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000
FXUS65 KGJT 122228
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
328 PM MST THU DEC 12 2013

.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 326 PM MST THU DEC 12 2013

SATELLITE IMAGERY AND LIGHTNING NETWORK SHOWING THE SOUTHERN LOW
BEGINNING TO ACCELERATE OUT OF SOUTHERN CALIFORNIA INTO WESTERN
ARIZONA AS THE KICKER UPSTREAM TROF MOVES INTO TOWARD THE NW
CONUS SHORELINE. WATER VAPOR IMAGERY AND THETA SURFACES SHOW ANY
MOISTURE ASSOCIATED WITH THESE STORMS BEING DIRECTED AWAY FROM OUR
CWA AND THE CHANCES OF ANY SIGNIFICANT SNOWFALL ALONG WITH IT.
SKIES ARE STILL MAINLY CLEAR EXCEPT FOR THE GROWING HAZE TRAPPED
IN THE INVERTED VALLEY REGIME. STILL TRYING TO ANTICIPATE WHEN
ENOUGH MOISTURE IN THIS LAYER WILL COMBINE WITH FAVORABLE PBL
CONDITIONS TO MAKE MORE WIDESPREAD DENSE FOG OR STRATUS...BUT THIS
IS PROVING TO BE QUITE DIFFICULT. SO WILL CONTINUE TO RUN WITH
PATCHY FOG TONIGHT...AGAIN MOST LIKELY IN THE GUNNINSON AND UINTA
BASINS AND ALONG THE OPEN WATER VALLEY BOTTOMS. THE LOW TO OUR
SOUTHWEST TREK EASTWARD ACROSS CENTRAL AZ AND NM OVERNIGHT AND
BESIDES SPREADING SOME MID AND HIGH CLOUDINESS INTO OUR SOUTHERN
ZONES IT SHOULD BE A NON- PLAYER TO OUR SENSIBLE WEATHER.
OVERNIGHT TEMPERATURES SHOULD BE IMPACTED A BIT BY THE CLOUDS AND
HAVE WARMER READINGS IN THE SOUTH. OTHERWISE WILL TRY AND GO A FEW
DEGREES NEAR PERSISTENCE.

THIS STORM WILL BE EXITING EASTWARD INTO THE SOUTHERN HIGH PLAINS
TOMORROW MORNING WHILE THE UPSTREAM TROF DIGS ACROSS THE GREAT
BASIN. LARGE SCALE ASCENT WITH THIS STORM IS NOW CENTERED SOUTH OF
THE 4 CORNERS WITH LEAD BATCH OF ENERGY IN THE BASE OF THE TROF. SO
WITH ONLY SOME CHANNELIZED VORTICITY SWINGING THROUGH OUR CWA FRIDAY
EVENING AND OVERNIGHT UPWARD MOTION IS WEAK. THE FAVORED DENDRITIC
LAYER DOES REACH MOUNTAIN TOP LEVEL BY LATE EVENING AND NORTHERLY
OROGRAPHICS SHOULD BE ABLE TO SQUEEZE OUT A FEW INCHES OVER THE
NORTHERN MOUNTAINS WITH A DUSTING DOWN TOWARD THE ELKS. SOUNDINGS
INDICATE THE NORTHERN VALLEYS HAVING A HARD TIME SATURATING ENOUGH
TO GET PRECIPITATION TO GROUND. STRATUS AND SEEDER FEEDER COULD BE A
PLAYER BUT DISCOUNTED ATTM. MIXING NOT LIKELY TO HAVE A HUGE IMPACT
TO VALLEY TEMPERATURES WITH THESE SYSTEMS BUT WILL BE COOLING THE
HIGHER COUNTY DOWN A BIT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 326 PM MST THU DEC 12 2013

A NORTHWEST FLOW WILL PERSIST OVER OUR AREA THROUGH EARLY IN THE
NEXT WORK WEEK. THIS WILL OCCUR AS THE AREA SITS BETWEEN A HIGH
PRESSURE RIDGE ALONG THE CALIFORNIA COAST-THE DESERT
SOUTHWEST...AND A LONG WAVE TROUGH OVER EASTERN NORTH AMERICA. A
COUPLE OF EMBEDDED DISTURBANCES WILL BRUSH THE NORTHERN DIVIDE
AREA DURING THIS TIME FRAME. ONE WAVE WILL BE EXITING AT THE
BEGINNING OF THE PERIOD. A FEW AREAS OF LIGHT OROGRAPHIC SNOW WILL
LINGER ON SATURDAY. THEN ANOTHER WAVE IS SCHEDULED TO PASS
SATURDAY NIGHT/SUNDAY MORNING. AGAIN THE NORTHERN DIVIDE AREA MAY
SEE LIGHT SNOWFALL...MAINLY FROM MIDNIGHT TO NOON. ADDITIONAL
IMPULSES MAY BRUSH THE NORTH. BUT AT THIS TIME THEY LOOK TOO WEAK
AND TOO FAR NORTH TO RESULT IN ANY SNOW FOR OUR AREA.

