Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 161750
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1050 AM MST TUE DEC 16 2014

.UPDATE...
ISSUED AT 928 AM MST TUE DEC 16 2014

SHORT WAVE IS CURRENTLY MOVING NORTHWARD ACROSS NORTHWEST
COLORADO. SNOW IS LIKELY ACROSS THIS AREA FOR THE REMAINDER OF
THIS MORNING...BUT DIMINISHES QUICKLY AS THE WAVE LIFTS NORTH.
MAY BE A QUICK BURST OF ONE HALF TO 1 INCH OF SNOW ACROSS NW
COLORADO. NEXT UPSTREAM WAVE BEGINS TO AFFECT SW COLORADO THIS
EVENING AND LATER UPDATES WILL TAKE A CLOSER LOOK.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 412 AM MST TUE DEC 16 2014

MOISTURE...CARRIED BY A WARM SOUTHWEST FLOW ON THE BACKSIDE OF A
FAST MOVING RIDGE...HAS BEGUN TO SPREAD OVER THE AREA EARLY THIS
MORNING. CLOUDS HAVE THICKENED IN THE PAST SEVERAL HOURS WITH A
MID LEVEL DECK ACROSS MOST OF WESTERN CO AT 4AM MST. UPSTREAM
OBSERVATIONS HAVE GENERALLY REPORTED MID LEVEL CLOUDS WITH LITTLE
PRECIPITATION. BUT OUR CWA SHOULD BE MORE FAVORED FOR
PRECIPITATION AS THIS WEAK WAVE AND WARM ADVECTIVE MOISTURE MOVES
INTO THE HIGHER TERRAIN OF EASTERN UT AND WESTERN CO. ALSO...THE
NORTHWEST CO VALLEYS REMAIN QUITE COLD THIS MORNING WHICH MAY
ENHANCE THE CHANCE FOR OVER-RUNNING PRECIPITATION. THAT SAID...WE
OFTEN DO NOT DO ALL THEN WELL IN A WARM ADVECTIVE PATTERN. THE 00Z
NAM REALLY UPPED POPS COMPARED TO ITS RUNS FOR THE PAST COUPLE OF
DAYS. THIS SOLUTION WAS ALSO MUCH JUICIER THAN THE GFS AND
ECMWF...WHICH HAVE BEEN FAIRLY CONSISTENT. THEREFORE DOWNPLAYED
THE NAM SOMEWHAT FOR THIS FORECAST. MODELS HAVE PRETTY MUCH
AGREED THAT THE PEAK WILL BE OVER THE NORTHERN HALF...AND
TEMPORALLY CENTERED LATE MORNING TO MIDDAY. THE NORTHERN DIVIDE
WILL HOLD ONTO SNOW LONGER...BUT STILL MOST ACTIVITY WILL BE OVER
BY DARK. SNOW WILL GENERALLY BE LIGHT WITH AN INCH OR TWO AT MOST.

THEN AFTER A DOWNTURN THIS EVENING. MOISTURE WILL AGAIN INCREASE
LATE TONIGHT AHEAD OF THE NEXT PACIFIC TROUGH MOVING INTO THE
GREAT BASIN. MOISTURE WILL DEEPEN THROUGH WEDNESDAY AS A SHORTWAVE
EJECTED OFF THE MAIN TROUGH PASSES OVER THE AREA. WHILE NOT
OVERLY IMPRESSIVE...THIS DISTURBANCE WILL CERTAINLY BE STRONGER
THAN WHAT WE EXPECT FOR TODAY. PRECIPITATION WILL SPREAD IN FROM
THE SOUTHWEST BEGINNING LATE TONIGHT AND PEAKING WEDNESDAY
AFTERNOON. THE SOUTHERN MOUNTAINS WILL BE FAVORED AS THE MAIN
TROUGH STAYS TO OUR WEST AND KEEPS THE FLOW SOUTHWEST THROUGH THE
DAY. SNOW LEVELS WILL REMAIN CHALLENGING WITH RAIN POSSIBLE IN
THE LOWER VALLEYS.

