Winter Storm in Colorado, December 22 to 23, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
729 PM MST TUE DEC 22 2009

.UPDATE...

CURRENTLY...LIGHT SNOW IS NOTED ACROSS MANY AREAS ALONG THE I-25
CORRIDOR. RADAR LAST FEW VOLUME SCANS HAS STARTED TO LIGHTEN UP
ACROSS S EL PASO...N PUEBLO...CROWLEY AND OTERO COUNTIES. THIS
APPEARS TO BE THE LOCATION OF THE 700 MB TROUGH AXIS SEPARATING SW
WINDS FROM 700 MB SE WINDS.

FOR THE NEXT 24 HOURS...BASED ON NEW NAM GUIDANCE COMING IN...DO NOT
REALLY SEE ANY SIGNIFICANT CHANGES TO CURRENT FCST AND PLAN TO
LEAVE THINGS AS IS. BEST SNOW FOR THE PUEBLO-PIKES PEAK REGION
WILL BE FROM NOW THROUGH MID MORNING...WITH ANOTHER SHOT COMING IN
WITH THE ARCTIC AIR MASS TOMORROW EVENING/NIGHT.

AS 700 MB LOW MOVES EAST OF REGION EARLY TOMORROW...SNOWS SHOULD
PICK UP ACROSS THE E FACING SLOPES OF THE S MTNS AND THEN ALONG
THE RATON MESA. STRONGER SFC WINDS SHOULD ALSO BEGIN TO PICK UP BY
LATER TOMORROW AFTERNOON AS 700 MB GRADIENT BEGINS TO TIGHTEN.
/HODANISH

&&

.PREV DISCUSSION... /ISSUED 330 PM MST TUE DEC 22 2009/

SHORT TERM...
(TONIGHT AND WEDNESDAY)

..SNOW AND COLD FOR TOMORROW...

WINTER STORM IS ON TRACK TO DELIVER LIGHT TO MODERATE SNOWFALL TO
THE REGION...ALONG WITH A BLAST OF COLD AIR. TEMPS HAVE STRUGGLED TO
GET OUT OF THE 30S OVR THE NRN I-25 CORRIDOR TODAY...WITH LOWERING
CIGS THRU THIS MORNING AND EARLY AFTERNOON. TO THE WEST...SNOW IS
COMING DOWN MODERATE TO HEAVY OVR THE SAN JUANS PER THE WOLF CREEK
SKI CAMS...AND IS LIKELY TO CONTINUE THRU AT LEAST THIS EVE. WARNING
CRITERIA LOOKS LIKELY TO BE MET THERE. ELSEWHERE...STORM DOES NOT
LOOK COLD ENOUGH...AND MID LEVEL WINDS NOT STRONG ENOUGH...FOR MAJOR
ACCUMULATIONS. HOWEVER...STILL FORESEE HAZARDOUS TRAVEL CONDITIONS
OVR A LARGE PORTION OF THE CWA...PARTICULARLY BY WED MORN AND LATER
AS WINDS PICK UP AND BLOWING SNOW BECOMES A CONCERN. OVERALL...4 TO
8 INCHES LOOKS ON TRACK IN GENERAL...WITH LESSER AMTS OVR THE
VALLEYS AND SOME HIGHER ACCUMS OVR THE HYR ELEVS. HAVE CONVERTED
REMAINING ZONES AND PREVIOUS WINTER STORM WATCH OVR THE PLAINS TO
SNOW AND BLOWING SNOW ADVISORIES. SHOULD BE A BRIEF WINDOW OF NE
WINDS OVR THE I-25 CORRIDOR...WHICH SHOULD ALLOW SOME ACCUMULATING
SNOW FOR EVEN THE KPUB-KCOS AREA...ALTHOUGH SHIFT TO N WINDS
TOMORROW MORN WILL MEAN AN END TO GOOD SNOW POTENTIAL THERE. BEST
SHOT FOR THIS AREA WILL BE IN THE 06Z-18Z TIME FRAME TONIGHT AND WED
MORNING. TEMPS NOT LIKELY TO RISE MUCH IF ANY TOMORROW AFTERNOON
WITH SNOW COVERAGE...LOW CLOUDS...AND FALLING TEMPS ALOFT. MID TO
UPPER 20S SHOULD HOLD FOR A GOOD PORTION OF THE PLAINS...WITH SOME
TEENS IN THE MTS IN DEEPER POWDER. 44

LONG TERM...
(WEDNESDAY NIGHT THROUGH NEXT TUESDAY)

