Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 282213
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
413 PM MDT THU APR 28 2016

.SYNOPSIS...THE UPPER LEVEL LOW PRESSURE SYSTEM APPROACHING THE
FOUR CORNERS REGION LATER TONIGHT WILL CONTINUE INTO THE CENTRAL
PLAINS STATES LATE FRIDAY. A SECOND STORM SYSTEM WILL FOLLOW THIS
WEEKEND...MAINTAINING COOL AND UNSETTLED CONDITIONS FOR MUCH OF
THE REGION.

&&

.SHORT TERM (UNTIL 00Z MONDAY)...THE UPPER LOW TRACKING EAST ALONG
THE UTAH/ARIZONA BORDER WILL SETTLE INTO THE FOUR REGION OVERNIGHT...
THEN CONTINUE EAST INTO THE CENTRAL PLAINS STATES BY LATE FRIDAY.
SCATTERED CONVECTION EAST OF THE ADVANCING LOW WILL LIKELY
INCREASE A BIT IN AREAL COVERAGE THROUGH THIS EVENING.

A SECOND AREA OF ORGANIZED PRECIP WILL LIKELY FORM IN THE STILL
DEFINABLE DEFORMATION AXIS ACROSS WEST-CENTRAL UTAH THROUGH
EXTREME SOUTHWEST WYOMING THIS EVENING. THIS DEFORMATION AXIS HAS
BEEN STRETCHED OUT ACROSS NORTHERN UTAH MUCH OF THE DAY. THIS
AXIS IS BEGINNING TO TILT ALONG THE SOUTHWEST TO NORTHEAST AXIS
AS THE UPPER LOW MOVES EAST ALONG OUR SOUTHERN BORDER. THE
DEFORMATION WILL WEAKEN CONSIDERABLY LATE TONIGHT...LEAVING
SCATTERED CONVECTION CLOSER TO THE LOW CENTER HEADING INTO FRIDAY
MORNING.

A BRIEF LULL IN PRECIP WILL OCCUR FRIDAY AS A WEAK SHORTWAVE RIDGE
MOVES INTO THE AREA AHEAD OF A SECOND PACIFIC UPPER LOW SCHEDULED
TO ARRIVE OVER THE WESTERN GREAT BASIN SATURDAY. THIS NEXT FEATURE
WILL TAKE A MORE NORTH TO SOUTH TRACK THROUGH THE BASIN IN
RESPONSE TO STRONG RIDGING JUST OFF THE WEST COAST. THE GLOBAL
MODELS HAVE TRENDED TOWARDS TAKING THE LOW CENTER FURTHER TO THE
WEST...WHICH WOULD SIGNIFICANTLY REDUCE THE AMOUNT OF PRECIP
STRETCHING EAST IN WESTERN UTAH ON SATURDAY.

ONCE THE UPPER LOW SETTLES INTO THE SOUTHERN GREAT BASIN/DESERT
SOUTHWEST LATE IN THE WEEKEND WILL SEE AN INCREASE IN AREAL
COVERAGE OF PRECIP ACROSS MAINLY THE SOUTHERN HALF OF UTAH ON
SUNDAY. THIS PRECIP WILL LIKELY CONTINUE BEYOND THE SHORT RANGE
FORECAST PERIOD.

POTENTIAL EXISTS FOR A SIGNIFICANT DOWNSLOPE/CANYON WIND EVENT
ALONG THE WASATCH FRONT/CACHE VALLEY SATURDAY NIGHT/SUNDAY. NEAR
700MB EASTERLY COLD ADVECTION OUT OF WYOMING WITH SPEEDS RUNNING
AROUND 30 TO 40 KTS AND A FAVORABLE NORTHEAST SURFACE PRESSURE
GRADIENT WILL ALMOST CERTAINLY CREATE STRONG CANYON WINDS ALONG
THE WASATCH FRONT/CACHE VALLEY. POTENTIAL DOES EXIST FOR A GENERAL
DOWNSLOPE WIND EVENT WITH TIGHT THETA SURFACE PACKING NEAR THE
RIDGETOPS SATURDAY EVENING WHICH COLLAPSES DOWN THE WEST SLOPES
LATE SATURDAY NIGHT/EARLY SUNDAY. WIND HIGHLIGHTS APPEAR LIKELY
WITH EITHER AN HIGH END ADVISORY OR HIGH WIND WARNING POSSIBLE.

.LONG TERM (AFTER 00Z MONDAY...AFTER MORE THAN A WEEK OF
UNSETTLED WEATHER WITH A NEAR-CONSTANT PROGRESSION OF CLOSED LOWS
DRIFTING THROUGH THE AREA...IT APPEARS THERE IS A BREAK ON THE
HORIZON STARTING NEXT WEEK. BY SUNDAY NIGHT...EXTENDED MODELS ARE
IN AGREEMENT THAT A CLOSED LOW WILL BE FILLING AND WEAKENING OVER
UTAH. LINGERING MOISTURE AND SLIGHT INSTABILITY COULD BE ENOUGH
FOR A FEW SHOWERS HERE AND THERE MONDAY AFTERNOON...BUT OTHERWISE
THINGS SHOULD BE DRYING OUT STARTING MONDAY ACROSS UTAH AND
SOUTHWEST WYOMING.

GRADUAL RIDGING BEGINS ACROSS THE GREAT BASIN TUESDAY. THE GFS
MODEL DOES INDICATE DAILY AFTERNOON INSTABILITY OVER THE HIGHER
TERRAIN OF UTAH...AS IS TYPICAL FOR THIS TIME OF YEAR. EACH DAY
LOOKS PROGRESSIVELY DRIER AND WARMER...SO EXPECTING MAYBE A FEW
SHOWERS OVER THE HIGHER TERRAIN MONDAY AND TUESDAY GIVING WAY TO
JUST A FEW CUMULUS CLOUDS BY LATER IN THE WEEK.

THE AXIS OF THE RIDGE PUSHES THROUGH AROUND MIDWEEK...BRINGING
TEMPERATURES AROUND 5-10 DEGREES ABOVE AVERAGE. HOWEVER...THE
NEXT ACTIVE PERIOD IS NOT FAR BEHIND. CURRENT IDEA IN THE EXTENDED
MODELS IS TO BRING YET ANOTHER CLOSED LOW THROUGH CALIFORNIA AND
INTO THE GREAT BASIN BY THE END OF THE WORK WEEK...MEANING COOL
AND UNSTABLE CONDITIONS COULD RETURN BY THE END OF THE WORKWEEK
AND INTO NEXT WEEKEND.

&&

.AVIATION...FOR THE KSLC TERMINAL...EXPECT UNSETTLED CONDITIONS TO
CONTINUE THIS AFTERNOON AND EVENING AS SHOWERS LINGER OVER
NORTHERN UTAH. VFR CONDITIONS WILL CONTINUE THROUGH THE
PERIOD...THOUGH CEILINGS MAY DIP BELOW 7KFT AGL AT TIMES. VICINITY
SHOWERS ARE A POSSIBILITY INTO THE EVENING...WITH A 10 PERCENT
CHANCE OF VICINITY THUNDERSTORMS THIS AFTERNOON. SOME CLEARING
CAN BE EXPECTED TONIGHT AS SHOWERS WIND DOWN...WITH CEILINGS FULLY
LIFTING ABOVE THE 7KFT THRESHOLD TONIGHT. LIGHT NORTHWEST WINDS
ARE EXPECTED TO GIVE WAY TO TYPICAL LAND BREEZES OVERNIGHT.

&&

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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...VAN CLEAVE

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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