Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 251658
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1058 AM MDT TUE AUG 25 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 325 AM MDT TUE AUG 25 2015

HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE CENTRAL ROCKIES
TODAY...WITH ITS CENTER SHIFTING FROM SOUTHWEST CO TODAY...TO
SOUTHEAST CO/NORTHEAST NM ON WED. THIS SHIFT IS THE RESULT OF THE
HIGH BEING NUDGED EAST AS A DISTURBANCE ROTATES AROUND THE
BACKSIDE OF THE HIGH. ALSO MOISTURE THAT HAS ACCUMULATED OVER THE
NORTHERN BAJA REGION WILL BEGIN TO HEAD NORTHWARD TODAY CARRIED BY
THE SOUTHERLY FLOW UP THE WEST SIDE OF THE HIGH. THIS MOISTURE
WILL BEGIN TO REACH INTO OUR FORECAST AREA BEGINNING THIS
AFTERNOON. TEMPERATURES WILL REMAIN ABOVE NORMAL FOR ONE MORE DAY
AND WILL PROVIDE GOOD THERMAL LIFT. THEREFORE WE SHOULD SEE AN
UPTICK IN SHOWERS AND THUNDERSTORMS THIS AFTERNOON. THIS ACTIVITY
WILL AGAIN FAVOR THE SOUTH AS THE MOISTURE REMAINS MORE PLENTIFUL
THERE.

MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTHWARD TONIGHT AND
THROUGH WED. THEN BY MIDDAY WED THE NAM12 SHOWS PRECIPITABLE WATER
VALUES INCREASING TO 1.5 INCHES IN EAST-CENTRAL UT...WITH 1.5 INCHES
IN THE UINTA BASIN AND WESTERN CO BY LATE WED AFTERNOON. MODELS HAVE
COME INTO BETTER AGREEMENT WITH THE TRACK AND TIMING OF THE
DISTURBANCE INTO SOUTHERN CA-CENTRAL AZ TODAY. THIS SHORTWAVE TROUGH
THEN HEADS NORTH INTO NV AND UT OVERNIGHT SO NOCTURNAL STORMS ARE
EXPECTED TONIGHT...MAINLY IN THE SOUTHWEST THIRD AND FAR WESTERN
EDGE OF OUR FORECAST AREA. WHILE THE LOW CENTER MOVES INTO
WYOMING BY LATE WED...THE NORTHWEST TO SOUTHEAST ORIENTED TROUGH
WILL PASS OVER EASTERN UT/WESTERN CO THROUGH THE DAY. THIS WILL
PROVIDE DYNAMICAL SUPPORT AND INSTABILITY...AND WILL BE TIMED
FAVORABLY FOR DIURNAL ENHANCEMENT. WIDESPREAD SHOWERS AND
THUNDERSTORMS WILL SPREAD FROM THE SOUTHWEST THIRD OF THE AREA
EARLY IN THE DAY...TO PRETTY MUCH COVER THE ENTIRE FORECAST AREA
DURING THE AFTERNOON. LOCALIZED HEAVY RAIN WILL BE POSSIBLE.

DUE TO THE INCREASED CLOUDS TONIGHT...LOW TEMPERATURES WILL BE MUCH
WARMER THAN RECENT READINGS...AND WELL ABOVE NORMAL FOR LATE AUG. ON
THE FLIP SIDE...THE INCREASED CLOUDS AND PRECIPITATION ON WED WILL
KEEP HIGH TEMPERATURES AS MUCH AS 15-20 DEGREES COOLER THAN TODAY`S
HIGHS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 325 AM MDT TUE AUG 25 2015

NUMEROUS SHOWERS/STORMS EXPECTED WEDNESDAY EVENING GIVEN TROUGH
PASSAGE AND A MOIST CONDITIONALLY UNSTABLE ENVIRONMENT. BOOSTED
POPS BY A NOTCH AS CONFIDENCE IS RISING THAT MUCH OF THE WESTERN
SLOPE WILL RECEIVE WETTING RAINS. A FEW HEAVY RAINERS WILL OCCUR
GIVEN RELATIVELY LIGHT STEERING FLOW AND PWAT VALUES AROUND 1.25+
INCHES.  WITH WIND SHEAR IN THE 20-25 KT RANGE SHOULD PRECLUDE A
WIDESPREAD FLASH FLOOD THREAT.  IN ADDITION...SOIL CONDITIONS ARE
NOT AS MOIST AS THEY WERE 4-6 WEEKS AGO WHEN SHOWERS SEEMED TO BE
A DAILY OCCURRENCE.

SHOWERS/STORMS WILL BE ON THE DECREASE FROM THE WEST ON THURSDAY...
EXCEPT NW COLORADO WHERE CYCLONIC NORTHWEST FLOW LINGERS THROUGH
THE AFTERNOON HOURS. WITH RIDGE AXIS BUILDING OVER UTAH...SHOWERS
BECOME LESS NUMEROUS OVER THE ERN UTAH DESERT AND LOWER WRN
COLORADO VALLEYS.

FRIDAY THROUGH MONDAY...DAY TO DAY CHANGES WILL BE SUBTLE WITH
HIGH PRESSURE POSITIONED OVER THE DESERT SOUTHWEST AND TILTED
TOWARD THE NRN PLAINS. WEAK MONSOONAL TAP STILL PREVAILS EACH DAY
WITH DIURNAL DRIVEN SHOWERS OVER THE HIGH COUNTRY...PRIMARILY
LIMITED TO THE SAN JUAN MOUNTAINS AND ALONG THE COLORADO SPINE.
WITH THE PREVAILING FLOW FROM THE SOUTHWEST...THE REGION SHOULD
SEE CONSIDERABLY LESS HAZY SKIES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1037 AM MDT TUE AUG 25 2015

ISOLD SHOWERS AND THUNDERSTORMS WILL FORM OVER THE SOUTHERN
MOUNTAINS...BUT EXPAND ACROSS THE LOWER ELEVATIONS OF SW COLORADO
AND SE UTAH AFTER 21Z TODAY THROUGH THIS EVENING. THUNDERSTORMS
COULD MOVE OVER THE TAF SITES OF KTEX AND KDRO. SCATTERED SHOWERS
WITH A FEW THUNDERSTORMS WILL CONTINUE OVERNIGHT OVER ERN UTAH AND
SW COLORADO. CIGS MAY FALL BELOW ILS BREAKPOINTS AT KTEX/KDRO FROM
ANY PASSING SHOWERS OR STORMS THIS EVENING AND OVERNIGHT.
PRECIPITATION COVERAGE WILL INCREASE FROM WEST TO EAST WED
MORNING.

&&

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

$$

SHORT TERM...EH
LONG TERM...PF
AVIATION...CC


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