Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 231717
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1117 AM MDT TUE SEP 23 2014

.UPDATE...
ISSUED AT 1115 AM MDT TUE SEP 23 2014

WEAK RIPPLES KEEP PASSING OVER THE NORTHERN FORECAST AREA WITH
PERSISTENT LOW CLOUDS. PRECIP WATER REMAINS AROUND 0.6-0.7 INCH
ACROSS THE NORTH THIS AFTERNOON. SO ISOLATED OROGRAPHIC AFTERNOON
STORMS ARE EXPECTED THERE. THESE SHOULD END BEFORE SUNSET.

AS FOR THE NEXT SURGE OVER THE WEEKEND...THE 12Z GFS HAS COME IN
SLOWER AND SIMILAR TO THE EC. THIS WOULD FAVOR A DRIER SATURDAY
THEN SHOWERS SUNDAY INTO MONDAY.

UPDATE ISSUED AT 834 AM MDT TUE SEP 23 2014

SHOWERS ADDED TO FORECAST FOR THIS MORNING IN WEST CENTRAL
CO MOUNTAIN AREAS...MUCH OF NW CO...AND EASTERN UINTA MOUNTAINS.
LOOKS LIKE THE BACK EDGE OF THIS MOISTURE ASSOCIATED WITH AN
EMBEDDED SHORTWAVE DISTURBANCE WILL ERODE LATER THIS MORNING
...LEADING TO DRIER CONDITIONS THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 423 AM MDT TUE SEP 23 2014

TODAY...FOLLOWING THE LAST TWO DAYS OF RAIN...SURFACE HUMIDITY IS
RUNNING HIGH AND AREAS OF FOG ARE EXPECTED THROUGH MIDMORNING AT
MANY LOCATIONS OF NORTHEAST UT AND WESTERN CO.

THE MAIN TROUGH IN THE UPPER LEVELS PASSED EAST OF THE AREA LAST
NIGHT AND ITS WEAK SURFACE AND MIDLEVEL FRONT WILL SLOWLY DRAG
ACROSS NORTHERN CO AND NE UT TODAY. A THICK BANK OF MID AND LOW
LEVEL CLOUDS OVER NE UT AND MOST OF NW AND CENTRAL CO WILL
GRADUALLY DISSIPATE AND MOVE EAST TODAY.

DRY CONDITIONS WILL PERSIST AS HIGH PRESSURE BUILDS OVER THE
REGION. BY WED AFTERNOON THIS LARGE HIGH PRESSURE RIDGE WILL
EXTEND FROM THE DESERT SOUTHWEST NORTH-NORTHEAST ACROSS THE
CENTRAL ROCKIES AND INTO THE NORTHERN PLAINS AND SOUTHERN
SASKATCHEWAN. THE WARMING TREND ALREADY UNDERWAY WILL CONTINUE.
HOWEVER IN THE DRIER AIR MASS... LITTLE CHANGE IS EXPECTED IN
OVERNIGHT LOWS AS COMPARED TO THIS MORNING/S. THEN DAYTIME HIGHS
ON WEDNESDAY WILL INCREASE ANOTHER FEW DEGREES OVER
TODAY/S...REACHING 5-10 DEGREES ABOVE NORMAL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 423 AM MDT TUE SEP 23 2014

THE HIGH CENTER WILL WORK ITS WAY NORTH/NORTHEAST-WARD...MAKING
IT INTO SOUTH DAKOTA BY THU AFTERNOON. AS THIS HAPPENS...LOW
PRESSURE WILL BEGIN TO UNDERCUT THE HIGH FROM THE EAST-NORTHEAST
TILTING THE UPPER RIDGE. A MODEST AMOUNT OF MOISTURE WILL BEGIN TO
CREEP UP FROM THE SOUTHEAST...WITH A FEW THUNDERSTORMS POSSIBLE
ALONG THE PEAKS OF THE SAN JUANS AND SOUTH-CENTRAL DIVIDE
MOUNTAINS THU AFTERNOON. THE WARMING TREND WILL CONTINUE AS THE
THERMAL HIGH MOVES TO A POSITION OVER THE CENTRAL ROCKING BY 00Z
FRI.

WEDNESDAY NIGHT THROUGH MONDAY...HIGH PRESSURE AND DRY CONDITIONS
WILL CONTINUE THROUGH THU MORNING...THOUGH BY ABOUT 21Z THU IN THE
GFS THE RIDGE WILL HAVE ERODED ENOUGH TO ALLOW SOME MOISTURE TO
SEEP INTO SW CO AND SE UT FROM AZ AND NM.

ON FRIDAY THE CLOSED LOW OFF THE WEST COAST WILL BEGIN MOVING
INLAND AND THE RIDGE WILL HAVE SLID EAST. THIS ALLOWS A
STRENGTHENING SW FLOW ALOFT TO DRAW MOISTURE NORTH AND INTO THE
AREA. THIS PATTERN CONTINUES THROUGH SATURDAY. THE MODELS ARE
REACHING A BETTER CONSENSUS...WHICH IS SIMILAR TO EARLY ECMWF
SOLN...WHERE THE LOW DEEPENS AND STALLS OVER NORTHERN CA. THIS
WILL ALLOW SUBSTANTIAL MOISTURE TO ADVECT NORTH ACROSS THE SW
U.S...THOUGH THE FRONT WILL MAKE SLOWER PROGRESS ACROSS THE GREAT
BASIN. CURRENTLY IT APPEARS THE FRONT WILL NOT REACH EASTERN UT
AND WESTERN CO UNTIL SUNDAY AFTERNOON AND EVENING. HAVE INCREASED
CLOUD COVER AND CHANCE OF RAIN ACROSS THE AREA FOR ALL DAY SUNDAY
THROUGH EARLY MONDAY MORNING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1115 AM MDT TUE SEP 23 2014

VFR CONDITIONS ARE EXPECTED TODAY THROUGH THURSDAY. ISOLATED
CIRCUMNAVIGABLE AFTERNOON THUNDERSTORMS ARE EXPECTED OVER THE
COLORADO MOUNTAINS FROM VAIL PASS NORTHWARD... AND THE UINTA
MOUNTAINS IN NE UTAH. KVEL MAY BE IMPACTED BY GUSTY ERRATIC
OUTFLOW WINDS. NO IMPACT IS EXPECTED AT OTHER REGIONAL TAF SITES.

&&

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

$$

UPDATE...JOE
SHORT TERM...CC/EH
LONG TERM...EH/CC
AVIATION...JOE


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