Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 022140
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
340 PM MDT SUN AUG 2 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 147 PM MDT SUN AUG 2 2015

A SMALL AND TIGHT CYCLONE ASSOCIATED WITH A 500-300MB DEFORMATION
ZONE WAS ROTATING ACROSS SW MESA COUNTY LATE THIS AFTERNOON. THIS
FEATURE WAS MOVING NORTH AT 5-10 MPH WITH WIDESPREAD RAIN AND
ISOLATED THUNDERSTORMS...AND HAS BEEN CAPTURED WELL IN THE NAM12.
IT WILL LIFT FROM THE I-70 CORRIDOR INTO THE PICEANCE BASIN LATE
THIS AFTERNOON AND EVENING. LIGHT TO MODERATE SHOWERS HAVE BEEN
ASSOCIATED WITH THIS DISTURBANCE. HOWEVER SOUTH OF THIS LINE
CONVECTION WILL BECOME MORE INTENSE THROUGH THE LATE AFTERNOON AND
EVENING. A STRONGER ROTATION WAS WORKING NORTHWARD INTO SE UTAH ON
THE NOSE OF THE 35KT JET. THIS WILL POTENTIALLY PRODUCE HEAVY RAIN
SHOWERS FAVORING SE UTAH AND FAR SW COLORADO THROUGH THIS EVENING.
STORMS WILL ALSO BECOME WIDESPREAD OVER THE SAN JUAN MTNS INTO
THIS EVENING.

THE INTENSITY OF SHOWERS AND THUNDERSTORMS WILL GRADUALLY WANE
AFTER MIDNIGHT...FIRST AS DIURNAL EFFECTS END...AND ALSO AS
LINGERING SMALLER SCALE BOUNDARY INTERACTIONS DIMINISH.

THE ABOVE MENTIONED LARGER ROTATION/SHORTWAVE MOVING INTO
SOUTHERN UT THIS EVENING WILL SLOWLY TRACK NORTHWARD INTO CENTRAL
UT BY MON MORNING. THIS FEATURE WILL THEN TRACK NORTH-NORTHEAST
ACROSS NORTHEAST UT/NORTHWEST CO ON MON...AND INTO SE WY MON
EVENING. AS A RESULT...WE WILL SEE THE BETTER AREA OF
SHOWERS/THUNDERSTORMS SHIFT FROM SOUTH TO NORTH THROUGH THE NEXT
12-18 HOURS. DRIER AIR WILL BEGIN TO WORK INTO THE SOUTHEAST
CORNER LATE TONIGHT. AND WHILE PRECIPITATION WILL STILL COVER MUCH
OF THE SOUTHERN HALF DURING THE MORNING...THAT AREA WILL SEE A
DRYING TREND THROUGH THE DAY. HOWEVER SOME DIURNAL AND TERRAIN
INDUCED THUNDERSTORMS WILL STILL FIRE IN THE AFTERNOON...
ESPECIALLY OVER THE HIGHER TERRAIN. OVER THE NORTH WIDESPREAD
SHOWERS WITH INCREASING THUNDERSTORM ACTIVITY IN THE AFTERNOON
WILL BE THE CALL FOR THE DAY AS THE DISTURBANCE MOVES OVER THAT
AREA. A FEW STORMS MAY PRODUCE LOCALLY HEAVY RAIN.

ACTIVITY WILL DIMINISH AS THE SHORTWAVE MOVES INTO WY MON EVENING
AND WITH THE LOSS OF DAYTIME HEATING. COOLER OVERNIGHT LOWS ARE
EXPECTED...ESPECIALLY OVER THE SOUTH WHERE MORE DRYING WILL HAVE
OCCURRED BY EARLY TUE MORNING.


.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 147 PM MDT SUN AUG 2 2015

THE RIDGE REBOUNDS ON TUE WITH WARMER AND DRIER CONDITIONS
EXPECTED. THIS WILL PERSIST THROUGH LATE IN THE WORK WEEK BEFORE
THE NEXT SURGE OF MONSOONAL MOISTURE MAKES IT INTO THE REGION.
MODELS DO SHOW A SHORTWAVE TROUGH PASSING FROM WEST TO EAST ACROSS
THE NORTHERN TIER STATES AND BRUSHING OUR FORECAST AREA WED
NIGHT/THU. AS A RESULT...WINDS SHOULD INCREASE ACROSS THE NORTH
WED AFTERNOON. BUT SO FAR...MODELS HAVE INDICATED ONLY MINOR
IMPACTS FROM THIS PASSING WAVE.

