FXUS65 KGJT 290259
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
759 PM MST SAT NOV 28 2009

...WINTER WEATHER IN STORE FOR THE SAN JUAN MOUNTAINS THROUGH NOON
SUNDAY...

.UPDATE...KPSO INDICATED SNOW AS OPPOSED TO RAIN ALREADY THIS
EVENING. EXPECT PRECIPITATION WILL CONTINUE AS SNOW FOR AREAS
AROUND PAGOSA SPRINGS WHICH WILL BRING FROM 2 TO 5 INCHES OF NEW
SNOW TO THE AREA BY LATE SUNDAY AFTERNOON. THEREFORE...ISSUED A
WINTER WEATHER ADVISORY. OTHER COMMUNITIES ALONG THE SOUTHERN FLANK
OF THE SAN JUAN MOUNTAINS (DURANGO...CORTEZ) LIKELY TOO LOW FOR
SIGNIFICANT ACCUMULATIONS...BUT WILL CONTINUE TO MONITOR.

&&

.SHORT TERM DISCUSSION...TONIGHT THROUGH MONDAY...
THE BIGGEST CHANGE IN THE MODELS THIS MORNING AND THE STORM SYSTEM IN
SATELLITE IMAGES IS THE LACK OF CLOUDS AND MOISTURE OVER NE UT AND NW
CO. THE NORTHERN PORTION OF THE SPLIT SHIFTED QUICKLY EAST AND HAD
MUCH LESS AMPLITUDE THAN PREVIOUS MODEL RUNS PREDICTED. HAVE
DECREASED CLOUD COVER AND CHANCE OF PRECIPITATION SIGNIFICANTLY NORTH
OF INTERSTATE 70 THROUGH MONDAY.

THE DEEP CUTOFF LOW CONTINUES TO FORM OVER THE SWRN U.S. WITH PLENTY
OF MOISTURE AND DIFFLUENT FLOW SPREADING OVER THE FOUR CORNERS AHEAD
OF THE SYSTEM. EVEN A FEW LIGHTNING STRIKES OCCURRED OVER SE UT AND
SW CO. AS THE 500 MB LOW SLOWLY MOVES ALONG THE AZ/MEXICO BORDER
TONIGHT THROUGH SUNDAY A DEFORMATION ZONES SETS UP OVER SW CO AND SE
UT. THIS PRODUCES A SOUTH TO SOUTHEAST FLOW OVER THE AREA. THE SYSTEM
AND ITS CLOUDS ARE SLOW TO MOVE OUT...BUT GENERAL DROP SOUTH OF THE
ARE SUNDAY NIGHT AND MONDAY. HAVE KEPT THE WINTER WEATHER ADVY FOR
THE SAN JUAN GOING UNTOUCHED.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

CLOSED UPPER LOW OVER NRN MEXICO MON NIGHT MOVES INTO WRN TX BY TUE
AFTERNOON. WRAPAROUND MOISTURE MAY KEEP SOME CLOUDS ALONG THE
SRN CO BORDER MON NIGHT...OTHERWISE MOSTLY CLEAR ARE EXPECTED MON
NIGHT THAT WILL PERSIST INTO TUE.

GFS MODEL CONSISTENCY HAS BEEN RATHER POOR FOR THE MID AND LATTER
PARTS OF NEXT WEEK...SO WILL LEAN TOWARD THE GFS ENSEMBLE AND ECWMF
FOR THE LARGER SCALE PATTERN...AND NOT BE TOO SPECIFIC ON THE SMALLER
SCALE FEATURES. THE LONGWAVE PATTERN EXPECTED TO AMPLIFY WITH A RIDGE
BUILDING IN THE VICINITY OF THE WEST COAST...AND A LARGE TROUGH
ENCOMPASSING THE CENTRAL AND EASTERN USA. THIS WOULD KEEP THE COLDER
AIR EAST OF THE ROCKIES...AND PROBABLY RESULT IN JUST LIMITED PAC
MOISTURE TOPPING THE RIDGE IN NWLY FLOW. 12Z MODELS CONTINUE TO SHOW
A SMALL AND WEAKENING PAC DISTURBANCE FIGHTING THROUGH THE LONGWAVE
RIDGE AND DROPPING ACROSS THE SOUTHWEST USA ABOUT WED-THU WHILE A
TROUGH ALSO DROPS INTO THE NRN PLAINS...SO MAINTAINED THE CURRENT LOW
POPS IN THE MTNS FOR WED-THU. A STRONGER SHORTWAVE TROUGH IS POSSIBLE
FOR NEXT WEEKEND...BUT WITH LARGE DISCREPANCIES BETWEEN THE GFS AND
ECWMF ON ITS TRACK AND DEVELOPMENT AND CONFIDENCE LOW...WILL JUST
BEGIN TO TREND POPS UPWARD SAT AFTER A MOSTLY DRY DAY ON FRI.

&&

.AVIATION...
VFR CONDITIONS EXPECTED AS HIGH CLOUDS CONTINUE TO STREAM OVER
FORECAST AREA THIS EVENING. CONDITIONS WILL DETERIORATE FOR THE FOUR
CORNERS...KMTJ INCLUDED...AS AN UPPER LEVEL LOW APPROACHES FROM THE
SOUTHWEST.  SNOWFALL EXPECTED OVR SRN AREAS WITH CIG AND VIS DROPPING
TO IFR...POSSIBLY TO LIFR...UNDER HEAVIER SNOW SHOWERS AFTER ABOUT
06Z. NRN/CEN MTN TOPS MIGHT BE OBSCURED AS CLOUDS LOWER AND SHOWERY
TYPE PRECIP OCCURS BUT TAF SITES...KEGE AND KASE...SHOULD REMAIN
VFR.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...WINTER WEATHER ADVISORY UNTIL 6 PM MST SUNDAY FOR COZ023.
     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST SUNDAY NIGHT FOR
     COZ018-019.
UT...NONE.

&&

$$

UPDATE.........NL
SHORT TERM.....CJC
LONG TERM......JAD
AVIATION.......TGJT