Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 212134
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
334 PM MDT MON APR 21 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 334 PM MDT MON APR 21 2014

TONIGHT SHOULD BE RELATIVELY BENIGN WITH MILDER TEMPERATURES AND
LIGHT WINDS. BEFORE SUNRISE SOUTHWEST TO SOUTHEAST OROGRAPHIC
DOWNSLOPE AND DOWNVALLEY WINDS SHOULD BE ENHANCED FROM THE
APPROACHING PACIFIC STORM SYSTEM.

THIS APPROACHING STORM WILL BE THE MAJOR WEATHER PLAYER THE NEXT
48 HOURS. SW WINDS WILL STEADILY INCREASE ACROSS THE AREA STARTING
TUE MID-MORNING AS THE MAIN TROUGH MOVES THROUGH THE WESTERN GREAT
BASIN. AFTER ABOUT 21Z IT SHOULD BE WINDY ACROSS THE ENTIRE AREA
WITH SOME LOWER ELEVATION ZONES APPROACHING AND REACHING WIND
ADVISORY CRITERIA. A WIND ADVISORY HAS BEEN ISSUED FOR THOSE ZONES
FROM 21Z TO 04Z TOMORROW EVENING. THE STRONG SW WINDS WILL ALSO
BOOST DAYTIME TEMPS ABOVE MODEL GUIDANCE SO AM ALSO CALLING FOR
NEAR RECORD HIGH TEMPS.

THERE IS ENOUGH MOISTURE AND WILL BE ENOUGH HEATING AND UPLIFT
FROM WARM ADVECTION THAT ISOLATED TO LOW-END SCATTERED SHOWERS AND
THUNDERSTORMS SHOULD DEVELOP. THESE WILL PRODUCE LITTLE MOISTURE
BUT STRONGER ERRATIC WIND GUSTS WILL BE POSSIBLE WITH VIRGA AND
SHOWERS. THIS SHOULD HELP PRODUCE WIND GUSTS TO ADVISORY CRITERIA
IN ADVISED ZONES. MOST OF THE CONVECTION WILL BE QUITE SHEARED SO
VERTICAL DEVELOPMENT WILL BE LIMITED.

THE SURFACE COLD FRONT IS NOT EXPECTED TO MOVE THROUGH UNTIL NEAR
AND AFTER MIDNIGHT...THEN SHOULD CLEAR THE CWA TO THE SOUTH AND
EAST BY ABOUT 12Z WEDNESDAY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 334 PM MDT MON APR 21 2014

THE MID TO LATE WEEK PERIOD WEATHER PATTERN WILL STAY PROGRESSIVE
ACROSS THE CONUS...BUT THIS WILL BE CHANGING BY THE WEEKEND. MUCH OF
THE BLOCKINESS AND STRONGER ENERGY IN THE HIGH LATITUDES WILL BE
DIRECTED INTO THE WESTERN AND CENTRAL CONUS BY A STRONG DIP IN THE
JET STREAM. THOUGH MODELS CONTINUE TO STRUGGLE WITH SOME OF THE
FINER DETAILS...THE ENSEMBLES OR MEANS OF THESE MODELS AGREE ON THIS
SHIFT IN THE PATTERN. WHAT THIS MEANS FOR THE EXTENDED PERIOD WILL
BE UNSETTLED CONDITIONS ON WEDNESDAY WARMING AND DRYING THROUGH
FRIDAY...FOLLOWED BY ANOTHER COOL DOWN AND WETTER CONDITIONS TO
CLOSE OUT THE WEEK.

A COLD FRONT WILL HAVE WORKED THROUGH NORTHEAST UTAH AND NORTHWEST
COLORADO BY SUNRISE WEDNESDAY AND SHOULD BE TO THE DIVIDE BY LATE
MORNING. A SECONDARY TROUGH/WAVE WITH SUPPORT FROM THE CYCLONICALLY
CURVED JET WILL KEEP SOME LARGE SCALE ASCENT IN PLACE THROUGH THE
AFTERNOON WEDNESDAY. THOUGH MOISTURE WILL BE ON THE
DOWNTURN...INSTABILITY AND THE UPWARD MOTION WILL BE ENOUGH TO KEEP
SCATTERED SHOWERS GOING OVER THE EASTERN TERRAIN. THIS CONVECTION
WILL END QUICKLY AFTER SUNSET AS THE UPPER RIDGE AND MORE STABLE AIR
MOVES IN ALOFT. WARMER AND DRIER CONDITIONS ARRIVE UNDER THIS RIDGE.
HIGHS ON WEDNESDAY LOOK TO END UP BELOW NORMAL...BUT THIS TREND
REVERSES THROUGH FRIDAY AS HIGHS WARM SOME 7 TO 12 DEGREES.

