Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 291643
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1043 AM MDT TUE JUL 29 2014

.UPDATE...
ISSUED AT 1034 AM MDT TUE JUL 29 2014

THE CIRCULATION CENTER OF THE APPROACH SHORTWAVE TROUGH IS EVIDENT
IN WV SATELLITE OVER EASTERN UT WITH THE PVA AND ASSOCIATION
SHOWERS MOVING THROUGH NW AND CENTRAL CO THIS MORNING. CLEARING IN
THE SUBSIDENCE BEHIND THE VORT LOBE WILL HOLD BACK CONVECTION FOR
A SHORT TIME...THEN SUNSHINE AND SURFACE HEATING SHOULD GET
CONVECTION GOING IN THE AREAS OF CLEARER SKIES...INITIALLY OVER
EASTERN UT THEN EXTENDING OVER WESTERN CO THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 400 AM MDT TUE JUL 29 2014

NOCTURNAL SHOWERS AND A FEW EMBEDDED THUNDERSTORMS CONTINUED TO
MOVE SLOWLY TO THE NORTHEAST OVER EAST-CENTRAL UTAH AND A LARGE
PORTION OF WEST-CENTRAL COLORADO. DUE TO THE DEPTH OF THE MONSOON
MOISTURE AND LIFT ASSOCIATED WITH AN MCV OVER THE WESTERN EDGE OF
THE GRAND VALLEY HEAVY SHOWERS OCCURRED AT KGJT AND SURROUNDING
AREAS. INTENSITY APPEARED TO BE WANING ALONG WITH AREAL COVERAGE
...THOUGH EXPECT SOME OF THIS ACTIVITY WILL PERSIST BEYOND
SUNRISE.

ACTIVITY WILL PICK UP AGAIN DURING THE AFTERNOON AS MOISTURE DEPTH
WILL BE NEAR ITS PEAK WITH THIS MONSOONAL SURGE. DEWPOINTS WERE IN
THE MID 50S TO AROUND 60 ACROSS THE FORECAST AREA EARLY THIS
MORNING AND WILL LIKELY SHOW LITTLE CHANGE THROUGHOUT THE DAY
ACCORDING TO GUIDANCE. SIMILARLY...PRECIPITABLE WATER IS PROGGED
TO REMAIN ABOVE 1 INCH AND WILL PROBABLY COME IN NEAR 1.2 INCHES
IN THE 12Z/GJT SOUNDING. COMBINE THIS DEEP MOISTURE WITH THE WELL
ADVERTISED SHORTWAVE TRAVERSING THE NORTHERN PORTION OF THE
FORECAST AREA DURING THE AFTERNOON AND ADDITIONAL HEAVY RAINFALL
AND LOCALIZED FLOODING SEEMS CERTAIN. THEREFORE...WILL CONTINUE TO
THE FLASH FLOOD WATCH ACROSS ALL BUT EXTREME SOUTHWEST COLORADO
AND SOUTHEAST UTAH. NEAR THE FOUR CORNERS MODELS INDICATED
THUNDERSTORM COVERAGE LIMITED SO SEE NO REASON TO ADD TO THE WATCH
AT THIS TIME.

EXPECT ANOTHER COOL DAY AS CLOUDS AND SHOWERS DOMINATE. MET
GUIDANCE BETTER THAN MAV YESTERDAY...BUT STILL TOO COOL FOR THE
MOST PART. THEREFORE...WILL CONTINUE TO FORECAST SOMEWHERE BETWEEN
THE TWO.

