FXUS65 KPUB 221342 AAB
AFDPUB
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
642 AM MST TUE DEC 22 2009
.SHORT TERM...
(TODAY AND TONIGHT)
UPPER TROF CURRENTLY DROPPING SOUTHWARD THROUGH CA INTERACTING WITH
FETCH OF SUBTROPICAL MOISTURE/JET MOVING THROUGH SRN AZ/CA. ALREADY
SEEING SOME FAIRLY WIDESPREAD PCPN DEVELOPING ACROSS WRN AZ/CEN NV
AND CA WITH SOME LIGHTNING NOTED ACROSS THE DESSERT SOUTHWEST.
MODELS AGREE IN CARVING OUT AN UPPER LOW AS IT DROPS THROUGH THE
GREAT BASIN TODAY...THEN TRANSLATING THE UPPER LOW EASTWARD ACROSS
CENTRAL AZ/NM TODAY. LATEST RUNS ARE A TAD FARTHER NORTH WITH THE
EASTWARD TRACK TODAY AND HENCE ARE HEAVIER WITH THE QPF ACROSS THE
AREA...ESPECIALLY LATE IN THE PERIOD. THUS SOME FAIRLY BIG CHANGES
TO GRID PACKAGE NEEDED.
AS FOR DETAILS...SHOULD SEE SNOW SPREAD INTO THE SOUTHWEST MOUNTAINS
FAIRLY QUICKLY THIS MORNING...BECOMING HEAVY AT TIMES BY THIS
AFTERNOON. WITH H7 WINDS AROUND 20-25 KTS FROM THE SOUTHWEST...BEST
LIFT/OROGRAPHIC ENHANCEMENT WILL STILL BE FOCUSED ACROSS THE EASTERN
SAN JUAN MOUNTAINS. SHOULD SEE 12 INCHES OR MORE FOR THIS AREA...SO
WARNINGS HERE LOOK GOOD. BY LATE AFTERNOON SHOULD START TO SEE
BROAD AREA OF WEAK TO MODERATE ISENTROPIC LIFT SPREAD ACROSS
NORTHERN SECTIONS OF THE FCST AREA. SO SHOULD START TO SEE SNOW
STREAMING OFF THE EASTERN SIDES OF THE SANGRES...WITH AREA OF SNOW
BLOSSOMING ACROSS NORTHERN SECTIONS OF THE AREA INCLUDING
CHAFFEE/LAKE...FREMONT AND TELLER/EL PASO COUNTIES ESPECIALLY BY
EARLY EVENING. LOW LVL FLOW (H85 AND BELOW) EVEN SWINGS AROUND FROM
AN EASTERLY DIRECTION PROVIDING SOME SHALLOW UPSLOPE FOR THE EASTERN
SLOPES OF TELLER/UPPER ARKANSAS RIVER VALLEY AND AS FAR SOUTH AS THE
WETS...WITH MODEST OVERRUNNING ABOVE THAT. HEAVIEST SNOW OF THE
EVENT FOR THE I-25 CORRIDOR FROM COS DOWN TO KPUB WILL PROBABLY BE
DURING THE 03Z TO 12Z TIME FRAME. THINK MODELS ARE OVERDOING THE
QPF A BIT FOR THIS AREA...THOUGH WOULDN'T BE SURPRISED TO SEE A 1-3
INCHES OF ACCUMULATION FOR COS/PUB AND CANON CITY...WITH HEAVIEST
AMOUNTS NEAR THE MOUNTAINS. ONCE FLOW SWINGS AROUND FROM A
NORTHERLY DIRECTION WEDNESDAY MORNING...SHOULD START TO SEE
DOWNSLOPE DRYING SHOW UP SOUTH OF KCOS. FOR NOW THINK THESE AREAS
WILL STAY BELOW ADVISORY SNOWFALL AMOUNTS...SO NO HIGHLIGHTS JUST
YET FOR THESE AREAS. HOWEVER CLOSER TO THE MOUNTAINS...WOULDN'T BE
SURPRISED TO SEE ADVISORY CRITERIA AMOUNTS JUST ABOUT ANYWHERE.
