Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 281656
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
956 AM MST SAT FEB 28 2015

.UPDATE...
ISSUED AT 955 AM MST SAT FEB 28 2015

FIRST WAVE OF SNOW HIT THE SOUTHERN CWA OVERNIGHT AND THIS MORNING
AND WOULD HAVE TO ADMIT TO BEING A BIT DISSAPOINTED. THE
FRONTOGENETICAL BAND THE MODELS HAD HINTED AT DID STAY JUST SOUTH
OF THE COLORADO BORDER. HOWEVER THERE IS STILL A DISTINCT
CONVECTIVE ELEMENT TO THE PRECIPITATION AND HEAVY SNOW BURSTS WILL
BE POSSIBLE THROUGHOUT THE DAY. CURRENTLY A BAND IS STRETCHING
ACROSS CORTEZ TOWARD RICO WHERE VISIBILITY HAS DROPPED TO 1/4 OF A
MILE. FARTHER NORTH DRY AIR STILL IN PLACE ACCORDING TO THE 12Z
KGJT RAOB. IT MAY TAKE A BIT LONGER TO GET SNOW THE GROUND AS
LARGE SCALE ASCENT LOOK DISORGANIZED. DID SCALE BACK SOME POPS
THIS AFTERNOON WITH MUCH OF THE NORTHERN MOUNTAINS STAYING OUT OF
THE ACTION UNTIL THIS EVENING.


&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 427 AM MST SAT FEB 28 2015

PRECIPITATION HAS BEEN MOVING EAST ACROSS THE SOUTHERN VALLEYS OF
COLORADO OVERNIGHT AND WE HAVE BEEN WATCHING CLOUD TOPS INCREASING
ON SATELLITE IMAGERY OVER SOUTHERN UTAH EARLY THIS MORNING. HEAVY
RAIN IS BEING REPORTED OVER THE AZ/UT BORDER WITH THIS AREA OF
PRECIPITATION MOVING NORTHEAST TOWARD SOUTHEASTERN UTAH AND
EVENTUALLY CENTRAL COLORADO LATE THIS MORNING. THIS BURLY AREA OF
PRECIPITATION IS EXPECTED TO SPREAD INTO CENTRAL AND SOUTHERN
PARTS OF UT/CO BY THIS EVENING LIFTING ALONG THE 125KT JET AXIS.
ALL OF THE FORECAST MODELS ARE IDENTIFYING A VORT MAX DEVELOPING
THIS EVENING ACROSS EAST-CENTRAL UTAH AND WEST-CENTRAL
COLORADO...SO DECIDED TO ISSUE A WINTER WEATHER ADVISORY FOR THE
GLENWOOD SPRINGS AND EAST CORRIDOR SINCE THIS AREA IS HIGHER
ELEVATION AND WILL BE ACCUMULATING FASTER. THINKING THAT THE
GRAND VALLEY AND ALONG I-70 FROM DEQEQUE TO JUST WEST OF GLENWOOD
WILL STAY WET WITH TEMPERATURES RIGHT AROUND THAT FREEZING MARK.
THE 06Z MODELS ARE KEEPING THIS AREA OF ENHANCEMENT OVER THE I-70
CORRIDOR THROUGH THE OVERNIGHT HOURS TONIGHT SO THIS MAY NEED TO
BE REASSESSED.

DURING THIS EVENT... THE DURANGO TO PAGOSA CORRIDOR AND THE
SOUTHERN SAN JUANS WILL PRECIPITATE PRETTY MUCH THE ENTIRE TIME.
TONIGHT MAY BE MUCH LIKE IT WAS OVERNIGHT...WITH THE HEAVIEST PRECIPITATION
SOUTH OF THE SAN JUANS...THOUGH FORECAST MODELS DO SUGGEST THAT
AREA OF SHOWERS ALONG THE I-70 CORRIDOR OF WESTERN COLORADO.
PRECIPITATION RATES INCREASE AGAIN ON SUNDAY AFTERNOON IN
SOUTHWEST FLOW...WHERE THE HEAVIEST SNOW HAS BEEN PROGGED FURTHER
NORTH ON THE 00Z AND 06Z RUNS. THIS MOISTURE WILL BE ACCOMPANIED
BY GOOD INSTABILITY AHEAD OF THE CENTER OF THE LOW AND LOOKS TO
TARGET NE UTAH AND NW COLORADO. AS MENTIONED IN PREVIOUS
DISCUSSIONS...SNOW LEVEL WILL BE AN ISSUE WITH THIS STORM AND DO
EXPECT A RAIN/SNOW MIX AT LOCATIONS LESS THAN 6500 FEET DURING THE
DAYTIME HOURS ESPECIALLY ON SUNDAY.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 427 AM MST SAT FEB 28 2015

MODELS CONTINUE TO FAVOR SAN JUANS FOR HEAVIEST PRECIP THROUGH THE
PERIOD THOUGH LATEST NAM/GFS 06Z RUN CONTINUES TO SHIFT PRECIP A
LITTLE MORE NORTHWARD. BY MIDNIGHT SUNDAY...THE SAN JUANS WILL
CONTINUE TO SEE IMPRESSIVE SNOWFALL RATES AND AMOUNTS WHILE
ANOTHER BAND OF SNOW LOOKS TO SET UP OVER THE NRN PART OF THE
UNCOMPAHGRE PLATEAU TO THE GRAND MESA AND THEN INTO THE CENTRAL
MTNS. BY MONDAY MORNING...THIS BAND WILL SHIFT FURTHER NORTH
HITTING THE FLATTOPS AND EVENTUALLY THE NRN VALLEYS AND NRN MTNS.

