FXUS65 KPUB 080432 AAB
AFDPUB

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
932 PM MST MON DEC 7 2009

.UPDATE...
QUICK CALL AROUND TO SPOTTERS THIS EVENING HAS YIELDED SOME
REPORTS OF SNOW INTENSIFYING ACROSS THE SOUTHWEST MOUNTAINS AND IN
THE DOWNWIND SIDE OF THE SANGRE DE CRISTO RANGE. IN
FACT...HEAVIEST REPORT TO THE LEE OF THE SANGRES WAS 12 INCHES 11
NNE OF CRESTONE WHICH FELL TODAY. SOUTHERN AREAS OF THE SANGRES ONLY
HAD AN INCH SO FAR. BUT GOOD ENHANCEMENT IN SAT IMAGERY IS MOVING
IN WITH NICE ISENTROPIC LIFT SPREADING IN AS UPPER TROF NEARS.
WINDS WILL GET QUITE STRONG OVER THE PEAKS AND THROUGH LA VETA
PASS TOMORROW AS WELL. THUS HAVE DECIDED TO UPGRADE THE WINTER
WEATHER ADVISORY FOR THE SANGRES TO A WARNING. WILL GO WITH SNOW
TOTALS IN THE 8 TO 18 INCH RANGE...THOUGH AMOUNTS ARE LIKELY TO
BE HIGHLY VARIABLE ACROSS THE LOWER EASTERN SLOPES WHERE AMOUNTS
WILL TAPER OFF QUICKLY ACROSS THE LOWER ELEVATIONS. -KT

&&

.PREV DISCUSSION... /ISSUED 500 PM MST MON DEC 7 2009/ 

UPDATE...

HAVE ADDED A BLOWING SNOW ADVISORY TO THE FAR SERN PLAINS. NOT
MUCH IN THE WAY OF ACCUMULATION EXPECTED...BUT WITH SNOW ON THE
GROUND AND MORE TO COME LATER TONIGHT...PLUS WINDS PICKING UP
ESPECIALLY WITH THE FRONT TOMORROW...FEEL AN ADVISORY IS JUSTIFIED
FOR HAZARDOUS CONDITIONS. WILL KEEP TIMING THE SAME AS OTHER
PRODUCTS...TONIGHT THROUGH TOMORROW AFTERNOON. 44

PREV DISCUSSION... /ISSUED 241 PM MST MON DEC 7 2009/ 

SHORT TERM...

(TONIGHT AND TOMORROW)

.THE SHOW HAS COMMENCED AS A MAJOR WINTER STORM SLAMS THE REGION...

CURRENTLY...

SO FAR WOLF CREEK HAS OVER 2 FEET AND THE HEAVIEST SNOW IS YET TO 
COME. 

OVER THE ENTIRE REGION...SKIES ARE CLOUDY TO MOSTLY CLOUDY. ACROSS 
NEARLY ALL OF THE REGION IT IS SNOWING. OVER THE PLAINS IT IS RATHER 
LIGHT WHILE THE MTNS...ESPECIALLY THE MTNS ALONG THE CONTDVD...IT IS 
HEAVY. WEB CAMS FROM CDOT AND THE SKI RESORTS ARE SHOWING VERY LOW 
VIS IN S++.

IT IS VERY COLD AT THIS HOUR (2 PM). THE LOWER ELEVATIONS OF THE 
PIKES PEAK REGION ARE IN THE SINGLE DIGITS...WHILE THE REST OF THE 
PLAINS ARE IN THE TEENS. THE SAN LUIS VALLEY IS RATHER WARM WITH 
TEMPS IN THE MID 30S. 

3H PRESSURE FALLS ARE WIDESPREAD...WITH NEARLY ALL AREAS IN AND 
AROUND COLORADO 3MB OR BETTER.

TONIGHT AND TOMORROW...

FIRST - FOR THE MOUNTAINS...

SNOWFALL RATES WILL ONLY INCREASE OVER THE SW MTNS. AS I STATED 
YESTERDAY ATTM...THE QPF VALUES ACROSS THE SW MTNS ARE INSANE WITH 
LIQUID EQUIVALENTS 3+. THE HEAVIEST SNOW WILL FALL BETWEEN 03Z THIS 
EVENING AND 15Z TUESDAY. A SIMPLE 1:10 RATIO IS 36 INCHES AND IT 
WILL BE HIGHER THAN THAT. I EXPECT WOLF CREEK WILL GET OVER 50". 
WINDS WILL HOWL AND SNOWSLIDES ARE LIKELY.

THE REST OF THE MTNS ALONG THE DIVIDE WILL ALSO GET HEAVY SNOW 
ALTHOUGH THE HEAVIEST FOR THE C MTNS WILL OCCUR TOMORROW INTO 
TOMORROW NIGHT AS WINDS BECOME MOPE NORTHWESTERLY.

THE REST OF THE MTNS WILL ALSO GET SNOW...BUT HOW MUCH?

