Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 211049
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
449 AM MDT MON APR 21 2014

.SYNOPSIS...A WARM SOUTHWEST FLOW WILL DEVELOP ACROSS THE GREAT
BASIN TODAY. STRONG SOUTH WINDS WILL FOLLOW FOR TUESDAY...AHEAD OF
A STRONG COLD FRONT AND ASSOCIATED STORM SYSTEM WHICH WILL CROSS
THE AREA LATE TUESDAY AFTERNOON THROUGH WEDNESDAY. HIGH PRESSURE
WILL FOLLOW FOR THURSDAY...BEFORE ANOTHER STORM SYSTEM ARRIVES
LATE FRIDAY THROUGH THE WEEKEND.

&&

.SHORT TERM (THROUGH 00Z FRIDAY)...SHORTWAVE RIDGING EXTENDS
ACROSS THE EASTERN GREAT BASIN EARLY THIS MORNING. A WEAK
VORTICITY LOBE EMBEDDED WITHIN THIS RIDGE IS NAVIGATING ACROSS
SOUTHERN UT...AND RESULTING IN AN AREA OF MID AND HIGH LEVEL CLOUD
COVER. SOME WEAK RETURNS ARE NOTED IN RADAR IMAGERY...HOWEVER THIS
IS LIKELY NOT REACHING THE SURFACE AND NO OBSERVATION SITES HAVE
REPORTED PRECIPITATION THUS FAR. THIS FEATURE SHOULD CLEAR THE
AREA BY SUNRISE.

AS THIS RIDGE SHIFTS EAST TODAY THE FLOW ALOFT WILL BACK TO
SOUTHWEST...INDUCING WARM ADVECTION ACROSS THE FORECAST AREA. THIS
WILL PUSH 700MB TEMPS TO AROUND 6C IN THE NORTH...AND 8-9C ACROSS
CENTRAL AND SOUTHERN UT...ALLOWING TEMPERATURES TO APPROACH THE
80F MARK ALONG THE WASATCH FRONT AND NEAR 90F IN ST GEORGE.
LINGERING MOISTURE COMBINED WITH DAYTIME HEATING WILL ALSO ALLOW
FOR A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE HIGHER
TERRAIN THIS AFTERNOON.

SOUTHERLY SURFACE WINDS WILL BEGIN TO STRENGTHEN THIS
AFTERNOON...THEN INCREASE OVERNIGHT. THIS INCREASING FLOW
OVERNIGHT WILL ALLOW FOR A MILD NIGHT ACROSS MOST AREAS.

SURFACE PRESSURE FALLS DURING THE DAY TUESDAY COUPLED WITH
STRENGTHENING 700MB FLOW INTO THE 40-50KT RANGE WILL ALLOW FOR
STRONG SOUTH WINDS ACROSS THE WESTERN VALLEYS DURING THE
AFTERNOON...AHEAD OF A STRONG COLD FRONT EXPECTED TO CROSS
NORTHWEST UT LATE TUESDAY AFTERNOON THROUGH TUESDAY EVENING.
SYNOPTICALLY SPEAKING THIS HAS ALL THE MAKINGS OF A CLASSIC
SPRINGTIME HIGH WIND EVENT WITH A STRONG SURFACE FRONT SURGING
ACROSS THE NORTHWEST DESERT AND INTO THE WASATCH FRONT DURING
PEAK HEATING. GOING HIGH WIND WATCHES LOOK GOOD ACROSS THE
WESTERN VALLEYS AND WOULD ANTICIPATE WARNINGS WILL BE NEEDED FOR
THESE AREAS...WHILE THE REMAINING SOUTHERN AND EASTERN VALLEYS
WILL LIKELY REQUIRE WIND ADVISORIES.

PRECIPITATIONWISE...A BAND OF CONVECTION WILL BE POSSIBLE ALONG
THIS SURGING FRONT AS IT CROSSES NORTHERN UT AND SOUTHWEST WY. IN
THE WAKE OF THIS FRONT PRECIPITATION IS EXPECTED TO BECOME MORE
WIDESPREAD ACROSS THE NORTHERN THIRD OF THE FORECAST AREA AS THE
MID LEVEL TROUGH AXIS SWEEPS THROUGH TUESDAY INTO THE OVERNIGHT
HOURS. INITALLY EXPECT MOUNTAIN SNOW AND VALLEY RAIN...HOWEVER AS
COLDER AIR QUICKLY FILTERS INTO THE REGION COULD SEE SNOW REACH
THE VALLEY FLOORS TOWARD THE END OF THE PRECIP EVENT EARLY
WEDNESDAY MORNING...AS 700MB TEMPS FALL AS LOW AS -11C ACROSS
NORTHERN UT. THIS VERY COLD AIR WILL ALSO BRING THE POTENTIAL FOR
LAKE EFFECT SQUALLS DOWNWIND OF THE GSL AND PERHAPS UTAH LAKE
WEDNESDAY MORNING.

GIVEN ABUNDANT CLOUD COVER AND REMAINING PRESSURE GRADIENT DO NOT
ANTICIPATE A HARD FREEZE IN THE NORTH WEDNESDAY NIGHT ALTHOUGH
COULD SEE A FEW OUTLYING SPOTS DIP NEAR FREEZING. SHORTWAVE
RIDGING RETURNS LATE WEDNESDAY NIGHT INTO THURSDAY ALLOWING FOR A
WARMING AND DRYING TREND.

&&

.LONG TERM (AFTER 00Z FRIDAY)...HIGH PRESSURE IS PROGGED TO SLIDE
EAST THURSDAY NIGHT/FRIDAY AHEAD OF THE NEXT APPROACHING STORM
SYSTEM. THE INITIAL FRONT LOOKS TO SLIDE INTO NORTHWEST UTAH FRIDAY
NIGHT WITH PRECIP SPREADING OVER THE STATE SATURDAY AS THE FRONT
MOVES THROUGH THE REST OF THE STATE. GFS STILL INDICATING THE SYSTEM
WILL MOVE THROUGH AS A WARMER AND FASTER MOVING CLOSED LOW. IN ITS
SOLUTION...PRECIP WOULD BE MOUNTAIN SNOW/VALLEY RAIN...PERSISTING
INTO SUNDAY BEFORE TAPERING OFF. THE LATEST EC STILL INDICATES A
COLDER OPEN WAVE THAT MOVES THROUGH IN A COUPLE OF PIECES THROUGH
MONDAY. 700 MB TEMPS WOULD SUPPORT SNOW TO THE BENCHES OR EVEN
VALLEY FLOORS FOR NORTHERN UTAH. HAVE INCREASED POPS WITH INCREASING
CONFIDENCE IN A MOIST AND UNSETTLED PATTERN OVER THE WEEKEND. BEHIND
THIS TROUGH...GLOBAL MODELS HINT AT STRONGER RIDGING BUILDING IN FOR
EARLY NEXT WEEK.



&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGHOUT THE
DAY WITH ANY CIGS REMAINING WELL ABOVE 6000 FT AGL. SOUTHEAST WINDS
ARE EXPECTED THROUGHOUT THE DAY...BECOMING GUSTY AT TIMES DURING THE
AFTERNOON. THERE IS A 30 PERCENT CHANCE OF A LATE SHIFT TO THE
NORTHWEST...BETWEEN 20Z AND 22Z.


&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING FOR
     UTZ002>005-014>016.

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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