A DIGGING TROUGH IN THE WEST WILL SWING UPPER WINDS TO THE SOUTHWEST
OVER OUR CWA BY FRIDAY MORNING. BREEZY TO WINDY CONDITIONS CAN BE
EXPECTED AGAIN IN THIS SET UP. MOSITURE AND LIFT WILL BE ARRIVING
LATE FRIDAY...BUT THE BULK OF THE ASCENT AND FORCING FROM A ROBUST
COLD FRONT SHOULD ARRIVE LATER SATURDAY INTO SATURDAY EVENING.
TEMPERATURES ON THE WAKE OF THE FRONT LOOK COLD ENOUGH TO PUSH SNOW
LEVELS DOWN IN THE UPPER VALLEYS BY SUNDAY MORNING. DETAILS WILL BE
IRONED OUT OVER THE NEXT FEW DAYS AS THIS STORM MOVES ONSHORE. FOR
NOW HOWEVER THE CHANCE FOR WIDESPREAD PRECIPITATION AND COOLER
TEMPERATURES FOR NEXT WEEKEND ARE LOOKING LIKE THE WAY TO LEAN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 334 PM MDT MON APR 21 2014

VFR CONDITIONS WILL PREVAIL ACROSS EASTERN UT AND WESTERN CO
TONIGHT THROUGH TUESDAY. ISOLD WEAK -SHRA OR -TSRA OVER THE HIGHER
RIDGES WILL DISSIPATE AFTER ABOUT 02Z THIS EVENING...WITH A LOW
CHANCE OF OUTFLOW WINDS TO 30 MPH AFFECTING KASE...KEGE...KRIL OR
KTEX UNTIL THEN.

A STRONG PACIFIC STORM WILL APPROACH TUE AND SOUTHWEST WINDS WILL
BEGIN INCREASING AFTER ABOUT 16Z AND CONTINUE TO BE STRONG INTO
LATE EVENING. THE COLD FRONT IS NOT EXPECTED TO REACH THE AREA
UNTIL JUST BEFORE MIDNIGHT TUESDAY EVENING. THERE WILL BE
WIDESPREAD MECHANICAL TURBULENCE OVER ALL RIDGES. ISOLD TO
SCATTERED THUNDERSTORMS FROM LATE AFTERNOON THROUGH LATE EVENING
WILL ALSO CAUSE ERRATIC STRONGER GUSTS...WITH ALL AIRPORTS AND
TAFS SITES SUSCEPTIBLE TO THE STRONG WINDS AND THUNDERSTORM
GUSTS.

&&

.FIRE WEATHER...
ISSUED AT 334 PM MDT MON APR 21 2014

THE MAIN CONCERN OVER THE NEXT 24-36 HOURS WILL BE STRONG
SOUTHERLY WINDS TUESDAY FOLLOWED BY A COLD FRONT PASSAGE
EARLY WEDNESDAY. WINDS OF 25 TO 35 MPH WITH HIGHER GUSTS
WILL BE COMMON OVER EASTERN UTAH AND PORTIONS OF WESTERN
COLORADO BY EARLY AFTERNOON. SOME OF THESE GUSTS MY BE AMPLIFIED
BY PASSING SHOWERS OR VIRGA. WELL ABOVE NORMAL TEMPERATURES WILL
ALSO HELP PUSH HUMIDITY LEVELS DOWN TO THE TEENS AND LOWER 20S IN
THE WESTERN VALLEYS. THE COLD FRONT WILL PASS THROUGH NORTHEAST
UTAH BY MIDNIGHT THEN TO THE DIVIDE BY MID WEDNESDAY MORNING.
WARMER AND DRIER CONDITIONS MOVE FOR THE LATE WEEK PERIOD FOLLOWED
BY ANOTHER PASSING STORM SYSTEM FOR THE WEEKEND.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WIND ADVISORY FROM 3 PM TO 10 PM MDT TUESDAY FOR COZ001-002-006-
     011-020-021.

UT...WIND ADVISORY FROM 3 PM TO 10 PM MDT TUESDAY FOR UTZ022-027-029.

&&

$$

SHORT TERM...CC
LONG TERM...15
AVIATION...CC
FIRE WEATHER...15



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