VALLEY INVERSIONS THROUGH EARLY NEXT WEEK WILL CONTINUE TO HOLD
STRONG. THEREFORE COLD TEMPERATURES AND STAGNANT AIR WILL PERSIST
IN THE LOWER CENTRAL VALLEYS...THE UINTAH BASIN INTO FAR NORTHWEST
CO...AND THE UPPER GUNNISON BASIN. THE PASSING WAVES OVER THE
NORTHERN DIVIDE SEEM TO BE ENOUGH TO KEEP THE CRAIG/MEEKER AREA-
EASTWARD OUT OF THE DEEP FREEZE FOR NOW. AREAS NOT AFFECTED BY THE
INVERSIONS SHOULD SEE TEMPERATURES CLOSER TO NORMAL VALUES.


THEN BY MIDWEEK THE FLOW WILL FLATTEN OVER OUR CWA AS THE NEXT
TROUGH DEVELOPS ALONG THE NORTHWEST PACIFIC COAST. THIS TROUGH
WILL KICK OUT A SOUTHERN CLOSED LOW THAT HAD BEEN WELL OFF THE
CALIFORNIA COAST. AS THESE DUAL DISTURBANCES MOVE EAST...THEY
PROMISE TO BE OUR NEXT WEATHER MAKERS. BUT THE DETAILS REMAIN
PROBLEMATIC. BY THU A SOUTHWEST FLOW WILL DEVELOP OVER THE CENTRAL
ROCKIES. MIDRANGE MODELS STILL UNCERTAIN IN THE HANDLING/TIMING.
THE FASTER 12Z ECMWF SHOWS THE SOUTHERN DISTURBANCE MOVING INTO
THE GREAT BASIN AS EARLY AS WED...WITH THE NORTHERN BRANCH
DROPPING FROM THE NORTHWEST AND ACROSS THE FORECAST AREA ON THU.
THE GFS IS SLOWER AND SHOWS THE SOUTHERN LOW WAITING FOR THU AS
THE KICKING TROUGH HOLDS BACK OFF THE SOUTHERN CA COAST.THIS
BIGGER TROUGH THEN MOVES ACROSS FROM THE WEST LATER IN THE WEEK.
SO FORECAST CONFIDENCE FOR WED...AND ESPECIALLY FOR THU IS NOT
HIGH. KEPT THE DRY FORECAST FOR WED...AND LOW MOUNTAIN POPS FOR
THU AS THE WHOLE SHEBANG MAY SLOW AS IT DISPLACES THE HIGH
PRESSURE.

EXPECT THAT THESE DISTURBANCES WILL BE ENOUGH TO BREAK THE STRONG
VALLEY INVERSIONS POSSIBLY BY THU. WED IS MORE QUESTIONABLE...BUT
THE VERY COLD TEMPERATURES SHOULD BEGIN TO SEE SOME MODIFICATION
EVEN THEN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 326 PM MST THU DEC 12 2013

VFR CONDITIONS WILL PREVAIL AT THE FORECAST TERMINALS UNTIL AROUND
03Z. THEN AS TEMPERATURES COOL THIS EVENING MVFR FOG WILL AGAIN
MOST LIKELY AFFECT THE KVEL TERMINAL DUE TO LIGHT FOG CONDITIONS
FROM AROUND 13/03Z UNTIL AROUND 13/18Z. PATCHY FOG OR LOW STRATUS
MAY ALSO BE POSSIBLE LATE TONIGHT IN OTHER LOCALIZED VALLEY AREAS.
ALSO ISOLATED SNOW SHOWERS ARE EXPECTED TO DEVELOP OVER THE
NORTHERN CO MOUNTAINS FRI AFTERNOON. OTHERWISE...IFR CONDITIONS
ARE EXPECTED.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.

UT...NONE.

&&

$$

SHORT TERM...15
LONG TERM...EH
AVIATION...EH