IF THE ARCTIC AIR WAS NOT IN PLACE AND THIS SYSTEM WAS NOT SO 
STRONG...THEN I WOULD ONLY BE PREDICTING SNOW SHOWERS FOR THE MTNS 
WITH THIS TYPE OF SYSTEM. HOWEVER...THERES ALOT OF MSTR ALOFT WITH 
THIS TROUGH...THE ARCTIC AIR IS IN PLACE AND THE DYNAMICS WITH THIS 
SYSTEM ARE IMPRESSIVE. LIKEWISE...I WOULD NOT BE TOO SURPRISED IF 
QUITE A FEW AREAS GET AT LEAST 4-8" WITH HIGHER AMOUNTS ATOP THE 
SANGRES. 

PARTS OF THE SAN LUIS VALLEY WILL ALSO SEE SIGNIFICANT SNOW. 
BLOWOVER FROM THE SAN JUANS IS A GIVEN AND WITH THE SOUTHERLY FLOW 
IN THE VALLEY THE W FACING SLOPES OF THE VALLEY MAY ALSO SEE SOME 
ENHANCED ACCUMS. FOR NOW WE HAVE A WINTER WX ADVISORY FOR THIS 
REGION. SOME AREAS NEAR THE MTNS MAY GO INTO WARNING CRITERIA 
THOUGH. 

THE PLAINS...

WITH THE ARCTIC AIR IN PLACE AND THE MSTR ALOFT RIDING ABOVE AND THE 
STRONG DYNAMICS COMING THROUGH LATER TONIGHT AND TOMORROW 
MORNING...I BELIEVE WE WILL SEE SOME STEADY SNOW TONIGHT OVER PARTS 
OF THE PLAINS. IT APPEARS THE BEST AREA WILL BE THE PIKES PEAK 
REGION AS THE BEST UPGLIDE WAS SHOWN IN THIS REGION (IT WAS ACTUALLY 
VERY IMPRESSIVE UPGLIDE FOR A FEW HOURS...SO DONT BE SURPRISED IF 
ITS SNOWING HEAVILY ACROSS THE PIKES PEAK AREA AROUND SUNRISE). OVER 
THE FAR EASTERN PLAINS...ESPECIALLY KIOWA COUNTY...SNOWFALL AMOUNTS 
MAY BE ENHANCED BY WRAPAROUND PRECIP LATER TOMORROW AFTERNOON. 
ELSEWHERE I EXPECT STEADY LIGHT SNOW TONIGHT WITH SOME ENHANCEMENT 
AS THE BEST DYNAMICS MOVE THROUGH TOMORROW MORNING. 

THE WINDS WILL PICK UP TOMORROW. STRONG NORTHERLIES WILL AFFECT THE 
PIKES PEAK REGION LATE MORNING AND THEN BLAST SOUTH ACROSS THE REST 
OF THE PLAINS DURING THE EARLY TO MID AFTERNOON TIME PD. ANY SNOW 
THAT DOES FALL (PLUS THE SNOW THAT HAS ALREADY FALLEN) WILL BLOW 
AROUND AND VIS WILL LIKELY BE NEAR ZERO AT TIMES TOMORROW ON THE 
PLAINS. 

GIVEN THE CHANCE OF SOME ENHANCED SNOW TONIGHT AND TOMORROW...PLUS 
THE WINDS...I THOUGHT IT BEST TO ISSUE A S/BS ADVISORY FROM THIS 
EVENING UNTIL TOMORROW AFTERNOON. \/34

LONG TERM...

(TUESDAY NIGHT THROUGH MONDAY)

POTENT UPPER TROUGH WILL PROGRESSING INTO THE CENTRAL PLAINS BY
TUESDAY EVENING WITH A QUICK MOVING SHORTWAVE TROUGH FOLLOWING
BEHIND INTO THE ROCKIES BY WEDNESDAY MORNING. EXPECT THE HEAVY
SNOW OVER THE EASTERN SAN JUANS TO DECREASE IN INTENSITY WITH
LIGHT SNOW EXPECTED BY WEDNESDAY MORNING. LIGHT SNOW WILL ALSO
COME TO AN END ACROSS THE EASTERN PLAINS TUESDAY EVENING AS THE
UPPER TROUGH DEPARTS THE REGION. THE ONLY EXCEPTION WILL BE OVER
THE CENTRAL MOUNTAINS. NORTHWESTERLY FLOW WILL PROVIDE UPSLOPE
FLOW OVER THE CENTRAL MOUNTAINS THROUGH TUESDAY NIGHT. THIS
UPSLOPE FLOW ALONG WITH EXTRA LIFT FROM THE QUICK PASSING
SHORTWAVE TROUGH WILL ALLOW FOR MODERATE TO HEAVY SNOW TO CONTINUE
INTO WEDNESDAY MORNING. VERY COLD TEMPERATURES WILL HELP PRODUCE
VERY HIGH SNOWFALL RATIOS SO IT WILL NOT TAKE MUCH MOISTURE TO
PRODUCE ADDITIONAL ACCUMULATIONS. EXTENDED THE WINTER STORM WARNING
FOR THE SAWATCH RANGE THROUGH 12Z WEDNESDAY WITH AN ADDITIONAL 5
TO 9 INCHES OF SNOW EXPECTED BY WEDNESDAY MORNING. TEMPERATURES
WILL BE VERY COLD ACROSS THE EASTERN PLAINS WEDNESDAY MORNING
WITH LOWS NEAR ZERO AND WIND CHILL VALUES APPROACHING -20F. A WIND
CHILL ADVISORY MAY BE NEEDED OVER PARTS OF THE EASTERN PLAINS AND
SAN LUIS VALLEY TUESDAY NIGHT INTO WEDNESDAY MORNING.

