Winter Storm in Colorado, December 1, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
435 AM MST THU DEC 1 2011

.SHORT TERM...

(TODAY AND TONIGHT)

SNOW FINALLY DEVELOPING OVER TELLER AND EL PASO COUNTIES AS OF 11Z
AS UPSLOPE FLOW DEEPENS...AND EXPECT SNOW TO EXPAND OVER MOST OF THE
MOUNTAINS AND I-25 CORRIDOR THROUGH THE MORNING AS UPWARD MOTION
GRADUALLY INCREASES. OVERALL...MODELS HAVE CONTINUED TO BACK OFF ON
SNOW AMOUNTS OVER THE AREA...WITH EVEN THE MORE AGGRESSIVE NAM
BARELY REACHING WARNING CRITERIA (8 INCHES) OVER THE WETS AND
SANGRES. FOR NOW...KEPT THE WINTER WEATHER HIGHLIGHTS INTACT AS
STRONG WINDS MAY MAKE UP FOR RELATIVELY LIGHT SNOW...THOUGH MAY END
SOME ADVISORIES LATER THIS MORNING OVER THE ARKANSAS VALLEY WHERE
06Z NAM HAS LITTLE ACCUMULATION. SUSPECT SHADOWED COLORADO
SPRINGS/PUEBLO/CANON CITY AREAS MAY SEE ONLY LIGHT SNOW (LESS THAN 2
INCHES)...AS STRONG NORTH DOWNSLOPE WINDS OVERCOME WEAK UPWARD
MOTION. SNOW FADES AWAY QUICKLY THIS EVENING WITH UPSLOPE FLOW
ENDING AS UPPER LOW WOBBLES WESTWARD ACROSS THE DESERT SOUTHWEST.
AREAS AROUND CUCHARA AND TRINIDAD WILL HANG ON TO SNOW THE
LONGEST...THOUGH EVEN HERE SUSPECT ONLY FLURRIES WILL REMAIN AFTER
06Z. MOST AREAS HAVE ALREADY REACHED THEIR HIGH TEMPERATURE FOR
TODAY...WITH STEADY TO SLOWLY FALLING TEMPS EXPECTED THROUGH THE
MORNING. STRONGER COLD ADVECTION ARRIVES THIS AFTERNOON...WITH A
MORE DRAMATIC PLUNGE IN TEMPS BY THIS EVENING. OVERNIGHT...EXPECT
MOST LOCATIONS TO SEE THEIR COLDEST NIGHT OF THE YEAR SO FAR AS
SKIES AT LEAST PARTIALLY CLEAR...WITH MAINLY SINGLE DIGITS ABOVE AND
BELOW ZERO OVER ALL BUT THE FAR SOUTHEAST PLAINS.

.LONG TERM...

(FRIDAY THROUGH THURSDAY)

...ACTIVE WEATHER THROUGH MONDAY...

MODELS IN GOOD AGREEMENT WITH A COLD AND ACTIVE PATTERN ACROSS
COLORADO INTO EARLY NEXT WEEK. THE FORECAST FOR THE FIRST PART OF
THE EXTENDED WILL FEATURE A DEEP TROUGH OVER THE ROCKIES WITH
SEVERAL DISTURBANCES DROPPING DOWN INTO THE REGION.

ON FRIDAY...A DEEP UPPER LOW OVER ARIZONA IS FORECAST TO OPEN AND
TRACK EAST INTO NEW MEXICO WHILE A STRONG TROUGH DROPS SOUTH OUT
OF THE NORTHERN ROCKIES INTO UTAH. EXPECT SNOW TO CONTINUE ALONG
THE CONTINENTAL DIVIDE...ESPECIALLY OVER THE SAN JUAN RANGE.
LIGHTER SNOW WILL BE POSSIBLE OVER THE CENTRAL AND EASTERN
MOUNTAINS THROUGH THE DAY ON FRIDAY. NOT ANTICIPATING ANY
PRECIPITATION OVER THE PLAINS GIVEN THE CURRENT STORM TRACK BEING
WELL TO THE SOUTH. TEMPERATURES WILL ALSO BE TROUBLESOME ON FRIDAY
FOR THE PLAINS AND REMAIN DEPENDENT ON SNOW COVER. GUIDANCE HAS
HIGHS RANGING FROM THE LOWER 30S TO LOWER 40S FOR THE PLAINS. FOR
NOW THE CURRENT THINKING IS WE WILL WARM INTO THE 30S FOR THE PLAINS.

