Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 310253
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
853 PM MDT SAT MAY 30 2015

.SYNOPSIS...HIGH PRESSURE ALOFT STRENGTHENING ACROSS THE INTERIOR
WEST WILL BRING A SIGNIFICANT WARMING TREND TO THE REGION THROUGH
THE REST OF THE WEEKEND. A COLD FRONT ASSOCIATED WITH A STORM SYSTEM
OVER THE PACIFIC NORTHWEST WILL ENTER NORTHERN UTAH EARLY NEXT
WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE BUILDING IN FROM
THE SOUTHWEST. AMDAR 400-250MB WIND OBSERVATIONS SHOW A 50-80KT
ANTICYCLONIC JET OVER THE PACIFIC NORTHWEST AND INTO THE ROCKIES.
GOES/GPS/RAP/00Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.35"-0.50" SOUTHWEST VALLEYS AND MOUNTAINS...TO
0.75"-1.0" ACROSS THE NORTHERN AND EASTERN VALLEYS.

WARMING ALOFT AND LOSS OF DIURNAL INSTABILITY WILL COMBINE TO THIN
OUT SHOWERS THIS EVENING. HAVE REMOVED ALL MENTION OF THUNDER AND
RESTRICTED SHOWERS THROUGH MIDNIGHT TO NORTHEAST UTAH AND
SOUTHWEST WYOMING TRACKING A WEAK SHORTWAVE ATOP THE BUILDING
RIDGE.

OTHERWISE TWEAKED SKY BASED ON SATELLITE TRENDS AND
TEMPERATURES/DEWPOINTS BASED ON OBSERVATIONS AND LAMP DATA. REST
UNCHANGED.

&&

PREVIOUS DISCUSSION...
HIGH PRESSURE IS IN PLACE OVER THE FORECAST AREA THIS
AFTERNOON...RESULTING IN A WARMING TREND WITH SOME DRYING. PWS ARE
STILL IN EXCESS OF 0.5 INCH OVER MUCH OF THE STATE...BUT
CONVECTION IS STRUGGLING A BIT TO FORM OVER THE HIGHER TERRAIN. SO
FAR IT IS MOSTLY CONFINED TO SOUTHERN UTAH...BUT SOME ADDITIONAL
DEVELOPMENT IS EXPECTED BEFORE THE LOSS OF DAYTIME HEATING THIS
EVENING. TEMPERATURES ARE NOTICEABLY WARMER THAN
YESTERDAY...RUNNING AT LEAST 5F ABOVE SEASONAL NORMS.

THE WARMING AND DRYING WILL CONTINUE INTO TOMORROW AS HIGH PRESSURE
BUILDS...WITH MAXES RUNNING AROUND 10F ABOVE CLIMO...THE HOTTEST
TEMPERATURES OF THE YEAR SO FAR. WITH MORE DRY AIR IN PLACE UNDER A
STABLE AIRMASS...AFTERNOON CONVECTION OVER THE HIGHER TERRAIN WILL
BE ISOLATED AT BEST.

A LARGE PACIFIC NORTHWEST STORM SYSTEM IS PROGGED TO MOVE ONSHORE ON
MONDAY...WITH A LEADING WAVE MOVING A COLD FRONT INTO NORTHERN UTAH
TUESDAY...PUSHING MAXES NEAR CLIMO OVER THE NORTH BY WEDNESDAY. BY
MIDWEEK...A SECOND WAVE FROM THE MAIN TROUGH IS EXPECTED TO MOVE
INTO THE STATE...RESULTING IN SOME INCREASING INSTABILITY FOR
PRIMARILY NORTHERN UTAH. HOWEVER...THE AIRMASS IS EXPECTED TO REMAIN
GENERALLY DRY. MODELS NOW INDICATE WEAK RIDGING DEVELOPING ON
THURSDAY...THOUGH INSTABILITY WILL LINGER OVER NORTHERN UTAH.

BY THE WEEKEND...EC/GFS MOVE THE MAIN LOW ONSHORE BUT CONTINUE TO
DISAGREE ON THE DETAILS. EC STILL DROPS THE LOW DOWN INTO SOUTHERN
CALIFORNIA ON FRIDAY BEFORE SLOWLY MOVING EAST OVER ARIZONA AND NEW
MEXICO OVER THE WEEKEND. MEANWHILE...THE GFS SHOWS A SPLITTING
SYSTEM. IN ITS SOLUTION THE STRONGER NORTHERN BRANCH GRAZES NORTHERN
UTAH OVER THE UPCOMING WEEKEND...WHILE THE SOUTHERN BRANCH DIVES
INTO NORTHERN MEXICO. HAVE KEPT POPS IN THE FORECAST...BUT
CONFIDENCE IS LOW WITH RESPECT TO THE END OF THE FORECAST PERIOD.

&&

.AVIATION...NORTHERLY OUTFLOW WINDS FROM SHOWERS PASSING TO THE
NORTH ARE EXPECTED TO SWITCH TO SOUTHEASTERLY BY 04Z. ANY CIGS
SHOULD REMAIN WELL ABOVE 6K AGL FOR THE REMAINDER OF THE EVENING. NO
OTHER OPERATIONAL CONCERNS ARE EXPECTED FOR THE SLC TERMINAL.

&&

.FIRE WEATHER...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE FIRE
DISTRICT THROUGH TONIGHT. THE HIGH WILL THEN SHIFT EAST TOMORROW
AFTERNOON...ALLOWING SOUTHWEST FLOW TO INCREASE OVER THE AREA. AN
APPROACHING STORM SYSTEM WILL PUSH A COLD FRONT INTO NORTHWEST UTAH
BY LATE MONDAY AFTERNOON. WARM...DRIER AND BREEZY TO WINDY
CONDITIONS CAN BE EXPECTED AHEAD OF THE FRONT...BUT FUELS HAVE NOT
CURED ENOUGH TO WARRANT ANY HIGHLIGHTS. ENOUGH MOISTURE MAY REMAIN
IN PLACE TO GENERATE A FEW TERRAIN-BASED THUNDERSTORMS
TOMORROW...THEN EXPECT GREATER COVERAGE OF THUNDERSTORMS ACROSS THE
NORTH ON MONDAY DUE TO THE COLD FRONT.

A WEST-SOUTHWEST FLOW WILL FOLLOW FOR THE REMAINDER OF NEXT WEEK.
HOWEVER...WEAK WEATHER DISTURBANCES EMBEDDED IN THIS FLOW WILL KEEP
A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE NORTH DURING THIS TIME
WHILE SOUTHERN UTAH WILL LIKELY REMAIN DRY.

&&

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

$$

PUBLIC...ROGOWSKI/TRAPHAGAN
FIRE WEATHER...CHENG
AVIATION...VERZELLA

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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