Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 211707
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1107 AM MDT TUE OCT 21 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 301 AM MDT TUE OCT 21 2014

THE FORECAST AREA GETS A GRAZING BLOW THIS AFTERNOON AND
OVERNIGHT AS A PACIFIC TROUGH LIFTS NE THROUGH IDAHO TODAY AND
MONTANA TONIGHT. THIS TROUGH DRAGS THE RIGHT ENTRANCE QUADRANT OF
A STANDUP 50KT JET ACROSS THE NORTH THIS AFTERNOON AND EVENING.
THE ASSOCIATED SURFACE FRONT WORKS ACROSS THE NORTH THROUGH THE
EVENING HOURS. THE FRONTAL BAND BECOMES STATIONARY ALONG THE ROAN-
TAVAPUTS- FLATTOPS- GORE MTN RANGES OVERNIGHT PROVIDING ENHANCED
FORCING THERE AND TO THE NORTH. NORTHERN SNOW LEVELS START OUT
AROUND 11KFT THIS AFTERNOON AND DROP TO AROUND 9KFT TOWARDS
WEDNESDAY MORNING. SNOW ACCUMULATIONS WILL BE LIGHT BELOW 10KFT
OVERNIGHT WITH A TRACE TO 2 INCHES EXPECTED DOWN TO 9KFT.

I-70 SOUTHWARD...MOISTURE WILL DEEPEN FROM THE SOUTH THROUGH THE
MORNING REACHING PRECIP WATER VALUES AROUND 0.8 INCHES. THIS IS
CLOSER TO THE GFS FORECAST OVER THE LAST FEW RUNS. OROGRAPHICS
AND AFTERNOON INSTABILITY WILL PRODUCE SCATTERED SHOWERS AND
LATE-DAY STORMS. THE LACK OF COLD ADVECTION AND UPPER SUPPORT WILL
LIMIT SHOWER AMOUNTS AND INSTABILITY. STORMS WILL FAVOR THE MTNS
BUT WILL BE ABLE TO MOVE INTO THE SURROUNDING VALLEYS.

WEDNESDAY...THE DECAYING FRONTAL BOUNDARY REMAINS ORIENTED W-E
NORTH OF I-70 PROVIDING A FOCUS FOR CONTINUING SHOWERS AS FAR
WEST AS THE UTAH TAVAPUTS INTO THE AFTERNOON. OTHERWISE SHOWERS
AND ISOLATED STORMS WILL BE LIMITED TO THE EASTERN MTNS WITH DRIER
AIR OVER THE WEST. EVEN THE EASTERN SHOWERS ARE EXPECTED TO END
BEFORE SUNSET. HIGH MTN SNOW ACCUMULATIONS WILL BE LIGHT.

INCREASING CLOUDS AND SHOWERS TODAY WILL BRING COOLER AFTERNOON
TEMPERATURES TO NEAR NORMAL TODAY. WEDNESDAY WILL BE ANOTHER 5
DEGREES COOLER NORTH OF THE I-70 CORRIDOR. ALL BUT THE HIGHEST
VALLEYS STAY ABOVE FREEZING TONIGHT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 301 AM MDT TUE OCT 21 2014

SOME RESIDUAL MOISTURE MAY PERSIST ALONG THE CONTINENTAL DIVIDE
WEDNESDAY NIGHT BUT BY AND LARGE...PRECIP WILL BE OVER. HIGH
PRESSURE WILL THEN BUILD IN BRINGING A RATHER PROLONGED PERIOD OF
BENIGN WEATHER. BOTH THE GFS AND EC HIGHLIGHT THE PACIFIC
NORTHWEST BEING ACTIVE THROUGH THE PERIOD IN RESPONSE TO THE JET
STREAM SETTING UP OFF THE PACIFIC BEFORE SLAMMING INTO THE WEST
COAST. THE HIGH PRESSURE OVER OUR AREA WILL FORCE SUPPORT AND THUS
PRECIP...TO STAY WELL TO OUR NORTH THROUGH THE WEEKEND. EXPECT
MORE ABOVE AVERAGE TEMPS THROUGH THE PERIOD.

ONE IMPORTANT CHANGE TO FORECAST IS SYSTEM ON SUNDAY AND MONDAY.
GFS REMAINS LARGELY UNCHANGED FROM PREVIOUS FORECASTS AS A
RELATIVELY WEAK SHORT WAVE MOVES OVER NRN PORTIONS OF THE CWA
BRINGING SOME LGT PRECIP TO NRN REACHES OF CWA SUNDAY NIGHT INTO
MONDAY. BIG CHANGE SHOWS UP IN EC WHICH HAS A MUCH DEEPER TROUGH
MOVING ACROSS THE REGION...SAME TIMEFRAME MIND YOU...BRINGING MORE
PRONOUNCED AND WIDESPREAD PRECIP TO THE AREA. LOW CONFIDENCE IN
EITHER SOLN AS THEY ARE SO DIFFERENT ATTM. STAY TUNED AS MODELS
GET THEIR ACTS TOGETHER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1107 AM MDT TUE OCT 21 2014

MOSTLY CLOUDY WITH SHOWERS SWEEPING WEST TO EAST ACROSS THE AREA
THROUGH THIS EVENING AS A COLD FRONT APPROACHES FROM THE WEST.
EVEN SO...ANTICIPATE MOST AREAS TO REMAIN VFR WITH SOME ISOLD MVFR
POSSIBLE IN THE AFTERNOON AND EVENING. ANY AREAS THAT SEE MVFR
THIS AFTERNOON NOT EXPECTED TO STAY THAT WAY EXCEPT MTNS THAT MAY
SEE A BIT MORE CLOUDS AND SHOWERS. ALL TAF SITES UNDER THE GUN BUT
AGAIN...DO NOT ANTICIPATE PROLONGED MVFR FOR ANY OF THEM. KTEX...
KASE...AND KEGE HAVE THE BEST CHANCE FOR MVFR DUE TO THEIR
LOCATION. EXPECT PRECIP WILL REACH A MAXIMUM BETWEEN 21Z TO 00Z.
AFTER 06Z...CONDITIONS WILL IMPROVE. OBSCURATIONS EXPECTED FOR
MOST MOUNTAINOUS TERRAIN.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

&&

$$

SHORT TERM...JOE
LONG TERM...TGR
AVIATION...TGJT



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