FXUS65 KGJT 220927 AAA
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
226 AM MST TUE DEC 22 2009

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...
BASED ON CONSISTENCY OF EVENING/EARLY MORNING MODEL RUNS WITH
PREVIOUS RUNS...DECIDED TO UPGRADE ADVISORIES TO WINTER STORM
WARNINGS SW SAN JUAN MOUNTAINS...DURANGO AREA...PAGOSA SPRINGS AREA.
ALSO ISSUING A WINTER STORM WARNING FOR EXTREME SE UTAH ABOVE 5000
FOOT LEVEL...MAINLY BLANDING AREA. OTHERWISE CLOSED UPPER LOW OVER
NRN OR DROPS RAPIDLY SOUTHWARD TO AROUND LAS VEGAS BY THIS EVENING.
ALL MODELS INDICATE SUBSTANTIAL QPF/SNOW DESPITE RATHER LACK LUSTER
FORCING...BUT ITS HARD TO IGNORE THE CONSISTENCY DISPLAYED BY
SEVERAL MDL RUNS. FOCUS OF PCPN MAINLY OVER THE SRN ZONES AS
COMBINATION OF OROGRAPHICS AND DIVERGENCE/DIFFLUENCE ALOFT WORK ON
INCREASING MSTR SUPPLY.

THE UPPER LOW SINKS INTO AZ TONIGHT AND THEN BEGINS TO MOVE
EASTWARD INTO NM. SOUTHERN ZONES REMAIN UNDER THE GUN WHILE WRAP
AROUND STARTS TO DEVELOP ACROSS THE NRN AND CNTRL MTNS BRINGING SUB
ADVISORY SNOW AMOUNTS. PCPN WILL BEGIN TO TAPER OFF ACROSS
THE SOUTH WEDNESDAY AS THE FLOW BECOMES NRLY AND FOCUS OF PCPN
SHIFTS TO THE NRN AND CNTRL MTNS. BY WEDNESDAY NIGHT THE GFS AND
ECMWF SHOW A SECONDARY WAVE HEADING FOR THE FORECAST AREA. THIS WILL
BRING A SURFACE COLD FRONT INTO THE REGION ...PROVIDING INSTABILITY
AND H7 FLOW OF 30 KTS OVER THE NORTH PROVIDING GOOD OROGRAPHIC
FORCING FOR ADDITIONAL SNOW ACCUMULATIONS.

.LONG TERM...THURSDAY THROUGH MONDAY NIGHT...
CLOSED LOW WILL BE OVR KS BY THUR AS WRAPAROUND MOISTURE AND
NRLY WIND FLOW KEEPS SNOW CHCS THRU FRI MORNING ESPECIALLY NRN AND
TO SOME DEGREE CEN MTNS DUE TO FAVORABLE OROGRAPHICS.  MODERATE
ACCUMULATIONS OF UP TO 6 INCHES ARE POSSIBLE AFTER ALL IS SAID AND
DONE...ESPECIALLY NRN MTNS.  BY THUR NIGHT...ANOTHER IMPULSE WILL
HAVE DROP DOWN FROM THE N REINFORCING THE COLD AIR ALREADY IN PLACE.
ALMOST NO PRECIP ASSOD WITH THIS PIECE OF ENERGY HOWEVER SO TOOK OUT
ALMOST ALL MENTION OF SNOW FROM FORECAST THOUGH SOME VERY ISOLD
SNOWSHOWERS ARE POSSIBLE NEAR GORE/PARK RIDGE MTNS.

FOR FRI AND SAT...WEAK RIDGING BUILDS IN AS SKIES CLEAR WHILE TEMPS
REMAIN BELOW NORMAL FRI DUE TO SECOND SHOT OF ENERGY.  BY SAT
HOWEVER...TEMPS WILL ALREADY START TO REBOUND.  DO ANTICIPATE
COLD AIR TO STICK AROUND THE VALLEYS AS INVERSIONS ONCE AGAIN SET UP
OVER REGION.  BY SUNDAY...SHEARED RIDGE AXIS WILL BE OVR CWA AS WINDS
BECOME MORE SLY AS WARM ADVECTION KICKS IN. AS THIS HAPPENS...
NEXT SHORTWAVE WILL UNDERCUT RIDGE CAUSING VERY SLIM CHC FOR PRECIP
OVR SRN CO AREAS MONDAY.

&&

.AVIATION...
KGJT AND KVEL REPORTING 3MI VIS DUE TO FOG ATTM BUT EXPECT
CONDITIONS TO START DETERIORATING FOR ALL TAF SITES TODAY AS SYSTEM
APPROACHES FROM THE W.  CLOUD BASES AND VSBY WILL DECREASE THROUGHOUT
THE DAY BECOMING MVFR TO IFR IN THE AFTN DUE TO THE NEXT STORM
SYSTEM AND WIDESPREAD SNOW.  SE UT AND SW CO WILL SEE MOST OF THE
SNOWFALL AND IFR CONDITIONS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...WINTER STORM WARNING FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON SW SAN JUAN MTS AND SOME SW CO VLYS...ZONES 19/22/23.
     WINTER WEATHER ADVISORY FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON NW SAN JUAN MTS AND SW CORNER OF CO...ZONES 18/21.
UT...WINTER STORM WARNING FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON EXTREME SE UT ABOVE 5000 FT LEVEL...ZONE 22.
     WINTER WEATHER ADVISORY FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON FOR LA SAL AND ABAJO MTS...ZONE 28.

$$

SHORT TERM...MC
LONG TERM....TGR
AVIATION.....TGR

$$