Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 302148
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
348 PM MDT SAT APR 30 2016

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL WORK ITS WAY THROUGH THE
DESERT SOUTHWEST OVER THE WEEKEND INTO EARLY NEXT WEEK. HIGH
PRESSURE ALOFT WILL RETURN TO THE INTERIOR WEST BY THE MIDDLE OF
NEXT WEEK.

&&

.SHORT TERM (THROUGH 06Z WEDNESDAY)...A LONGWAVE TROUGH CONTINUES
TO ENCOMPASS MUCH OF THE WESTERN AND CENTRAL CONUS. AN UPPER LOW
ROTATING INTO THE BASE OF THIS MEAN TROUGH IS CURRENTLY CROSSING
THE LOWER CO RIVER VALLEY..AND IS FORECAST TO STALL ACROSS AZ
TONIGHT BEFORE LIFTING AND WEAKENING ACROSS THE FOUR CORNERS
REGION SUNDAY. SHOWERS ASSOCIATED WITH THIS CIRCULATION CONTINUE
ACROSS SOUTHERN UT AND SHOULD GRADUALLY WEAKEN AND SHIFT SOUTHWARD
THROUGH THE EVENING HOURS. MEANWHILE CONVECTION ACROSS THE NORTH
REMAINS MORE ISOLATED..AND SHOULD LARGELY DISSIPATE THIS EVENING
WITH THE LOSS OF DAYTIME HEATING.

ATTENTION QUICKLY TURNS TO A FAVORABLE SETUP FOR STRONG DOWNSLOPE
WINDS...WERE A COMBINATION OF STRONG 700MB EASTERLY FLOW WITH
FORECAST NEAR 50 KTS BY 12Z SUNDAY...A RIBBON OF STRONG COLD
ADVECTION AND A FAVORABLE GRADIENT ALL COME TOGETHER TO SUPPORT A
DOWNSLOPE WIND EVENT ALONG THE WASATCH FRONT BEGINNING THIS
EVENING...AND CONTINUING THROUGH SUNDAY MORNING BEFORE DIMINISHING
DURING THE AFTERNOON. LITTLE CHANGED WITH THE 12Z GUIDANCE WITH
RESPECT TO THE OVERALL SCENARIO...AND THE 12Z LOCAL HI-RES MODELS
AND LATEST HRRR RUNS CONTINUE TO HIT DAVIS COUNTY THE HARDEST
WITH GUSTS IN EXCESS OF 70 MPH POSSIBLE. ONE POTENTIAL FLY IN THE
OINTMENT ARE THE MOST RECENT HI-RES LOCAL MODEL RUNS CURRENTLY
TRICKLING IN...WHICH HAVE SIGNIFICANTLY BACKED OFF. ALTHOUGH THIS
DOES GIVE PAUSE...THE OVERALL SETUP STILL APPEARS QUITE
FAVORABLE FOR STRONG WINDS.

WENT AHEAD AND UPGRADED TO A HIGH WIND WARNING FOR THE
NORTHERN WASATCH FRONT...AND INCLUDED A WIND ADVISORY FOR
NORTHEASTERN SALT LAKE COUNTY FROM PARLEYS TO THE UNIVERSITY...AS
WELL AS THE MOUTH OF PROVO CANYON AND EASTERN PORTIONS OF THE
CACHE VALLEY.

WINDS SHOULD DIMINISH BY EARLY AFTERNOON ALONG THE WASATCH
FRONT...AND ALTHOUGH THERE MAY BE A SECONDARY PEAK SUNDAY EVENING
SPEEDS WOULD BE MORE IN THE ADVISORY RANGE AT BEST ALONG THE
NORTHERN WASATCH FRONT.

THE UPPER LOW IS FORECAST TO MEANDER AROUND THE FOUR CORNERS
REGION SUNDAY WITH WRAP AROUND MOISTURE WORKING INTO SOUTHEASTERN
PORTIONS OF THE AREA DURING THE AFTERNOON. THIS LOW IS FORECAST TO
GRADUALLY FILL AND WEAKEN AS MID LEVEL HEIGHTS BUILD EARLY IN THE
WEEK. THE RESULT WILL BE A WARMING TREND BUT WITH A THREAT OF
DIURNALLY DRIVEN CONVECTION ASSOCIATED WITH LINGERING MOISTURE
AND THE REMNANTS OF THE LOW.

.LONG TERM (AFTER 06Z WEDNESDAY)...THE RIDGE AXIS IS EXPECTED TO
SHIFT EAST OF THE FORECAST AREA DURING THE DAY WEDNESDAY AS A BROAD
PACIFIC STORM SYSTEM SLOWLY MOVES ONSHORE ALONG THE CALIFORNIA
COAST. LATEST GFS IS A BIT QUICKER MOVING THE ASSOCIATED MOISTURE
INTO THE FORECAST AREA COMPARED TO THE ECMWF...BRINGING THE
POSSIBILITY OF A FEW SHOWERS OVER WESTERN UTAH BY THURSDAY
AFTERNOON.

THE CLOSED LOW IS EXPECTED TO SLOWLY TRACK ACROSS THE GREAT BASIN
THROUGH MONDAY...BRINGING TEMPERATURE TO NEAR OR SLIGHTLY BELOW
CLIMO BY SATURDAY WITH PERIODS OF MOUNTAIN SNOW/VALLEY RAIN. HAVE
SHOWED INCREASING POPS TOWARD THE END OF THE FORECAST PERIOD...WITH
CHANCE POPS IN MOST AREAS BY DAY 7.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGHOUT
THE DAY WITH SOME HIGH AND MID LEVEL CLOUDS. NORTHWEST WINDS ARE
EXPECTED TO SHIFT TO THE SOUTHEAST BETWEEN 03Z AND 05Z.
HOWEVER...NEARBY DOWNSLOPE WINDS ALONG THE WASATCH FRONT WILL CAUSE
PERIODS OF ERRATIC WIND DIRECTIONS AT THE TERMINAL THIS EVENING AND
OVERNIGHT...THOUGH WINDS AT THE TERMINAL SHOULD REMAIN UNDER 20 MPH.

&&

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WIND ADVISORY FROM 9 PM THIS EVENING TO 3 PM MDT SUNDAY FOR
     UTZ001-003-004.

     HIGH WIND WARNING FROM 9 PM THIS EVENING TO 3 PM MDT SUNDAY FOR
     UTZ002.

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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