Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 210546
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1046 PM MST TUE JAN 20 2015

UPDATED AVIATION SECTION

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 242 PM MST TUE JAN 20 2015

AREAL WEB CAMS IN UINTAH COUNTY SHOW A SUNNY VERNAL...BUT THE
STRATUS CLOUD IS LURKING NEARBY. EXPECT THE FOG TO EXPAND QUICKLY
THIS EVENING (PERHAPS SHORTLY AFTER SUNSET) WITH POOR VISIBILITY.
WILL ISSUE ANOTHER DENSE FOG ADVISORY THROUGH NOON WEDNESDAY. THE
GOOD NEWS IS THAT A NORTHEAST LIGHT BREEZE DEVELOPS BY WEDNESDAY
AFTERNOON AND THIS MAY GET RID OF THE TRAPPED LOW LEVEL MOISTURE.

LEAF CLOUD STREAMING INLAND EXTENDS FROM SRN CALIF TO THE GRAND
CANYON...THIS FEATURE BECOMES A PLAYER FOR OUR FORECAST AREA BY
LATE TONIGHT. ISENTROPIC FIELDS SHOW NICE STRUCTURE WITH UPGLIDE
REACHING THE FAR SRN PORTION OF SW COLORADO. THE BAROCLINIC ZONE
OR DEFORMATION AXIS STAYS MOSTLY OVER NW NEW MEXICO...SO THE SAN
JUAN MOUNTAINS AND THE FOOTHILLS DO NOT GET THE FULL BRUNT OF THIS
FEATURE. NRN STREAM SHORT WAVE CARVES OUT A SHARP TROUGH AXIS OVER
NE UTAH WEDNESDAY AFTERNOON...THEN CONTINUES TO DIVE INTO NE
ARIZONA. THIS CAUSES POTENTIAL FOR FAIR AMOUNT OF SNOW NEAR PAGOSA
SPRINGS AND EASTWARD. SNOW AMOUNTS MAY REACH 2 TO 6 INCHES ACROSS
ARCHULETA COUNTY...BUT CONFIDENCE IS NOT HIGH ENOUGH TO HOIST A
WINTER WEATHER ADVISORY. LATER SHIFTS NEED TO MONITOR SHORT TERM
GUIDANCE AND WATCH THE INTERACTION BETWEEN THE TWO SYSTEMS.

FOR THE REMAINDER OF THE FORECAST AREA...THE CHANCE OF SNOW
EXTENDS NORTHWARD ALONG THE SAWATCH RANGE AND GORE MOUNTAINS. THE
SNOW CHANCES DECREASES FARTHER WEST. NORTHEAST FLOW USHERS IN
COLDER AIR...BUT DOES NOT TAP INTO ANY ARCTIC SOURCE (THE COOLING
TREND WILL NOT BE DRASTIC). DRIER AIR AND RADIATIONAL COOLING WILL
RESULT IN A COLDER WEDNESDAY NIGHT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 242 PM MST TUE JAN 20 2015

MID LEVEL TEMPERATURES DROP TO THEIR COLDEST READINGS THURSDAY
MORNING AS THE BACK OF THE UPPER TROUGH PASSES OVERHEAD. THESE
TEMPERATURES BEGIN A GRADUAL AND CONTINUOUS CLIMB INTO EARLY NEXT
WEEK. THE MAIN CHALLENGE IN THE EXTENDED FORECAST LIES WITH SNOW
COVER...STRATUS AND FOG INHIBITING AFTERNOON WARMING...WHILE
PROMOTING FOG AND STRATUS DEVELOPMENT. ATTM PERSISTENCE SUGGESTS
THE GUNNISON AND UINTA BASINS ARE PRIME FOR THIS AND WILL TREND
TEMPERATURES DOWN IN THIS AREAS. OTHER PROBLEMATIC AREAS INCLUDE
THE YAMPA RIVER VALLEY...AND THE 4 CORNERS VALLEYS AND FOOTHILLS.
CONFIDENCE NOT AS HIGH HERE. SEEING TEMPERATURES AS THE MAIN
CHALLENGE SHOULD BE A HINT OF A DRY FORECAST...AND THIS IS THE
CASE FROM THURSDAY ONWARD. THE PERSISTENTLY STRONG LEFT COAST
RIDGE THIS WINTER WILL RE-EMERGE BY LATE WEEK WITH A REX TYPE
BLOCK SETTING UP NEAR THE BAJA REGION. THIS LEAVES US IN A DRY
NORTHWEST FLOW PATTERN WITH PASSING WAVES AND MOISTURE BRINING
HIGH CLOUDINESS ACROSS OUR EASTERN CWA AND NOT MUCH ELSE. THE
RIDGE GETS A PUSH EASTWARD NEXT WEEK WHEN TEMPERATURES SHOULD PUSH
WELL ABOVE NORMAL. THIS WILL BE DUE TO LOW PRESSURE FILLING UP THE
EASTERN PACIFIC BASIN. COULD THIS BE A PATTERN CHANGE THAT WILL BE
FAVORABLE FOR PRODUCING PRECIPITATION IN WESTERN COLORADO AND
EASTERN UTAH...STAY TUNED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1044 PM MST TUE JAN 20 2015

FOG WILL PERSIST IN ERN UINTA BASIN AND KEEP KVEL BELOW AIRPORT MINS
MUCH OF THE TIME THROUGH WED MORNING. AN UPPER LOW OVER SRN CA THIS
EVENING WILL PASS SOUTH OF THE FOUR CORNERS 18Z WED TO 00Z THU...
PRECEDED BY A SURFACE TROUGH THAT WILL BRING SOME LOWER CLOUDS AND
A CHANCE OF PRECIPITATION TO THE FOUR CORNERS WITH LIGHT SNOW
DEVELOPING OVER THE SAN JUAN MTNS. KDRO AND KPSO WILL BE IMPACTED
BY THIS EVENT WITH PERIODS OF IFR CONDITIONS IN SNOW ESPECIALLY
TONIGHT AS ANOTHER DISTURBANCE DROPS DOWN FROM THE NORTH BY 06Z
THU. SNOW AND OCNL MOUNTAIN OBSCURATION WILL BE ALONG THE
CONTINENTAL DIVIDE NORTH TO ABOUT VAIL AND KCCU WED AFTERNOON AND
EVENING.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...DENSE FOG ADVISORY UNTIL NOON MST WEDNESDAY FOR UTZ024.

&&

$$

SHORT TERM...PF
LONG TERM...15
AVIATION...JAD


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