000
FXUS65 KGJT 201031
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
331 AM MST THU NOV 20 2008
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
AFTER SEVERAL DAYS OF DOMINANCE...THE GREAT BASIN UPPER RIDGE IS
UNDER ATTACK. ALOFT...PACIFIC MOISTURE IS STREAMING ACROSS NE UTAH
AND NW COLORADO. AT THE SURFACE...A COLD FRONT ON THE FRONT RANGE IS
LEAKING INTO THE NORTHWEST COLORADO WITH SFC CONVERGENCE INTO THE
MORNING HOURS THERE. BUT AT 3AM THIS MORNING...TEMPERATURES AND
DEWPOINTS SHOWED VIRTUALLY NO 24HR CHANGE.
WHATEVER COOL AIR THAT LEAKS INTO THE NORTH THIS MORNING GETS
QUICKLY ERODED THIS AFTERNOON AS SW FLOW ADVECTS WARMER AIR.
AFTERNOON TEMPERATURES SHOULD BE CLOSE TO WEDNESDAY. INCREASING
GRADIENT WINDS WILL PRODUCE A BIT BETTER VERTICAL MIXING THIS
AFTERNOON.
TONIGHT-FRIDAY NIGHT: A TROUGH...ALONG THE WASHINGTON COAST THIS
MORNING...WILL PASS THROUGH THE NORTHERN ROCKIES TONIGHT. ITS COLD
FRONT WILL JUST BRUSH THE NORTH INTO FRIDAY MORNING. MOISTURE AND
DYNAMICS ARE WIMPY THIS FAR SOUTH. THE PARK RANGE COULD SEE A FEW
FLURRIES MAINLY FRIDAY MORNING BUT DO NOT EXPECT MEASURABLE SNOWFALL.
OTHERWISE BETTER MIXING IS EXPECTED FRIDAY AFTERNOON ENDING QUICKLY
WITH SUNSET IN THE VALLEYS.
.LONG TERM...SATURDAY THROUGH THURSDAY...
MIDRANGE MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE WEATHER PATTERN
FOR SATURDAY THROUGH TUESDAY. THE MODEL SOLUTIONS FOR WEDNESDAY AND
THURSDAY SHOW LARGE DIFFERENCES BETWEEN THE MODELS AS WELL AS POOR
RUN-TO-RUN CONSISTENCY.
SAT THROUGH TUE...ZONAL FLOW ALOFT WITH WEAK TROUGHING OVER THE
WESTERN U.S. ON SAT SHOULD GIVE WAY TO STRONG RIDGING SUNDAY. THE
RIDGE SHOULD MOVE SLOWLY EAST AS IT WILL BE PINNED BETWEEN STRONG LOW
PRESSURE DIGGING INTO THE GREAT LAKES STATES AND DEEPENING LOW
PRESSURE OFF THE WEST COAST. THE RESULT SHOULD BE GRADUAL WARMING AND
DRY CONDITIONS.
WED AND THU...THE TROUGHING OFF THE WEST COAST IS THE BIG PROBLEM IN
TONIGHT`S MODEL SOLUTIONS. THE GFS AND DGEX CREATE A SPLIT TROUGH
WITH SIGNIFICANT ENERGY OVER THE PACIFIC NW AND SOUTHERN CALIFORNIA.
EACH MODEL MOVES THESE FEATURES INLAND AND SPREADS HIGH CLOUDS OVER
THE AREA WED. BY THU...A SURFACE FRONT AND SCATTERED PRECIPITATION IS
PROJECTED INTO EASTERN UT AND WESTERN CO. THE ECMWF CREATES A MUCH
STRONGER CLOSED LOW OFF THE SOUTHERN CA COAST WED WITH VERY LITTLE
NORTHERLY COMPONENT OF A SPLIT TROUGH. IT THEN LIFTS THIS TROUGH NE
AND INTO THE GREAT BASIN THU...WHILE CREATING A SECOND STRONG CLOSED
LOW OF THE PACNW COAST. CANNOT TELL WHICH SOLUTION IS BETTER AT
PRESENT SO HAVE MADE ONLY MINOR ADJUSTMENTS TO THE GRIDS FOR WED AND
THU.
&&
.AVIATION...
VFR CONDITIONS CONTINUE INTO NEXT WEEK. SOME MODERATE TURBULENCE WILL
DEVELOP TODAY AND TONIGHT AS INCREASING STABLE SOUTHWEST WINDS ALOFT
CREATE SOME MOUNTAIN WAVE AFFECTS. COLD FRONTAL PASSAGE FRIDAY
MORNING ACROSS FAR NE UTAH AND NW COLORADO COULD PRODUCE LOCAL MVFR
CEILINGS AND STRONG TURBULENCE.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...NONE.
$$
SHORT TERM.....JOE
LONG TERM......CJC
AVIATION.......EH+JOE
