Snow Advisory 10, NWS Pueblo, CO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
838 PM MST WED DEC 27 2006

.UPDATE...

A LOT OF FORECAST CHALLENGES WITH THE TRACK AND EVOLUTION OF THE
APPROACHING STORM SYSTEM SCHEDULED THU AFTERNOON THROUGH POSSIBLY
SUN MORNING.

NOT ALL THE NEW MODEL DATA IS AND WILL BE IN BEFORE 9PM AND 10PM
NEWS TIME TO REVIEW AND ALTER THE DIGITAL FORECAST DATABASE. THE
NEW 00Z/28 WRF12 SHOWS THE H5 AND H7 CLOSED LOWS TRACKING SLOWLY
ACROSS NORTHERN NM THU AFTERNOON THROUGH FRI...AND LOW ACTUALLY
ELONGATES ON FRI WHICH LOOKS ODD. NEXT...THE LOW PARKS NEAR
EXTREME SOUTHEAST CO FRI AFTERNOON THROUGH SAT...AND BEGINS TO
PULL AWAY FROM EASTERN CO ON SUN. AS WITH THESE SYSTEMS...THE
BIGGEST CHALLENGE WILL BE THE POTENTIAL MIDLEVEL DRY SLOTS THAT
KILLS HEAVY SNOWFALL AND THE WRF HAS ONE ACROSS MUCH OF CO DURING
FRI DAYTIME FORECAST PERIOD. IT APPEARS ANY POTENTIAL PRECIPITATION
DEVELOPING WILL BE OVER THE MOUNTAINS THU AFTERNOON. THE WRF12 HAS
NO PRECIPITATION FOR TONIGHT AND THU MORNING. GIVEN SATELLITE AND
RADAR TRENDS...INCLUDING UPPER AIR DATA...THIS SEEMS REASONABLE...
SO WILL ADJUST POPS AND WX APPROPRIATELY. AS FOR THE HEADLINES...I
HAVE THOUGHT ABOUT THIS OVER THE LAST 3 HOURS AND HAVE DECIDED TO
MAINTAIN THE WINTER STORM WATCH...BUT ADJUST THE TIMING FOR A
SLOWER START. WILL HAVE THE WINTER STORM WATCH FOR THE MOUNTAINS
THU AFTERNOON AND CONTINUE THROUGH THU NIGHT. FOR THE SOUTHEAST CO
MOUNTAINS AND ADJACENT I-25 CORRIDOR...THE WATCH WILL BE FOR THU
AFTERNOON AND WILL CONTINUE THROUGH FRI NIGHT. FOR THE SOUTHEAST
CO PLAINS...I HAVE PUSHED BACK THE WATCH FOR THU NIGHT THROUGH FRI
NIGHT. GIVEN MODEL SOUNDINGS...THERE MAY ACTUALLY BE A MIX OF RAIN
AND SNOW ACROSS SOUTHEAST CO THU AFTERNOON...BUT EVAPORATION
COOLING COULD ALLOW FOR A QUICKER CHANGE OVER. SINCE THE EVENT
WILL NOT BE STARTING UNTIL THU AFTERNOON...DECIDE TO GIVE THE
MIDNIGHT SHIFT ANOTHER MODEL RUN...OR TWO...TO PINDOWN THE
FORECAST DETAILS.

THIS STORM STILL COULD HAVE THE POTENTIAL TO DROP SIGNIFICANT
SNOWFALL ACROSS THE SOUTHEAST CO MOUNTAINS AND ADJACENT PLAINS
BETWEEN THU AFTERNOON AND EARLY SUN MORNING. METZE

&&

.PREV DISCUSSION... /ISSUED 429 PM MST WED DEC 27 2006/

.SHORT TERM...
(TONIGHT AND THURSDAY)

SHORT TERM CONCERNS CONTINUE TO BE TIMING AND EFFECTS OF
STRONG STORM SYSTEM MOVING INTO THE GREAT BASIN TODAY.

CURRENT WATER VAPOR IMAGERY INDICATING PAC NW SYSTEM MOVING ACROSS
THE WEST COAST WITH A STRONG 130+ KT NORTH/SOUTH JET DIGGING DOWN
THE BACKSIDE OF THE SYSTEM ATTM. CURRENT WATER VAPOR IMAGERY GIVING
CREDENCE TO SLOWER MOVEMENT OF SYSTEM ACROSS THE AREA...AND HAVE
GONE CLOSER THE LATEST GFS SOLUTION...WHICH IS SIMILAR IN TIMING
AND LOCATION TO THE ECMWF...UKMET AND CANADIAN SPECTRAL MODELS.