THE WARM MOIST FLOW WILL RESULT IN MODERATE TEMPERATURES ACROSS
THE AREA BY THIS AFTERNOON...WITH A FEW DEGREES OF WARMING AS
COMPARED TO MONDAY`S NUMBERS. MILD OVERNIGHT TEMPERATURES ARE THEN
EXPECTED AS MOISTURE AND CLOUDS AGAIN INCREASE LATE TONIGHT. THE
INCREASED CLOUDS AND PRECIPITATION ON WED WILL KEEP TEMPS JUST A
TAD COOLER THAN TODAY`S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 412 AM MST TUE DEC 16 2014

A BROAD SPLIT TROUGH REMAINS OVER THE REGION THURSDAY NIGHT WITH A
SECONDARY SHORTWAVE TROUGH MOVING TO THE SOUTH OF THE FORECAST
AREA THURSDAY NIGHT. GIVEN THAT MUCH OF THE ENERGY WILL BE TO THE
SOUTH AND MOISTURE WITH THIS PACIFIC AIRMASS NOT NEARLY AS
PLENTIFUL AS WITH THE LAST STORM...EXPECT SNOWFALL WILL BE
RELATIVELY LIGHT. SNOW CHANCES CONTINUE INTO THE THURSDAY AS A
TERTIARY WAVE MOVES ACROSS THE REGION. THOUGH SNOW TOTALS NOT ALL
THAT IMPRESSIVE...CANNOT RULE OUT LOW END WINTER WEATHER ADVISORY
ACCUMULATIONS WEDNESDAY INTO THURSDAY. AS THE TROUGH PASSES EAST
THURSDAY NIGHT...FLOW SWINGS AROUND TO THE NORTHWEST AND DRYING
ENSUES WITH JUST A FEW SHOWERS LINGERING ALONG THE NORTHERN
CONTINENTAL DIVIDE INTO FRIDAY.

THE PATTERN REMAINS PROGRESSIVE INTO SATURDAY AS YET ANOTHER
SHORTWAVE ARRIVES FROM THE NORTHWEST BRINGING A CHANCE OF SNOW TO
THE NORTHERN COLORADO MOUNTAINS DURING THE AFTERNOON. MODELS
DIVERGE SATURDAY NIGHT THROUGH MONDAY. THE GFS CARRIES A HIGH
AMPLITUDE SHORTWAVE TROUGH OVER THE AREA SATURDAY NIGHT BRINGING
SNOW TO THE DIVIDE MOUNTAINS. IN CONTRAST...THE ECMWF SETS UP A
MOIST NORTHWEST FLOW REGIME WITH STRONG WINDS AND PERSISTENT
SNOWFALL OVER THE NORTHERN AND CENTRAL COLORADO MOUNTAINS. GIVEN
MODEL DIFFERENCES WILL DEFER TO BLENDED SOLUTIONS.

TRANSIENT DISTURBANCES WILL CONTINUE TO LIMIT WARMING AND EXPECT
TEMPERATURES WILL HOVER NEAR NORMAL DURING THE LATTER PART OF THE
WEEK AND INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1050 AM MST TUE DEC 16 2014

IFR CONDITIONS ACROSS NW COLORADO NORTH OF I70 WILL HAVE RAPID
IMPROVEMENT BETWEEN 18Z-21Z WITH DISSIPATING CIGS AND VIS BECOMING
P6SM. OTHERWISE VFR PREVAILS THOUGH MID EVENING.

AFTER 06Z TONIGHT...CIGS WILL LOWER OVERNIGHT WITH LOCALIZED IFR
CIGS SOUTH OF I70 AT MOUNTAIN AIRFIELDS AS LIGHT SNOW DEVELOPS
OVER THE MOUNTAINS.

&&

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

$$

UPDATE...PF
SHORT TERM...EH
LONG TERM...NL
AVIATION...PF



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