Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 200958
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
358 AM MDT SAT SEP 20 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 357 AM MDT SAT SEP 20 2014

DRY AND STABLE CONDITIONS WILL PREVAIL AGAIN TODAY AS HIGH
PRESSURE AND LOW PRECIPITABLE WATER CONTINUE OVER THE AREA. THE
CLOSED LOW OFF THE SRN CA COAST WILL MOVE VERY SLOWLY INLAND OVER
SRN AND CENTRAL CA THIS AFTERNOON. A SHORTWAVE TROUGH ROTATING
AROUND THE EASTERN PORTION OF THIS STORM WILL HELP THE RIDGE TO
FUNNEL MOISTURE INTO THE AREA LATER THIS AFTERNOON...WITH A
RESULTING INCREASE IS SHOWER AND THUNDERSTORM DEVELOPMENT OVER SW
CO. FORECAST SOUNDINGS NEAR THE FOUR CORNERS SHOW THE PWAT
INCREASING TO OVER 0.75 INCHES AFTER 21Z AND CONTINUING TO
INCREASE THEREAFTER. HAVE INCREASED CLOUD COVER AND PRECIP CHANCES
OVER THE SOUTHERN HALF OF THE AREA THIS AFTERNOON.

THE CLOSED UPPER LOW TRACKS NORTHEAST ACROSS CENTRAL CA TONIGHT AND
CENTRAL NV ON SUNDAY. MOISTENING ISENTROPIC UPLIFT IN SOUTHERLY
UPSLOPE FLOW TONIGHT WILL BRING A CHANCE OF SHOWERS TO MAINLY SE
UT/SW CO LATE TONIGHT. THIS CHANCE SPREADS ACROSS MUCH OF OUR AREA
SUNDAY MORNING AS THIS BAND LIFTS NORTHWARD. SOME BRIEF CLEARING MAY
OCCUR ACROSS THE SOUTH AROUND MIDDAY PER THE 315K/320K ISENTROPIC
HUMIDITY FIELDS...BUT DAYTIME HEATING AND THE APPROACH OF A
WEAKENING 300 MB JET MAX SHOULD CAUSE SCATTERED SHOWERS AND STORMS
TO FILL IN SUNDAY AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 357 AM MDT SAT SEP 20 2014

SUNDAY NIGHT COULD BE RATHER ACTIVE AS THE UPPER LOW MOVES ACROSS SE
ID/NW UT. THE WEAKENING UPPER JET SLIPS OVER SE UT/SW CO...WHILE A
500 MB VORTICITY LOBE SWINGS ACROSS NE UT/NW CO. THE LOSS OF HEATING
SUNDAY NIGHT WILL BE COMPENSATED FOR BY BETTER DYNAMICS. BEST
COMBINATION OF 0-6KM VERTICAL WIND SHEAR AND MUCAPE IS SHOWN SUNDAY
EVENING AND SUNDAY NIGHT FOR THE POTENTIAL OF A FEW STRONGER
STORMS...WITH STRONG GUSTY OUTFLOW WINDS AND HAIL POSSIBLE. WITH
PRECIPITABLE WATER VALUES NEAR AN INCH SUNDAY EVENING...LOCALLY
HEAVY RAIN ALSO IN THE MIX.

FLOW ALOFT SHIFTS FROM SOUTHERLY SUNDAY NIGHT TO WESTERLY ON MONDAY
AS THE UPPER LOW MOVES ACROSS WY. THIS SHOULD PULL IN SOME DRIER AIR
CONFINING SCATTERED SHOWERS/STORMS MAINLY THE NORTH. TEMPS A FEW
DEGREES COOLER ON MONDAY.

TUESDAY THROUGH FRIDAY...THE 500 MB TROUGH WILL BE WELL EAST OF CO
TUE MORNING WITH NW FLOW OVER THE AREA AND REMNANT MOISTURE AND
SHOWERS HUGGING THE NORTHERN AND CENTRAL CO MOUNTAINS. BY TUE
AFTERNOON MOST OF THESE SHOULD DISSIPATE AND/OR MOVE EAST OF THE
AREA AS MOISTURE ERODES QUICKLY.

A BIG RIDGE IS PROJECTED TO DOMINATE THE WEATHER ACROSS MUCH OF
THE WESTERN U.S. TUE AFTERNOON THROUGH THU MORNING. DRIER
CONDITIONS WITH A WARMING TREND ARE EXPECTED IN THIS TIME PERIOD.

THURSDAY AFTERNOON AND FRIDAY...THE MIDRANGE MODELS ARE COMING
INTO AGREEMENT ON THIS BEING A TRANSITION PERIOD. THE RIDGE IS
PROJECTED TO ERODE TO THE SOUTHEAST AND ANOTHER STRONG PACIFIC
TROUGH MOVES INLAND. AN IMPRESSIVE LOOKING STAND-UP COLD FRONT
WILL MOVE INTO WESTERN AND CENTRAL UT FRIDAY...AND APPROACH
EASTERN UT FRIDAY AFTERNOON. HAVE INCREASED CLOUDS AND PRECIP
CHANCES FROM WEST TO EAST FRIDAY AFTERNOON. AS THE SYSTEM ACROSS
THE GREAT BASIN FRIDAY...A STRONG JET ROUNDS THE BASE OF THE
TROUGH WITH GOOD DIVERGENCE ALOFT AND AMPLE MOISTURE OVER MUCH OF
UT. THIS COULD BE A VERY INTERESTING SYSTEM.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 357 AM MDT SAT SEP 20 2014

VFR CONDITIONS WILL PREVAIL THROUGH 18Z UNDER MOSTLY CLEAR SKIES.
AFTER 18Z...ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER
THE MOUNTAINS...WITH A SLIGHT CHANCE OF A THUNDERSTORM IN THE
VICINITY OF KTEX AFTER ABOUT 21Z.

SHOWERS AND THUNDERSTORMS WILL INCREASE OVER SOUTHWEST CO AND
SOUTHEAST UT AFTER 03Z AS A DISTURBANCE ROTATES NORTH FROM AZ AND
NM. THERE IS ABOUT A 20 PERCENT CHANCE OF MVFR VSBYS IN HEAVIER
SHOWERS AT KDRO AND KTEX THROUGH 12Z.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

SHORT TERM...CC/JAD
LONG TERM...JAD/CC
AVIATION...CC


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