FXUS65 KPUB 060337
AFDPUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
837 PM MST SAT DEC 5 2009
.UPDATE...HAVE UPGRADED OUR BLIZZARD WATCH FOR THE SAN JUANS TO A
BLIZZARD WARNING. LATEST MODEL GUIDANCE STILL VERY MUCH ON TRACK
WITH PREVIOUS RUNS. CONFIDENCE IS VERY HIGH THAT BLIZZARD CONDITIONS
WILL AFFECT THE HIGHER ELEVATIONS INCLUDING THE HIGH PASSES LIKE
WOLF CREEK FROM MON MORNING THROUGH TUE. WORST OF THE STORM SHOULD BE
EARLY TUE MORNING...MIDNIGHT THROUGH ABOUT 15Z OR SO...WHEN 70 KT RIDGE
TOP WINDS CROSS THE DIVIDE. NEEDLESS TO SAY...NOT A VERY SMART
TIME TO BE PLANNING ANY BACKCOUNTRY ACTIVITIES IN THE SAN JUANS
THOSE DAYS. WITH INCREASING LAPSE RATES...WILL LIKELY SEE SNOWFALL
RATES OF 2-4 INCHES PER HOUR TUE MORN. ANTICIPATE ROAD CLOSURES
AND AN INCREASED AVALANCHE THREAT BUILDING THROUGH THE END OF THIS
COMING WEEK. STAY TUNED FOR THE LATEST UPDATES. ROSE
&&
.PREV DISCUSSION... /ISSUED 330 PM MST SAT DEC 5 2009/
SHORT TERM...
(TONIGHT AND TOMORROW)
CURRENTLY...
SURFACE OBSERVATIONS ALONG WITH 3H PRESSURE CHANGE CHARTS AT 2 PM
INDICATE LEADING EDGE OF COOLER AIR WAS LOCATED ON THE NORTH SIDE OF
THE PALMER DIVIDE...ROUGHLY ALONG AND N OF I-70. SAME CHARTS WERE
INDICATING A SURFACE LOW WAS GETTING ITS ACT TOGETHER SOUTH OF KLHX.
REGIONAL RADAR WAS INDICATING IT WAS STILL RATHER DRY...WITH JUST
SOME HI CLOUD ECHOES BEING PICKED UP OVER THE W PART OF THE STATE.
AN ARCTIC COLD FRONT WAS LOCATED FROM ROUGHLY RAPID CITY TO SOUTH OF
SALT LAKE CITY. OVER THE FAR SE PLAINS AND IMMEDIATELY E OF THE WET
MTNS...TEMPS WARMED UP INTO THE 50S...WITH 40S OVER THE REST OF THE
PLAINS.
REST OF TODAY AND TONIGHT...
OVERALL DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE ONGOING FCST. AS
HAS BEEN ADVERTISED THE LAST FEW DAYS...MAIN ACTIVITY WITH THIS
FIRST WEATHER SYSTEM WILL OCCUR MAINLY NORTH OF HIGHWAY 50. NAM
INDICATES RAPID CHANGES WILL OCCUR ALONG THE I-25 CORRIDOR THIS
EVENING AS 700 MB TEMPS DROP RAPIDLY. THIS WILL ALLOW LOW CLOUDS TO
QUICKLY DEVELOP LATER THIS EVENING AND LIGHT PRECIP SHOULD DEVELOP
AFTER 9 PM ACROSS THE PIKES PEAK REGION. MODEST ISENTROPIC LIFT WAS
INDICATED THROUGHOUT THE EVENING AND INTO TONIGHT...AND SEVERAL
INCHES OF SNOW SHOULD OCCUR ACROSS THE PIKES PEAK REGION. DECIDED
AGAINST ANY HIGHLIGHTS FOR NOW BUT THIS AREA WILL NEED TO BE
WATCHED. OVER THE REST OF THE PLAINS...SKIES SHOULD CLOUD UP LATE
THIS EVENING WITH LOW CIGS. BEST CHANCE OF LIGHT SNOW WILL OCCUR
LATER TONIGHT NORTH OF A LINE FROM KTAD TO KLHX.
AS FOR THE MTNS...SOUTHWEST MTNS SHOULD SEE ONLY SOME LIGHT ACCUMS
TONIGHT. CENTRAL MTNS HOWEVER WILL SEE BETTER QG LIFT ALONG WITH
GOOD OROGRAPHICS...SO ANTICIPATE 6 TO 10 INCHES OF NEW SNOW TO FALL
THROUGH NEXT 24H. FOR THIS REASON ISSUED A WINTER WEATHER ADVISORY FOR
THE CENTRAL MTNS.