UPPER LOW EJECTS INTO THE SOUTHERN PLAINS...WITH MID LEVEL CENTER
MIGRATING FROM EASTERN COLORADO WED EVENING INTO CENTRAL KS BY
EARLY THU MORNING. BEST LIFT OVERNIGHT LOOKS TO BE ALONG AND
NORTH OF THE PALMER DIVIDE...THOUGH COMBINATION OF SATURATED AIR
MASS AND WEAK SURFACE UPSLOPE GRADIENT WILL KEEP AT LEAST SOME
LIGHT SNOW GOING MOST AREAS THROUGH THE NIGHT. ADDITIONAL
ACCUMULATIONS LOOK FAIRLY LIGHT...GENERALLY 2 INCHES OR LESS. WINDS
WILL INCREASE OVER THE EASTERN HALF OF THE AREA AFTER 06Z AS
SURFACE LOW DEEPENS...WITH INCREASING CHANCES OF BLOWING SNOW OVER
THE PLAINS BY MORNING. WITH THE WINDS...EXPECTING BELOW ZERO WIND
CHILLS OVER MOST OF THE REGION FROM LATE WED NIGHT INTO MIDDAY
THU. ON THURSDAY...FIRST PIECE OF THE UPPER SYSTEM EJECTS
EASTWARD INTO THE MISSOURI VALLEY...WHILE SECOND UPPER LOW
PINWHEELS SOUTH INTO EASTERN COLORADO. LOW AND MID LEVEL FLOW
BECOMES INCREASINGLY DOWNSLOPE OVER THE AREA DURING THE DAY...THOUGH
AIR MASS MAY BE JUST MOIST AND UNSTABLE ENOUGH TO GENERATE FAIRLY
WIDESPREAD SNOW SHOWERS THROUGH SUNSET. KEPT THE WINTER WEATHER
ADVISORY GOING UNTIL EARLY THU EVENING MAINLY DUE TO POTENTIAL FOR
BLOWING AND DRIFTING SNOW...AS NORTHERLY WINDS ON THE PLAINS COULD
GUST TO 50 MPH ALONG THE KS BORDER THROUGHOUT THE DAY.

UPPER SYSTEM PULLS SLOWLY EASTWARD THU NIGHT...THOUGH QUICK LOOK
AT 18Z GFS SUGGESTS EASTWARD PROGRESSION MAY BE EVEN SLOWER THAN
12Z MODELS INDICATED. THIS SLOWER MOVEMENT MAY ALLOW SNOW SHOWERS
AND BLOWING SNOW TO CONTINUE OVER THE FAR EASTERN PLAINS THROUGH
MUCH OF THU NIGHT...ESPECIALLY NEAR THE KANSAS BORDER. AT THIS
POINT...WILL LET HIGHLIGHTS EXPIRE THU EVENING AND WILL WAIT TO
SEE HOW MUCH SNOW FALLS ON THE PLAINS BEFORE ANY EXTENSION.

CHRISTMAS DAY LOOKS COLD AND BREEZY...WITH MASSIVE UPPER LOW
LIFTING SLOWLY NORTHEAST INTO THE MISSISSIPPI VALLEY BY EVENING.
COULD BE ENOUGH WRAP AROUND MOISTURE FOR A FEW FLURRIES THROUGH
THE DAY...THOUGH CHANCES LOOK TOO LOW TO MENTION. WILL BE A WHITE
CHRISTMAS MOST AREAS...AS ANY SNOW THAT FALLS WED/THU WONT BE
MELTING WITH DAYTIME TEMPS ONLY IN THE 20S.

BOTH GFS AND ECMWF PUSH THE UPPER LOW FAR ENOUGH EAST TO ALLOW AN
UPPER RIDGE TO BUILD OVER THE ROCKIES...THOUGH BOTH MODELS SUGGEST
A RATHER DEEP POCKET OF RESIDUAL COLD AIR WILL LINGER OVER THE
SOUTHERN ROCKIES...KEEPING MAX TEMPS COOL BOTH SAT AND SUN. WENT
AT OR BELOW GUIDANCE BOTH DAYS...ESPECIALLY RATHER EXTENSIVE SNOW
COVER.

FOR MON/TUE...FAIR AGREEMENT AMONG THE MODELS WITH RATHER
SUBSTANTIAL ENERGY UNDERCUTTING THE RIDGE...THOUGH DETAILS BEGIN
TO DIVERGE BY TUE...AS GFS KEEPS MOST ENERGY SUPPRESSED WELL SOUTH
OVER TEXAS...WHILE ECMWF LIFTS A RATHER HEALTHY UPPER LEVEL LOW
INTO THE SOUTHERN PLAINS...SPREADING MODERATE TO HEAVY SNOW OVER
TO THE SOUTHERN HALF OF THE FORECAST AREA BY LATE TUE. LOW POPS
FROM MON NIGHT INTO TUE LOOK FINE FOR NOW...WITH TEMPERATURES
REMAINING ON THE COOLER SIDE OF GUIDANCE. --10

AVIATION...SHOULD SEE DETERIORATING CONDITIONS TONIGHT OVR ALL OF
THE AREA...WITH WORST CONDITIONS OVR THE MTS AND PORTIONS OF THE
PALMER DVD AND ERN CO PLAINS TOMORROW MORN. WORST CONDITIONS FOR
THE TAF SITES SHOULD BE IN THE 09Z-15Z TIME FRAME...WHEN KCOS AND
POSSIBLY KPUB COULD SEE LIFR CONDITIONS IN SNOW. N WINDS WILL
INCREASE THRU THE DAY ON WED OVR THE ERN  COUNTIES NR THE KS
BORDER...RESULTING IN BLSN AT THE SURFACE. 44

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 5 PM MST THURSDAY
FOR COZ087>089-093-094-097>099.

