Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 171657
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1057 AM MDT FRI OCT 17 2014

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 448 AM MDT FRI OCT 17 2014

AS A RIDGE GAINS SOME AMPLITUDE OVER THE GREAT BASIN TODAY...HIGH
CLOUDS WILL SPREAD NORTH FROM THE TROUGH MOVING ONSHORE OVER BAJA
CALIFORNIA INTO SW AZ. THE MOISTURE AND CLOUDS WILL START OFF HIGH
BUT THEN LOWER TOWARD SUNSET. A FEW SHOWERS WILL DEVELOP OVER THE SAN
JUAN MTS BY SUNSET. TEMPERATURES WILL REMAIN SIGNIFICANTLY ABOVE
NORMAL TODAY.

SOUTHERLY FLOW TONIGHT THROUGH THE WEEKEND WILL KEEP A FETCH OF
SUBTROPICAL MOISTURE POINTED AT OUR REGION...SOME FROM THE LEFT
COAST AND SOME FROM THE GULF OF MEXICO PER 310K THETA SURFACES. A
SUBTROPICAL WAVE ENTRENCHED IN THIS FLOW WILL BE LIFTING ACROSS THE
FOUR CORNERS OVERNIGHT BEFORE SWINGING EASTWARD BY SUNRISE. THE
FORCING FOR ASCENT REMAINS FOCUSES MAINLY TO OUR SOUTH AS MODELS
HAVE SUGGESTED THE PAST FEW DAYS AND CONFIDENCE IS STILL QUITE LOW
ON MUCH PRECIPITATION REACHING THE LOWER ELEVATIONS. OROGRAPHICS AND
THIS MOISTURE SHOULD BRING SOME LIGHT QPF TO THE SAN JUAN
MOUNTAINS OVER THE NEXT 24 TO 36 HOURS...BUT OVERALL THE MORE
ORGANIZED PRECIP WILL BE SOUTHEAST OF HERE. POPS LOOKED ON TRACK
AND ONLY MADE SOME SMALL TWEAKS. TEMPERATURES WILL BE IMPACTED BY
THE CLOUD COVER AND SHOULD BE MILDER IN THE SOUTH OVERNIGHT AND
COOLER GOING INTO SATURDAY AS CLOUD COVER LIMITS HEATING.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 354 AM MDT FRI OCT 17 2014

A TROUGH WILL BE SHEARING APART ON SATURDAY AND BY THE EVENING THE
SOUTHERN ENERGY WILL BE FORMING A BROAD CIRCULATION OVER THE
DESERT SOUTHWEST. AGAIN FORCING FROM THIS FEATURE WILL BE PASSING
TO OUR SOUTH...BUT HEIGHT FALLS TO OUR WEST WILL INCREASE THE MID
LEVEL FLOW...AND DIRECT THE MOIST...WARM CONVEYOR BELT TOWARD THE
FOUR CORNERS. ISOLATED SHOWERS WILL BE POSSIBLE OVERNIGHT AS THIS
MOISTURE PUSHES IN. ADDED INSTABILITY DURING SUNDAY AFTERNOON DUE
TO SLIGHTLY COOLER TEMPERATURES ALOFT WILL HELP SPREAD SHOWERS
OVER MORE OF THE CENTRAL AND SOUTHERN MOUNTAINS. STILL NOT
CONVINCED MUCH OTHER THAN SPRINKLES CAN REACH THE LOWER
ELEVATIONS. THE SOUTHERN FOOTHILLS OF THE SAN JUANS WILL HAVE THE
BEST CHANCE OF THIS HAPPENING. TEMPERATURE FORECAST WILL STAY NEAR
PERSISTENCE.

SUNDAY NIGHT AND MONDAY MORNING THE FLOW AHEAD OF AND AROUND THE
LOW CENTER WILL KEEP MOISTURE AND SCATTERED PRECIP OVER SW
CO...WITH ISOLATED SHOWERS ELSEWHERE. THE NAM12 IS THE MOST
OPTIMISTIC WITH ITS PRECIPITATION PREDICTION AND HAVE STAYED
FAIRLY CLOSE TO IT AS THE UPWARD MOTION AHEAD OF AND OVER THE
NORTH AND NORTHWEST PORTIONS OF THE CIRCULATION SHOULD PROVIDE
SOME DYNAMIC LIFT...FOCUSING MOSTLY SOUTH OF A LINE FROM ABOUT
DELTA TO VAIL.

MONDAY AFTERNOON AND NIGHT THE MOISTURE WILL GRADUALLY MOVE EAST
OF THE AREA ACCORDING TO THE GFS AND ECMWF. TUE NIGHT THROUGH THU THE
NEXT PACIFIC TROUGH WILL MOVE THROUGH. THE ECMWF STARTS DIGGING THE
TROUGH AND TRYING TO FORM A SPLIT OR CLOSED 500 MB LOW OVER
SOUTHERN CO AND NORTHERN NMEX WED AFTERNOON AND NIGHT. THE LOW
DEEPENS THE MOST TUE NIGHT AND EARLY WED MORNING...AND IF THIS
COMES TRUE THIS PERIOD SHOULD PRODUCE THE MOST WIDESPREAD PRECIP.
THE GFS SOLUTION IS SIGNIFICANTLY DIFFERENT IN THAT IT KEEPS THIS
STORM AS AN OPEN TROUGH WHICH MOVES MORE QUICKLY THROUGH THE
AREA. LATE WED NIGHT THE MODELS MOVE MOST OF THE MOISTURE EAST OF
THE AREA...WITH THE GFS A GOOD BIT DRIER. THE EC BEGINS TO SHOW
SIGNS OF CUTTING OFF THE LOW OVER SRN NMEX THURSDAY AFTERNOON...
WITH THE GFS SHOWING NO SIGNS OF THIS. SO QUITE A BIT OF
UNCERTAINTY REMAINS IN THE FORECAST FOR WED AND THU.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1057 AM MDT FRI OCT 17 2014

HOWEVER CLOUDS WILL INCREASE ACROSS SOUTHEAST UTAH AND SOUTHWEST
COLORADO THIS AFTERNOON...THEN SPREAD INTO THE CENTER OF THE
FORECAST AREA TONIGHT. A FEW SHOWERS WILL BE POSSIBLE OVER THE SAN
JUAN MOUNTAINS AFTER AROUND 21Z. ISOLATED SHOWERS WILL SPREAD INTO
THE CENTRAL COLORADO MOUNTAINS AFTER AROUND 15Z SATURDAY. VFR
CONDITIONS WILL PREVAIL ACROSS THE AREA...HOWEVER LOWER CLOUDS AND
PRECIPITATION MAY BRIEFLY OBSCURE MOUNTAINS...AND BRIEFLY IMPACT
TAF SITE KTEX.

&&

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

$$

SHORT TERM...CC/15
LONG TERM...CC/15
AVIATION...EH


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