Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 291513
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
913 AM MDT WED OCT 29 2014

.UPDATE...
ISSUED AT 912 AM MDT WED OCT 29 2014

THE FREEZE WARNING HAS EXPIRED AND THE HEADLINE HAVE BEEN REMOVED.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 427 AM MDT WED OCT 29 2014

EXPECT ANOTHER MOSTLY SUNNY DAY AS A RIDGE OF HIGH PRESSURE TO
THE WEST KEEPS MOISTURE OUT OF THE REGION. AFTER ANOTHER COLD
START TO THE DAY...TEMPERATURES WILL WARM TO NEAR NORMAL LEVELS
THIS AFTERNOON. MEANWHILE...A MODERATE MID-LEVEL HEIGHT GRADIENT
OVER THE NORTHERN COLORADO MOUNTAINS WILL RESULT IN SOME
BREEZINESS IN THE HIGHER ELEVATIONS.

UPPER LEVEL RIDGING WILL BE AMPLIFYING OVER THE GREAT BASIN
OVERNIGHT INTO THURSDAY AS HIGH LATITUDE ENERGY CARVES A NEW TROUGH
OVER THE EASTERN STATES...AND DIGS ANOTHER OFF THE LEFT COAST.
DERIVED SATELLITE IMAGERY INDICATES A DECENT PACIFIC MOISTURE TAP
DIRECTED INTO THE NORTHWEST CONUS THIS MORNING. THERE IS LITTLE
CHANCE OF THIS MOISTURE SURVIVING THE TREK OVER THE AMPLIFIED
RIDGE AND EXPECT ONLY PASSING HIGH CLOUDINESS OVER THE NORTHEAST
CWA DURING THIS TIME PERIOD. TEMPERATURES WILL BE THE TRICKY PART
AS SUBSIDENCE UNDER THE RIDGE WILL RESTRICT MIXING GOING INTO
THURSDAY AS MID LEVEL CAPPING STRENGTHENS. FOR NOW HAVE KEPT THE
FORECAST CLOSER TO THE COOLER MET GUIDANCE EVEN THOUGH SUNNY SKIES
WILL BE IN PLACE.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 427 AM MDT WED OCT 29 2014

THE BLOCKY PATTERN SHIFTS SLOWLY EASTWARD THURSDAY NIGHT INTO
FRIDAY  AS A STRONG JET DROPS OUT OF CENTRAL CANADA...FORCING THE
ACTIVE PART OF THE TROUGH INTO THE MID ATLANTIC STATES. THIS SHIFT
ALLOWS THE WESTERN TROUGH TO BEGIN TO MOVE ON-SHORE AND HOPEFULLY
BRING MUCH NEEDED PRECIPITATION TO NORTHERN CALIFORNIA. THERE IS A
WEAKER SOUTHERN STREAM SYSTEM CROSSING THE BAJA TOWARD THE 4
CORNERS DURING THIS TIME PERIOD AS WELL...WITH A SOURCE REGION IN
THE SUBTROPICS. THERE IS NOT MUCH MOISTURE ASSOCIATED WITH THIS
FEATURE BUT DOES LOOK TO START TO PULL GULF MOISTURE NORTHWARD
EARLY FRIDAY. SOUTHERLY H7 WINDS INCREASE DUE TO HEIGHT FALLS
MOVING IN WITH THE SYSTEM AND THEN AS THE WESTERN TROUGH MOVES
INLAND. LIFT IS WEAK SO THIS SHOULD BE IN THE FORM OF MID AND HIGH
CLOUDINESS AND POSSIBLY SOME LATE DAY VIRGA. TEMPERATURES INCREASE
GOING INTO THE END OF THE WEEK AS DEEP MIXING IMPROVES.

MODELS WERE PRETTY CONSISTENT IN MOVING THE DEEP WESTERN TROUGH
OVER THE WESTERN GREAT BASIN ON SATURDAY. AS MENTIONED ABOVE...
HEIGHT FALLS AHEAD OF THE SYSTEM COMBINED WITH A 90 KT JET
ROTATING THROUGH THE BASE OF THE TROUGH WILL GENERATE STRONG WINDS
AHEAD OF THE FRONT ASSOCIATED WITH THIS SYSTEM. INCREASING
MOISTURE WILL BRING SCATTERED SHOWERS AND EMBEDDED THUNDERSTORMS
...MAINLY OVER THE SOUTHERN AND CENTRAL COLORADO MOUNTAINS AND THE
EASTERN UINTAS DURING THE DAY ON SATURDAY AND INTO SATURDAY NIGHT.

THE COLD FRONT IS PROGGED TO PLOW THROUGH THE REGION SATURDAY
NIGHT INTO SUNDAY WITH THE GFS MORE PROGRESSIVE THAN THE ECMWF
WHICH STALLS THE FRONT SOUTHWEST TO NORTHEAST OVER THE REGION.
BOTH MODELS DO...HOWEVER...GENERATE A SPLIT IN THE FLOW EVENTUALLY
CUTTING OFF A LOW OVER THE DESERT SOUTHWEST. SHOWERS SHOULD
CONTINUE OFF AND ON IN THE COL BETWEEN THE NORTHERN FLOW AND THE
SOUTHERN LOW ON MONDAY BEFORE DRYING ARRIVES TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 912 AM MDT WED OCT 29 2014

VFR CONDITIONS UNDER HIGH PRESSURE AND DRY NORTHWEST FLOW ALOFT
WILL PERSIST FOR THE NEXT 24 HOURS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

UPDATE...CC
SHORT TERM...NL/15
LONG TERM...15/NL
AVIATION...CC



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