Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 302142
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
342 PM MDT SUN AUG 30 2015

.SYNOPSIS...A COLD FRONT OVER EASTERN UTAH WILL WEAKEN THIS
EVENING. WITH THE REGION BETWEEN A RIDGE OF HIGH PRESSURE FROM
THE UPPER MIDWEST TO THE SOUTHERN PLAINS AND A TROUGH OF LOW
PRESSURE OVER THE PACIFIC NORTHWEST...A GENERALLY DRY SOUTHWEST
FLOW WILL PREVAIL FOR MOST OF THE UPCOMING WEEK.

&&

.SHORT TERM...UPPER TROUGH CONTINUES TO MAKE ITS WAY ACROSS IDAHO
AND MONTANA THIS AFTERNOON. THE ASSOCIATED COLD FRONT HAS MOVED
INTO EASTERN UTAH AND SCATTERED SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED ALONG AND AHEAD OF THE BOUNDARY WHERE THE AIRMASS IS
MORE MOIST AND THERE ARE GOOD DYNAMICS. THESE STORMS WILL
CONTINUE INTO THE EARLY EVENING...WITH THE POTENTIAL TO PRODUCE
HEAVY RAIN AND GUSTY WINDS. TEMPERATURES BEHIND THE FRONT ARE
NOTICEABLY COOLER THAN YESTERDAY...WITH MAXES RUNNING IN EXCESS OF
10F BELOW VALUES OBSERVED YESTERDAY OVER NORTHERN UTAH.

AS THE TROUGH MOVES INTO THE CENTRAL UNITED STATES AND THE COLD
FRONT WEAKENS...A DRIER AND MORE STABLE AIRMASS WILL MOVE INTO THE
AREA...RESULTING IN A SLOW WARMING TREND FOR THE EARLY PART OF THE
WEEK. MOISTURE AND INSTABILITY WILL LINGER OVER SOUTHERN UTAH
TOMORROW...ALLOWING FOR SHOWER AND THUNDERSTORM ACTIVITY TO FOCUS
OVER THAT AREA. HOWEVER...CONVECTION SHOULD BE MORE ISOLATED IN
NATURE COMPARED TO TODAY. BY TUESDAY...MOISTURE WILL DECREASE
FURTHER SO ANY LINGERING CONVECTION SHOULD BE CONFINED TO THE
HIGHER TERRAIN. SOUTHWEST WINDS WILL ALSO BEGIN TO INCREASE AS A
PACIFIC NORTHWEST TROUGH SLOWLY MOVES ONSHORE.

&&

.LONG TERM (AFTER 12Z WEDNESDAY)...A PERSISTENT LONG WAVE TROUGH WILL
RESIDE OVER THE PACNW/NORTHERN ROCKIES STATES THROUGH THE LONG TERM
PERIOD. EMBEDDED SHORT WAVE ENERGY WILL GRADUALLY ROTATE AROUND THE
BASE OF THIS MID/LATE WEEK ALLOWING HEIGHTS TO GRADUALLY TREND LOWER
ACROSS THE EASTERN GREAT BASIN AS THIS ENERGY LIFTS NE THROUGH THE
NORTHERN ROCKIES...FURTHER IMPINGING ON THE PLAINS RIDGE AND HOLDING
IT WELL EAST. A DEEP AND DRY SOUTHWESTERLY FLOW WILL PERSIST AS
SUCH.

H7 TEMPS AT KSLC WILL EVER SO SLIGHTLY LOWER DURING THE WED-FRI
TIMEFRAME COINCIDENT WITH THE FALLING HEIGHTS...THOUGH TEMPS WILL
REMAIN NEAR SEASONAL NORMS THROUGH THE END OF THE WORKWEEK. DEEP
MIXING OF FAIRLY STRONG SOUTHWESTERLY FLOW ALOFT WILL AID BREEZY TO
GUSTY CONDITIONS ACROSS MUCH OF THE AREA.

GLOBAL MODELS LARGELY AGREE THAT AMPLIFICATION OF THE EASTERN
PACIFIC RIDGE FRIDAY WILL DRIVE INCREASED AMPLIFICATION OF THE LAST
SHORT WAVE OF THE SERIES...CARVING THE MEAN TROUGH FURTHER
SOUTH/EAST INTO THE NORTHERN GREAT BASIN FRIDAY NIGHT/SATURDAY. THIS
SAID...SOME TIMING/AMPLIFICATION ISSUES BEGIN TO ARISE BETWEEN
EC/GFS AND A FAIR AMOUNT OF SPREAD CONTINUES IN THE GEFS. THIS IS
ESPECIALLY TRUE REGARDING THE ATTENDANT COLD FRONTAL PASSAGE AS IT
WORKS EAST INTO THE FORECAST AREA /LATE FRIDAY GFS...SATURDAY
MORNING EC/. REGARDLESS...GLOBALS DO AGREE THAT FAIRLY STOUT CAA
WILL BE OCCURRING SATURDAY AND HAVE FURTHER LOWERED TEMPS TO WELL
BELOW SEASONAL NORMS NEXT WEEKEND. SAID FRONT DOES APPEAR QUITE
SHALLOW AND MOISTURE STARVED OWING TO A CONTINUATION OF DRY AND
BREEZY CONDITIONS THROUGH DAY 7.

&&

.AVIATION...NORTHERLY WINDS WILL PREVAIL AT KSLC THROUGH THE
REMAINDER OF THE AFTERNOON BEFORE SWITCHING BACK TO THE SOUTH
BETWEEN 02-03Z. THERE IS A 30 PERCENT CHANCE THIS WIND SHIFT IS
DELAYED UNTIL 04Z OR LATER. ISOLATED SHOWERS IN THE VICINITY OF THE
TERMINAL WILL CONTINUE THROUGH THE AFTERNOON...WITH A 20 PERCENT
CHANCE FOR GUSTY ERRATIC OUTFLOW WINDS. VFR CONDITIONS WILL PREVAIL
THROUGH THE PERIOD.

&&

.FIRE WEATHER...SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER
EASTERN UTAH ALONG AND AHEAD OF A COLD FRONT MOVING THROUGH THE
DISTRICT. THE CONVECTION WILL TEND TO DISSIPATE THIS EVENING WITH
THE LOSS OF DAYTIME HEATING AND THE WEAKENING OF THE BOUNDARY. A
DRIER AND MORE STABLE AIRMASS WILL MOVE BACK IN FOR THE EARLY PART
OF THE WEEK. WITH ANOTHER TROUGH APPROACHING...SOUTHWEST WINDS
WILL BECOME GUSTY DURING THE MIDDLE TO LATTER PART OF THE WORK
WEEK. THIS MAY PRODUCE AREAS OF CRITICAL FIRE WEATHER CONDITIONS
WHERE FUELS ARE DRY...PARTICULARLY OVER WESTERN UTAH.

&&

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

$$

SHORT TERM/FIRE WEATHER...TRAPHAGAN
LONG TERM...MERRILL
AVIATION...SEAMAN

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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