Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 190144
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
744 PM MDT SAT APR 18 2015

.UPDATE...
ISSUED AT 744 PM MDT SAT APR 18 2015

UPPER LOW CONTINUES TO ROTATE IN PLACE OVER THE EASTERN PLAINS
THIS EVENING. WRAP AROUND MOISTURE KEEPING SNOW GOING IN THE HIGH
COUNTRY...A MIXTURE ACROSS THE MESA AND PLATEAU REGION AND
THUNDERSTORMS ACROSS EASTERN UTAH. STEEP LAPSE RATES DUE TO
HEATING OUTSIDE OF THE THICKER CLOUD SHIELD IS AIDING THE WEAK
WAVE DROPPING THROUGH EASTERN UTAH. STORMS STARTED OUT QUITE
ROBUST WEST OF THE COLORADO RIVER...BUT AS THEY TRAVEL SOUTHEAST
ACROSS THE INSTABILITY GRADIENT...THEY WEAKEN OVER OUR CWA. WILL
LOSS OF HEATING EXPECT THE COVERAGE TO SLOWLY WANE OVER THE NEXT
HOUR OR SO. WILL BE WATCHING THE AFFECT OF NIGHTFALL ON EASTERN
PASSES AS MELTING HAS KEPT ROADS IN DECENT SHAPE. MAY KEEP SOME
OF THE HEADLINES ALONG DIVIDE IF NECESSARY PAST MIDNIGHT. LASTLY
DEW POINTS DID CREEP UP A BIT THIS AFTERNOON INTO THE 40S OVER THE
WESTERN VALLEYS. WILL BE MONITORING THE THREAT OF DENSE FOG
AS WELL.

&&

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 325 PM MDT SAT APR 18 2015

THE LOW PRESSURE RESPONSIBLE FOR THE MUCH NEEDED PRECIP OVER THE
LAST FEW DAYS IS NOW LOCATED OVER THE FRONT PLAINS WHILE CYCLONIC
FLOW CONTINUES TO PUMP IN MOISTURE FROM THE NORTH TO SOUTH. THIS
FLOW STARTS IN NERN WY AND THE PLUME REACHES AS FAR SOUTH AS THE
SAN JUANS. SNOW AND RAIN HAS FALLEN MUCH OF THE DAY UNDER THIS
PLUME OF MOISTURE AND WILL CONTINUE TO DO SO THROUGH THIS EVENING.
CURRENT WINTER HIGHLIGHTS LOOK GOOD SO NO CHANGES THERE. AN UPPER
LEVEL DISTURBANCE OVER SRN CANADA IS TRAILING A TROUGH THAT IS
CAUSING THE AREA OF LOW PRESSURE TO KEEP MOVING EWRD. THE REASON
THIS IS HAPPENING SO SLOWLY IS THE LACK OF ANY STRONG JET FEATURES
TO REALLY GET THIS SYSTEM MOVING. EVEN SO...THE CLOUD SHIELD/PLUME
WILL BRING MORE PRECIP TO THE AREA AS THE ATTENDANT LOW PRESSURE
MEANDERS EAST. BY MIDNIGHT...PRECIP WILL FAVOR THE NRN AND CENTRAL
MTNS ALONG WITH THE FLATTOPS DUE TO THEIR FAVORABLE LOCATION SO
ADDITIONAL ACCUMULATIONS STILL POSSIBLE UP THERE. THE REST OF THE
CWA MAY SEE AN ODD SHOWER OR TWO BUT NOTHING TOO SIGNIFICANT.

BY SUNDAY...THE CANADIAN LOW WILL BE JUST TO THE NORTH OF
MINNESOTA WHILE HIGH PRESSURE BUILDS INTO THE PACNW. THIS WILL
CAUSE OUR CWA TO BE SANDWICHED BETWEEN THESE TWO FEATURES. WEAK
PIECES OF ENERGY WILL DROP DOWN FROM THE NW POSSIBLY CAUSING SOME
PRECIP FOR THE CWA. THE GFS HIGHLIGHTING TWO DISTINCT WAVES...ONE
SUNDAY EVENING AND ANOTHER MONDAY MORNING. THE NAM12 ONLY SHOWING
SOME SPOTTY SHOWERS AT BEST WITH SOME CONVECTION THROWN IN. THE
HRRR AND RAP SHOWING MUCH LESS IN THE WAY OF PRECIP. THIS ALL
MEANS UNSETTLED WX WILL CONTINUE BUT WITH MUCH MORE DEFINITIVE
BREAKS BETWEEN DISTURBANCES.  FORECAST BRINGS MOSTLY BENIGN
WEATHER SUNDAY WITH INCREASING CHANCES FOR PRECIP FROM
MIDAFTERNOON ONWARDS...MAINLY FAVORING THE CONTINENTAL DIVIDE.

