FXUS65 KGJT 271006
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
306 AM MST FRI NOV 27 2009
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...
THE RIDGE LINE PASSES TO THE EAST TODAY AND THE FLOW ALOFT BACKS TO
THE SOUTHWEST AS UPSTREAM PACIFIC TROF DEVELOPS OVER NRN
CALIFORNIA. GRADIENT TIGHTENS A BIT ACROSS THE NORTH WHICH MAY
PRODUCE LOCALLY BREEZY CONDITIONS. TONIGHT THE TROF ALONG THE WEST
COAST CLOSES AND SINKS SOUTHWARD ALONG THE CA COAST WITH SOME
INCREASE IN HIGH LEVEL MOISTURE OCCURRING OVER OUR REGION. SATURDAY
THE GFS MOVES THE CLOSED LOW NEAR LAS VEGAS BY EARLY EVENING...WHILE
THE NAM IS A LITTLE SLOWER. EITHER WAY MOISTURE INCREASES FROM THE
SOUTH. EXPECT PCPN TO BREAK OUT OVER THE SRN MTNS AROUND NOON THEN
BECOME SLOWLY MORE WIDESPREAD LATER IN THE DAY.
THE MAIN WEATHER HOLDS OFF UNTIL SATURDAY NIGHT WHEN THE REGION
WILL BE UNDER A WELL DEFINED DEFORMATION ZONE WITH SHORT WAVE OVER
WYOMING AND CLOSED LOW NEAR SOUTHWESTERN AZ. INTERACTION OF JET
SEGMENTS WITH EACH SYSTEM PRODUCES GOOD DIFLUENCE/DIVERGENCE ALOFT
WITH CONVERGENCE COUPLET NEAR THE SURFACE...THIS RESULTS IN A GOOD
QPF SIGNATURE FAVORING THE SRN MTNS. CURRENTLY EXPECT SNOWFALL OVER
THE SAN JUANS TO RANGE FROM 6-12 INCHES BY SUNDAY EVENING ALTHO
CONFIDENCE NOT INSPIRING SO WILL ISSUE A WATCH FOR MAXIMUM
FLEXIBILITY. LOWER ELEVATIONS NEAR DURANGO AND PAGOSA NEED TO BE
WATCHED SAT NIGHT AND SUNDAY. DONT EXPECT TO MUCH UP NORTH HOWEVER
WEAK FRONTAL BAND ASSOCIATED WITH NORTHERN TROF SEEMS TO STALL AROUND
I-70 CORRIDOR WHICH MAY PROVIDE FOCUS FOR PCPN OVER THE NRN AND CNTRL
MTNS...BUT WITH LIGHTER AMOUNTS.
.LONG TERM...SUNDAY THROUGH THURSDAY NIGHT...
CLOSED LOW OVER CA/WRN AZ WILL CONTINUE TO DRAW IN PRECIP OVER SAN
JUANS/CEN MTNS THRU MON MORNING THOUGH COVERAGE AND INTENSITY WILL
DECREASE THROUGH THE PERIOD. A FEW MORE INCHES POSSIBLE OVER
MOUNTAINOUS AREAS AS CUT-OFF LOW CONTINUES SLOW EWRD PROGRESSION.
WHAT A DIFFERENCE 24 HRS MAKES...HUGE DIFFERENCE FROM YESTERDAY TO
TODAY BTWN MODEL RUNS FOR MONDAY ONWARDS. WEAK RIDGE STILL CONTINUES
TO BUILD IN CWA...IN ALL MODELS...BUT MODELS DIVERGE WITH COLD FRONT
DROPPING DOWN FROM CANADA LATE TUE NIGHT/EARLY WED MORNING. PREVIOUS
THINKING PLACED TAIL END OF FRONT OVER ROCKIES KICKING OFF SOME SNOW
SHOWERS WHILE LATEST RUN SHOWS ALMOST NO UPPER LEVEL SUPPORT AND NO
PRECIP OVR CO. IN FACT...GFS NOT BRINGING ANY PRECIP TO AREA UNTIL
THUR WHEN WEAK UPPER LEVEL DISTURBANCE/VORT MAX DROPS DOWN FROM ID
CAUSING SHOWERY TYPE PRECIP. EUROPEAN ALSO LEANING TOWARDS THIS
SCENARIO THOUGH PRECIP DOES MOVE THRU EXTREME NERN CO.
UNDERSTANDABLY...NOT MUCH CONFIDENCE IN CURRENT MODEL SPREAD SO MADE
VERY MINOR CHANGES TO CURRENT FORECAST.
&&
.AVIATION...
HIGH PRESSURE REMAINS IN CONTROL BRINGING YET ANOTHER DAY OF VFR
CONDITIONS ACROSS COLORADO AND UTAH.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR COZ018-019.
UT...NONE.
&&
$$
SHORT TERM.....MC
LONG TERM......TGR
AVIATION.......TGJT