TOMORROW...
BEST CHANCE OF SNOW WILL CONTINUE OVER C MTNS THROUGH THE DAY. SNOW
WILL ALSO OCCUR ON THE PLAINS MAINLY N OF HIGHWAY 50...WITH MOST OF
THE SNOW OCCURRING DURING THE MORNING HOURS. BY AFTERNOON...
ISENTROPIC LIFT DISSIPATES AND BETTER FORCING MOVES OFF TO THE
NORTHEAST. SKIES SHOULD REMAINS CLOUDY ACROSS THE
REGION...ESPECIALLY THE PLAINS.
IT WILL BE QUITE COLD TOMORROW AS ARCTIC AIR REMAINS ENTRENCHED OVER
REGION. TEMPS SHOULD BE ABOUT 20F COOLER THAN TODAYS HIGHS.
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LONG TERM...
(SUNDAY NIGHT THROUGH SATURDAY)
..HEAVY SNOW FOR THE CENTRAL AND WESTERN MOUNTAINS...
QUICK MOVING TROUGH WILL LIFT OUT OF THE ROCKIES AND INTO THE
PLAINS SUNDAY NIGHT WHILE A MORE POTENT STORM SYSTEM DROPS INTO
THE GREAT BASIN. SNOW WILL DECREASE IN COVERAGE OVER THE CENTRAL
AND WESTERN MOUNTAINS WITH A FEW FLURRIES LINGERING THROUGH
MORNING. TEMPERATURES WILL BE QUITE COLD ACROSS THE REGION WITH
SINGLE DIGITS TO LOW TEENS OVER THE EASTERN PLAINS...AND BELOW
ZERO OVER THE MOUNTAIN WEST.
STRONG STORM SYSTEM DROPS SOUTH ACROSS THE GREAT BASIN ON MONDAY
AND MONDAY NIGHT TURNING OUR FLOW SOUTHWESTERLY AND PUMPING
MOISTURE INTO THE ROCKIES. WEAK VORT ENERGY WILL SPREAD ACROSS THE
WESTERN MOUNTAINS WITH SNOW ONCE AGAIN DEVELOPING. SNOW COULD BE
HEAVY AT TIMES IN THE HIGHER ELEVATIONS WITH SEVERAL INCHES
THROUGH THE DAY.
FOCUS TURNS TO MONDAY NIGHT AND TUESDAY WITH BLIZZARD CONDITIONS
OVER THE EASTERN SAN JUANS AND HEAVY SNOW OVER THE CENTRAL
MOUNTAINS. UPPER TROUGH MOVES INTO THE INTERMOUNTAIN WEST ON
MONDAY NIGHT AND ACROSS THE SOUTHERN ROCKIES ON TUESDAY. STRONG
JET WRAPS AROUND THE LOW AND SUBTROPICAL MOISTURE WILL BE PUMPED
NORTHWARD INTO SOUTHWESTERN COLORADO. WINDS WILL INCREASE MONDAY
NIGHT OVER THE WESTERN MOUNTAINS WITH GUSTS OVER 50 KTS. STRONG
WIND AND HEAVY SNOW WILL COMBINE TO PRODUCE BLIZZARD CONDITIONS
OVER THE EASTERN SAN JUANS THROUGH TUESDAY...SNOW ACCUMULATIONS WILL
BE SIGNIFICANT WITH 40 TO 60 INCHES OVER THE SAN JUANS. OVER THE
CENTRAL MOUNTAINS...SNOWFALL TOTALS WILL BE SOMEWHAT LESS WITH 20
TO 30 INCHES. ELSEWHERE...THE SANGRE DE CRISTOS WILL SEE 4 TO 8
INCHES OF SNOWFALL AND 1 TO 2 INCHES EXPECTED IN THE SAN LUIS
VALLEY. ANOTHER CONCERN FOR TUESDAY WILL BE WINDS AND TEMPERATURES
ACROSS THE PLAINS. STRONG WINDS ALOFT COULD SET THE STAGE FOR
STRONG SURFACE WINDS TUESDAY ALONG THE LEE SLOPES. CURRENT CROSS
SECTIONAL ANALYSIS INDICATES MORE OF A TRAPPED LEE WAVE EVENT WITH
WINDS GUSTING TO NEAR 40 KTS IN ALONG THE LEE SLOPES OF THE SANGRE
DE CRISTO AND WET MOUNTAINS. IF CONDITIONS BEGIN TO INDICATE
DUCTING WITH FUTURE MODEL RUNS...HIGHER WINDS WILL BE LIKELY WITH
GREATER DOWNSLOPE POTENTIAL. WARMED TEMPERATURES SIGNIFICANTLY
ACROSS THE SOUTHEASTERN PLAINS ON TUESDAY WITH STRONG MIXING AND
DELAYED ARRIVAL OF THE SURFACE FRONT. HIGHS WILL REACH IN THE
UPPER 30S TO NEAR 40 ALONG THE LEE SLOPES AND ADJACENT PLAINS.
