Area Forecast Discussion
Issued by NWS Grand Junction, CO

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411
FXUS65 KGJT 151706
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1106 AM MDT FRI MAY 15 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 306 AM MDT FRI MAY 15 2015

THE SURFACE COLD FRONT IS STALLED FROM N TO S OVER CENTRAL UTAH
EARLY THIS MORNING. STRONG SOUTHERLY FLOW IS IN PLACE AND
APPARENT IN STORM MOTION WITH A ROTATING STORM SUSTAINING ITSELF
NEAR THE COLORADO AND GREEN RIVER THE PAST SEVERAL HOURS. THE MAIN
TROUGH AND SPLITTING LOW IS STILL WELL TO WEST OF HERE. WATER
VAPOR IMAGERY CLEARLY SHOWS THE JET ROUNDING THE BASE OF THIS
TROUGH OVER NORTHERN BAJA...AND WILL EVENTUALLY BEGIN TO CURVE
CYCLONICALLY EAST OF THE 4 CORNERS BY MID MORNING. THIS JET CORE
WILL NOT ONLY SUPPLY AMPLE LARGE SCALE ASCENT TODAY...BUT HELP
PULL THE COLD FRONT THROUGH OUR CWA LATE THIS MORNING THROUGH MID
AFTERNOON. EXPECT SHOWERS TO BLOSSOM AGAIN IN THE SOUTH PRIOR TO
SUNRISE IN THIS ACCENTUATED AREA OF LIFT AND PUSH QUICKLY
NORTHWARD THROUGH THE EARLY AFTERNOON. THE COLD FRONT WILL HELP
AID THUNDERSTORMS AND AREAS OF HEAVIER PRECIPITATION AS IT PUSHES
EAST AS WELL. TEMPERATURES WERE COOLER THAN ANTICIPATED ON
THURSDAY AND SHOULD DROP ANOTHER 5 TO 10 DEGREES TODAY AS HEIGHTS
DECREASE ALOFT WITH LOW PRESSURE COVERING ALL OF THE GREAT BASIN.
CONVECTION WILL PLAY A HUGE ROLE IN SNOW LEVELS AS WELL BUT THE
BEST ACCUMULATIONS CONTINUE TO BE TARGETED AT OR ABOVE 9000 FEET.
SOME SNOW IS POSSIBLE BELOW THIS...SIMILAR TO LAST WEEKEND.
ANOTHER PUSH OF ENERGY THEN ROTATES AROUND THE BASE OF THE TROUGH
TONIGHT ASSOCIATED WITH THE MAIN JET CORE. ASCENT INCREASES OVER
THE DESERT SOUTHWEST AND LIFTS INTO THE 4 CORNERS AND ACROSS
WESTERN COLORADO TONIGHT INTO SATURDAY. OROGRAPHICS...INSTABILITY
AND GOOD MOISTURE ADVECTION INTO OUR SOUTHERN MOUNTAINS WILL BRING
SOME DECENT SNOW RATES AND MODEL ENSEMBLES SUGGEST AN INCH OR TWO
OF SNOW MAY FALL IN THE SOUTHERN VALLEYS ADJACENT TO THE FOOTHILLS
INCLUDING DURANGO AND PAGOSA. AS SATURDAY WARMS SNOW LEVELS SHOULD
PUSH BACK UP THE HILLS WITH SLUSH STILL POSSIBLE OVER THE HIGHER
PASSES. GREAT JUMP BY DAY SHIFT ON HEADLINES WHICH LOOK ON TRACK.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 306 AM MDT FRI MAY 15 2015

WIDESPREAD RAIN AND SNOWFALL COMES TO AN END SATURDAY NIGHT/SUNDAY
MORNING AS THE AREA OF LOW PRESSURE AND UPPER LEVEL SUPPORT
RESPONSIBLE FOR ALL THE WX SHIFTS NE OVER SOUTH DAKOTA AND
NEBRASKA. EVEN SO...WRAPAROUND FLOW WILL STILL ALLOW SOME SHOWERY
TYPE PRECIP SUNDAY...MAINLY FAVORING FAR NRN PORTIONS OF THE CWA.