WINTER WEATHER ADVISORY UNTIL 5 PM MST THURSDAY FOR COZ058>066-
072>082-084.

WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 5 PM MST
THURSDAY FOR COZ083-085-086-095.

WINTER STORM WARNING FROM 11 PM THIS EVENING TO 5 PM MST
THURSDAY FOR COZ096.

WINTER STORM WARNING UNTIL 11 AM MST WEDNESDAY FOR COZ068.

WINTER WEATHER ADVISORY UNTIL 5 AM MST WEDNESDAY FOR COZ067.

&&

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HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
351 PM MST TUE DEC 22 2009

COZ058>089-093>099-232300-
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-
351 PM MST TUE DEC 22 2009

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

AN APPROACHING WINTER STORM WILL CONTINUE TO PRODUCE MODERATE TO
HEAVY SNOW ALONG THE CONTINENTAL DIVIDE THIS AFTERNOON AND
OVERNIGHT...WITH SNOW SPREADING INTO THE EASTERN MOUNTAINS AND
ADJACENT INTERSTATE 25 CORRIDOR LATE THIS AFTERNOON THROUGH THIS
EVENING. SNOW WILL THEN SPREAD ACROSS ALL OF THE SOUTHEAST PLAINS
BY LATE TONIGHT. THE HEAVIEST SNOW THROUGH TONIGHT IS EXPECTED TO
FALL ACROSS THE HIGHER ELEVATIONS OF THE EASTERN SAN JUAN
MOUNTAINS WHERE SIGNIFICANT SNOWFALL ACCUMULATIONS OF 8 TO 12
INCHES ARE EXPECTED. ANOTHER BAND OF MODERATE SNOWFALL IS EXPECTED
TO FALL ACROSS EASTERN PORTIONS OF KIOWA COUNTY AFTER
MIDNIGHT...WITH GENERALLY LIGHT TO MODERATE SNOWFALL EXPECTED
ACROSS THE REMAINDER OF SOUTH CENTRAL AND SOUTHEAST COLORADO
OVERNIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SNOW...BLOWING SNOW...COLDER TEMPERATURES AND GUSTY WINDS WILL
CONTINUE OVER MOST SOUTHERN COLORADO FROM WEDNESDAY INTO THURSDAY.
CONDITIONS WILL IMPROVE FROM WEST TO EAST LATE THURSDAY INTO
CHRISTMAS DAY...THOUGH COLD TEMPERATURES WILL LINGER.

TOTAL SNOW ACCUMULATIONS BY THURSDAY EVENING OF UP TO 10 INCHES
ARE FORECAST OVER THE PIKES PEAK/TELLER COUNTY REGION...THE WET
MOUNTAINS...THE SANGRE DE CRISTO MOUNTAINS AND THE HIGHER PEAKS OF
THE CENTRAL AND WESTERN MOUNTAINS. AREAS ALONG THE PALMER DIVIDE
AND EXTREME NORTHEAST KIOWA COUNTY WILL SEE SNOWFALL AMOUNTS
AROUND 8 INCHES. THE REMAINDER OF THE AREA...INCLUDING COLORADO
SPRINGS AND PUEBLO...WILL SEE STORM TOTAL SNOWFALL AMOUNTS OF 3 TO
6 INCHES BY THURSDAY EVENING...WITH SOME LOCALLY HIGHER AMOUNTS
POSSIBLE NEAR THE KANSAS BORDER AND ALONG THE RATON MESA.

STRONG NORTH WINDS WINDS OF 20 TO 40 MPH WILL DEVELOP OVER THE
EASTERN MOUNTAINS AND PLAINS BY WEDNESDAY AFTERNOON...CONTINUING
INTO THURSDAY EVENING. THESE WINDS WILL PRODUCE FAIRLY WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH HAZARDOUS TRAVEL CONDITIONS
LIKELY...ESPECIALLY OVER THE EASTERN PLAINS DURING THE DAY
THURSDAY. WIND CHILL VALUES WILL FALL BELOW ZERO OVER MUCH OF THE
AREA BY WEDNESDAY NIGHT...WITH VERY COLD WIND CHILLS PERSISTING
THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER CONDITIONS THAT MEET REPORTING CRITERIA FOR SPOTTERS WILL BE
LIKELY ACROSS THE MOUNTAINS AND PLAINS TONIGHT.

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