FXUS65 KGJT 150347
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
847 PM MST MON DEC 14 2009
.UPDATE...TEMPERATURE AND DEW POINTS CLOSING TOGETHER QUICK TONIGHT
WITH LOW CLOUDS AND FOG ALREADY DEVELOPING ACROSS THE VALLEYS OF
EASTERN UTAH. SNOWMELT EARLIER TODAY COMBINED WITH STRENGTHENING
INVERSIONS WILL ALLOW THE VALLEY FOG AND LOW CLOUDS TO BECOME MORE
WIDESPREAD OVERNIGHT. UPDATED FORECAST TO INCLUDE MENTION OF FOG FOR
MOST VALLEY LOCATIONS FOR THE REST OF TONIGHT THROUGH MIDDAY TUESDAY.
&&
.PREVIOUS DISCUSSION /ISSUED AT 351 PM MST MON DEC 14 2009/...
.SHORT TERM...TONIGHT THROUGH WEDNESDAY...
WEAK TRANSITORY RIDGE IS CURRENTLY BUILDING INTO FORECAST AREA
EVIDENCED BY INCREASING SUNSHINE AND DECREASING CLOUDS. LOCAL
WEBCAMS HIGHLIGHTING SOME LINGERING SNOWSHOWERS OVER NRN/CENT MTNS
BUT ANY ACCUMULATION WILL BE VERY MINOR. RIDGE AXIS WILL BE OVER CO
TOMORROW MORNING AND MOVE EWRD THROUGHOUT THE DAY. AREAS SOUTH WILL
SEE MOSTLY SUNNY SKIES WHILE NERN UT/NRN CO WILL SEE MORE CLOUDS AS
H7 RH VALUES INDICATE PLENTY OF MOISTURE. NEXT DISTURBANCE WILL BE
MOVING TOWARDS CWA TUESDAY FROM IDAHO BUT AS IT MOVES OUR WAY...
SYSTEM WILL DRY OUT CONSIDERABLY. SO MUCH SO THAT ONCE IT REACHES
UINTAS...E OF SALT LAKE CITY...NO PRECIP WILL MAKE IT INTO OUR
REGION. AT THIS POINT...JET WILL BE WELL TO OUR N SO ANY SUPPORT
WILL BE NON-EXISTENT LEAVING SOME CLOUDY SKIES FOR EXTREME NERN
UT/NRN CO.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...
...MILD MOUNTAIN SLOPE TEMPERATURES WHILE THE VALLEYS GET MIRED IN
INVERSIONS...
MODELS REMAIN IN GOOD AGREEMENT INTO THE WEEKEND. THESE PERIODS BEGIN
WITH A FLAT WEST-EAST FLOW ACROSS THE CONTINENTAL U.S. THIS PATTERN
BEGINS TO AMPLIFY BY THURSDAY AS A TROUGH DEEPENS IN THE EASTERN
PACIFIC. THIS AMPLIFIES A RIDGE OVER THE GREAT BASIN. THE 12Z GFS
BRINGS A STRONG SHORTWAVE ON TO THE WEST COAST BY SATURDAY NIGHT
WHILE ALL OTHER MODELS ARE SLOWER. FOLLOWING THE CONSENSUS...RIDGING
WILL DOMINATE INTO EARLY NEXT WEEK.
LIGHT SHOWERS ARE POSSIBLE ACROSS THE NORTHERN MOUNTAINS THURSDAY-
FRIDAY...FAVORING THE PARK RANGE...WITH LITTLE TO NO ACCUMULATION.
TEMPERATURE FORECAST WILL BE COMPLICATED. WITH THE TOP OF A STRONG
INVERSION AT 700MB...MOUNTAIN SLOPE TEMPERATURES WILL LIKELY BE
MILDER THAN THE VALLEYS. MEX GUIDANCE TEMPS ARE MILD FOR THE
VALLEYS TOO. BUT WITH LOW SUN ANGLE NEAR SOLSTICE AND WITH SNOW
COVER STILL COVERING MANY OF THE VALLEYS...EXPECT SURFACE-BASED
INVERSIONS TO SET UP AND BECOME STRONG. SLOPE TEMPERATURES WILL
MOST LIKELY BE WARMER THEN THE NEARBY VALLEYS. VALLEY AIR QUALITY
WILL LIKELY DETERIORATE. BASIN FOG IS POSSIBLE...BUT AM NOT CONFIDENT
ENOUGH ABOUT WHERE OR WHEN TO PUT IT IN THE FORECAST YET. SNOWPACK
WILL GLAZE AND CRUST OVER...ESPECIALLY ON SOUTH-FACING SLOPES.
&&
.AVIATION...
MOST TAF SITES TO REMAIN VFR TODAY AS RIDGING BUILDS IN FROM THE
WEST. KEGE AND KASE MAY SEE SOME MVFR CONDITIONS BRIEFLY AS
CONVECTIVE TYPE SNOWSHOWERS DROP VIS AND CIGS THROUGH THIS
EVENING. SOME NRN/CNTRL/SRN MTNS WILL HAVE OBSCURED TOPS THAT WILL
DECREASE IN COVERAGE AS THE EVENING PROGRESSES. VFR CONDITIONS
EXPECTED FOR THE OVERNIGHT HOURS THOUGH SOME MORNING FOG POSSIBLE
NEAR KGJT...KRIL...KMTJ.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...NONE.
$$
UPDATE.......JDC
SHORT TERM...TGR
LONG TERM....JOE
AVIATION.....TGR
$$
