Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 251656
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
956 AM MST SUN JAN 25 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 408 AM MST SUN JAN 25 2015

REX PATTERN BECOMING A BIT MORE DEFINED OFF THE LEFT COASTLINE OF
NOAM THIS MORNING WITH DEEP TROUGHING TO THE EAST. NORTHWEST FLOW AT
THE INTERFACE OF THIS PATTERN IS PULLING PACIFIC MOISTURE OVER THE
CREST THE RIDGE TOWARD THE CENTRAL ROCKIES. THIS MOISTURE IS PILED
UP AGAIN OUR NORTHERN AND CENTRAL MOUNTAINS BUT OUTSIDE THE
DENDRITIC ZONE SO LITTLE IF ANY PRECIPITATION HAS BEEN FALLING OUT.
LOW LEVEL MOISTURE ALSO IS POOLING UNDER THE UPPER RIDGE IN THE
VICINITY OF THE SURFACE HIGH PRESSURE CENTER OVER THE SALT LAKE
BASIN INTO EASTERN IDAHO. THE CHALLENGE WILL BE WHAT WILL HAPPEN TO
THE MOISTURE IN THE LOWER LAYERS AS THE UPPER RIDGE AXIS FOLDS
EASTWARD INTO THE GREAT BASIN. THE SHIFT IN THE RIDGE AXIS BRINGS IN
WARMER...AND DRIER AIR ALOFT...STRENGTHENING MID LEVEL INVERSIONS.
THERE WILL BE GOOD WARMING IN MID SLOPE AREAS NEAR THIS INVERSION.
THE VALLEYS ARE SOMEWHAT MORE PROBLEMATIC. LACK OF SNOW COVER OVER
MUCH OF OUR WESTERN LOW VALLEYS SUGGESTS TEMPERATURES CONTINUE TO
CLIMB THE NEXT FEW AFTERNOONS...WITH HIGHS ABOVE NORMAL. THE UPPER
VALLEYS AND ESPECIALLY THE GUNNISON BASIN WILL STRUGGLE. IN FACT
WILL STAY WITH PERSISTENCE IN THE GUNNY AREA WITH HIGHS STRUGGLING
THROUGH THE TEENS. VERNAL A BIT MORE TRICKY YET AS THE NAM PBL
MOISTURE PROFILE SUGGESTING STRATUS FORMING OVERNIGHT. THIS IS WHERE
THE SURFACE HIGH IS SETTLING THE NEXT 24 HOURS. THE NAM12 WAS
SUPERIOR CATCHING STRATUS TRENDS THE LAST TIME THIS HAPPENED AND
GUIDANCE SLOW TO CATCH UP. FOR NOW HAVE JUST HINTED AT THIS IN
GRIDS AND WILL WATCH THE TREND. OTHERWISE DRY WEATHER CONTINUES
WITH HIGH PRESSURE IN CONTROL.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 408 AM MST SUN JAN 25 2015

CLOSED LOW CURRENTLY WEST OF BAJA CALIFORNIA WILL BE LIFTING
NORTHWARD MONDAY NIGHT AND TUESDAY. A SHORT WAVE EXTENDS EAST AND
REACHES THE FOUR CORNERS AREA. STRONG RIDGE AXIS WEAKENS THE
NORTHWARD MOVING SHORT WAVE...EVIDENT IN THE MOISTURE/HUMIDITY
FIELDS THAT SHRINK WITH TIME. THE CLOSED LOW BECOMES A
PROGRESSIVE TROUGH AS IT PHASES WITH A NRN STREAM SHORT WAVE ON
TUESDAY NIGHT AND WEDNESDAY. THE COLD CORE TRACKS NORTH OF THE
COLORADO BORDER...BUT MOISTURE AND COLD ADVECTION BRIEFLY AFFECTS
THE NRN/CENTRAL MOUNTAINS OF WRN COLORADO. THE NET RESULT IS LIGHT
QPF OVER THE SOUTHWEST ASPECTS OF THE SRN MOUNTAINS. SNOW LEVELS
WILL BE MODERATELY HIGH WITH A FLUCTUATING WET BULB ZERO LINE BUT
GENERALLY AROUND 9K FEET). THE NRN AND CENTRAL MOUNTAINS STAND A
BETTER CHANCE AT GETTING APPRECIABLE QPF AMOUNTS. COLD ADVECTION
IS GOOD ENOUGH TO LOWER SNOW LEVELS TO THE MOUNTAIN BASES...BUT
SNOW ACCUMULATION APPEARS LIGHT AS THIS WILL BE A SHORT LIVED
EVENT AS THE SHORT WAVE ACCELERATES DOWNSTREAM.

FRIDAY AND SATURDAY...ANOTHER CLOSED LOW FORMS NEAR BAJA CALIFORNIA
AND SENDS MORE MOISTURE INTO THE DESERT SOUTHWEST. LESS CLEAR HOW
MUCH MOISTURE SPREADS INTO UTAH AND COLORADO. THIS UNCERTAINTY IS
REFLECTED IN THE FORECAST GRIDS WITH 20 TO 30 PERCENT POPS ACROSS
MUCH OF THE FORECAST AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 956 AM MST SUN JAN 25 2015

MVFR CONDITIONS WILL CONTINUE THROUGH AROUND 20Z ACROSS THE
NORTHERN AND CENTRAL VALLEYS RESULTING IN MVFR CIGS FOR KASE.
AROUND THIS TIME EXPECT CLOUDS WILL DISSIPATE AS DRIER AIR MIXES
IN THIS AFTERNOON. OTHERWISE VFR CONDITIONS WILL BE THE NORM THIS
AFTERNOON THROUGH MIDDAY MONDAY.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

&&

$$

SHORT TERM...15
LONG TERM...PF
AVIATION...NL



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