVER THE LEE SLOPES WEST OF I-25...WHILE COLD AIR
HOLDS ON OVER THE LOWER ARKANSAS VALLEY. MAIN QUESTION FOR TUES IS
LOCATION OF THE SURFACE LOW AND DEPTH OF THE COLD AIR MASS...AS
ECMWF/GFS ARE SLIGHTLY FURTHER NORTH WITH THE LOW AND THUS WARMER
OVER MUCH OF THE EAST. NAM IS FARTHER SOUTH...KEEPING THE SURFACE
LOW OVER NORTHERN NM AND THUS LEAVING MOST OF EASTERN COLORADO IN
THE COLD AIR MASS THROUGH THE DAY TUE. CURRENT TEMP FORECAST A
COMPROMISE BETWEEN THE 2 SOLUTIONS...SO FEW CHANGES WERE MADE TO
AVOID FLIP-FLOPPING THE FORECAST...THOUGH HUNCH IS COLDER NAM WILL
WIN OUT AS COLD AIR IS USUALLY SLOWER TO LEAVE THE PLAINS THAN
FORECAST. IF COLD AIR CAN DEEPEN BEFORE MAIN UPPER TROUGH PASSES
TUE AFTERNOON...MUCH OF THE EAST COULD PICK UP A QUICK INCH OF TWO
OF WIND-DRIVEN SNOW...BEFORE DYNAMICS AND LIFT RACE QUICKLY
EASTWARD INTO KS BY TUE EVENING. CURRENT CHANCE POPS THROUGH THE
DAY TUE LOOK FINE FOR NOW.
FOR WED...COLD AIR DROPPING SOUTH BEHIND THE DEPARTING LOW WILL
KEEP THE AREA COLD...WITH MAX TEMPS BELOW FREEZING MOST LOCATIONS.
AT LEAST SOME LIGHT SNOW WILL PERSIST ALONG THE CONTINENTAL DIVIDE
AS SEVERAL WEAK DISTURBANCES MOVE ALONG THE FAST UPPER JET OVER
THE SOUTHERN U.S. SHOULD SEE A SLOW WARMING TREND...ESPECIALLY
OVER THE EAST...FROM THU INTO SAT AS COLD AIR MASS SLOWLY
ERODES...WHILE OCCASIONAL BOUTS OF LIGHT SNOW CONTINUE ALONG THE
DIVIDE AS UNSETTLED NORTHWEST FLOW LINGERS. -PETERSEN
&&
.AVIATION...EXPECTING IFR AND OCCASIONAL LIFR CONDITIONS FOR THE
COS AND PUB TAFS WITH OCCASIONAL LIGHT SNOWFALL PERSISTING
THROUGH THE EARLY AFTERNOON. SNOW TO LIFT NORTH AND EAST INTO
NORTHEASTERN COLORADO THROUGH THE AFTERNOON THOUGH WILL CONTINUE
TO SEE MVFR AND IFR CIGS AND FLURRIES ACROSS THE EASTERN PLAINS
WITH A COLD AIRMASS IN PLACE. VFR CONDITIONS EXPECTED AT ALS WITH
BREEZY SW WINDS OF 15 TO 20 MPH IN THE AFTERNOON.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 5 AM MONDAY TO 5 PM MST TUESDAY FOR
COZ058>061-064-065-067.
BLIZZARD WARNING FROM 5 AM MONDAY TO 5 PM MST TUESDAY FOR COZ066-
068.
WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ058-
060.
&&
$$
23/10