AGAIN...ITS NOT LOOKING LIKE A HEAVY EVENT...BUT WORTH ISSUING AN
ADVISORY FOR...GIVEN THE HOLIDAY TRAVEL PERIOD. SOME AREAS WILL BE ON THE
LOW SIDE OF THE CRITERIA...WHILE OTHERS COULD BE A LITTLE MORE.
MAIN CHANGE TO HAZARD GRID WAS TO BUMP UP TIMING OF ADVISORIES FOR
MOUNTAINS/PALMER DIVIDE TO AROUND 00Z AS PCPN BREAKS OUT EARLIER IN
LATEST MODELS.
CHALLENGES STILL EXIST FOR THE EASTERN PLAINS. EVERY OTHER RUN OF
THE NAM INCREASES THEN BACKS OFF ON QPF ACROSS THE PLAINS AFTER 06Z
WED AND BEYOND. GFS HAS BEEN THE MOST CONSISTENT OF THE MODELS.
THERE HAS BEEN AGREEMENT OVER THE PAST FEW DAYS THAT AT LEAST
EASTERN SECTIONS OF KIOWA COUNTY MAY MEET WARNING CRITERIA SNOW
AMOUNTS...SO WILL UPGRADE THIS AREA TO AN WARNING...WITH WESTERN
PORTIONS OF THE COUNTY UNDER AN ADVISORY FOR NOW WITH SNOW AMOUNTS
JUST SHY. 06Z NAM AND 00Z GFS HOLD OFF ON PRODUCING MUCH SNOW
ACROSS THE REMAINDER OF THE SOUTHEAST PLAINS UNTIL AFTER 12Z. GIVEN
THAT LATEST MODEL RUNS ARE NOW FARTHER WEST WITH WHERE THE UPPER LOW
WRAPS UP ACROSS THE PLAINS...THERE IS STILL QUITE A BIT OF
UNCERTAINTY WITH POTENTIAL SNOW/BLOWING SNOW IMPACTS ACROSS THE
PLAINS...ESPECIALLY BEYOND THE TONIGHT PERIOD...SO PER COORDINATION
WITH LONG TERM DESK AND SURROUNDING OFFICES WILL GO WITH A WATCH FOR
THE REMAINDER OF THE SOUTHEAST PLAINS BEGINNING AT 12Z. -KT
.LONG TERM...
(WEDNESDAY THROUGH MONDAY)
COMPLEX PATTERN EXPECTED TO CONTINUE OVER THE CWFA INTO THURSDAY
EVENING WITH NUMEROUS METEOROLOGICAL ISSUES TO CONTEND
WITH(INCLUDING BUT NOT LIMITED TO SNOW AMOUNTS...TEMPERATURES AND
WINDS).
RECENT LONGER TERM COMPUTER SIMULATIONS...FORECAST SOUNDINGS AND
REAL-TIME DATA SUGGEST THAT CLOSED UPPER LOW OVER CENTRAL NEW
MEXICO AT 18Z WEDNESDAY SHIFTS INTO WESTERN KANSAS BY 06Z
THURSDAY AND THEN MOVES INTO CENTRAL NEBRASKA BY 18Z THURSDAY.
SECONDARY UPPER LOW THEN ROTATES NEAR/ACROSS CWFA FROM LATER
CHRISTMAS EVE INTO THURSDAY NIGHT. UPPER LOW FINALLY MOVES INTO
THE MIDWEST BY LATE CHRISTMAS AFTERNOON WITH COLD NORTHERLY UPPER
FLOW CONTINUING OVER SOUTHERN COLORADO INTO SATURDAY.
FOR SENSIBLE WEATHER...HAVE ISSUED NUMEROUS WINTER WEATHER
HIGHLIGHTS FROM WEDNESDAY INTO THURSDAY EVENING(PLEASE SEE...PUB
WATCHES/WARNINGS/ADVISORIES AT THE BOTTOM OF THIS DISCUSSION).