MOISTURE WILL BEGIN TO RETURN FRI NIGHT AND ESPECIALLY ON SAT FOR
A POTENTIALLY WET NEXT WEEKEND.

HIGH TEMPERATURES WILL CLIMB TO NORMAL OR A LITTLE ABOVE NORMAL
VALUES THROUGH THE WORK WEEK. THEN WILL COOL FOR THE WEEKEND.
IN THE DRIER AIR...LOW TEMPERATURES WILL BE ON THE COOL SIDE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY NOON)
ISSUED AT 823 AM MDT SUN AUG 2 2015

SHOWERS AND STORMS WILL EXPAND ACROSS THE ENTIRE REGION THIS
AFTERNOON...SHOWERS BECOMING NUMEROUS SOUTH OF I-70. THE STRONGEST
CELLS WILL PRODUCE 4SM +TSRA CIGS BKN030. ILS CIGS AND
OBSCURATIONS WILL BE COMMON AT MOUNTAIN TAF SITES AS
SHOWERS/STORMS MOVE OVERHEAD. SHOWERS WILL CONTINUE OVERNIGHT.
WITH A SHORT WAVE PASSING THROUGH UTAH AND COLORADO THIS AFTERNOON
AND TONIGHT...CONVECTIVE CELLS WILL BE LONGER LIVED AND MERGERS
MAY OCCUR TO ENHANCE +SHRA WITH FREQUENT LIGHTNING. SCATTERED
STORMS AND SHOWERS WILL CONTINUE OVERNIGHT WITH A 40 PERCENT
CHANCE OF -SHRA/-TSRA AT KVEL KCNY KGJT AFTER 06Z. OTHER TAF
SITES BEST CHANCES OF -TSRA/SHRA OCCUR BEFORE 06Z.


&&

.HYDROLOGY...
ISSUED AT 147 PM MDT SUN AUG 2 2015

A FLASH FLOOD WATCH IS IN EFFECT UNTIL 3AM MON MORNING. DEEP
MONSOONAL MOISTURE WILL CONTINUE TO STREAM INTO THE AREA FROM THE
SOUTH THROUGH THIS EVENING. IN ADDITION...ONE TIGHT ROTATION
LIFTING ACROSS WEST CENTRAL COLORADO THIS AFTERNOON...AND A LARGER
LOW PRESSURE SHORTWAVE APPROACHING THE FOUR CORNERS THIS AFTERNOON
WILL CONTINUE TO IMPACT THE AREA AS THEY SHIFT NORTHWARD THIS
EVENING AND OVERNIGHT. THESE DISTURBANCES IN COMBINATION WITH THE
DEEP MOISTURE...WILL CONTINUE TO PRODUCE WIDESPREAD SHOWERS AND
THUNDERSTORMS. HEAVY RAIN IS EXPECTED WITH SOME STORMS...
ESPECIALLY ACROSS THE SOUTHERN TWO THIRDS OF THE CWA. IN
ADDITION...RECENT RAINS HAVE RESULTED IN LOCALLY SATURATED SOILS
ACROSS PORTIONS OF SOUTHWEST CO AND SOUTHEAST UT. THEREFORE FLASH
FLOODING...AS WELL AS DEBRIS AND MUD FLOWS ACROSS ROADWAYS...HIGH
FLOWS IN SMALLER CREEKS AND STREAMS...AND EXCESSIVE RUNOFF IN
NORMALLY DRY WASHES WILL BE POSSIBLE ACROSS THE WATCH AREA.

THUNDERSTORMS AND RAIN INTENSITY WILL GRADUALLY DECREASE AFTER
MIDNIGHT.

ALSO SEE THE SHORT TERM DISCUSSION ABOVE.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR COZ006>012-014-
     017>023.

UT...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR UTZ022-027>029.

&&

$$

SHORT TERM...JOE+EH
LONG TERM...EH
AVIATION...PF/JOE
HYDROLOGY...EH


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