Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241021
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
421 AM MDT SUN AUG 24 2014

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 403 AM MDT SUN AUG 24 2014

UPPER LEVEL LOW PRESSURE SYSTEM CONTINUES TO LIFT NORTHEAST ACROSS
EASTERN MONTANA THIS MORNING WITH SUBTLE DRYING EXPECTED ACROSS
THE FORECAST AREA TODAY. STILL WORKING ON WEAK JET SUPPORT THAT
WILL TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...ALTHOUGH
ACTIVITY SHOULD BE CONFINED TO OUR NORTHERN AND CENTRAL ZONES WITH
HIGHEST POPS NORTH OF INTERSTATE 70. OTHERWISE A DRIER DAY IS
UPPER LEVEL SUPPORT DIMINISHES WITH THE JET LIFTING OUT AND DRIER
AIR SLOWLY FILTERS BACK INTO THE AREA. STILL PLENTY OF LOW LEVEL
MOISTURE TO START THE DAY WITH SOME PATCHY FOG ACROSS THE HIGHER
ELEVATIONS IN AREAS THAT RECENTLY RECEIVED HEAVIER RAIN. STORMS
TODAY WILL STILL BE ABLE TO PRODUCE LOCALLY HEAVY RAIN...WITH
HAIL AND GUSTY WINDS BECOMING MORE OF A THREAT. AFTER YESTERDAYS
RECORD SETTING COOL DAY IN GRAND JUNCTION...READINGS ARE EXPECTED
TO REBOUND BY 10 TO 15 DEGREES IN MOST AREAS.

THE REAR ENTRANCE REGION OF A DEPARTING UPPER JET AND A SHEARED
MID-LEVEL VORTICITY AXIS WILL KEEP A CHANCE OF SHOWERS ACROSS THE
CENTRAL AND NORTH TONIGHT. NOT MUCH CHANGE IS EXPECTED ON MONDAY
WITH SCATTERED THUNDERSTORMS DEVELOPING OVER THE HIGHER TERRAIN.
FLOW ALOFT BECOMES SOUTHWEST MONDAY AS A TROUGH DIGS SOUTHWARD
INTO THE WESTERN GREAT BASIN. INHERITED GRIDS ACCOUNT FOR
THIS...SO MADE LITTLE CHANGE.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 403 AM MDT SUN AUG 24 2014

UPPER JET STRENGTHENS OVER THE FORECAST AREA MONDAY NIGHT AND
TUESDAY AS THE GRADIENT TIGHTENS BETWEEN THE DIGGING GREAT BASIN
TROUGH AND A PERSISTENT UPPER LEVEL HIGH OVER TEXAS. SOUTHWEST FLOW
CONTINUES LOOKS TO TAP SOME SUBTROPICAL MOISTURE FROM HURRICANE
MARIE...WHICH IS EXPECTED TO TRACK NORTHWESTWARD WELL OFF THE WEST
COAST OF MEXICO. PRECIPITABLE VALUES INCREASE TO 0.70 TO 1.00 INCH
BY TUE MORNING. GFS THEN THE QUICKEST TO BEGIN A DRIER WESTERLY FLOW
TUE AFTERNOON. THIS NOT FULLY BELIEVED AT THE MOMENT AS IT HAS BEEN
THE FAST OUTLIER OF LATE. EXPECT TO SEE AN UPTICK IN SHOWER AND
THUNDERSTORM ACTIVITY TUESDAY AS A RESULT OF THE INCREASED MOISTURE
AND LIFT WITH THE APPROACHING TROUGH. INSTABILITY NOT THAT
IMPRESSIVE BUT DECENT VERTICAL WIND SHEAR COULD PRODUCE SOME LONGER
LIVED STORMS.

CONFIDENCE BEYOND TUESDAY CONTINUES TO DROP AS MODELS DIVERGE AND
CREATE A MORE PROBLEMATIC FORECAST SCENARIO. THE ECMWF WANTS TO
CLOSE OFF THE DIGGING GREAT BASIN TROUGH DRAWING UP DEEP
SUBTROPICAL MOISTURE BACK NORTH ACROSS THE FORECAST AREA. THIS
RESULTS IN SOME IMPRESSIVE QPF TOTALS IN FAVORABLE DIFLUENT FLOW
WITH JET SUPPORT AND SHORTWAVE ENERGY LIKELY ROTATING THROUGH. THE
GFS AND TO SOME EXTENT THE NAM DRIVING THE LOW MORE NORTHEAST AND
EAST ACROSS IDAHO...WYOMING AND THE OUT INTO THE PLAINS. EC MUCH
SLOWER IN KICKING OUT THE MEAN TROUGH ACROSS OUR REGION WHILE
THE GFS INDICATING RIDGING BUILDING IN. WILL MAINTAIN A MORE
BLENDED SOLUTION THROUGH THE LATER HALF OF THE EXTENDED PERIOD
WITH TEMPS EXPECTED TO RUN IN THE COOL SIDE OF NORMAL THROUGH THIS
PERIOD.


&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 403 AM MDT SUN AUG 24 2014

LINGERING LOW AND MID LEVEL MOISTURE WILL LEAD TO SCATTERED
AFTERNOON AND EARLY EVENING THUNDERSTORMS ACROSS THE MOUNTAINS AND
NORTHERN VALLEYS. GUSTY WINDS TO 40 MPH...HAIL AND BRIEF HEAVY
RAIN WILL ACCOMPANY THE STRONGER STORMS...WHICH ARE EXPECTED
MAINLY NORTH OF INTERSTATE 70 BETWEEN 18Z AND 03Z TODAY.

&&

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

$$

SHORT TERM...JDC/JAD
LONG TERM...JAD/JDC
AVIATION...JDC



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