Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 261031
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
331 AM MST MON JAN 26 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 331 AM MST MON JAN 26 2015

THE EAST PACIFIC REX BLOCK IS BEGINNING TO BREAK DOWN WITH THE
ARRIVAL OF UPSTREAM TROUGHING. THIS WILL FORCE THE TO TAKE ON A
NEGATIVE TILT BY THIS AFTERNOON...ALIGNING FROM THE WEST TEXAS
PLAINS TO GREAT BASIN AN PACIFIC NORTHWEST. WITH THIS NEGATIVE
TILT IT WILL BE RATHER STUBBORN TO PUSH EASTWARD AND THE UPPER LOW
OFF THE BAJA COAST WILL BE FORCED NORTHWARD INTO CALIFORNIA
OVERNIGHT...BEFORE GAINING MOMENTUM EASTWARD THROUGH THE NORTHERN
GREAT BASIN TUESDAY. WHAT MIGHT HAVE ONCE BEEN A PROMISING OUTLOOK
FOR PRECIPITATION OVER OUR CWA IS QUICKLY CRUMBLING. SUBSIDENCE
AND DRY AIR UNDER THE RIDGE WILL BE HARD TO OVERCOME...ESPECIALLY
WITH THE MAIN FORCING WITH THIS STORM WELL OFF TO OUR WEST. THE
SATURATED DENDRITIC LAYER THAT APPROACHES THE 4 CORNERS BY
SUNRISE...QUICKLY THINS AS IT PUSHES NORTHWARD INTO OUR SOUTHERN
AND WESTERN ZONES THROUGH THE DAY TUESDAY. CONFIDENCE THAT THIS
WON/T BE MUCH MORE THAN VIRGA OR VERY LIGHT SHOWERS IS WANING. AS
A RESULT DELAYED POPS SOME TONIGHT AND LOWERED ON TUESDAY. SOME
OF THE HIGH COUNTRY WILL PROBABLY SEE SOME SHOWERS AT THE HIGHER
ELEVATIONS...WITH SNOW LEVELS NEAR 10000 FEET. THE ONLY POSITIVE
TO COME OUT OF THIS WILL BE AN RAIN ON SNOW WILL BE LIGHT.
TEMPERATURES WILL BE MILD AGAIN TODAY WITH PLENTY OF SUNSHINE IN
PLACE. THE UINTA BASIN DID MIX NICELY WITH ONLY THE GUNNISON BASIN
KEEPING THE COLD AIR LOCKED IN PLACE. HARD NOT TO LEAN TOWARD
PERSISTENCE AND USED HIGHS FROM YESTERDAY AS A BASE WITH TWEAKED
UPWARD. CLOUD COVER TOMORROW AND SLIGHTLY COOLER TEMPERATURES
MOVING IN ALOFT WILL PUSH HIGHS DOWN BACK SEVERAL DEGREES FOR
TUESDAY...BUT REMAIN WELL ABOVE NORMAL FOR LATE JANUARY.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 331 AM MST MON JAN 26 2015

EACH MODEL RUNS SHOWS LESS QPF AS BAJA CALIFORNIA SHORT WAVE
ENCOUNTERS STRONG RIDGE AXIS. ON TUESDAY NIGHT...THE GFS 315K
ISENTROPIC LEVEL DEPICT THE HUMIDITY FIELDS BECOMING FRAGMENTED
AND STRETCHED AS IT CROSSES THE WESTERN SLOPE. THE COLD CORE ALONG
THE CALIFORNIA COAST GETS ENTRAINED INTO THE WESTERLIES AND SHEARS
ACROSS WYOMING. THERE IS A BRIEF PERIOD OF COLD ADVECTION AND
OROGRAPHIC LIFT AS THE SHORT WAVE DRAGS ACROSS NW COLORADO EARLY
WEDNESDAY MORNING. AS OF RIGHT NOW...APPEARS THAT MOUNTAIN SNOW
POTENTIAL IS IN THE 1-3 INCH RANGE...AND THIS MAY BE OPTIMISTIC.

THE SRN STREAM REMAINS ACTIVE FROM THURSDAY THROUGH SUNDAY TIME
PERIOD. ANOTHER SHORT WAVE TROUGH FORMS NEAR THE SOUTHERN/BAJA
CALIFORNIA COAST AND SENDS MOISTURE INTO THE DESERT SOUTHWEST. HOW
MUCH IMPACTS UTAH AND COLORADO REMAINS TO BE SEEN. THERE IS SOME
MODEL SPREAD THAT BRINGS UNCERTAINTY ON HOW THIS MOISTURE SURGE
INTERACTS WITH THE NRN STREAM. THE ECMWF SHOWS MOISTURE SPREADING
ACROSS THE ENTIRE REGION ON FRIDAY BEFORE GETTING PUSHED SOUTHWARD
ON SATURDAY NIGHT. THE GFS SHOW THE MOISTURE REACHING SW COLORADO
ON FRIDAY BUT RETREATS SOUTHWARD ON SATURDAY. THE BEST CHANCE FOR
PCPN APPEARS CENTERED ON FRIDAY OVER SW COLORADO.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 331 AM MST MON JAN 26 2015

VFR THROUGH THE FORECAST PERIOD WITH NO AVIATION HAZARDS EXPECTED.

&&

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

$$

SHORT TERM...15
LONG TERM...PF
AVIATION...PF



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