Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 181121
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
521 AM MDT FRI JUL 18 2014

.SYNOPSIS...MOISTURE WILL INCREASE FROM THE WEST AGAIN TODAY... THEN
REMAIN IN PLACE THROUGH THE WEEKEND. DRIER AIR WILL RETURN TO THE
AREA MONDAY.

&&

.DISCUSSION...A WEST TO NORTHWEST FLOW REMAINS IN PLACE OVER THE
FORECAST AREA THIS MORNING. THIS HAS STARED TO DRAW SOME MOISTURE
THAT WAS OVER NEVADA INTO UTAH. IN FACT...A FEW VERY WEAK SHOWERS
DID MANAGE TO DEVELOP OVER PORTIONS OF NORTHERN UTAH AND SOUTHWEST
WYOMING OVERNIGHT IN CONJUNCTION WITH A SHORTWAVE DISTURBANCE
CROSSING UTAH. EXPECT SHOWER AND THUNDERSTORM ACTIVITY TO INCREASE
THROUGHOUT THE DAY AS MOISTURE CONTINUES TO INCREASE AND ADDITIONAL
DISTURBANCES RIPPLE THROUGH THE AREA. FOCUS LOOKS TO BE OVER CENTRAL
UTAH THIS AFTERNOON AND SHIFTING SLIGHTLY NORTH BY THIS EVENING AS A
SUBTLE WAVE CURRENTLY OVER EAST-CENTRAL NEVADA LIFTS ACROSS THE
AREA. SOME CONCERN EXISTS FOR GUSTY OUTFLOW WINDS WITH THE SHOWERS
DUE TO THE DRY LOW LEVELS...BUT NOT A MAJOR CONCERN FOR HEAVY RAIN
WITH PWATS PROGGED TO BE IN THE 0.7-0.9 INCH RANGE.

MODELS HAVE A WEAK BOUNDARY SLIPPING INTO NORTHERN UTAH THIS
EVENING...ESTABLISHING AN AREA OF WEAK LOW-LEVEL CONVERGENCE ACROSS
CENTRAL UTAH BY SATURDAY WHILE SLIGHTLY DRIER AIR SPREADS INTO THE
FAR NORTH. AS A RESULT...EXPECT ACTIVITY TO BE GREATEST CENTRAL AND
SOUTH ON SATURDAY. A SHORTWAVE DISTURBANCE IS THEN DEPICTED ON THE
GFS...EC AND NAM TO LIFT SOUTH TO NORTH THROUGH THE AREA SATURDAY
NIGHT THROUGH SUNDAY. SHOULD SEE NOCTURNAL SHOWERS ASSOCIATED WITH
THIS WAVE WITH BEST ACTIVITY ACROSS THE NORTH DURING PEAK HEATING
SUNDAY AFTERNOON/EVENING.

BEHIND THIS WAVE...DRIER AIR WILL SPREAD BACK INTO UTAH. WITH BROAD
HIGH PRESSURE DEVELOPING OVER EASTERN NEW MEXICO...IT WILL BE A
WHILE BEFORE MONSOONAL MOISTURE MAKES ITS WAY BACK TO UTAH. ALTHOUGH
THE GFS DOES WANT TO BRING SOME MOISTURE BACK TO THE AREA LATE
TUESDAY INTO WEDNESDAY...THE RIDGE WILL START TO FLATTEN...CUTTING
OFF THE MOISTURE TAP BY LATE NEXT WEEK.

&&

.AVIATION...SOUTHEAST WINDS ARE EXPECTED AT THE SLC TERMINAL THROUGH
ABOUT 17Z BEFORE SHIFTING TO THE NORTHWEST. THERE IS A 20 PERCENT
CHANCE OF THIS SHIFT HOLDING OFF UNTIL 18Z. THERE IS A SLIGHT CHANCE
OF THUNDERSTORMS LATE THIS AFTERNOON AND EVENING. THE MAIN THREAT
FROM THESE STORMS WILL BE GUSTY OUTFLOW WINDS. VFR CONDITIONS ARE
EXPECTED TO PREVAIL THROUGH THE TAF PERIOD.

&&

.FIRE WEATHER...MOISTURE AT MAINLY HIGH LEVELS WILL CONTINUE TO
SPREAD IN ACROSS UTAH FROM THE WEST TODAY AHEAD OF A WEAK TROUGH
MOVING IN FROM THE PACIFIC NORTHWEST. THIS TROUGH WILL MOVE INTO THE
NORTHWEST THIS EVENING WHICH CAUSES SOME CONCERN FOR DRY
THUNDERSTORMS AS LOW LEVELS WILL BE DRY BUT THE AMOUNT OF COVERAGE
APPEARS TO BE ISOLATED AT THIS TIME. THE MOISTURE POOL WILL BE THE
DEEPEST ACROSS CENTRAL UTAH SUPPORTING THE BEST CHANCE FOR ANY
WETTING RAINS WHILE FARTHER SOUTH THE AIR MASS WILL BE A LITTLE
DRIER. THIS PATTERN REPEATS ITSELF SATURDAY WITH MOISTURE IN THE
SAME PLACE AND ANOTHER TROUGH SWINGING IN ACROSS THE NORTHERN
PORTION OF THE STATE SATURDAY EVENING. THE PATTERN QUICKLY CHANGES
BY SUNDAY AS A SOUTHERLY FLOW DEVELOPS AHEAD OF A DISTURBANCE MOVING
UP THE LOWER COLORADO RIVER VALLEY. THIS DISTURBANCE WILL TAP
ADDITIONAL MOISTURE AND SWEEP IT IN ACROSS THE REGION SUNDAY.
HOWEVER...THIS MOISTURE SURGE WILL BE SHORT LIVED AS RAPID DRYING
FROM THE SOUTH IS EXPECTED TO MOVE IN MONDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

CHENG/STRUTHWOLF

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)



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