FXUS65 KPUB 152202
AFDPUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
302 PM MST TUE DEC 15 2009
.SHORT TERM...
(TONIGHT AND WEDNESDAY)
CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING
MODERATE WESTERLY FLOW ALOFT ACROSS THE STATE WITH STRONGER FLOW
PERSISTING ACROSS THE NORTHERN TIER OF STATES. WATER VAPOR IMAGERY
ALSO INDICATING PACIFIC MOISTURE ALONG WITH SHORT WAVES EMBEDDED
WITHIN THE STRONGER ZONAL FLOW WITH ONE MOVING ACROSS THE NORTHERN
ROCKIES AND ANOTHER MOVING ONSHORE ACROSS THE PAC NORTHWEST COAST
ATTM. AT THE SFC...LEE TROUGHING STRENGTHENING ACROSS THE I-25
CORRIDOR WITH SOUTHERLY RETURN FLOW HELPING TO SCOUR OUT THE SHALLOW
COLD AIRMASS ACROSS THE FAR EASTERN PLAINS ATTM.
TONIGHT AND WEDNESDAY...NOT MUCH CHANGE IN CURRENT FORECAST THINKING
WITH MILD OVERNIGHT LOWS EXPECTED...ESPECIALLY ACROSS THE LOWER
EASTERN SLOPES AND IMMEDIATE ADJACENT PLAINS ALONG AND WEST OF
I-25...WITH LEE TROUGH KICKING EAST LATE TONIGHT AS NORTHERN ROCKIES
SHORT WAVE CONTINUES OUT ACROSS THE NORTHERN HIGH PLAINS. COLDEST
READINGS TO BE ACROSS THE CENTER OF THE SAN LUIS VALLEY WHERE STRONG
INVERSIONS TO REMAIN IN PLACE...THOUGH LOWS COULD BE TEMPERED BY
INCREASING HIGH CLOUDS THROUGH THE EARLY MORNING. HIGH CLOUDS TO
CONTINUE TO FILTER ACROSS THE AREA THROUGH THE DAY ON WEDNESDAY AND
ALONG WITH DEVELOPING WEAK EASTERLY UPSLOPE FLOW WILL TEMPER HIGHS
ACROSS THE AREA...THOUGH STILL EXPECT READINGS TO BE ABOVE SEASONAL
AVERAGES WITH LOWER TO MID 50S ACROSS THE EASTERN PLAINS AND MAINLY
30S AND 40S ACROSS THE HIGHER TERRAIN. -MW
.LONG TERM...
(WEDNESDAY NIGHT THROUGH TUESDAY)
...TREND TOWARDS COLDER TEMPERATURES BY LATE WEEK...
ZONAL FLOW ALOFT WEDNESDAY NIGHT TRANSITIONS TO NORTHWESTERLY AS
UPPER RIDGE BUILDS ALONG THE WEST COAST. THIS ALLOWS THE FIRST IN
SERIES OF SHORTWAVES TO DROP DOWN THROUGH THE NRN U.S. ROCKIES
GLANCING THROUGH EASTERN CO THURS NIGHT/EARLY FRI. ONE MORE WARM
DAY EXPECTED FOR THURSDAY...THOUGH WEAK FRONT MAY TRY TO BACK DOOR
INTO THE EASTERN PLAINS DURING THE AFTERNOON. MAIN BRUNT OF THE COLD AIR
WILL DROP DOWN THURSDAY NIGHT...AND AFTER ONE MORE DAY WITH HIGHS IN
THE 50S ACROSS THE PLAINS...SHOULD SEE AROUND A 10 TO 15 DEGREE
COOL DOWN FOR FRIDAY. STILL SOME DISCREPANCIES BETWEEN MODELS ON
PRECIPITATION ASSOC WITH THIS SYSTEM. 12Z GFS AND 00Z ECMWF FROM
YESTERDAY BROUGHT A BRIEF SHOT OF SNOW TO THE CENTRAL MTS/PORTIONS
OF THE EASTERN PLAINS. 12Z NAM IS DRIER BUT SPREADS SOME LIGHT SNOW
ACROSS THE PLAINS LATER ON FRIDAY WITH SECONDARY FAST MOVING SHORTWAVE
ON THE HEALS OF THE FIRST. 12Z ECMWF HAS DRIED OUT ACROSS SE CO
FROM ITS PREVIOUS RUN. PLAN TO MAINTAIN ISOLATED POPS FOR CENTRAL
MTS/EASTERN PLAINS. OVERALL DOESN'T LOOK LIKE A HEAVY SNOW
EVENT...BUT A COUPLE INCHES OR SO FOR THE CENTRAL MOUNTAINS
CERTAINLY POSSIBLE.
BRIEF WARM UP FOR SATURDAY AS LEE TROF REDEVELOPS...THEN NEXT
POTENTIAL SHORTWAVE DROPS DOWN WRN U.S. RIDGE BRINGING ANOTHER
GLANCING BLOW OF SNOW SATURDAY NIGHT AND SUNDAY. OF COURSE THERE
ARE STILL UNCERTAINTIES WITH THIS SYSTEM AS ECMWF IS MUCH LESS
AMPLIFIED WITH THIS WAVE. EITHER WAY...SHOULD SPELL ANOTHER COOL
DOWN FOR SUNDAY.
POTENTIALLY MUCH COLDER FOR EARLY NEXT WEEK AS GFS DROPS ANOTHER LOW
DOWN FROM CANADA INTO THE GREAT LAKES/UPPER MID WEST BY TUESDAY.
ECMWF BY CONTRAST TRANSLATES THE WESTERN U.S UPPER RIDGE EASTWARD
INTO THE CENTRAL PLAINS DURING THE SAME TIME PERIOD WITH ANOTHER LOW
DROPPING INTO THE GREAT BASIN BY TUES. LOTS OF UNCERTAINTIES
DURING THESE PERIODS. PLAN TO KEEP GRIDS ON THE COLD SIDE OF
GUIDANCE FOR NOW. -KT
&&
.AVIATION...
EXPECTING VFR CONDITIONS FOR ALL TAF SITES FOR THE NEXT
24 HOURS WITH INCREASING HIGH CLOUDS THROUGH THE PERIOD. -MW
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
23/31