AS THIS LOW KEEPS MOVING E...THE NEXT WX MAKER...ANOTHER CLOSED
LOW...WILL BE JUST OFF THE CENTRAL CALIFORNIA COAST AND WILL
INDUCE A WEAK RIDGE OVER MUCH OF THE INTERMOUNTAIN WEST FOR
MONDAY. WHILE ONE WOULD EXPECT NICE WEATHER UNDER THE RIDGE...THIS
ISN`T THE CASE AS THE LOW PRESSURE COMES ASHORE OVER CALIFORNIA
AND SOUTHERLY FLOW ALLOWS MOISTURE TO CREEP UNDER THE RIDGE AND
BRING A RETURN TO CLOUDS AND PRECIP...MOSTLY OVER HIGHER
ELEVATIONS. PRECIP WILL INCREASE IN INTENSITY AND COVERAGE AS THE
UPPER LEVEL TROUGH ASSOD WITH THE CLOSED LOW MOVES OVERHEAD MONDAY
NIGHT THROUGH TUESDAY BEFORE FINALLY SLACKENING OFF WEDNESDAY
MORNING. NOT MUCH BREAK THOUGH AS A WEAK OPEN WAVE DRIFTS ACROSS
THE CWA AND BECOMES THE NEXT FOCUS OF PRECIPITATION.

THE MAIN GIST FOR THE NEXT WEEK IS PLENTY OF CLOUDS AND PRECIP
WITH SOME BREAKS HERE AND THERE...WITH MONDAY AND WEDNESDAY BEING
THE `NICEST` DAYS. TEMPS WILL GENERALLY BE BELOW NORMAL FOR
EASTERN UTAH AND WESTERN COLORADO THOUGH ANY LONGER PERIODS OF
SUNSHINE WILL ALLOW TEMPS TO WARM FAIRLY QUICKLY. SNOW LEVELS LOOK
TO VARY FROM 10K TO 11K FEET SO SOME ACCUMULATIONS POSSIBLE ABOVE
THAT. MTN PASSES MAY SEE SOME SLICK ROADS BUT EXPECT MOST SNOWFALL
TO MELT ON ANY ROAD SURFACES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1055 AM MDT FRI MAY 15 2015

THE MAIN PRECIPITATION SHIELD IS WRAPPING NORTHEAST AROUND THE
CLOSED LOW OVER SOUTHWESTERN UTAH. EXPECT THIS BROAD BAND OF
STRATIFORM PRECIPITATION TO PUSH NORTH OF INTERSTATE 70 OVER THE
AFTERNOON HOURS. SHOWERS AND A FEW THUNDERSTORMS WILL DEVELOP
DURING THE AFTERNOON HOURS AND WILL CONTINUE THROUGH THE EVENING
HOURS. EXPECT MORE WIDESPREAD PRECIPITATION OVER THE HIGHER
TERRAIN THAN THE LOWER ELEVATIONS WITH CIG/VSBY DROPPING DURING
ANY SHOWER ACTIVITY. HEAVY RAIN...GUSTY WINDS OF 40 TO 45 MPH AND
SMALL HAIL ARE POSSIBLE WITH ANY THUNDERSTORMS THAT FORM THROUGH
THIS EVENING. CURRENTLY THE RAIN/SNOW LINE IS AROUND 8000 FEET
AND EXPECT THIS LEVEL TO DROP SLOWLY DURING THE EVENING HOURS
WITH MOUNTAIN OBSCURATIONS EXPECTED. BEST CHANCE OF CATEGORICAL
POPS WILL REMAIN OVER THE SOUTHWEST TAF SITES OVERNIGHT WITH SNOW
EXPECTED AT TEX.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL 9 AM MDT SUNDAY FOR COZ009-010-012-
     018-019.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT SATURDAY NIGHT FOR
     COZ017.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM MDT
     SUNDAY FOR COZ004-013.

UT...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT SATURDAY NIGHT FOR
     UTZ028.

&&

$$

SHORT TERM...15
LONG TERM...TGR
AVIATION...MPM



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