TEMPS WILL WARM UP CONSIDERABLY TOMORROW THOUGH STILL REMAIN 5 TO
10 DEGREES BELOW NORMAL.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 325 PM MDT SAT APR 18 2015

UNSETTLED NW FLOW IS EXPECTED MONDAY AND TUESDAY. AN EMBEDDED WAVE
SHOULD FOCUS THE BEST CHANCE OF SHOWERS OVER THE NORTHERN AND
CENTRAL MOUNTAINS MONDAY AFTERNOON AND EVENING. DAYTIME INSTABILITY
WILL KEEP ISOLATED TO SCATTERED SHOWERS OVER THE MTNS ON TUESDAY.

TEMPORARY RIDGING DEVELOPS OVER THE AREA BY MIDWEEK AS A TROUGH
FORMS ALONG THE WEST COAST...WITH AN UPPER LOW OVER SRN CA BY THU
MORNING. ENOUGH RESIDUAL MOISTURE LINGERS FOR A FEW AFTERNOON
SHOWERS OR THUNDERSTORMS. FLOW ALOFT BECOMES SOUTHWEST...AND THE
SRN CA LIFTS ACROSS THE FOUR CORNERS/DESERT SOUTHWEST THU NIGHT
AND FRI MORNING. TIMING AND TRACK A BIT DIFFERENT BETWEEN MODELS
BUT STILL LOOKING LIKE A BETTER CHANCE OF PRECIPITATION WITH SOME
THUNDERSTORMS LATE NEXT WEEK. BOOSTED POPS FOR THU AFTERNOON
THROUGH FRI OVER THE BLENDED FORECAST GUIDANCE AS A RESULT.

GFS AND ECMWF SOLUTIONS CONTINUE TO DIVERGE ON SATURDAY. ECMWF MORE
AMPLIFIED AS IT DIGS A PAC NW TROUGH TO THE SRN GREAT BASIN BY
SATURDAY...RESULTING IN DOWNSTREAM RIDGING AND SW FLOW OVER OUR
AREA. GFS DROPS SOME ENERGY FROM THE PAC NW TROUGH DOWN THE WEST
COAST BUT SENDS MORE OF IT ACROSS THE NRN ROCKIES WITH WESTERLY
FLOW ACROSS UT/CO. WILL FOLLOW THE BLENDED GUIDANCE FOR SAT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 641 PM MDT SAT APR 18 2015

THE SLOW MOVING LOW PRESSURE SYSTEM WHICH HAS IMPACTED THE REGION
FOR THE LATTER PART OF THE WEEK WILL CONTINUE TO BRING PRECIPITATION
TO THE AREA TONIGHT. AIRPORTS WILL HAVE OCCASIONAL RAIN OR SNOW
SHOWERS RESULTING MVFR CIGS/VSBY WITH LOCALIZED IFR CONDITIONS.
MOUNTAINS WILL LARGELY BE OBSCURED IN CLOUDS AND SHOWERS. LATER
TONIGHT SOME AREAS MAY EXPERIENCE FOG CAPABLE OF YIELDING IFR
CONDITIONS. FOG WILL LINGER THROUGH 17Z THEN RAPIDLY DISSIPATE.
VFR CONDITIONS RETURN TO THE AREA SUNDAY AFTERNOON AS THE STORM
SHIFTS EAST. HOWEVER...MOUNTAIN SNOW SHOWERS WILL CONTINUE OVER
THE DIVIDE MOUNTAINS AND THE EASTERN UINTAS THOUGH IMPACTS ON
ADJACENT AIRPORTS IS UNLIKELY.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR COZ009-010-
     012-017-018.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR COZ003-
     004-013.

UT...NONE.
&&

$$

UPDATE...15
SHORT TERM...TGR
LONG TERM...JAD
AVIATION...NL


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