COLD FRONT RACES SOUTH ON TUESDAY EVENING WITH WINDS TURNING
NORTHERLY AND MUCH COLDER AIR FILTERING INTO THE REGION. UPPER
TROUGH WILL ALSO BE PROGRESSING OVER THE AREA WITH SNOW SPREADING
EASTWARD OUT OF THE MOUNTAINS AND INTO THE PLAINS. NOT MUCH IN THE
WAY OF ACCUMULATIONS EXPECTED OVER THE EASTERN PLAINS WITH AMOUNTS
GENERALLY NEAR AN INCH. SNOW WILL DECREASE TUESDAY NIGHT OVER THE
WESTERN AND CENTRAL MOUNTAINS AND COME TO AN END ACROSS THE PLAINS
BY WEDNESDAY MORNING. WHILE MODELS ARE IN AGREEMENT WITH THIS
STORM SYSTEM...SLIGHT DEVIATIONS IN TRACK AND SPEED WILL IMPACT
WHAT AREAS SEE HEAVY SNOWFALL AND HOW MUCH SNOW WILL FALL.
A SHORTWAVE TROUGH IS FORECAST TO DROP IN BEHIND THE DEPARTING
TROUGH ON WEDNESDAY BRINGING ANOTHER QUICK SHOT OF SNOW TO THE
WESTERN AND CENTRAL MOUNTAINS WITH AN ADDITIONAL FEW INCHES OF
SNOWFALL EXPECTED. MODELS DIVERGE LATE IN THE WEEK WITH THE GFS
GENERATING WESTERLY ZONAL FLOW WHILE THE ECMWF REMAINS MORE
AMPLIFIED WITH THE CANADIAN LOW. THE GFS SOLUTION WOULD BRING
WARMER CONDITIONS TO THE REGION WHILE THE ECMWF KEEPS THE REGION
COOLER. NO SIGNIFICANT CHANGES MADE TO THE FORECAST THURSDAY
THROUGH SATURDAY. 88
AVIATION...
FOR KALS...
EXPECT VFR CONDITIONS NEXT 24 HOURS. GUSTY SW SURFACE WINDS WILL
BECOME A CONCERN BY TOMORROW AFTERNOON OVER THE VALLEY...EXPECT SW
WINDS OF 20 TO 30 MPH.
FOR KCOS...
HIGH IMPACT EVENT EXPECTED. MAIN CONCERN WILL BE LOW CIGS AND
POSSIBLY RESTRICTED VIS DUE TO BOTH SNOW AND FOG. LOW CIGS SHOULD
DEVELOP AFTER 04Z AS ARCTIC AIR MOVES IN. CIGS LIKELY TO GO INTO THE
LIFR CATEGORY. SNOW NOT EXPECTED TO BE HEAVY...BUT COULD BE STEADY
FOR A 12-15H PERIOD FROM MIDNIGHT TO EARLY AFTERNOON SUNDAY.
TEMPS WILL BE VERY COLD WITH TEENS AND 20S EXPECTED FOR TOMORROWS
HIGHS.
FOR KPUB...
MODERATE TO HIGH IMPACT EVENT EXPECTED. MAIN CONCERN WILL BE CIGS AS
IFR CONDITIONS EXPECTED FROM LATER TONIGHT INTO TOMORROW AFTERNOON.
COULD ALSO SEE SOME LIGHT SNOW AND FOG.
COLD TEMPS EXPECTED AS HIGHS ONLY EXPECTED INTO THE LOWER 20S.
REST OF AREA...
ARCTIC AIRMASS WILL OVERSPREAD PLAINS LATER THIS EVENING AND LAST
THROUGH SUNDAY. HEAVY SNOWS EXPECTED ALONG CENTRAL MTN REGION WITH
LIGHTER SNOWS SW MTNS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH TUESDAY
AFTERNOON 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 SUNDAY FOR COZ058-060.
&&
$$
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