Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 212319
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
519 PM MDT TUE OCT 21 2014

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 317 PM MDT TUE OCT 21 2014

AN INITIAL SURGE OF MOISTURE COMBINED WITH JET DIVERGENCE
CONTINUED TO GENERATE AREAS OF LIGHT SHOWERS AND A FEW EMBEDDED
THUNDERSTORMS ACROSS WESTERN COLORADO THIS AFTERNOON. MEANWHILE
...THE MAIN TROUGH WAS DRIVING A COLD FRONT ACROSS NORTHERN UTAH
AND WILL CONTINUE TO TRACK ACROSS WYOMING THIS EVENING. PASSAGE OF
THE TROUGH WILL CONTINUE TO GENERATE SCATTERED TO NUMEROUS SHOWERS
AND A FEW THUNDERSTORMS THIS EVENING. AS MENTIONED IN PREVIOUS
DISCUSSIONS...SNOW WILL FALL AT THE HIGHER ELEVATIONS WITH MODELS
INDICATING A SNOW LEVEL NEAR 10000 TO 10500 FEET. LIFT ASSOCIATED
WITH THE TROUGH PASSAGE NOT IMPRESSIVE SO ACCUMULATIONS WILL BE
LIGHT AND CONFINED TO THE PEAKS.

LINGERING MOISTURE...INSTABILITY...AND OROGRAPHIC LIFT WILL
CONTINUE TO GENERATE LIGHT SHOWERS OVER THE MOUNTAINS WEDNESDAY
BEFORE PRECIPITATION ENDS WEDNESDAY NIGHT. THE COLD FRONT STALLS
ACROSS THE NORTHERNMOST ZONES WHICH WILL BRING COOLER TEMPERATURES
THERE TONIGHT. ELSEWHERE...CAA ON THE BACKSIDE OF THE SYSTEM
COMBINED WITH FEWER CLOUDS IN THE WESTERN VALLEYS WILL BRING MORE
SEASONABLE LOWS. HIGHS WILL BE NEAR OR A LITTLE ABOVE NORMAL
WEDNESDAY...THEN COLDER WEDNESDAY NIGHT AS CLOUDS CLEAR OVER THE
AREA.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 317 PM MDT TUE OCT 21 2014

HIGH PRESSURE BUILDS OVER MUCH OF THE WESTERN AND CENTRAL US ON
THURSDAY AND KEEPS DRY WEATHER AND WARM TEMPERATURES OVER THE
REGION THROUGH SATURDAY. THE NEXT TROUGH COMES ONSHORE THE
PACIFIC NORTHWEST COAST ON SATURDAY MORNING WHICH WILL HELP TO
INCREASE THE GENERAL WINDS ACROSS EASTERN UTAH AND EXTREME
NORTHWESTERN COLORADO BY SATURDAY AFTERNOON. THERE IS CONSISTENCY
ON THIS PACIFIC NW TROUGH MOVING EAST INTO THE FORECAST AREA
SOMETIME DURING THE LATE WEEKEND INTO THE EARLY WORKWEEK...HOWEVER
THERE ARE SOME DISCREPANCIES WITH HOW FAR SOUTH THE PRECIPITATION
WILL BE ON SUNDAY INTO MONDAY. BOTH THE 12Z GFS AND EC MODELS ARE
INDICATING A TWO-PART SYSTEM...WITH THE FIRST A WEAKER DISTURBANCE
ON SUNDAY AND A SECOND PART ON MONDAY ASSOCIATED WITH A RELATIVELY
STRONG COLD FRONT. 700MB TEMPS BY MONDAY MORNING ARE FORECAST TO
BE AROUND -5C TO -7C OVER NORTHERN UT/CO AND AROUND ZERO TO -3C
OVER SOUTHERN UT/CO...WHICH WOULD BRING TEMPERATURES TO NEAR
NORMAL FOR THIS TIME OF YEAR. AM MODERATELY CONFIDENT THAT A
TROUGH WILL REACH THE AREA LATE OVER THE WEEKEND INTO MONDAY BUT
THE DETAILS MAY CHANGE AS SUBSEQUENT WX MODELS CHANGE THE TIMING
AND AMPLITUDE OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 515 PM MDT TUE OCT 21 2014

A COLD FRONT WILL WORK ACROSS NW COLORADO BETWEEN 00Z AND 06Z.
EXPECT A LINE OF -TSRA PRODUCING BRIEF VRB15G30KT VIS LESS THAN
6SM CIG 030-050 AT KCAG KHDN KCAG KEEO WITH SOME POTENTIAL AT
KEGE AND KASE. ISOLATED -TSRA ARE POSSIBLE AT ALL AIRPORTS UNTIL
06Z. THEN EXPECT IMPROVING CONDITIONS EXCEPT CONTINUED -SHRA AND
MOUNTAIN OBSCURATIONS EAST OF A LINE FROM KCAG TO KDRO. THESE
SHOWERS AND OBSCURATIONS END BY 22Z WEDNESDAY.


&&

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

$$

SHORT TERM...NL
LONG TERM...JAM
AVIATION....JOE



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