FXUS65 KGJT 151200
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
500 AM MST TUE DEC 15 2009

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...
A WEAK RIDGE DEVELOPS OVER THE AREA TODAY...THEN GETS FLATTENED ON
WEDNESDAY AS A VERY WEAK DISTURBANCE RIDES OVER THE TOP OF THE RIDGE.
THIS WILL BRING AN INCREASE IN CLOUDS...BUT NO APPRECIABLE WEATHER IS
EXPECTED.

STRONG INVERSIONS HAVE FORMED THIS MORNING UNDER MOSTLY CLEAR SKIES.
TEMPERATURES ARE RUNNING 5-10 DEGREES FAHRENHEIT COOLER OVER THE
SOUTH AND OVER 20 DEGREES COLDER OVER THE NORTH AS COMPARED TO MONDAY
MORNING'S VALUES. AREAS OF FOG HAVE FORMED AT SOME VALLEY LOCATIONS
DUE TO MOISTURE FROM THE MELTING OF SNOW ON MONDAY. EXPECT SOME
INCREASE THROUGH DAYBREAK...BUT DO NOT EXPECT WIDESPREAD DENSE FOG
TO FORM THIS MORNING. SO FAR THE ONLY OBSERVATIONS CARRYING FOG HAVE
BEEN FROM KCNY...BUT SATELLITE IMAGES INDICATE IT IS IN OTHER VALLEYS
AS WELL. THE FOG SHOULD DIMINISH BY MID MORNING. EXPECT FOG TO FORM
AGAIN LATE TONIGHT...BUT SOME HIGH LEVEL CLOUDS WILL ACT TO INHIBIT
ITS FORMATION SOMEWHAT.

THE OTHER CHALLENGE THIS MORNING IS THE TEMPERATURE FORECAST. EXPECT
SOME WARMING AT 700 MB BY THIS AFTERNOON. HOWEVER...THE WARMING
AT THE SURFACE WILL BE SEEN MAINLY AT THE HIGHER ELEVATIONS. COLD
AIR WILL REMAIN TRAPPED UNDER THE STRONG VALLEY INVERSIONS. THEREFORE
HIGHS AT SOME LOWER LOCATIONS WILL BE COOLER THAN YESTERDAY'S. BUT
TEMPS WILL TOP OUT A FEW DEGREES WARMER IN THE MOUNTAINS. THIS
PATTERN WILL CONTINUE THROUGH WEDNESDAY AND WEDNESDAY NIGHT.

.LONG TERM...THURSDAY THROUGH MONDAY...
THURSDAY AND FRIDAY...THE PARK RANGE AND THE ELKHEAD MOUNTAINS WILL
BE ON THE SRN FRINGE OF A DAMPENING SHORT WAVE PASSING TO OUR
NORTH.  WRN CONUS RIDGE AXIS AMPLIFIES BEHIND THE WAVE...THIS COULD
HELP GENERATE LIGHT OROGRAPHIC SNOW OTHERWISE THE GFS SHOWS
DIMINISHING QPF THURSDAY NIGHT AND FRIDAY.  POPS MAY BE OVERDONE
WITH THE RESPECT TO THE GFS...BUT THE ECMWF SHOWS A STRONGER
AMPLIFYING TROUGH WHICH WORKS BETTER WITH THE CURRENT POP GRIDS.
HOWEVER A STRONGER WAVE WOULD MEAN A WEAKER VALLEY INVERSION ON
FRIDAY.  GRIDDED DATA HANDLE THE TRENDS WELL AND NO CHANGES ARE
NEEDED.

SATURDAY THROUGH MONDAY...THE ECMWF IS A LITTLE STRONGER WITH THE
WRN CONUS RIDGE...WHILE THE GFS SHOWS A FLATTER RIDGE BUT WITH
ENERGY STAYING NORTH OF OUR FORECAST AREA.  A QUICK GLANCE AT THE
06Z GFS SEEMS TO BE LEANING TOWARD THE ECMWF SOLUTION.  EITHER WAY
IT DOES NOT LOOK LIKE MUCH PCPN THROUGH THE LONG TERM PERIOD WITH
TEMPERATURE INVERSIONS HOLDING IN THE VALLEYS.  ALTHOUGH THE GFS
SHOWS MORE PACIFIC ENERGY MOVING ACROSS THE WEST BEYOND THE LONG
TERM PERIOD.

&&

.AVIATION...
CONTINUED VFR FOR MOST OF THE REGION...BUT SATELLITE FOG IMAGES
SHOW SOME LOW LYING STRATUS IN THE UINTA BASIN AND PARTS OF THE
GRAND FLAT AROUND CANYONLANDS AIRPORT (KCNY).  PATCHY FOG MAY
ALSO EXIST ALONG THE RIVERS.  ANY PATCHY FOG WILL DISSIPATE BY
17Z...EXCEPT FOR AREAS SOUTH OF VERNAL (KVEL).  LOW LYING STRATUS
MAY DEVELOP ONCE AGAIN LATER TONIGHT.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

$$

SHORT TERM...EH
LONG TERM....PF
AVIATION.....PF

$$