Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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804
FXUS65 KSLC 281630
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1030 AM MDT THU APR 28 2016

.SYNOPSIS...THE UPPER LEVEL LOW PRESSURE SYSTEM CENTERED OVER
NORTHWEST ARIZONA WILL CONTINUE EAST TO THE FOUR CORNERS REGION
LATER TONIGHT. A SECOND STORM SYSTEM WILL FOLLOW FOR THE UPCOMING
WEEKEND.

&&

.DISCUSSION...TWO AREAS OF ORGANIZED PRECIPITATION ARE IMPACTING
UTAH THIS MORNING. THE FIRST IS A BAND OF GENERALLY LIGHT PRECIP
ALONG A DEFORMATION AXIS ACROSS NORTHERN UTAH. THIS DEFORMATION
WILL GAIN A MORE SOUTHWEST TO NORTHEAST ORIENTATION AS THE UPPER
LOW CURRENTLY OVER NORTHWEST ARIZONA ADVANCES EAST TODAY. THE BAND
OF PRECIP SHOULD HOLD TOGETHER FAIRLY WELL...WITH THE HEAVIEST
PRECIP EXTENDING FROM WEST-CENTRAL UTAH THROUGH SOUTHWEST WYOMING
BY LATE THIS AFTERNOON.

THE SECOND AREA OF ORGANIZED PRECIP IS ASSOCIATED WITH THE UPPER
LOW OVER NORTHWEST ARIZONA THIS MORNING. THE MOIST AND UNSTABLE
AIR MASS ACROSS SOUTHERN/CENTRAL UTAH WORKING WITH A BROAD AREA OF
SYNOPTIC-SCALE LIFT ASSOCIATED WITH UPPER LOW HAS GENERATED
WIDESPREAD LIGHT PRECIP ACROSS THE SOUTHERN/CENTRAL PORTIONS OF
THE STATE. EMBEDDED CONVECTIVE ELEMENTS ARE PRODUCING AREAS OF
MODERATE PRECIP...ESPECIALLY ACROSS THE HIGHER ELEVATIONS WHERE
SEVERAL INCHES OF SNOW COULD ACCUMULATE THROUGH EARLY THIS
EVENING.

THE POSITIONING OF THE UPPER LOW NEAR THE FOUR CORNERS TONIGHT
WILL MAINTAIN WIDESPREAD PRECIP IN THE WRAP AROUND BAND ALONG THE
NORTH AND WEST FLANKS OF THE LOW OVERNIGHT. THE CENTRAL AND
SOUTHERN MOUNTAINS WILL LIKELY SEE ACCUMULATING SNOWS CONTINUE
WITH THE HEAVIEST SNOWS EXPECTED IN THE CENTRAL MOUNTAINS THIS
EVENING.

A BRIEF APPEARANCE OF A SHORTWAVE RIDGE FRIDAY WILL BE FOLLOWED BY
ANOTHER UPPER LOW CROSSING THE WESTERN GREAT BASIN FRIDAY NIGHT.
THE LATEST RUNS OF THE GFS AND ECMWF INDICATE STRONG RIDGING OVER
THE EASTERN PACIFIC WHICH WILL DRIVE THIS SECOND SYSTEM ON A MORE
NORTH TO SOUTH TRAJECTORY THROUGH THE BASIN. WITH LOW TRACKING
FURTHER WEST OVER NEVADA WILL LIMIT THE BEST CHANCE FOR PRECIP TO
FAR WESTERN UTAH FRIDAY NIGHT/EARLY SATURDAY. ONCE THE UPPER LOW
SETS UP OVER EXTREME SOUTHERN NEVADA/NORTHWEST ARIZONA LOOK FOR
WIDESPREAD PRECIP TO RETURN SOUTHERN/CENTRAL UTAH FOR THE WEEKEND.
NORTHERN UTAH WILL RECEIVE SOME PRECIP...THOUGH THE DEEP EAST-
NORTHEAST FLOW ALOFT WILL SOMEWHAT LIMIT THE AREAL COVERAGE AND
INTENSITY OF ANY PRECIP WEST OF THE WASATCH RANGE IN NORTHWEST
UTAH.

ISSUED AN EARLY UPDATE TO INCREASE POPS AND SNOW ACCUMULATIONS FOR
THE SOUTHERN AND CENTRAL MOUNTAINS. ALSO MADE A FEW SHORT TERM
ADJUSTMENTS TO POPS FOR VALLEY LOCATIONS BASED ON THE LATEST HRRR
MODEL.

&&

.AVIATION...FOR THE KSLC TERMINAL...EXPECT UNSETTLED CONDITIONS TO
CONTINUE TODAY WITH OCCASIONAL RAIN SHOWERS AND CEILINGS DROPPING
BELOW 7 THOUSAND FEET AGL AT TIMES. THE WIND FORECAST IS
CHALLENGING THIS MORNING WITH SEVERAL COMPETING FORCES IN THE
ATMOSPHERE. THE OVERALL SYNOPTIC SETUP FAVORS NORTHERLY BREEZES AT
THE SURFACE TODAY. HOWEVER...ONLY A FEW THOUSAND FEET UP...WINDS
SHIFT TO EASTERLY...AND ARE ALSO EASTERLY CLOSER TO THE WASATCH
FRONT. THUS...EXPECTING NORTHERLY WINDS IN GENERAL...WITH A 30
PERCENT CHANCE OF EASTERLY WINDS AT TIMES. ALSO...EXPECTING A BIT
OF WIND SHEAR WITH THE SWITCH TO EASTERLY WINDS OF 15-20 KTS JUST
ABOVE THE GROUND AS SEEN ON THE KMTX WIND PROFILER CURRENTLY.

THERE IS ABOUT A 10 PERCENT CHANCE OF VICINITY THUNDERSTORMS THIS
AFTERNOON...THEN PARTIAL CLEARING LATE TODAY WITH CEILINGS LIFTING
ABOVE THE 7KFT THRESHOLD. SHOWERS SHOULD WIND DOWN BY LATE THIS
EVENING...WITH TYPICAL LAND BREEZES SETTING UP OVERNIGHT.

&&

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

$$

PUBLIC...
AVIATION...

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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