Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 250440
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
940 PM MST SAT JAN 24 2015

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM MST SAT JAN 24 2015

THE SYNOPTIC PATTERN FEATURED A STRONG RIDGE OVER THE WESTERN U.S.
AND A DEEP TROUGH OVER THE CENTER OF THE COUNTRY. ELEVATED
MOISTURE IN NORTHWEST FLOW BROUGHT A BROAD AND THICK CIRRUS SHIELD
WHICH ENVELOPED MUCH OF THE FORECAST AREA TODAY RESULTING IN
CLOUDY OR MOSTLY CLOUDY SKIES ACROSS ALL BUT SOUTHEAST UTAH.

MEANWHILE...SITES ACROSS NORTHERN COLORADO HAVE SEEN A LOWERING OF
CLOUDS AS MOISTURE DEEPENS AHEAD OF A WEAK DISTURBANCE TO THE
NORTH. THE NAM WAS MORE PRODUCTIVE WITH RESPECT TO SNOW COVERAGE
ACROSS THE NORTHERN MOUNTAINS FROM LATE EVENING THROUGH NOON
SUNDAY RESULTING FROM THE WEAK MOISTURE SURGE AS COMPARED TO BOTH
THE ECMWF AND GFS MODELS. OROGRAPHIC LIFT PROVIDED BY MODERATE
NORTHWEST FLOW APPEARED TO BE THE PRIMARY FORCING MECHANISM WITH
DYNAMIC LIFT LACKING. WAA AT RIDGE LEVEL WORKS AGAINST SNOWFALL
AND SHOULD LIMIT ACCUMULATIONS TO AN INCH OR A LITTLE MORE
THROUGH NOON SUNDAY. SNOW SHOWERS END SUNDAY AFTERNOON AS DRIER
AIR FILLS IN ACROSS THE AREA AND REMAINS THROUGH SUNDAY NIGHT.

SKIES WILL BE CLEARING OVER ALL BUT NORTHERN COLORADO TONIGHT
WHICH WILL ALLOW TEMPERATURES TO AGAIN FALL TO NEAR NORMAL LEVELS.
HOWEVER...HIGHS ON SUNDAY WILL BE A BIT MILDER FOR ALL BUT
STRONGLY INVERTED VALLEYS LIKE THE GUNNISON BASIN. EXPECT LOWS TO
MODERATE SLIGHTLY SUNDAY NIGHT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 300 PM MST SAT JAN 24 2015

THE WEST COAST RIDGE WILL BE PUSHED EAST AND OVER OUR FORECAST
AREA ON MONDAY AS A SOUTHERN LOW PRESSURE SYSTEM TRACKS NORTHWARD
OFF THE BAJA/SOUTHERN CALIFORNIA COAST. THE FLOW OVER OUR FORECAST
AREA WILL BECOME SOUTHERLY LATE MON/MON NIGHT AS THIS LOW OPENS UP
AND EJECTS TO THE NORTHEAST. THIS OPEN WAVE WILL EVENTUALLY GET
PICKED UP BY THE WESTERLIES IN THE NORTHERN STREAM ON WED. HOWEVER
AS THIS DISTURBANCE ROTATES AROUND THE HIGH...IT WILL MAINLY STAY
FIRST TO OUR WEST...AND THEN TO OUR NORTH AS THE RIDGE REMAINS AN
EFFECTIVE BLOCK. MOISTURE WILL INCREASE IN THE SOUTH-SOUTHWEST
FLOW AHEAD OF THE WAVE. AS THE DISTURBANCE BRUSHES FIRST THE WEST
THEN NORTHERN PORTION OF THE AREA...MOUNTAIN SNOW AND VALLEY RAIN
WILL BE POSSIBLE....MAINLY ALONG THE WESTERN EDGE ON TUE...AND
THEN OVER THE NORTH TUE NIGHT INTO WED. SNOW LEVELS WILL REMAIN ON
THE HIGH SIDE DUE TO THE PACIFIC ORIGIN OF THE LOW...WITH
PRECIPITATION GENERALLY LIGHT AS THE DISTURBANCE STRUGGLES AGAINST
THE RIDGE.

THE DOMINANT HIGH PRESSURE RIDGE OVER THE WESTERN CONUS WILL
REBOUND AFTER TUE`S WAVE. HOWEVER THE SOUTHERN STREAM WILL REMAIN
ACTIVE WITH ANOTHER CLOSED LOW OFF THE BAJA COAST SET TO MOVE
INLAND. MODELS DO AGREE THAT THE SOUTHWEST FLOW AROUND THE BASE OF
THIS LOW WILL TAP INTO DEEPER MOISTURE THAT WILL STREAM UP INTO
THE DESERT SOUTHWEST LATE IN THE WORK WEEK. HOWEVER MODEL
AGREEMENT HAS BEEN RATHER POOR FOR OTHER ASPECTS OF THE
PATTERN...RESULTING IN BIG DIFFERENCES FOR OUR CWA. THE QUESTION
REMAINS AS TO HOW MUCH OF THE MOISTURE/ENERGY WILL MAKE IT NORTH
INTO OUR FORECAST AREA. THE ECMWF HAS CONSISTENTLY KEPT MOST OF
THE ACTION WELL TO OUR SOUTH. WHILE THE GFS INDICATES WE WILL BE
WETTER AND MORE UNSETTLED BEGINNING EARLY FRI AND PERSISTING INTO
SUN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 940 PM MST SAT JAN 24 2015

A MOIST NORTHERLY FLOW IS BRINGING MID AND HIGH CLOUDINESS TO MUCH
OF THE NORTHERN AND CENTRAL HIGH COUNTRY THIS EVENING. FLIGHT
TERMINALS ARE AT VFR CONDITIONS AS PRECIPITATION IS SPARSE AND
MOST LIKELY LIMITED TO THE HIGHEST PEAKS. KASE AND KEGE ARE
CURRENTLY UNDER ILS CIGS. NAM CROSS SECTIONS MIRROR CURRENT
CONDITIONS AND SUGGEST SOME LOWERING OF THE CIGS THROUGH THE
NIGHT...WITH THE NORTHERLY FLOW DIRECTING MOISTURE UP THE ROARING
FORK VALLEY. KASE COULD DIP TO NEAR MVFR CONDITIONS BY 09Z. NO
OTHER PROBLEMS ANTICIPATED AT THE FORECAST TERMINALS THE NEXT 24
HOURS.

&&

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

$$

SHORT TERM...NL
LONG TERM...EH
AVIATION...TGJT


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