Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 042034
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
234 PM MDT TUE AUG 4 2015

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 234 PM MDT TUE AUG 4 2015

ISOLATED STORMS WILL PERSIST INTO THE EARLY EVENING. BUT WITH
MEAGER INSTABILITY AND NO APPARENT FORCING THIS AFTERNOON...
STORMS ARE EXPECTED TO END WITH SUNSET. THE RIDGE BUILDS IN FROM
THE WEST OVERNIGHT. UNDER CLEARING SKIES AND LIGHT GRADIENT...
TEMPERATURES TONIGHT WILL BE BELOW GUIDANCE AND BELOW NORMAL.

A SHORTWAVE WILL MOVE THROUGH NORTHERN UTAH AND SW WYOMING WEDNESDAY
AFTERNOON AND EVENING CAUSING THE GRADIENT TO TIGHTEN FOR NORTHERN
AND CENTRAL PORTIONS OF NE UTAH AND NW COLORADO PARTICULARLY NORTH
AND ALONG I-70. WINDS OF 25 KTS OR GREATER ARE EXPECTED WITH
POSSIBLE FIRE WEATHER CONCERNS FOR THE NORTHWEST COLORADO ZONES
WHERE FUELS ARE CRITICAL. SEE FIRE WEATHER DISCUSSION FOR MORE
DETAILS. SOME ISOLATED STORMS ARE POSSIBLE OVER THE EASTERN UINTAS
AND NW COLORADO MOUNTAINS BUT OVERALL...LOOKS LIKE A FAIRLY DRY AND
BREEZY DAY. TEMPERATURES WILL BE WARMER WITH VALUES ABOVE NORMAL FOR
WEDNESDAY AFTERNOON AS THE BREEZY CONDITIONS AND TIGHT GRADIENT HELP
TO KEEP THE ATMOSPHERE WELL MIXED.  THE SFC PRESSURE GRADIENT
REMAINS TIGHT THROUGH WEDNESDAY EVENING BUT RELAXES AFTER MIDNIGHT
AS THE DISTURBANCE AND POSSIBLE WEAK FRONT MOVES THROUGH.  EXPECTING
MINIMUM TEMPERATURES WEDNESDAY NIGHT TO BE BELOW NORMAL AND COOLER
THAN GUIDANCE WITH GOOD RADIATIONAL COOLING DUE TO CLEAR SKIES AND
NO ENHANCED DRAINAGE WINDS EXPECTED GIVEN THE RELAXED GRADIENT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 234 PM MDT TUE AUG 4 2015

THURSDAY...A SLOW DRYING TREND WILL CONTINUE INTO THURSDAY WITH
MOSTLY SUNNY SKIES AND CONTINUED WARM TEMPERATURES. ENOUGH MOISTURE
WILL LINGER FOR SOME AFTERNOON THUNDERSTORMS OVER THE HIGHER TERRAIN
OF WESTERN COLORADO.

FRIDAY THROUGH SUNDAY...MONSOONAL MOISTURE WILL SURGE BACK INTO THE
REGION FRIDAY INTO SATURDAY AS A LOW PRESSURE TROUGH MOVES INLAND
OVER THE NORTHERN CALIFORNIA COASTLINE...PUSHING THE RIDGE OF HIGH
PRESSURE FURTHER EAST INTO TEXAS AND OKLAHOMA. THIS INCREASES THE
SOUTHWESTERLY FLOW INTO THE FOUR CORNERS REGION WITH PRECIPITABLE
WATER (PW) VALUES INCREASING TO AN INCH OR GREATER IN SE UTAH ON
FRIDAY WITH 0.75 INCH VALUES IN WESTERN COLORADO. PW VALUES WILL BE
ABOVE 0.75 INCHES ACROSS THE ENTIRE CWA BY SATURDAY WITH AN INCH
TOWARDS THE FOUR CORNERS REGION.  THIS WILL ALL RESULT IN AN
INCREASE IN SHOWERS AND THUNDERSTORMS FRIDAY AFTERNOON INTO SATURDAY
WITH POTENTIAL FOR STRONGER STORMS ON SATURDAY AS A DISTURBANCE IN
THE FORM OF A 70KT JET STREAK MOVES THROUGH NORTHERN UTAH INTO
WYOMING. OUR CWA WILL BE IN THE FAVORED LEFT EXIT REGION WITH SOME
DECENT SHEAR AND STORM MOTION. THE JET LAYS OVER ACROSS THE NORTH IN
A WESTERLY FLOW ON SUNDAY WITH DRIER AIR OVER NE UTAH AND NW
COLORADO. SOUTHERLY FLOW AND ENOUGH MOISTURE IS STILL PRESENT ACROSS
SE UTAH AND CENTRAL AND SOUTHERN PORTIONS OF WESTERN COLORADO TO
GENERATE AFTERNOON STORMS MAINLY OVER HIGHER TERRAIN. TEMPERATURES
WILL BE COOLER DURING THIS PERIOD DUE TO INCREASING CLOUDS AND
SHOWERS.

MONDAY THROUGH TUESDAY...MOISTURE SURGES BACK NORTHWARD AGAIN ON
MONDAY AND TUESDAY AFTER THE BRIEF DOWNTURN ON SUNDAY AS THE HIGH
PRESSURE REMAINS OVER THE TEXAS-OKLAHOMA PANHANDLE WITH
SOUTHWESTERLY FLOW ACROSS THE CWA. THIS WILL RESULT IN INCREASING
COVERAGE OF SHOWERS AND STORMS INITIALLY OVER HIGHER TERRAIN WITH
SOME DRIFTING INTO VALLEYS LATER IN THE DAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY NOON)
ISSUED AT 1110 AM MDT TUE AUG 4 2015

EXPECT A FEW THUNDERSTORMS OVER THE HIGHER TERRAIN THROUGH 02Z.
THIS ACTIVITY IS UNLIKELY TO IMPACT AIRPORTS ACROSS THE REGION AND
VFR CONDITIONS ARE EXPECTED TO PREVAIL DURING THE NEXT 24 HOURS.

&&

.FIRE WEATHER...
ISSUED AT 234 PM MDT TUE AUG 4 2015

POSSIBLE FIRE WEATHER CONCERNS WILL EXIST WEDNESDAY AFTERNOON AND
EARLY EVENING FOR THE NORTHERN COLORADO FIRE ZONES WHERE FUELS ARE
CRITICAL (PARTICULARLY COLORADO FIRE ZONE 200...202...AND 203 BELOW
7000 FT) AS A DISTURBANCE MOVES ACROSS NORTHERN UTAH INTO SW WYOMING
RESULTING IN A TIGHTENING PRESSURE GRADIENT.  WINDS OF 25 MPH OR
GREATER CAN BE EXPECTED WITH SOME HIGHER GUSTS POSSIBLE FOR AREAS IN
NE UTAH AND NW COLORADO ALONG AND NORTH OF INTERSTATE 70.

THE ONLY QUESTION MARK IS THE RELATIVE HUMIDITY LEVELS WHICH WILL BE
BORDERLINE FOR CRITICAL FIRE WEATHER CRITERIA TO BE MET.  RH LEVELS
LOOK TO BE IN THE 15 TO 20 PERCENT RANGE. SOMETHING TO KEEP AN EYE
ON AS SOME AREAS MAY REACH CRITERIA BUT DOES NOT LOOK WIDESPREAD
ENOUGH TO ISSUE ANY FIRE WEATHER HIGHLITES AT THIS TIME.

&&

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

$$

SHORT TERM...JOE/MDA
LONG TERM...MDA
AVIATION...NL/JOE
FIRE WEATHER...MDA


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