AS THE ABOVE OCCURS...A STRONG COLD FRONT WILL CONTINUE TO DROP
DOWN FROM THE NW MONDAY AFTERNOON SHUNTING THE PRECIP EWRD. BY
MONDAY NIGHT THE COLD FRONT WILL BE ON OUR DOORSTEP WITH A LULL
FOR MOST AREAS EXCEPT ALONG THE SPINE OF THE ROCKIES. THE COLD
FRONT WILL PUSH THROUGH TUESDAY MORNING BRINGING ANOTHER ROUND OF
PRECIP TO THE AREA. HOWEVER...AS THE FRONT MOVES THROUGH WINDS
WILL BECOME MORE WEST TO NORTHWEST WHICH WILL FAVOR THE NRN MTNS.
AS WE`VE SAID FOR SOME TIME...THIS IS A COMPLICATED STORM WITH
MANY MOVING PARTS AND ANY SMALL PERTURBATIONS COULD HAVE RATHER
DRAMATIC EFFECTS. THESE CHANGES NOT AFFECTING TOTAL SNOWFALL AMTS
TOO MUCH. SAN JUANS STILL GET PUMMELED WITH THE CENTRAL MTNS NOW
PROGGED TO GET A BIT MORE SNOW THAN ORIGINALLY THOUGHT AND THE NRN
MTNS TOO AS THE COLD FRONT MOVES THROUGH. SPEAKING OF...TEMPS WILL
BE MUCH COLDER WEDNESDAY ONWARD WITH LOWS THURSDAY MORNING
ANYWHERE FROM 20 TO POSSIBLY 30 DEGREES BELOW NORMAL. SOME
NUMBERS...CRAIGS LOW IS USUALLY AROUND 15F...THURSDAY MORNING MOS
GUIDANCE SUGGESTING A LOW OF -13F. GRAND JUNCTION LOW IS USUALLY
UPPER 20S...FORECAST LOW THURSDAY IS 10F AND SO ON ACROSS THE CWA.
APPARENTLY WINTER NOT DONE WITH US YET.

MOST PRECIP WILL BE DONE BY WED MORNING THOUGH A FEW SHOWERS WILL
PERSIST OVER HIGHER TERRAIN AS NW FLOW CONTINUES TO PUMP IN MUCH
COLDER AIR. THURSDAY AND FRIDAY WILL BRING CLEAR AND CRISP DAYS
WITH A SLOW WARM-UP EXPECTED FOR THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 955 AM MST SAT FEB 28 2015

SNOW BANDS...HEAVY TO MODERATE AT TIMES WILL IMPACT THE SOUTHERN
TERMINAL SITES THROUGH MUCH OF THE DAY BRINGING IFR/LIFR FLIGHT
CONDITIONS. IN BETWEEN SHOWERS IMPROVENT MAY NOT GET ABOVE MVFR.
SNOW AND MIXED PRECIPITATION WILL SPREAD INTO THE I-70 CORRIDOR
THROUGH THE AFTERNOON WITH IMPACTS FROM CNY-GJT-KRIL-KEGE AND KASE
EXPECTED TO PERSIST INTO THE OVERNIGHT HOURS. KVEL LOOKS TO BE
PROTECTED FROM THE HEAVIER PRECIPITATION BUT HOWEVER THERE IS SOME
INDICATION OF LOW CLOUDS AND FOG POSSIBLY BRINGING IN MVFR
CONDITIONS AFTER 01/06Z. EXPECT IMPACTED FLIGHT CONDITIONS TO
PERSIST OVER THE NEXT 24 HOURS IN MANY AREAS...LIKELY CONTINUING
THROUGH EARLY NEXT WEEK.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 9 AM MST
     WEDNESDAY FOR COZ003-013.

     WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH WEDNESDAY
     MORNING FOR COZ001-002-004-005.

     WINTER STORM WARNING UNTIL 8 PM MST MONDAY FOR COZ017>019-022-
     023.

     WINTER WEATHER ADVISORY UNTIL 8 PM MST MONDAY FOR COZ014.

     WINTER WEATHER ADVISORY UNTIL 8 PM MST MONDAY FOR COZ021.

     WINTER STORM WARNING UNTIL 8 PM MST MONDAY FOR COZ009-010-012.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 8 AM MST
     MONDAY FOR COZ008.

UT...WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 9 AM MST
     WEDNESDAY FOR UTZ025.

     WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH WEDNESDAY
     MORNING FOR UTZ023-024.

     WINTER STORM WARNING UNTIL 8 PM MST MONDAY FOR UTZ028.

&&

$$

UPDATE...15
SHORT TERM...JAM
LONG TERM...TGR
AVIATION...TGJT



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