Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 231038
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
438 AM MDT SAT MAY 23 2015

.SYNOPSIS...A SLOW MOVING LOW PRESSURE SYSTEM WILL SLOWLY CROSS
THE REGION THROUGH SUNDAY. HIGH PRESSURE WILL BRIEFLY DEVELOP
MONDAY...BEFORE THE NEXT SYSTEM IMPACTS THE REGION FOR THE MIDDLE
TO LATTER HALF OF NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z WEDNESDAY)...EARLY MORNING WATER VAPOR
IMAGERY DEPICTS AN UPPER LOW SPINNING NEAR THE UT/AZ
BORDER...WHILE A FAIRLY WELL DEFINED WAVE ROTATING AROUND THE
NORTHERN PERIPHERY OF THIS LOW IS NOTED MOVING INTO NORTHERN
UT/SOUTHERN ID. AS THE PRIMARY UPPER CIRCULATION SLOWLY SHIFTS
INTO EASTERN UT TODAY...THIS NORTHERN WAVE IS FORECAST TO DROP
SOUTHWARD ACROSS WESTERN UT THROUGHOUT THE DAY FOCUSING THE
GREATER PRECIPITATION THREAT ACROSS WEST CENTRAL AND SOUTHWEST UT
AS THE DAY PROGRESSES. IN THE WAKE OF THIS FEATURE DRIER AIR ALOFT
CURRENTLY EXTENDING ACROSS EASTERN UT IS EXPECTED TO WRAP INTO
NORTHERN UT LATER ON...AND COUPLED WITH LARGE SCALE SUBSIDENCE MAY
LIMIT THE PRECIPITATION COVERAGE THIS AFTERNOON OVER THE NORTHERN
THIRD OF THE FORECAST AREA.

IN THE MEANTIME SHOWERS AND ISOLATED THUNDERSTORMS HAVE EXPANDED
IN COVERAGE ACROSS NORTHERN UT OVER THE PAST COUPLE HOURS...AND
ANTICIPATE THESE TO CONTINUE THROUGH AT LEAST MID MORNING BEFORE
SHIFTING SOUTH IN ASSOCIATION WITH THE AFOREMENTIONED WAVE. HAVE
MAINTAINED LIKELY TO CATEGORICAL POPS THIS MORNING ACROSS THE
NORTH...THEN TRENDED POPS DOWNWARD A BIT ACROSS THE NORTH AND
SHIFTED FOCUS FURTHER SOUTH FOR THE AFTERNOON. POPS MAY BE A BIT
OVERDONE OVER THE NORTHERN THIRD OF THE AREA FOR THE
AFTERNOON...ALTHOUGH WITH DAYTIME HEATING ADDITIONAL CONVECTION
IS CERTAINLY POSSIBLE WITH LINGERING LOW LEVEL MOISTURE.

FOR THE REMAINDER OF THE HOLIDAY WEEKEND A NORTHWESTERLY FLOW
ALOFT IS FORECAST TO PREVAIL IN THE WAKE OF THE DEPARTING UPPER
LOW. RESIDUAL MOISTURE SHOULD BE SUFFICIENT TO FUEL ADDITIONAL
SHOWERS AND THUNDERSTORMS LARGELY FOCUSED ON THE HIGHER
TERRAIN...BUT DRIFTING EASTWARD INTO THE ADJACENT VALLEYS AT
TIMES. THESE STORMS WILL LIKELY BE MORE NUMEROUS SUNDAY AS THE
REGION REMAINS UNDER A CYCLONIC FLOW ALOFT...BEFORE A PROGRESSIVE
SHORTWAVE RIDGE BEGINS TO AMPLIFY ACROSS THE FORECAST AREA ON
MONDAY. THIS RIDGE IS DOWNSTREAM FROM THE NEXT UPSTREAM
TROUGH...WHICH IS FORECAST TO DROP INTO THE PACIFIC NORTHWEST AND
INFLUENCE NORTHERN UT TUESDAY BRINGING ANOTHER INCREASE IN
SHOWERS AND THUNDERSTORMS.

.LONG TERM (AFTER 00Z WEDNESDAY)...GLOBAL MODELS COMING INTO BETTER
AGREEMENT WITH THE TRACK OF THE PACIFIC NORTHWEST LOW FOR THE
MIDWEEK PERIOD. EC/GFS TRACK IT SLOWLY INTO IDAHO AND MONTANA BY
WEDNESDAY BEFORE IT WEAKENS AND SLOWLY CONTINUES EAST FOR THURSDAY
AND FRIDAY. THIS WOULD KEEP A BROAD TROUGH OVER THE FORECAST AREA
THROUGH MUCH OF THE WORK WEEK...THOUGH THE BEST MOISTURE AND
INSTABILITY WILL BE CONFINED TO NORTHERN UTAH...WITH THE EXTENT OF
THIS MOISTURE SHRINKING AS THE WEEK GOES ON. MADE ONLY SMALL CHANGES
TO THE POP GRIDS FOR THIS PART OF THE FORECAST...AS SCATTERED POPS
SLOWLY BECOMING ISOLATED SEEMS TO COVER THE EXPECTED SITUATION WELL.
ALSO CONTINUING TO INDICATE SOME VERY SLOW WARMING OF TEMPERATURES
AS MOISTURE DECREASES.

BY THE UPCOMING WEEKEND...HIGH PRESSURE IS FINALLY EXPECTED TO BUILD
BACK INTO UTAH AND SOUTHWEST WYOMING...THOUGH THIS IS A BIT MORE
AMPLIFIED IN THE EC COMPARED TO THE LATEST GFS. HAVE DROPPED POPS
WELL BELOW CLIMO FOR DAY 7 WITH A CONTINUED WARMING TREND.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAY AT THE
SLC TERMINAL. SHOWERS ARE EXPECTED TO KEEP CIGS PRIMARILY NEAR OR
BELOW 6000 FT AGL THROUGH THE MORNING. SOUTHEAST WINDS ARE EXPECTED
TO SHIFT TO THE NORTHWEST BETWEEN 21Z AND 23Z...THOUGH SHOWERS WILL
LIKELY RESULT IN PERIODS OF GUSTY AND/OR ERRATIC WINDS INTO THE
AFTERNOON HOURS.

&&

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

$$

SEAMAN/TRAPHAGAN

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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