Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 302135
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
335 PM MDT TUE JUN 30 2015

.SYNOPSIS...STRONG HIGH PRESSURE ALOFT CENTERED ACROSS THE WESTERN
GREAT BASIN WILL SHIFT EAST TO THE FOUR CORNERS THIS WEEKEND.
SUFFICIENT MOISTURE WILL BE IN PLACE FOR AFTERNOON AND EVENING
THUNDERSTORMS THROUGH SATURDAY. INCREASING MOISTURE AND SOMEWHAT
COOLER TEMPERATURES WILL MOVE INTO THE REGION EARLY NEXT WEEK.

&&

.SHORT TERM (UNTIL 06Z SATURDAY)...THE UPPER HIGH CURRENTLY
POSITIONED ACROSS THE WESTERN GREAT BASIN WILL BEGIN A SLOW
EASTWARD SHIFT THROUGH THE REMAINDER OF THE WEEK. TERRAIN-BASED
CONVECTION THIS AFTERNOON APPEARS TO HAVE A LITTLE GREATER AREAL
COVERAGE...WITH SOME OF THIS ACTIVITY PRODUCING BRIEF AND LOCALLY
HEAVY RAINFALL.

THE WESTERN VALLEYS MAY BECOME INVOLVED WITH THIS CONVECTIVE
ACTIVITY THIS EVENING. THE NAM/GFS HAVE FOR A COUPLE OF MODELS
RUNS GRABBED ON TO A WEAK SHORTWAVE OVER EASTERN NEVADA WHICH ENDS
UP TRACKING SLOWLY EAST THROUGH WEST-CENTRAL UTAH THIS EVENING.
THIS SHORTWAVE WILL BE MOVING INTO A REGION OF FAIRLY HIGH CAPE
VALUES. THIS COMBINATION OF DYNAMIC SUPPORT AND PRIMED AIR MASS
SHOULD LEAD TO A PERIOD OF LOOSELY ORGANIZED CONVECTION ACROSS
WEST-CENTRAL THROUGH NORTHWEST UTAH THIS EVENING. GENERALLY WEAK
SHEAR INDICATES THAT STRONG CONVECTION IS UNLIKELY...THOUGH
STRONG MICROBURST STILL A GOOD BET THIS EVENING.

MODESTLY DRIER AIR /LOWER PWAT VALUES/ WILL WORK INTO THE REGION
FOR THE LATTER HALF OF THE WEEK. STILL LOOKING AT TERRAIN-BASED
CONVECTION BOTH DAYS...THOUGH THE AREAL COVERAGE WILL LIKELY BE
REDUCED WHEN COMPARED TO THE PRIOR COUPLE OF DAYS.

.LONG TERM (AFTER 06Z SATURDAY)...DRIER CONDITIONS CONTINUE THROUGH
SATURDAY ACROSS THE FORECAST AREA WITH THE RIDGE AXIS OVERHEAD. THIS
WILL BRING A WARMING TREND IN TEMPERATURES ON SATURDAY...WITH
TEMPERATURES RISING TO AROUND 100F ONCE AGAIN ALONG THE WASATCH
FRONT.

GFS/EC CONTINUING TO SHOW THE RIDGE AXIS MOVING EAST
SUNDAY...RESULTING IN SOUTHERLY FLOW OVER THE AREA. THIS WILL DRAW
TROPICAL MOISTURE INTO THE AREA...BRINGING THE THREAT OF
SHOWERS/THUNDERSTORMS TO MUCH OF THE AREA. EARLIER GUIDANCE
INDICATED TROPICAL MOISTURE WOULD STICK AROUND INTO EARLY NEXT WEEK.
HOWEVER...MODELS NOW INDICATE MORE OF A WESTERLY COMPONENT TO THE
FLOW BY MONDAY AS ANOTHER PACIFIC NORTHWEST TROUGH FLATTENS THE
RIDGE. THIS WOULD ALLOW DRIER AIR TO MOVE BACK INTO AT LEAST
SOUTHERN AND WESTERN UTAH BY MONDAY AFTERNOON WITH THE DRYING TREND
INCREASING THROUGH DAY 7. FOR NOW...HAVE ONLY LOWERED POPS SLIGHTLY
BUT CURRENT FORECAST MAY BE TOO WET IF THE TREND IN GUIDANCE HOLDS.

&&

.FIRE WEATHER...THE STRONG HIGH PRESSURE OF THE PAST SEVERAL DAYS
WILL GRADUALLY SHIFT FROM THE WESTERN GREAT BASIN TO THE FOUR
CORNERS REGION BY THIS WEEKEND. FOR THE BALANCE OF THE WEEK
SUFFICIENT MOISTURE WILL EXIST TO SPAWN CONVECTION ACROSS THE
HIGHER TERRAIN DURING THE AFTERNOON AND EVENING HOURS...WITH SOME
OF THIS ACTIVITY SPILLING INTO THE WESTERN AND SOUTHERN VALLEYS
DURING THE LATE AFTERNOON AND EVENING HOURS. ONCE THE HIGH
PRESSURE SHIFTS TO THE FOUR CORNERS MOISTURE WILL INCREASE AS WILL
THE AREAL COVERAGE OF CONVECTION HEADING INTO EARLY NEXT WEEK. THE
INCREASE IN CLOUD COVER/PRECIP ALONG WITH MODESTLY COOLER AIR
ALOFT WILL LEAD TO TEMPERATURES FALLING BACK TO NEAR NORMAL LEVELS
BEGINNING SUNDAY.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE SLC TERMINAL THROUGH
THE TAF PERIOD. NORTHWEST WINDS THIS AFTERNOON ARE EXPECTED TO
SWITCH TO THE SOUTHEAST BETWEEN 0300-0500 UTC.  THERE IS A 20
PERCENT CHANCE THAT THE TERMINAL WILL BE IMPACTED BY OUTFLOW WINDS
FROM SHOWERS AND STORMS IN THE AREA BETWEEN 0000-0600 UTC.

&&

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

$$

SHORT TERM/FIRE WEATHER...CONGER
LONG TERM...TRAPHAGAN
AVIATION...GRAHAM

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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