Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 211118
AFDSLC

AREA FORECAST DISCUSSION...CORRECTED SYNOPSIS
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
518 AM MDT THU AUG 21 2014

.SYNOPSIS...THE AIRMASS OVER THE FORECAST AREA WILL SLOWLY DRY
THROUGH FRIDAY...ALTHOUGH CONDITIONS WILL REMAIN UNSETTLED. A
COLD TROUGH WILL MOVE ACROSS NORTHERN UTAH FRIDAY NIGHT AND
SATURDAY. A BRIEF WARMING AND DRYING TREND IS EXPECTED SUNDAY AND
MONDAY BEFORE ANOTHER TROUGH IMPACTS THE AREA FOR THE MIDDLE OF
THE UPCOMING WEEK.

&&

.DISCUSSION...RATHER SLOW DRYING CONTINUING OVER THE REGION
TONIGHT. SATELLITE DERIVED PWS ARE PRIMARILY IN THE 0.6 TO 0.8
INCH RANGE COMPARED TO MORE LIKE 0.8 TO 1.0 INCH LAST NIGHT.
STILL...AN UNSTABLE AIRMASS REMAINS OVER THE AREA WITH A PACIFIC
TROUGH JUST TO THE NORTH AND AN UPPER LOW OVER SOUTHERN
CALIFORNIA. THE NORTHERN TROUGH HAS KEPT CONVECTION GOING
OVERNIGHT OVER FAR NORTHERN UTAH...THOUGH THE BEST SHOWERS REMAIN
OVER SOUTHERN IDAHO.

AS THE NORTHERN TROUGH CONTINUES EASTWARD...INSTABILITY WILL
REMAIN ENHANCED OVER NORTHWEST UTAH THROUGH THE AFTERNOON.
ADDITIONALLY...AS THE CALIFORNIA LOW MOVES INTO ARIZONA ADDITIONAL
INSTABILITY WILL MOVE INTO SOUTHERN UTAH. OTHERWISE...CONVECTION
THIS AFTERNOON WILL BE PRIMARILY TERRAIN BASED. BY FRIDAY...THE
FIRST PIECE OF THE PACIFIC NORTHWEST TROUGH MOVES EAST OF THE AREA
BUT THE MUCH STRONGER SECOND PIECE APPROACHES BY FRIDAY
AFTERNOON...ALLOWING INSTABILITY TO INCREASE OVER NORTHERN UTAH
ONCE AGAIN. GLOBAL MODELS ALL MOVE THE SOUTHERN LOW INTO FAR
SOUTHEAST UTAH BY FRIDAY AFTERNOON...AND THAT MAY BECOME A FOCUS
FOR CONVECTION AS WELL.

MODELS REMAIN IN GOOD AGREEMENT WITH REGARD TO THE COLD TROUGH FOR
FRIDAY NIGHT AND SATURDAY. THE FRONT PUSHES THROUGH NORTHERN UTAH
FRIDAY NIGHT/EARLY SATURDAY AND INTO CENTRAL AND SOUTHERN UTAH BY
SATURDAY AFTERNOON. THE ASSOCIATED TROUGH WILL FOLLOW CLOSE
BEHIND...PRODUCING A BROAD AREA OF PRECIP OVER NORTHERN UTAH AS IT
PASSES THROUGH. HAVE RAISED POPS WITH INCREASING CONFIDENCE.
MODELS ALSO APPEAR TO BE TRENDING SLIGHTLY COLDER WITH THE
SYSTEM...PARTICULARLY THE EC WHICH INDICATES 700 MB TEMPS AS LOW
AS +3C MOVING INTO FAR NORTHERN UTAH FOR SATURDAY...COMPARED TO
700 MB TEMPS OF +8C TO +10C JUST AHEAD OF THE SYSTEM. THE TRACK OF
THE SYSTEM WOULD KEEP SOUTHERN UTAH DRY...WITH JUST A LITTLE BIT
OF COOLING.

BY SUNDAY...THE TROUGH IS EXPECTED TO EXIT THE FORECAST
AREA...ALLOWING FOR A BRIEF WARMING AND DRYING TREND THROUGH
MONDAY. AFTER THAT...MODELS SHOW THE REGION BEING IMPACTING BY
ANOTHER TROUGH BEGINNING TUESDAY BUT HAVE DIVERGED ON THE DETAILS.
THE GFS REMAINS CONSISTENT...MOVING IN A SYSTEM SIMILAR TO THE
WEEKEND TROUGH MONDAY NIGHT AND TUESDAY THAT WOULD PRIMARILY
IMPACT NORTHERN UTAH. IN THE LATEST EC...THE TROUGH CLOSES OFF AS
IT DIVES DOWN THE PACIFIC COAST MONDAY NIGHT/TUESDAY BEFORE
SLOWING MOVING ACROSS THE AREA TUESDAY NIGHT THROUGH EARLY
THURSDAY...WHICH WOULD RESULT IN MORE WIDESPREAD PRECIPITATION.
HAVE LEANED TOWARD THE GFS AT THIS TIME AS IT HAS BEEN MORE
CONSISTENT. ALL MODELS INDICATE HIGH PRESSURE RETURNING BEHIND
THIS SYSTEM...AT LEAST FOR A TIME.

&&

.AVIATION...SOUTHERLY WINDS ARE EXPECTED AT THE SLC TERMINAL THROUGH
THE TAF PERIOD. WINDS WILL INCREASE AFTER 15Z AND ARE LIKELY TO BE
THE STRONGEST BETWEEN 17Z AND 21Z WHEN GUSTS TO 25 KT ARE EXPECTED.
CIGS SHOULD REMAIN ABOVE 7K FT BUT COULD TEMPORARILY LOWER TO UNDER
7KT FT AGL IN HEAVIER SHOWERS OR THUNDERSTORMS AFTER 18Z.


&&

.FIRE WEATHER...FIRE SEASON REMAINS ON STANDBY AS DEEP MONSOONAL
MOISTURE REFUSES TO EXIT THE REGION. ANOTHER COUPLE OF DAYS OF
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS
THE REGION THROUGH FRIDAY. THEN A SIGNIFICANT LOOKING COLD FRONT
WILL SWEEP ACROSS THE REGION SATURDAY BUT NOT BEFORE INTERACTING
WITH THE DEEP MOISTURE IN PLACE ACROSS THE NORTHERN AND CENTRAL
PORTIONS OF THE STATE PRODUCING WIDESPREAD RAIN...ESPECIALLY ACROSS
THE NORTH. SIGNIFICANT DRYING IS EXPECTED SUNDAY BEHIND THIS SYSTEM
AND IT WILL LINGER INTO MONDAY BUT ANOTHER SYSTEM IS EXPECTED TO
BRING ANOTHER ROUND OF UNSETTLED WEATHER COME TUESDAY OR WEDNESDAY.
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THIS PERIOD AND RH
VALUES WILL BE ELEVATED THROUGH SATURDAY BUT WILL LOWER SUNDAY AND
MONDAY.

&&

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

$$

PUBLIC...TRAPHAGAN
AVIATION/FIRE WX...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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