FRIDAY NIGHT AND SATURDAY...THE STORM SYSTEM OVER NEW MEXICO WILL
QUICKLY EJECT INTO THE CENTRAL PLAINS WHILE THE UTAH STORM SYSTEM
CONTINUES SOUTH INTO ARIZONA. THIS WILL SEND ANOTHER STRONG COLD
FRONT ACROSS THE REGION. THE GFS AND ECMWF DEVELOP A DECENT ROUND
OF SNOWFALL FOR THE WHOLE REGION WHILE THE NAM KEEPS MOST OF THE
REGION DRY. TRENDED WITH THE GFS AND ECMWF FOR THE FORECAST AND
SPREAD LIKELY POPS ACROSS MUCH OF THE REGION. GIVEN THE COLD
ATMOSPHERIC PROFILE...THINK SOME ACCUMULATIONS WILL BE
POSSIBLE...ESPECIALLY OVER THE RATON MESA AND THE SOUTHEASTERN SANGRE
DE CRISTO MOUNTAINS. IT IS STILL TOO EARLY TO PUT SNOWFALL TOTALS
OUT FOR THIS STORM...WITH TOTALS BEING HIGHLY DEPENDENT ON STORM
TRACK AND WIND FLOW. EXPECT PRECIPITATION TO DECREASE IN COVERAGE
ACROSS THE PLAINS SATURDAY NIGHT WITH LIGHT SNOW CONTINUING FOR
THE MOUNTAINS HEADING INTO SUNDAY.

ONE LAST FINAL DISTURBANCE WILL DROP SOUTH OUT OF THE NORTHERN
ROCKIES SUNDAY AFTERNOON INTO MONDAY. THIS WILL BRING ANOTHER COLD
FRONT AND CHANCE FOR SNOWFALL TO THE PLAINS. MOISTURE DOES NOT
LOOK AS GREAT WITH THIS STORM AND IT WILL MOVE THROUGH RATHER
QUICKLY. ANY SNOW THAT DOES FALL FROM THIS STORM WILL BE LIGHT AND NOT
AMOUNT TO MUCH IN THE WAY OF ACCUMULATIONS. TEMPERATURES WILL BE
COLDEST ON SATURDAY WITH HIGHS ONLY IN THE 20S FOR THE REGION.
TEMPERATURES WILL ONLY REACH THE LOWER TO MID 30S FOR SUNDAY AND
MONDAY FOR THE PLAINS.

BEYOND MONDAY...A LONG WAVE TROUGH IS FORECAST TO DEVELOP OVER THE
WESTERN HALF OF THE CONUS WITH ENERGY DROPPING SOUTH OVER
CALIFORNIA. THIS WILL PUT COLORADO UNDER SOUTHWESTERLY FLOW WITH
WARMING CONDITIONS THROUGH THE MIDDLE OF THE WEEK. MODELS IN
AGREEMENT WITH KEEP THE REGION DRY WITH PRECIPITATION REMAINING
NORTH OF THE CWA. TEMPERATURES WILL WARM SLIGHTLY WITH HIGHS
GENERALLY IN THE 40S TO LOWER 50S FOR THE PLAINS.  MOZLEY

&&

.AVIATION...

AT KCOS...EXPECT SNOW TO DEVELOP 12Z-13Z...WITH A PERIOD
OF IFR CONDITIONS DUE TO LOW VISIBILITY IN SNOW AND BLOWING SNOW
FROM 14Z THROUGH ABOUT 21Z. CONDITIONS GRADUALLY IMPROVE TO MVFR
AFTER 21Z AS SNOW INTENSITY AND WINDS DECREASE...WITH VFR AFTER 04Z
AS CLOUDS BEGIN TO CLEAR. AT KPUB...EXPECT SNOW AFTER 15Z...WITH A
BRIEF PERIOD OF IFR FROM 16-21Z. MVFR CONDITIONS FORECAST IN THE
21Z-04Z TIME FRAME WITH OCCASIONAL LIGHT SNOW...THEN VFR. SNOW
ACCUMULATION AT BOTH KPUB AND KCOS SHOULD BE 2 INCHES OR LESS. AT
KALS...PERHAPS SOME BRIEF...LESS THAN AN HOUR...PERIODS OF IFR OR
MVFR CONDITIONS DUE TO -SHSN WILL BE POSSIBLE THROUGH ABOUT
23Z...THEN VFR OVERNIGHT. IF ENOUGH SNOW FALLS AROUND KALS...WILL
HAVE TO WATCH FOR THE POSSIBILITY OF PATCHY GROUND FOG AFTER 12Z
FRI. OVER THE MOUNTAINS...MOST HIGHER TERRAIN AND MOUNTAIN PASSES
WILL REMAIN OBSCURED TODAY DUE TO LOWER CLOUDS AND SNOW...WITH SOME
GRADUALLY CLEARING AFTER 06Z TONIGHT.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ078-
087-088-094.

WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING FOR COZ072>075-
079-080.

WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ076-
077-083-085-086.

WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ081-
082.

WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR COZ084.

&&

10/88

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
815 PM MST WED NOV 30 2011

COZ058>089-093>099-011400-
WESTERN MOSQUITO RANGE/EAST LAKE COUNTY ABOVE 11000 FT-
LEADVILLE VICINITY/LAKE COUNTY BELOW 11000 FT-
EASTERN SAWATCH MOUNTAINS ABOVE 11000 FT-
WESTERN CHAFFEE COUNTY BETWEEN 9000 AND 11000 FT-
CENTRAL CHAFFEE COUNTY BELOW 9000 FT-
WESTERN MOSQUITO RANGE/EAST CHAFFEE COUNTY ABOVE 9000 FT-
SAGUACHE COUNTY WEST OF CONTINENTAL DIVIDE BELOW 10000 FT-
SAGUACHE COUNTY EAST OF CONTINENTAL DIVIDE BELOW 10000 FT-
LA GARITA MOUNTAINS ABOVE 10000 FT-
UPPER RIO GRANDE VALLEY/EASTERN SAN JUAN MOUNTAINS BELOW 10000 FT-
EASTERN SAN JUAN MOUNTAINS ABOVE 10000 FT-
DEL NORTE VICINITY/NORTHERN SAN LUIS VALLEY BELOW 8500 FT-
ALAMOSA VICINITY/CENTRAL SAN LUIS VALLEY BELOW 8500 FT-
SOUTHERN SAN LUIS VALLEY-
NORTHERN SANGRE DE CRISTO MOUNTAINS BETWEEN 8500 AND 11000 FT-
NORTHERN SANGRE DE CRISTO MOUNTAINS ABOVE 11000 FEET-
SOUTHERN SANGRE DE CRISTO MOUNTAINS BETWEEN 7500 AND 11000 FT-
SOUTHERN SANGRE DE CRISTO MOUNTAINS ABOVE 11000 FT-
NORTHWESTERN FREMONT COUNTY ABOVE 8500 FT-
WESTERN/CENTRAL FREMONT COUNTY BELOW 8500 FT-
WET MOUNTAIN VALLEY BELOW 8500 FEET-
WET MOUNTAINS BETWEEN 6300 AND 10000 FT-
WET MOUNTAINS ABOVE 10000 FT-
TELLER COUNTY/RAMPART RANGE ABOVE 7500 FT/PIKES PEAK BETWEEN
7500 AND 11000 FT-PIKES PEAK ABOVE 11000 FT-
CANON CITY VICINITY/EASTERN FREMONT COUNTY-
NORTHERN EL PASO COUNTY/MONUMENT RIDGE/RAMPART RANGE BELOW
7500 FT-
COLORADO SPRINGS VICINITY/SOUTHERN EL PASO COUNTY/RAMPART RANGE
BELOW 7400 FT-PUEBLO AND VICINITY/PUEBLO COUNTY BELOW 6300 FT-
WALSENBURG VICINITY/UPPER HUERFANO RIVER BASIN BELOW 7500 FT-
TRINIDAD VICINITY/WESTERN LAS ANIMAS COUNTY BELOW 7500 FT-
CROWLEY COUNTY-LA JUNTA VICINITY/OTERO COUNTY-
EASTERN LAS ANIMAS COUNTY-WESTERN KIOWA COUNTY-
EASTERN KIOWA COUNTY-LAS ANIMAS VICINITY/BENT COUNTY-
LAMAR VICINITY/PROWERS COUNTY-SPRINGFIELD VICINITY/BACA COUNTY-
815 PM MST WED NOV 30 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL...EAST
CENTRAL...SOUTH CENTRAL AND SOUTHEAST COLORADO.

.DAY ONE...TONIGHT

AN ARCTIC COLD FRONT WILL DROP THROUGH SOUTH CENTRAL AND SOUTHEAST
COLORADO LATE TONIGHT...SPREADING GUSTY WINDS...COLD TEMPERATURES
AND SNOW ACROSS MUCH OF THE REGION. SNOW WILL SPREAD INTO THE
PIKES PEAK REGION AFTER MIDNIGHT AND WILL CONTINUE TO SPREAD
SOUTHWARD INTO THE EARLY MORNING HOURS ON THURSDAY. COLD AIR
ARRIVING BEHIND THE FRONT WILL CAUSE ANY INITIAL MELTING ON
ROADWAYS TO QUICKLY FREEZE WHICH WILL RESULT IN ICY ROADWAYS AND
BLACK ICE FOR THE MORNING COMMUTE...ESPECIALLY THOSE TRAVELING
NORTH TO DENVER. IN ADDITION...GUSTY NORTH WINDS 15 TO 30 MPH
WITH GUSTS TO 40 MPH WILL CAUSE POOR VISIBILITIES IN BLOWING SNOW
OVER NORTHERN EL PASO COUNTY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SNOW WILL CONTINUE TO SPREAD SOUTHWARD ACROSS THE UPPER ARKANSAS
RIVER VALLEY AND SOUTHEAST MOUNTAINS AND ADJACENT PLAINS EARLY
THURSDAY MORNING. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHEAST FACING SLOPES OF THE WET AND SANGRE DE CRISTO MOUNTAINS
THROUGH THE DAY ON THURSDAY BEFORE TAPERING OFF DURING THE EVENING
HOURS. TOTAL SNOWFALL AMOUNTS ACROSS SOUTH CENTRAL AND SOUTHEAST
COLORADO WILL RANGE FROM

