Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 301005
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
405 AM MDT TUE SEP 30 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 405 AM MDT TUE SEP 30 2014

BROAD CYCLONIC FLOW COVERS THE WRN STATES WITH AN EMBEDDED SHORT
WAVE MOVING ACROSS WRN COLORADO THIS AFTERNOON. THIS WILL TRIGGER
ANOTHER ROUND OF SHOWERS AND STORMS...MOSTLY ACROSS THE NORTH AS
THE AIR MASS IS DRIER ACROSS THE SOUTH. PRECIPITABLE WATER IS
LOWER TODAY...OR THE DEEP MOIST LAYER IS NOT AS PREVALENT. SHOWERS
AND STORMS WILL BE WEAKER THIS AFTERNOON. WITH DECENT GRADIENT
WESTERLY FLOW...RAP13 AND NAM MODELS SHOWING THAT SHOWERS WILL BE
CONCENTRATED OVER THE NRN HIGH COUNTRY. SHOWERS WILL BE LESS
NUMEROUS SOUTH OF THE I70 CORRIDOR.

TONIGHT ONE WEAK DISTURBANCE EXITS EAST BUT THE NEXT STRONGER
NORTHERN PACIFIC WAVE DIVES THROUGH THE NORTHERN GREAT BASIN
OVERNIGHT. MODELS HAVE CONSISTENTLY SHOW SOME FORCING ACROSS THE
NORTH OVERNIGHT FOR SHOWERS THROUGH THE NIGHT. INSTABILITY IS
LIMITED SO LIGHTNING WILL BE ISOLATED IF AT ALL. DRY CONDITIONS
ARE EXPECTED THROUGH THE NIGHT SOUTH OF THE I-70 CORRIDOR THOUGH
SHOWERS WILL BEGIN TO SPREAD SOUTH TOWARDS SUNRISE.

WEDNESDAY THERE IS STILL SOME SLIGHT TIMING DIFFERENCE IN THE
MODELS. THE POLAR FRONT JET STRETCHES ALONG THE CO-NM STATE LINE
WITH THE SURFACE FRONT INDICATING THE TROUGH WILL IMPACT NEARLY
ALL OF THE FORECAST AREA. THE COLD FRONT WORKS INTO NE UT-NW CO
EARLY IN THE MORNING AND WORKS QUICKLY SOUTH OF I-70 BY NOON AND
THROUGH THE SOUTH IN THE AFTERNOON. THE BEST COLD ADVECTION...
MOISTURE AND FORCING OVER NW COLORADO WILL PRODUCE THE HEAVIEST
SHOWERS THERE. THE COLD ADVECTION IS THE STRONGEST OF THE SEASON
SO FAR. A -20C COLD CORE OVER THE NORTH WILL LIKELY LOWER SNOW
LEVELS TO AROUND 8KFT IN THE AFTERNOON. THE DOWNSIDE OF THIS STORM
IS LIMITED INSTABILITY AND A LACK OF A GOOD MOISTURE TAP.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 405 AM MDT TUE SEP 30 2014

COLD ADVECTION CONTINUES ACROSS THE CWA OVERNIGHT. FLOW VEERS TO
NNW FAVORING NORTH-FACING SLOPES WITH SNOW. THE FIRST WINTER
HIGHLIGHTS OF THE SEASON STILL LOOK POSSIBLE FOR THE NORTHERN AND
CENTRAL MTNS AND PERHAPS THE COLORADO NORTHERN HIGH VALLEYS WITH
THE FIRST SIGNIFICANT ACCUMULATIONS OF THE COOL SEASON. SNOW
LINGERS ALONG THE COLORADO SPINE INTO THURSDAY MORNING BUT SHOULD
END BY AROUND SUNRISE. FREEZING TEMPERATURES ARE POSSIBLE IN
THE NORTHERN VALLEYS...THE ROARING FORK VALLEY...AND PERHAPS EVEN
INTO DURANGO-PAGOSA.

THURSDAY WILL BE DRY BUT WITH DAYTIME TEMPERATURES 5-10 DEGREES
BELOW NORMAL. ANOTHER COLD NIGHT IS IN STORE THURSDAY NIGHT WITH
ALL BUT THE LOWEST VALLEYS THREATENED WITH FREEZING TEMPERATURES.

DRY WEATHER EXPECTED THROUGH THE PERIOD GIVEN HIGH PRESSURE
COVERING THE SWRN CONUS. MAIN WESTERLY JET STAYS WELL NORTH OF
COLORADO AND ALLOWS TEMPS TO REBOUND TO A FEW DEGREES ABOVE
CLIMATOLOGY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 947 PM MDT MON SEP 29 2014

ISOLATED REMNANT CLOUDS AND SHOWERS WILL HUG THE NORTHERN AND
CENTRAL CO MTNS OVERNIGHT CAUSING LOCAL MT OBSCURATIONS. VFR
CONDITIONS WILL PREVAIL TUESDAY MORNING. AFTER 18Z ISOLATED TO
SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL CAUSE LOCAL
MOUNTAIN OBSCURATIONS ACROSS THE AREA...WITH ONLY A SLIGHT CHANCE
OF SHOWERS AFFECTING FLIGHT CONDITIONS AT KEGE...KRIL...KASE...AND
KTEX.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FREEZE WARNING UNTIL 8 AM MDT THIS MORNING FOR COZ014-023.

UT...NONE.
&&

$$

SHORT TERM...PF/JOE
LONG TERM...JOE/PF
AVIATION...CC


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