Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 220957
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
357 AM MDT TUE APR 22 2014

.SYNOPSIS...STRONG SOUTHERLY FLOW WILL DEVELOP TODAY...AHEAD OF A
POTENT COLD FRONT WHICH WILL SWEEP ACROSS THE REGION LATE THIS
AFTERNOON THROUGH TONIGHT. HIGH PRESSURE WILL FOLLOW FOR THE
LATTER PORTION OF THE WEEK...BEFORE ANOTHER STORM SYSTEM ARRIVES
LATE FRIDAY THROUGH THE WEEKEND.

&&

.SHORT TERM (THROUGH 00Z FRIDAY)...A SHORTWAVE TROUGH CURRENTLY
ALONG THE PACIFIC COAST WILL MOVE INLAND THIS MORNING...BEFORE
LIFTING ACROSS THE GREAT BASIN THIS AFTERNOON THROUGH TONIGHT. THE
ASSOCIATED SURFACE FRONT WILL REACH NORTHWEST UT MID-
AFTERNOON...THEN PUSH EAST THROUGH NORTHERN UT DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS. THIS SETUP HAS ALL THE MAKINGS
OF A CLASSIC SPRINGTIME HIGH WIND EVENT ACROSS THE FORECAST
AREA...AS A STRONG COLD FRONT WITH TIGHT THERMAL PACKING WILL
SURGE EAST ACROSS NORTHERN UT DURING THE PEAK HEATING HOURS.

A TIGHTENING PRE-FRONTAL SOUTHERLY GRADIENT COMBINED WITH
STRENGTHENING FLOW ALOFT WILL ALLOW SOUTH WINDS TO RAMP UP DURING
THE MORNING AND EARLY AFTERNOON HOURS AREA-WIDE...WITH GUSTS
REACHING 60 MPH AT TIMES ACROSS MOST WESTERN VALLEYS BY MID
AFTERNOON. THIS FRONT IS FORECAST TO SWEEP INTO NORTHWEST UT BY
MID AFTERNOON...THEN CONTINUE EAST REACHING THE WASATCH FRONT NEAR
00Z. STRONG NORTHWEST WINDS WILL ACCOMPANY THIS FRONT AS WELL AS
PERSIST IN THE WAKE OF THIS BOUNDARY INTO THE EVENING HOURS ACROSS
THE NORTH. THE CURRENT HIGH WIND WARNING LOOKS IN GOOD SHAPE...AND
HAVE EXPANDED THE GOING WIND ADVISORY TO COVER MUCH OF THE HIGHER
TERRAIN AS WELL AS THE WASATCH BACK THROUGH THIS EVENING. LEFT THE
CACHE VALLEY OUT OF THE ADVISORY AS MOST GUIDANCE SUGGESTS WINDS
WILL REMAIN A BIT LIGHTER OVER THIS AREA.

PRECIPITATION-WISE...MAY SEE HIGH BASED CONVECTION DEVELOP ALONG
THE HIGHER TERRAIN AHEAD OF THIS FRONT DURING THE MID TO LATE
AFTERNOON HOURS...AS WELL AS SCATTERED CONVECTION ALONG THE
FRONTAL BOUNDARY AS IT SURGES EAST. HOWEVER...THE WINDOW FOR MORE
WIDESPREAD PRECIPITATION ACROSS NORTHERN UT LOOKS TO HOLD OFF
UNTIL EARLY EVENING WITH THE PASSAGE OF THE APPROACH AND PASSAGE
OF THE MID LEVEL TROUGH AXIS. AS SUCH HAVE LOWERED POPS INTO THE
CHANCE/SCATTERED CATEGORY FOR THE AFTERNOON HOURS ACROSS THE
NORTH. SNOW LEVELS WILL FALL AT LEAST TO THE BENCHES
OVERNIGHT...WITH SNOW POSSIBLY MIXING IN DOWN TO THE VALLEY FLOORS
WITH ANY LINGERING SHOWERS WEDNESDAY MORNING. WITH 700MB TEMPS
FALLING TO NEAR -10C WEDNESDAY MORNING MAY SEE SHOWERS DEVELOP OFF
THE GSL. GIVEN THE ABUNDANCE OF CLOUD COVER EXPECTED OVERNIGHT...A
HARD FREEZE IS NOT ANTICIPATED ACROSS THE NORTHERN VALLEYS.