3 TO 7 INCHES WITH LOCALLY HIGHER AMOUNTS ACROSS PORTIONS OF
TELLER...AND NORTHERN EL PASO COUNTIES...

6 TO 12 INCHES ACROSS THE SANGRE DE CRISTO MOUNTAINS AND WET
MOUNTAINS WITH THE HEAVIEST ALONG THE NORTHEAST FACING SLOPES...

2 TO 6 INCHES ACROSS THE HIGHER ELEVATIONS OF FREMONT
COUNTY...THE WET MOUNTAIN VALLEY...AND THE SOUTHERN INTERSTATE 25
CORRIDOR INCLUDING THE WALSENBURG AND TRINIDAD AREAS...

AND 1 TO 2 INCHES ACROSS CENTRAL FREMONT COUNTY...SOUTHERN EL PASO
COUNTY...AND PUEBLO COUNTY...INCLUDING THE CITIES OF COLORADO
SPRINGS...PUEBLO...AND CANON CITY.

FOR THE REMAINDER OF SOUTH CENTRAL AND SOUTHEAST COLORADO...MOUNTAIN
AREAS COULD SEE ANYWHERE FROM 2 TO 6 INCHES...WITH GENERALLY A TRACE
TO 2 INCHES FOR THE VALLEYS...AND PLAINS EAST OF INTERSTATE 25.

COMBINED WITH GUSTY NORTH TO NORTHEAST WINDS 15 TO 30 MPH WITH
GUSTS TO 40 MPH...VISIBILITIES WILL BE REDUCED TO LESS THAN A MILE
AT TIMES IN BLOWING SNOW...ESPECIALLY ACROSS THE PALMER DIVIDE AND
RATON RIDGE. TEMPERATURES ON THURSDAY WILL BE FALLING INTO THE 20S
AND EVEN TEENS FOR NORTHERN AREAS BY LATE AFTERNOON...AND COMBINED
WITH THE WIND...WILL RESULT IN WIND CHILLS IN THE SINGLE DIGITS
AND TEENS ACROSS THE LOWER ELEVATIONS...TO BETWEEN 0 AND 10 BELOW
ZERO ACROSS THE HIGHER MOUNTAIN PEAKS.

RESIDENTS AND TRAVELERS ACROSS SOUTH CENTRAL AND SOUTHEAST COLORADO
SHOULD BE PREPARED FOR THE ARRIVAL OF WINTER LIKE CONDITIONS LATE
TONIGHT AND THURSDAY. ANY SNOW THAT FALLS WILL LIKELY ACCUMULATE
AS THE GROUND TEMPERATURES QUICKLY DROP BELOW FREEZING...WHICH
COULD LEAD TO ICY AND OR SNOW PACKED ROADS.

AFTER A BRIEF BREAK IN THE WEATHER FRIDAY...COLDER AIR AND A
CHANCE FOR SNOW WILL RETURN TO MUCH OF SOUTHERN COLORADO FRIDAY
NIGHT AND SATURDAY...AS ANOTHER ARCTIC COLD FRONT DROPS SOUTH
THROUGH THE STATE. SIGNIFICANT SNOWFALL WILL BE POSSIBLE OVER
MAINLY THE EASTERN MOUNTAINS AND PLAINS ONCE AGAIN...WITH AREAS
SOUTH OF THE ARKANSAS RIVER HAVING THE BEST CHANCE FOR HEAVY SNOW.
STRONG WINDS MAY ALSO ACCOMPANY THE SNOWFALL...WITH BLOWING AND
DRIFTING SNOW PRODUCING DIFFICULT TRAVEL CONDITIONS EAST OF
INTERSTATE 25 DURING THE DAY SATURDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER CONDITIONS THAT MEET REPORTING CRITERIA FOR SPOTTERS WILL BE
POSSIBLE ACROSS THE AREA LATE TONIGHT.

23/23