WITH SLOWER TIMING OF SYSTEM HAVE DELAYED START TIME OF WINTER STORM
WATCH FOR ZONES 58/60/66/68 UNTIL 12Z THU AND ADDED ZONES
61/63/65/67 TO THE WATCH...AS DEEP MOISTURE SLOWER TO INCREASE
ACROSS WESTERN COLORADO. HAVE ALSO KEPT CURRENT WATCH IN TACT
ACROSS THE EASTERN MTS AND PLAINS STARTING AT 19Z THU FOR...THOUGH
MAY NEED TO DELAY START ESPECIALLY ACROSS THE PLAINS.

AT ANY RATE...UPPER LOW PROGGED ACROSS WEST CENTRAL NEW MEXICO
AROUND 12Z THU AND CONTINUES TO SLOWLY MOVE EAST WITH EAST TO
SOUTHEAST UPPER FLOW DEVELOPING THROUGH THE DAY. EAST TO NORTHEAST
LOW LEVEL FLOW ACROSS THE EASTERN PLAINS DEVELOPS THU AFTERNOON IN
RESPONSE TO DEVELOPING SFC LOW ACROSS EAST CENTRAL NEW MEXICO.
DEFORMATION BAND PRECIP EXPECTED TO DEVELOP ACROSS THE SW MTS AND
SOUTHERN SOUTHERN SAN LUIS VALLEY WITH THE EASTERN SLOPES AND FAR
WESTERN EDGES OF THE SAN LUIS VALLEY LIKELY SEEING 3-6 INCHES BY
LATE THURSDAY AFTERNOON. WITH THE DEVELOPING SFC-H7 EAST TO
NORTHEAST WINDS...EXPECTING TO SEE LIGHT SNOW BREAKING OUT ACROSS
THE EASTERN MTS AND IMMEDIATE ADJACENT PLAINS THU AFTERNOON...AS
ATMOSPHERE CONTINUES TO SATURATE FROM TOP TO BOTTOM. AGAIN WITH
SLOWER TIMING OF SYSTEM ALONG WITH INTRA-OFFICE COLLABORATION...WILL
NOT UPDATE ANY HIGHLIGHTS ATTM. -MW

LONG TERM...
(THU NITE THROUGH NEXT WED)

...BLIZZARD POSSIBLE IN SOME AREAS...STORM COULD BE LONG DURATION EVENT
   FOR PARTS OF THE REGION...

BASED ON CURRENT DISCUSSIONS...BOTH INTERNAL AND
EXTERNAL...DECIDED TO GO WITH 12Z GFS GUIDANCE AS 12Z NAM APPEARS
TO BE TOO FAR NORTH IN LATER PERIODS. IN ADDITION...GFS MATCHING
UP WELL WITH OTHER GUIDANCE INCLUDING OTHER INTERNATIONAL
GUIDANCE. AS HPC PUT IT SO ELOQUENTLY IN THEIR 1944Z
DISCUSSION...ANOTHER JUGGERNAUT (OF A WINTER STORM IS) ON THE
HORIZON FOR COLORADO.

STORM WILL LIKELY COME IN TWO PARTS:

THE FIRST SIGNIFICANT EVENT IS GOING TO HIT THE PIKES PEAK
REGION/PALMER DIVIDE AREA FRIDAY. BLIZZARD CONDITIONS WILL BE
POSSIBLE...ESPECIALLY DURING THE AFTERNOON. I CURRENTLY HAVE
SUSTAINED WINDS IN THE 30-40KNT RANGE WITH HIGHER GUSTS...ESPECIALLY
DURING THE AFTERNOON AND EARLY EVENING FRIDAY. SNOWFALL AMOUNTS ARE
AROUND 20 INCHES....10 INCHES FOR S COS...AND LESSER AMOUNTS FOR
THE PUEBLO BROWN HOLE.

NOTE...SINCE THINGS ARE A BIT DELAYED...AND DISCUSIONS AMONGST OTHER
OFFICES...DECIDED NOT TO UPGRADE THE WATCH AT THIS TIME. HOWEVER...I
DID MAKE ADJUSTMENTS TO THE TIMING OF THE WATCH FOR THE E PLAINS (SEE
BELOW)

SECOND...LATE FRIDAY INTO SATURDAY...IT APPEARS THE FAR EAST PLAINS
WILL GET INTO THE ACT WITH STRONG WINDS AND HEAVY SNOW. LATEST GFS
(12Z) SLOWS THE SYSTEM DOWN AND TRACKS IT A BIT FARTHER SOUTH. THIS
SHOULD ALLOW FOR SIGNIF WRAP AROUND TO DEVELOP OVER THE EASTERN
PLAINS.