FOR NOW WILL GO WITH WINTER WEATHER ADVISORY FOR ZONES
58>63...72>82...84/87/88 AND 95 FROM TONIGHT/WEDNESDAY MORNING
INTO THURSDAY EVENING...ALTHOUGH IF RECENTLY ARRIVED 06Z/22ND GFS40
VERIFIES...THEN UPGRADES TO A WARNING MAY BE NEEDED FOR SEVERAL OF
THESE ZONES. ALSO THE 06Z/22ND GFS40 IS COMING IN QUITE AGGRESSIVELY
WITH THE QPF OVER THE SOUTHEASTERN PLAINS FROM WEDNESDAY INTO
THURSDAY...SO CURRENT WINTER STORM WATCH MAY BE UPGRADED TO A
WARNING IF LATEST COMPUTER MODELS AND REAL-TIME TRENDS CONTINUE TO
SUPPORT 06Z GFS40 TREND. WOULD NOT BE SURPRISED IF 06Z FRIDAY
ENDING TIME FOR CURRENT ADVISORIES/WATCH WILL NEED TO BE SHAVED BY
SEVERAL HOURS...BUT FOR NOW WILL CONTINUE WITH THE LATER ENDING
TIME TO ATTEMPT TO TRY TO ACCOUNT FOR THE POTENTIAL SECONDARY
UPPER WAVE MOVING ACROSS REGION BY LATER THURSDAY. WFO WILL
CONTINUE TO MONITOR CLOSELY AND ISSUE HIGHLIGHTS/ADJUSTMENTS
AS NEEDED.
IN ADDITION TO THE SNOW...WINDS WILL BE ON THE INCREASE...ESPECIALLY
FROM LATER WEDNESDAY INTO THURSDAY...OVER EASTERN SECTIONS AND
HAVE DEPICTED THIS IN LATEST GRIDS/ZONES. ALSO...MUCH COLDER
CONDITIONS ANTICIPATED...ESPECIALLY EASTERN SECTIONS FROM
WEDNESDAY INTO CHRISTMAS.
FINALLY...WITH FOCUS ON GRIDS/ZONES FROM WEDNESDAY THROUGH
CHRISTMAS DAY FRIDAY...ONLY DID MINOR ADJUSTMENTS TO THE REMAINDER
OF THE LONG TERM GRIDS/ZONES.
&&
.AVIATION...
SNOW WILL SPREAD INTO THE CONTINENTAL DIVIDE THIS MORNING WITH
WIDESPREAD MT OBSCURATIONS EXPECTED BY AFTERNOON. VFR CIGS WILL
SPREAD ACROSS THE EASTERN PLAINS BY AFTERNOON...WITH CEILINGS
LOWERING THROUGH THE EVENING AS EASTERLY UPSLOPE FLOW DEVELOPS.
EXPECT IFR CIGS TO BEGIN AT KCOS BETWEEN 01Z-03Z WITH LIGHT SNOW
DEVELOPING AROUND/AFTER 03Z. LOCAL LIFR CIGS NEAR THE MOUNTAINS
WILL BE POSSIBLE. SNOW WILL BEGIN TO SPREAD INTO KPUB AROUND/AFTER
06Z. FOR NOW...SNOWFALL AMOUNTS OF AN INCH OR TWO WILL BE POSSIBLE
AT ALL 3 AIRPORTS...WITH BEST WINDOW FOR LIGHT TO MODERATE
SNOWFALL AFTER 06Z. IFR CIGS WILL BECOME WIDESPREAD ACROSS THE
SOUTHEAST PLAINS BY EARLY WEDNESDAY MORNING AS LIGHT SNOW SPREADS
ACROSS THE AREA. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY EVENING
FOR COZ089-093-094-097>099.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM MST
THURSDAY FOR COZ058>063-072>082-084.
WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 11 PM MST
THURSDAY FOR COZ095.
WINTER STORM WARNING FROM 11 PM THIS EVENING TO 11 PM MST
THURSDAY FOR COZ096.
WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 11 PM MST
THURSDAY FOR COZ087-088.
WINTER WEATHER ADVISORY UNTIL 11 AM MST WEDNESDAY FOR COZ066-067.
WINTER STORM WARNING UNTIL 11 AM MST WEDNESDAY FOR COZ068.
&&
$$
