Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 302208 AAA
AFDSLC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
408 PM MDT THU JUL 30 2015

.UPDATE...ADDED ISOLATED MENTION OF TSTMS TO ABOUT THE SRN 1/4 OF
THE CWA FOR THE REST OF THIS AFTN AND THIS EVE AS THE MOISTURE
OVER SRN UTAH HAS SET OFF A FEW SMALL CELLS OVER WASHINGTON CO AND
NEAR LAKE POWELL THAT ARE NOT TIED TO THE TERRAIN. EXPECT THIS
ACTIVITY TO EXPAND A BIT THROUGH EARLY EVE THEN TEND TO DIMINISH.
THERE IS A POSSIBILITY THAT A FEW OF THESE COULD PERSIST OVERNIGHT
AS THE DEEPER MOISTURE TO OUR S CONTINUES TO SEEP NORTH.

&&

.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE REGION
THROUGH THE END OF THE WEEK...THEN SHIFT EASTWARD EARLY NEXT WEEK.
MOISTURE WILL SLOWLY INCREASE ACROSS SOUTHERN UTAH THROUGH
FRIDAY...THEN SPREAD SLOWLY NORTHWARD LATE IN THE WEEKEND.

&&

.DISCUSSION...AN UPPER-LEVEL RIDGE AXIS EXTENDS FROM THE SOUTHERN
PLAINS WESTWARD THROUGH UTAH AND NEVADA INTO NORTHERN CALIFORNIA.
RETURN FLOW AROUND THE RIDGE HAS LIFTED PWATS ABOVE 1.0" OVER AREAS
SOUTHWEST OF THIS AXIS...INCLUDING FAR SOUTHERN UTAH...BUT
CONDITIONS ARE MUCH DRIER FURTHER NORTH. THIS AFTERNOON AND
EVENING...ISOLATED SHOWERS AND STORMS ARE EXPECTED OVER THE HIGHER
TERRAIN ACROSS THE SOUTH WHILE CLEAR SKIES PREVAIL ELSEWHERE. THIS
SETUP WILL PERSIST THROUGH SATURDAY AS AN APPROACHING CUTOFF LOW
OFFSHORE GRADUALLY TURNS FLOW MORE SOUTHERLY AND ALLOWS MOISTURE TO
CREEP NORTHWARD OVER THE SOUTHERN HALF OF THE CWA.

ON SUNDAY...BOTH THE EC AND GFS DEVELOP A VORTICITY MAX OVER
SOUTHERN UTAH IN AN AREA OF ENHANCED CONVECTION. WHILE THE GFS HINTS
AT THIS FEATURE PROPAGATING INTO NORTHERN UTAH AND INCREASING POPS
SOMEWHAT...THE EC SEEMS TO GO TOO FAR WITH ITS DEVELOPMENT. FOR
NOW...THE FORECAST LEANS TOWARD DRIER CONDITIONS GIVEN LOW
CONFIDENCE.

NEXT WEEK...MODELS ARE STRUGGLING TO RESOLVE THE TIMING AND PHASING
OF A CUTOFF LOW ALONG THE CALIFORNIA COAST AN UPPER-LEVEL TROUGH
DROPPING SOUTHWARD OFF THE BRITISH COLUMBIA COAST. THE EC SOLUTIONS
RESULTS IN A MORE WESTERLY FLOW COMPONENT WHEREAS THE GFS BUILDS A
RIDGE AND VERY WARM TEMPERATURES OVERHEAD. BOTH CASES SUGGEST
PRIMARILY DRY CONDITIONS OVER NORTHERN UTAH...BUT THE GFS SOLUTION
WOULD ALLOW FOR MOISTURE TO CREEP INTO THE SOUTHERN CWA
AND AID IN CONVECTION SOUTH AND EAST OF THE MOUNTAINS.


&&

.AVIATION...NORTHERLY WINDS WILL PREVAIL AT THE SLC TERMINAL
THROUGH AROUND 04Z BEFORE RETURNING TO SOUTHERLY. OTHERWISE...EXPECT
VFR CONDITIONS UNDER MOSTLY CLEAR SKIES THROUGH THE NIGHT.

&&

.FIRE WEATHER...THE POTENTIAL OF ISOLATED HIGH BASED THUNDERSTORMS
AND DRY LIGHTNING WILL INCREASE THROUGH THE UPCOMING WEEKEND FROM
SOUTH TO NORTH. MOISTURE CURRENTLY ALONG AND SOUTH OF THE UT/AZ
BORDER WILL GRADUALLY SPREAD NORTH BEGINNING SATURDAY AHEAD OF A
DEVELOPING WEAK DISTURBANCE THAT WILL MOVE THROUGH THE DISTRICT
SUNDAY INTO MONDAY. MOISTURE IS EXPECTED TO REMAIN PRIMARILY AT THE
MID AND UPPER LEVELS DURING THAT TIME OWING TO THE POTENTIAL OF SOME
DRY LIGHTNING STRIKES AND A HIGH LIKELIHOOD OF GUSTY WINDS WITH ANY
STORMS THAT FORM. AREAL COVERAGE OF THESE ISOLATED STORMS IS
EXPECTED TO BE GREATEST SUNDAY INTO MONDAY. SOUTHWESTERLY FLOW ALOFT
WILL SPREAD IN BEHIND THIS DISTURBANCE TUESDAY ALLOWING BOTH A
FURTHER DRYING TREND AND A NET INCREASE OF SOUTHERLY SURFACE WINDS
FOR THE MID WEEK PERIOD.

&&

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

$$

PUBLIC...RUTZ/WILENSKY
AVIATION...CHENG
FIRE WEATHER...MERRILL

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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