Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 261711
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1111 AM MDT TUE AUG 26 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 346 AM MDT TUE AUG 26 2014

TRANSITION DAY TODAY AS WE START TO SEE THE INFLUENCE OF STRONG
FALL LIKE SYSTEM DIGGING INTO THE GREAT BASIN. MOISTURE WRAPPING
AROUND THE SOUTHERN AND EASTERN FLANKS OF THE STRENGTHENING LOW
PRESSURE SYSTEM WILL BRING WIDESPREAD SHOWERS AND THUNDERSTORMS TO
MUCH OF WESTERN COLORADO AND EASTERN UTAH OVER THE NEXT FEW DAYS.
MODELS HAVE BACKED OFF A BIT ON POTENTIAL QPF VALUES THIS
AFTERNOON...BUT INCREASING DYNAMICS ASSOCIATED WITH THE
APPROACHING LOW AND AVAILABLE MOISTURE CLIMBING BACK TO AN INCH
ACROSS THE FOUR CORNERS WILL RESULT IN LOCALLY HEAVY RAINFALL BY
LATE THIS AFTERNOON...MAINLY OVER THE SAN JUANS AND ADJACENT
SOUTHERN VALLEYS. FOUR CORNERS REGION BEING HIGHLIGHT BY WPC FOR
EXCESSIVE RAINFALL OVER THE NEXT 24 TO 36 HOURS AND CURRENT FLASH
FLOOD WATCH REMAINS ON TRACK. BULK OF HEAVIER RAIN WILL BE HOLDING
OFF UNTIL LATE IN THE DAY BASED ON LATEST 06Z MODELS...SO HAVE
TWEAKED DAYTIME POPS AND QPF DOWN A BIT AND NUDGED OVERNIGHT
VALUES UP A BIT. HAVE ALSO EXTENDED THE FLASH FLOOD WATCH THROUGH
9 AM WEDNESDAY MORNING AS BEST FORCING ASSOCIATED WITH THE LOW
MOVING IN OVERNIGHT. TEMPS WILL BE DOWN A FEW DEGREES TODAY WITH
INCREASED CLOUD COVER AND LOW LEVEL MOISTURE.

THE UPPER LOW SWINGS INTO WRN UT THIS EVENING. SHOWERS AND SCATTERED
THUNDERSTORMS CONTINUE IN DIFLUENT FLOW AHEAD OF THE LOW.
INSTABILITY NOT GREAT PER MODEL LIFTED INDEX AND CAPE...BUT MOISTURE
IS AMPLE ESPECIALLY ACROSS THE SOUTH WHERE LIFT SHOULD BE AIDED BY
SOUTHERLY UPSLOPE FLOW INTO THE SAN JUANS.

THE UPPER LOW CENTER IS FORECAST TO BE OVER NE UT BY NOON WED AND
ACROSS WRN CO WED EVENING. LARGE-SCALE ASCENT ASSOCIATED WITH THE
LOW CENTER PLUS LOWER LEVEL MOISTURE CONVERGENCE AS THE MOISTURE
STREAM WRAPS INTO THE LOW WILL KEEP RAIN/RAIN SHOWERS WITH EMBEDDED
THUNDERSTORMS A DECENT BET FOR MUCH OF THE CENTRAL AND NORTH WED.
UPPER JET CUTS ACROSS THE 4 CORNERS BY MIDDAY ENTRAINING SOMEWHAT
DRIER AIR ALOFT. RAIN COVERAGE LOOKS LESS ACROSS THE SOUTH BUT
STORMS COULD BE STRONGER WITH MODEST CAPE/INSTABILITY...SOME DRYING
ALOFT AND BETTER VERTICAL SHEAR WITH THE JET PASSING. NUDGED THE WED
POPS UPWARD TONIGHT AND WED. TEMPS REMAIN ON THE COOL SIDE OF
NORMAL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 346 AM MDT TUE AUG 26 2014

THE UPPER TROUGH MOVES INTO ERN UT BY THURSDAY AFTERNOON.
NORTHWESTERLY FLOW DEVELOPS BEHIND THE TROUGH WHICH WILL KEEP
SCATTERED PRECIP ACROSS THE CO MTNS. DRIER AIR SPREADS ACROSS ERN UT
INTO FAR WRN CO THU.

FLAT RIDGING FRIDAY GIVES WAY TO BRIEF PERIOD OF ZONAL FLOW
SATURDAY AND EARLY SUNDAY...BEFORE HEIGHTS DROP ONCE AGAIN AS
ANOTHER PACIFIC SYSTEM SLIDES ACROSS WYOMING. THIS WAVE CLIPS THE
NORTHERN HALF OF THE FORECAST AREA...BRINGING A CHANCE FOR SHOWERS
AND THUNDERSTORMS LATE SUNDAY AND SUNDAY NIGHT WITH A FEW SHOWERS
LINGERING INTO THE DAY ON MONDAY. TEMPS WILL MODERATE A BIT FRIDAY
AND SATURDAY...BEFORE DROPPING BACK BELOW SEASONAL NORMS AS WE
MOVE INTO THE NEW WORK WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY NOON)
ISSUED AT 1110 AM MDT TUE AUG 26 2014

SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST THROUGH
WEDNESDAY...WITH COVERAGE INCREASING THROUGHOUT THIS AFTERNOON
AND TONIGHT. EXPECT AREAS OF MVFR CIGS TO DEVELOP TONIGHT AS
RAINFALL INCREASES...ESPECIALLY SOUTH OF INTERSTATE 70. HEAVY
RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS WILL OCCUR NEAR THE
STRONGER STORMS. ALL SITES WILL SEE THE POTENTIAL FOR SHOWERS AND
THUNDERSTORMS EXCEEDING 50 PERCENT THROUGH WEDNESDAY.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR COZ018-019-
     021>023.

UT...NONE.
&&

$$

SHORT TERM...JDC/JAD
LONG TERM...JAD/JDC
AVIATION...JDC/JOE



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