SHORTWAVE TROUGH WILL MOVE QUICKLY INTO THE CENTRAL PLAINS
WEDNESDAY MORNING BEFORE A FINAL SHORTWAVE TROUGH DROPS SOUTH OUT
OF THE ROCKIES WEDNESDAY EVENING. SNOW MAY TAPER OFF FOR A FEW
HOURS OVER THE CENTRAL MOUNTAINS MIDDAY WEDNESDAY BEFORE PICKING
UP AGAIN AS THE WAVE MOVES ACROSS COLORADO. NORTHWESTER UPSLOPE
FLOW AND HIGH SNOW RATIOS WILL LIKELY PRODUCE SEVERAL MORE
INCHES OF SNOWFALL THROUGH WEDNESDAY EVENING. THINGS BEGIN TO
IMPROVE ON THURSDAY AS THE MAIN CANADIAN LOW STARTS TO SHIFT TO
THE EAST. THIS WILL KEEP ALL SHORTWAVE ACTIVITY WELL TO THE NORTH
AND EAST. COLD AIR IN PLACE ALONG WITH WEAK UPSLOPE FLOW AND SNOW
COVER WILL KEEP THE PLAINS COLD WEDNESDAY AND THURSDAY WITH HIGHS
IN THE LOWER TO UPPER 20S.

MODELS BEGIN TO DIVERGE HEADING INTO THE WEEKEND. CURRENTLY
THINKING ECMWF HAS THE BEST HANDLE ON HOW THE LARGE SCALE WILL
EVOLVE WITH SUBTROPICAL BRANCH UNDERCUTTING THE ALASKAN HIGH. THIS
WOULD KEEP AN ACTIVE WAVE PATTERN OVER THE DESERT SOUTHWEST AND
SOUTHERN ROCKIES HEADING INTO EARLY NEXT WEEK. GFS MORE ZONAL
WITH WEAK EMBEDDED WAVES...HOWEVER HAS VERY LITTLE SUPPORT FROM
ENSEMBLES LIKE THE ECMWF SOLUTION. THE MAIN IMPACTS WILL BE SNOW
FOR THE EASTERN SAN JUANS THIS WEEKEND AND EARLY NEXT WEEK. THE
ECMWF HAS TWO SYSTEMS TRANSVERSING THE REGION...A QUICK MOVING
WAVE ON SATURDAY AND A MUCH STRONGER STORM ON MONDAY. THIS WOULD
BRING MORE MOUNTAIN SNOWS TO THE REGION WITH THE SAN JUANS HAVING
THE BEST CHANCE OF SEEING HEAVY SNOW. THERE IS STILL A LOT OF
UNCERTAINTY THIS FAR OUT IN THE FORECAST...BUT IT IS SOMETHING TO
WATCH. 88

AVIATION...

AT KCOS...SNOW AND LOW CIGS WILL OCCUR NEXT 24H. SNOW WILL BECOME 
STEADY AND MAY BECOME HEAVY FOR A FEW HOURS AROUND SUNRISE AS THE 
TROUGH AXIS MOVES ACROSS. STRONG NORTHERLY WINDS WILL DEVELOP AROUND 
17Z AND LAST UNTIL SUNSET. EXPECT 20-40 MPH WINDS AND SIGNIFICANT 
BLOWING SNOW. THIS COULD DEVELOP INTO A HIGH IMPACT EVENT FOR KCOS 
TOMORROW. 

AT KPUB...LOW CIGS AND LIGHT SNOW WILL BE LIKELY THROUGH AT LEAST 
TOMORROW MORNING. STRONG NW WINDS OF 25 TO 35 MPH WILL BE POSSIBLE 
DURING THE AFTERNOON. 

AT KALS...SNOW SHOWERS WILL CONTINUE THROUGH THE NIGHT WITH THE 
PRECIP ENDING TOMORROW MORNING. SOME ACCUMULATIONS IS POSSIBLE. 
GUSTY NW WINDS WILL BE POSSIBLE TOMORROW. \/34

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 PM MST TUESDAY FOR COZ062-063-
069>071-076>089-093>099.

WINTER STORM WARNING UNTIL 5 AM MST WEDNESDAY FOR COZ058>061.

WINTER STORM WARNING UNTIL 5 PM MST TUESDAY FOR COZ064-065-067-
072>075.

BLIZZARD WARNING UNTIL 5 PM MST TUESDAY FOR COZ066-068.

&&

$$

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