Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 251725
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1125 AM MDT SAT JUL 25 2015

.UPDATE...
ISSUED AT 1125 AM MDT SAT JUL 25 2015

HIGHER RESOLUTION MODELS SUCH AS THE HRRR NOT VERY EXCITED ABOUT
CONVECTIVE POTENTIAL THIS AFTERNOON. HRRR SHOWS ISOLATED ACTION
OVER THE ERN SAN JUAN MOUNTAINS...BUT QUIET ELSEWHERE. WATER VAPOR
SHOWS MOISTURE PLUME CUTS ACROSS THE SW COLORADO CORNER BUT
MOISTURE TRANSPORT IS WEAK. GOES SOUNDER SHOW STABLE LIFTED
INDICES ACROSS THE WESTERN SLOPE AND ERN UTAH...SUPPORTING THE
RAP/HRRR MODELS OF MINIMAL CONVECTIVE ACTIVITY THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 418 AM MDT SAT JUL 25 2015

CONDITIONS WILL BE MUCH DRIER TODAY AS A SHORTWAVE DISTURBANCE
MOVING ACROSS THE NORTHERN GREAT BASIN AND NORTHERN ROCKIES HELPS
PUSH THE MOISTURE PLUME THAT WAS OVER PORTIONS OF SOUTHWEST AND WEST-
CENTRAL COLORADO YESTERDAY FURTHER TO THE EAST-SOUTHEAST WITH THE
FLOW SHIFTING TO MORE OF A WESTERLY DIRECTION. PRECIPITABLE WATER
(PW) VALUES ARE FORECASTED TO BE LESS THAN 0.5 INCHES ACROSS MUCH OF
THE AREA WHICH SHOULD TRANSLATE TO MUCH LESS CLOUDS AND STORMS.  THE
BEST MOISTURE WILL RESIDE ACROSS SOUTHERN PORTIONS OF THE FORECAST
AREA WITH THE BEST CHANCES OF SHOWERS AND STORMS OVER THE SAN JUANS
AND MAYBE WEST ELKS.  OTHERWISE A MUCH DRIER DAY.  BREEZY CONDITIONS
MAY OCCUR AT TIMES WITH GUSTS OF 15 TO 25 MPH ACROSS PORTIONS OF NE
UTAH AND NW COLORADO AS THE JET REMAINS OVERHEAD WITH A VORT MAX
MOVING THROUGH LATE THIS AFTERNOON. CONDITIONS WILL BE MARGINAL FOR
RED FLAG CRITERIA AND DO NOT APPEAR TO WARRANT ANY FIRE WEATHER
HIGHLIGHTS AT THIS TIME BUT SHOULD BE MONITORED.

AN AREA OF LOW PRESSURE OVER THE PACIFIC NW WILL BEGIN TO CARVE A
TROUGH OVER THE WESTERN U.S. ON SUNDAY. THIS WILL SHIFT THE WINDS
BACK TO THE SOUTHWEST...ALLOWING MONSOONAL MOISTURE TO SURGE BACK
NORTHWARD OVER OUR CWA WITH THE HIGH PRESSURE STILL CENTERED NEAR
THE TEXAS-OKLAHOMA PANHANDLE REGION. PW VALUES INCREASE TO 0.75
INCHES AND GREATER SOUTH OF I-70 ON SUNDAY WITH NEAR AN INCH IN
SPOTS...MAINLY FOCUSED NEAR THE FOUR CORNERS AND SOUTHWEST COLORADO.
A SHORTWAVE DISTURBANCE WILL ROUND THE BASE OF THE TROUGH MOVING
THROUGH UTAH ON SUNDAY AS EVIDENT IN 5H WIND STREAMLINES AND 1.0 PVU
VORTICITY FIELDS...HELPING TO INCREASE STORM ACTIVITY. LEANED
TOWARDS THE GFS FOR THIS FORECAST AS THIS MODEL INITIALIZED MUCH
BETTER WITH YESTERDAYS PRECIPITATION THAN THE OTHER MODELS.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 418 AM MDT SAT JUL 25 2015

NOT MUCH DIFFERENCE IN THE LONGER TERM MODEL SOLUTIONS. THE BASIC
PATTERN STARTS OFF WITH HIGH PRESSURE CENTERED OVER OKLAHOMA AND
LOW PRESSURE ALONG THE PACNW AND BRITISH COLUMBIA COAST. THE LOW
OVER THE NW MOVES INLAND MONDAY AS THE HIGH PRESSURE IS PUSHED
EAST. THIS BRINGS A FAIRLY STRONG JET OVER NORTHERN NV AND UT AND
INTO SOUTHERN ID AND WESTERN WY MONDAY AFTERNOON. THE GRADIENT
TIGHTENS OVER NE UT AND THE NW AND WEST-CENTRAL CO MON AFTERNOON
AND EVENING. SURFACE WINDS MAY BECOME STRONG ENOUGH TO CAUSE FIRE
WEATHER CONCERNS. FORECAST TIME-HEIGHT GRAPHS AND FORECAST
SOUNDINGS SHOW 50-60 KTS OF SW WINDS AT 300 MB. 700 MB WINDS MONDAY
AFTERNOON ARE PREDICTED TO RANGE FROM 15-20 KTS IN THE GFS TO 25
KTS IN THE ECMWF. THE STRONGEST WINDS APPEAR TO REMAIN NW OF THE
FORECAST AREA. MONDAY WILL BE WATCHED CLOSELY FROM A FIRE WEATHER
STANDPOINT.

THE NW LOW WILL RIDE QUICKLY EAST ALONG THE CAN/U.S. BORDER AND
THE GRADIENT FLOW SHOULD DECREASE TUE. AS THE LOW REACHES THE
GREAT LAKES WED...THE HIGH SE OF THE AREA WILL SLIDE WEST OVER
THE FOUR CORNERS. BY THU THIS HIGH WILL BE CENTERED OVER SW UT AND
BUILD A LARGE RIDGE OVER THE WESTERN U.S. THIS SHOULD BE A
SIGNIFICANT PATTERN CHANGE THAT WILL REMAIN FOR SEVERAL DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1125 AM MDT SAT JUL 25 2015

ISOLATED -TSRA/-SHRA WILL DEVELOP OVER THE SWRN COLORADO MOUNTAINS
THIS AFTERNOON BETWEEN 20Z-01Z. ANY STORMS WILL BE SHORT LIVED AND
MOVE EASTWARD. OTHERWISE NO WEATHER RELATED AVIATION HAZARDS ARE
EXPECTED THROUGH THE FORECAST PERIOD.

&&

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

$$

UPDATE...PF
SHORT TERM...MDA
LONG TERM...CC
AVIATION...PF


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