FXUS65 KGJT 272255
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
355 PM MST FRI NOV 27 2009

.SHORT TERM DISCUSSION...TONIGHT THROUGH SUNDAY...

UPPER TROUGH CROSSING THE WA/OR COAST IN THE PROCESS OF SPLITTING
THIS AFTERNOON. HIGH CLOUDS WERE SLOWING SPREADING ACROSS UT AND
SLIP INTO OUR AREA TONIGHT.

SRN PORTION OF THE SPLITTING TROUGH EXPECTED TO FORM A CLOSED LOW
THAT DROPS TO SRN CA/SWRN AZ BY LATE SAT AND THEN INTO NWRN OLD
MEXICO SUNDAY. 12Z GFS A LITTLE FARTHER EAST THAN ITS PREVIOUS RUN
AND THE OTHER MODELS...SO STILL SOME UNCERTAINTY THERE. NRN PORTION
BRUSHES NE UT/NW CO SAT NIGHT. OUR FORECAST AREA ENDS UP UNDERNEATH
THE SPLIT AND IN THE DEFORMATION ZONE SAT NIGHT-SUN MORNING WITH WEAK
Q-G DYNAMICS AND OROGRAPHICS. COLD ADVECTION MINIMAL SO NO
STRENGTHENING EXPECTED. BUT...BOTH NAM AND GFS FOCUS 300 MB
DIVERGENCE OVER SW CO SAT NIGHT-SUN MORNING IN THE DIFLUENT AREA NE
OF THE CLOSED LOW CENTER...ABOVE SOME 700 MB CONVERGENCE PROBABLY
ASSOCIATED WITH REMNANT SFC FRONTAL BOUNDARY. THE SOUTH IS ALSO WHERE
THE BEST MOISTURE EXPECTED.  ALL THIS REFLECTED IN MODEL PRECIP
AMOUNTS FOCUSING ON THE SAN JUAN MTNS SAT NIGHT AND EARLY SUNDAY.

WILL CONTINUE WITH THE WINTER STORM WATCH FOR THE WESTERN SAN JUAN
MTNS SAT AFTN-SUN AFTN. BUT WITH THE CLOSED LOW CENTER SO FAR AWAY...
DYNAMICS WEAK...AND BEST CHANCE OF SNOW NOT UNTIL SAT NIGHT...NOT
CONFIDENT ENOUGH TO UPGRADE AT THIS TIME. WITH THE WATCH OUT...PUBLIC
AWARENESS HAS ALREADY BEEN ELEVATED FOR THE BUSY TRAVEL WEEKEND. WILL
NEED TO KEEP AN EYE ON THE SAN JUAN FOOTHILLS INCLUDING DURANGO AND
PAGOSA SPRINGS FOR SNOW LATE SAT NIGHT AND SUN MORNING.

NORTHERN AND CENTRAL MTNS SHOULD ALSO SEE SOME SNOW SAT NIGHT-SUN AS
THE SYSTEM PASSES...BUT SNOW ACCUMS WILL BE HELD IN CHECK BY MORE
LIMITED MOISTURE AND FORCING. SUBSIDENCE ON THE NORTH OF
SHEAR/DEFORMATION AXIS TAKES HOLD ON SUNDAY FOR DECREASING CHANCE
OF PRECIP ACROSS THE N BY MIDDAY SUNDAY.

.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY...
UPPER LEVEL CLOSED LOW CONTINUES TO SLIDE SOUTH INTO MEXICO SUNDAY
NIGHT. LINGERING SHOWERS WILL DISSIPATE THROUGH THE OVERNIGHT OVER
THE SAN JUAN MOUNTAINS AND ASSOCIATED HIGHER TERRAIN. THE NORTHERN
PART OF THE SPLIT SYSTEM IS WELL EAST OF THE CWA BY SUNDAY NIGHT.
THE UPPER LOW REMAINS ALONG THE SOUTHERN US BORDER AND TRACKS EAST
TOWARD FAR WEST TEXAS. CONDITIONS REMAIN RELATIVELY DRY OVER THE
REGION AS A RIDGE BUILDS BEHIND AND NORTH OF THE CLOSED LOW THROUGH
TUESDAY. THEN THE MODELS BECOME DIVERGENT AND CONFIDENCE IS REDUCED
GREATLY. THE EC HAS HAD BETTER RUN TO RUN CONSISTENCY THAN THE GFS
ALTHOUGH TIMING AND HOW DEEP THE NEXT TROUGH DIGS IS STILL IN
QUESTION EVEN WITH THE EC. KEPT THE CURRENT FORECAST TREND WITH
MINOR CHANGES TO POPS AND TEMPERATURES.

&&

.AVIATION...
VFR CONDITIONS EXPECTED THROUGH 18Z SAT. INCREASING HIGH CLOUDS WILL
GRADUALLY LOWER DURING THE DAY SAT WITH SOME MTN SNOW AND AREAS OF
MVFR CONDITIONS FOR MTN AIRPORTS DEVELOPING SAT AFTERNOON.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
     AFTERNOON FOR COZ018-019.
UT...NONE.

&&

$$

SHORT TERM.....JAD
LONG TERM......AS
AVIATION.......JAD