AS ALWAYS THE CASE...WHERE THE DRYSLOT SETS UP WILL DEPEND ON SNOW
AMOUNTS.

IN THE MEANTIME...SNOW SHOULD BE ONGOING IN THE MTNS BY 00Z FRI (5
PM THU EVE)...AND SHOULD BE STARTING IN EARNEST ON THE EAST SLOPES
OF THE S MTNS...INCLUDING THE GREATER COS AREA. DO NOT BELIEVE
THINGS WILL GET REAL BAD UP IN THE TELLER/EL PASO REGION UNTIL THE
SYSTEM STARTS INTENSIFYING ON THE SE PLAINS ON FRIDAY.

REGARDING THE INTERIOR MTS...THIS WILL BE AN EAST SLOPE EVENT...SO
THE E SLOPES OF THE SW MTNS AND C MTNS SHOULD GET THE BRUNT OF IT
GIVEN THE DEEP EASTERLY UPSLOPE ASSOCIATED WITH THIS LARGE CUTOFF
LOW. THE W SIDE OF THE SAN LUIS VALLEY MAY ALSO SEE SOME DECENT
AMOUNTS THU EVE.

IF YOU TAKE THE GFS AS A PERFECT PROG...THIS SYSTEM COULD BE WITH US
WELL INTO THE WEEKEND. FOR THIS REASON...EXTENDED THE WATCH OUT INTO
LAT LEAST 13Z SATURDAY FOR THE I-25/EASTERN PLAINS REGION. IT MAY
NEED TO BE EXTENDED OUT FARTHER AS THE STORM MAY LAST INTO SUNDAY
OVER THE FAR E PLAINS. /34

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM THURSDAY EVENING THROUGH LATE FRIDAY
NIGHT FOR COZ089-093>099.

WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH LATE FRIDAY
NIGHT FOR COZ072>088.

WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY
NIGHT FOR COZ058-060-061-063-065>068.

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
859 PM MST WED DEC 27 2006

COZ058>089-093>099-290400-
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-
859 PM MST WED DEC 27 2006

...WINTER STORM WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT FOR THE EASTERN SAN JUAN AND LA GARITA MOUNTAINS
AND FOR THE WESTERN MOSQUITO RANGE AND THE EASTERN SAWATCH
MOUNTAINS...

...WINTER STORM WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH
LATE FRIDAY NIGHT FOR THE SOUTHEAST MOUNTAINS AND ADJACENT
INTERSTATE 25 CORRIDOR...

...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH LATE
FRIDAY NIGHT FOR THE SOUTHEAST COLORADO PLAINS...

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

.DAY ONE...TONIGHT

ISOLATED TO SCATTERED SNOW SHOWERS ARE EXPECTED THIS AFTERNOON
AND TONIGHT OVER THE SAN JUAN...LA GARITA...SAWATCH...AND MOSQUITO
MOUNTAIN RANGES. SOME LIGHT SNOW ACCUMULATIONS...GENERALLY UNDER 2
INCHES...WILL BE POSSIBLE TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SIGNIFICANT SNOWFALL IS POSSIBLE ACROSS THE MOUNTAINS AND HIGH
VALLEYS THURSDAY THROUGH FRIDAY...AND ACROSS THE SOUTHEAST PLAINS
LATE THURSDAY AFTERNOON THROUGH FRIDAY NIGHT. THIS SNOWFALL WILL
BE CAUSED BY A STORM SYSTEM THAT WILL MOVE ACROSS NEW MEXICO
THROUGH FRIDAY...AND WILL THEN MOVE OVER THE WESTERN TEXAS
PANHANDLE AND INTO WESTERN KANSAS THROUGH SATURDAY. WINDY
CONDITIONS ARE EXPECTED TO DEVELOP LATE THURSDAY NIGHT...AND
CONTINUE INTO FRIDAY NIGHT OVER MUCH OF THE SOUTHEAST COLORADO
PLAINS...CAUSING BLOWING AND DRIFTING SNOW...WHICH COULD RESULT IN
NEAR ZERO VISIBILITY AT TIMES. AS THIS WEATHER SYSTEM GETS CLOSER
TO THE AREA...WINTER WEATHER WARNING OR ADVISORIES WILL LIKELY BE
ISSUED FOR MUCH OF THE AREA...SO BE SURE TO MONITOR THE LATEST
FORECAST PRODUCTS. TRAVEL COULD BECOME DIFFICULT IN MANY AREAS
LATE THURSDAY THROUGH FRIDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

CONDITIONS THAT MEET REPORTING CRITERIA FOR SPOTTERS WILL BE
POSSIBLE TONIGHT OVER PORTIONS OF THE CENTRAL AND SOUTHWEST
MOUNTAINS.