TODAY/S SHORTWAVE WILL CONTINUE TO ROTATE CLOCKWISE ACROSS THE
TOP OF THE RIDGE...WITH THE TROUGH AXIS STILL EXTENDING ACROSS
NORTHWEST CO THROUGH WED MID-MORNING. WHILE SHOWERS AND
THUNDERSTORMS WILL WIND DOWN SOMEWHAT LATE THIS EVENING...THE
POSITION OF THE SHORTWAVE WILL KEEP MORE THAN THE USUAL NOCTURNAL
PRECIPITATION ON-GOING INTO WED MORNING. THE SHORTWAVE WILL
CONTINUE TO DROP SOUTHEAST THROUGH THE DAY...BRUSHING OUR EASTERN
EDGE. EXPECT A DOWNTURN IN SHOWERS AND THUNDERSTORMS ON WED AS
COMPARED TO TODAY. HOWEVER THE STILL NEARBY SHORTWAVE COMBINED
WITH LINGERING MOISTURE AND DAYTIME HEATING WILL KEEP GOOD
COVERAGE OF CONVECTION OVER THE FORECAST AREA...FAVORING THE
EASTERN MOUNTAINS. AGAIN EXPECT THAT SOME SHOWERS COULD BE HEAVY.
AND WITH THE RECENT HEAVY RAINS...LOCALIZED FLOODING MAY AGAIN BE
A CONCERN.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 400 AM MDT TUE JUL 29 2014

THE DRYING TREND WILL BE MORE PRONOUNCED THROUGH SATURDAY AS OUR
SUMMERTIME HIGH PRESSURE RIDGE GETS PUSHED WEST BY THE EXITING
SHORTWAVE. THIS IS A LESS FAVORABLE POSITION FOR MONSOONAL
MOISTURE TO STREAM INTO THE AREA FROM THE SOUTH...BUT EXPECT THAT
ENOUGH MOISTURE WILL LINGER FOR SOME SHOWERS AND THUNDERSTORMS.
THESE WILL MOSTLY BE OVER THE HIGHER TERRAIN DURING THE AFTERNOON.

WITH LESS CLOUDS/PRECIPITATION...TEMPERATURES WILL BEGIN TO
REBOUND ON THU. HOWEVER HIGHS WILL REMAIN A COUPLE DEGREES OFF
NORMAL.

COOLER AND WETTER CONDITIONS ARE EXPECTED SUNDAY INTO MONDAY AS
MODELS PICKING UP ON AN EASTERLY WAVE MOVING INTO THE AREA FROM
THE SOUTHWEST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1034 AM MDT TUE JUL 29 2014

SCATTERED SHOWERS WILL MOVE SLOWLY EAST OVER THE CENTRAL AND NW CO
MOUNTAINS EAST OF OF A LINE FROM KCAG TO KRIL TO KGUC...CAUSING
LOCAL MOUNTAIN OBSCURATIONS. THIS ACTIVITY WILL HAVE LITTLE
IMPACT ON FLIGHT OPERATIONS.

MUCH LIKE YESTERDAY...DEEP MONSOONAL MOISTURE WILL FUEL SCATTERED
TO NUMEROUS THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH RAIN
SHOWERS PERSISTING OVERNIGHT. THERE IS A GOOD CHANCE THAT SOME
STORMS WILL MOVE OVER AREA TAF SITES THROUGH 06Z THIS EVENING...
WITH A SLOWLY DIMINISHING CHANCE AFTER 06Z. A MAJORITY OF THESE
STORMS WILL BE CAPABLE OF GENERATING HEAVY RAIN WHICH WILL LIKELY
RESULT IN IFR VSBY. IN ADDITION...SOME STORMS MAY GENERATING
OUTFLOW WINDS OF 30 MPH OR MORE.

&&

.HYDROLOGY...
ISSUED AT 400 AM MDT TUE JUL 29 2014

HIGH PRECIPITABLE WATER CONTENT AND EMBEDDED DISTURBANCE WITHIN
THE MONSOON FLOW WILL CONTINUE THE POTENTIAL FOR HEAVY RAIN AND
FLASH FLOODING THIS AFTERNOON AND EVENING OVER CENTRAL AND NW CO
AND NE UTAH.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH THIS EVENING FOR COZ001>014-017>020-
     022-023.

UT...FLASH FLOOD WATCH THROUGH THIS EVENING FOR UTZ023>025-027-028.

&&

$$

UPDATE...CC
SHORT TERM...NL/EH
LONG TERM...EH/NL
AVIATION...CC
HYDROLOGY...TGJT



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