THIS WAVE IS FORECAST TO LIFT NORTHEAST OF THE FORECAST AREA
WEDNESDAY...LEAVING A FAIRLY COOL AIRMASS IN ITS WAKE. SHORTWAVE
RIDGING IS FORECAST TO QUICKLY BUILD ACROSS THE REGION WEDNESDAY
NIGHT INTO THURSDAY ALLOWING FOR A WARMING TREND.

&&

.LONG TERM (AFTER 00Z FRIDAY)...THE RIDGE WILL WEAKEN AND SHIFT EAST
THURSDAY NIGHT/FRIDAY MORNING AHEAD OF THE NEXT APPROACHING STORM
SYSTEM. BY FRIDAY AFTERNOON...THE PRESSURE GRADIENT INCREASES OVER
THE FORECAST AREA AGAIN AHEAD OF THE NEXT APPROACHING FRONT...WITH
MODELS INDICATING 700 MB FLOW UP TO 50 KTS BY EARLY FRIDAY EVENING.
THEREFORE...GUSTY WINDS BECOME A POSSIBILITY ONCE AGAIN.

EC/GFS ARE IN MUCH BETTER AGREEMENT WITH THE TIMING...TRACK...AND
STRUCTURE OF THE SYSTEM THAN THEY WERE THE PAST COUPLE OF DAYS. BOTH
NOW INDICATE THE SYSTEM WILL MOVE THROUGH AS AN OPEN WAVE WITH THE
FRONTAL BOUNDARY MOVING THROUGH LATE FRIDAY NIGHT THROUGH SATURDAY.
VALLEY RAIN/MOUNTAIN SNOW DEVELOPS WITH THE FRONT AND CONTINUES IN
EARNEST THROUGH SATURDAY EVENING AS THE TROUGH MOVES THROUGH.
MOISTURE AND INSTABILITY IS EXPECTED TO REMAIN OVER THE AREA THROUGH
EARLY MONDAY WITH THE COLD POOL AND BACK EDGE OF THE TROUGH MOVING
ACROSS. WITH THIS INCREASE IN CONFIDENCE...HAVE RAISED POPS
SIGNIFICANTLY WITH THE PASSAGE OF THE SYSTEM...PARTICULARLY ON
SATURDAY.

BEHIND THE EXITING TROUGH...HIGH PRESSURE IS EXPECTED TO BUILD BACK
IN...BRINGING A DRYING AND WARMING TREND TO THE FORECAST AREA.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGH THE DAY
WITH SOME HIGH AND MID LEVEL CLOUDINESS. GUSTY SOUTH TO SOUTHEAST
WINDS WILL BECOME STRONG BY THE EARLY AFTERNOON BEFORE SHIFTING TO
THE NORTHWEST BETWEEN 21Z AND 23Z WITH THE PASSAGE OF A COLD FRONT.
WINDS WILL REMAIN STRONG OUT OF THE NORTHWEST FOR AT LEAST A COUPLE
OF HOURS BEHIND THE FRONT. SHOWERS WILL DEVELOP ALONG AND BEHIND THE
FRONT...AND THERE IS A 20 PERCENT CHANCE OF A THUNDERSTORM DIRECTLY
IMPACTING THE TERMINAL DURING THE LATE AFTERNOON/EARLY EVENING.

&&

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WIND ADVISORY FROM 8 AM THIS MORNING TO 9 PM MDT THIS EVENING
     FOR UTZ006-007-009-010-013-019>021-517-518.

     HIGH WIND WARNING FROM 8 AM THIS MORNING TO 9 PM MDT THIS
     EVENING FOR UTZ002>005-014>016.

     WIND ADVISORY FROM 6 PM THIS EVENING TO 6 AM MDT WEDNESDAY FOR
     UTZ011-012.

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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