Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 231125
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
525 AM MDT THU APR 23 2015

.SYNOPSIS...AN UPPER LEVEL WEATHER DISTURBANCE CROSSING THE NORTHERN
ROCKIES WILL BRING A WEAK COLD FRONT THROUGH THE AREA TODAY. A COLD
AND ENERGETIC PACIFIC STORM SYSTEM WILL IMPACT THE REGION THIS
WEEKEND.

&&

.SHORT TERM (THROUGH 12Z SUNDAY)...A SPLIT STORM SYSTEM IS CURRENTLY
TRACKING EAST ACROSS THE GREAT BASIN THIS MORNING...WITH THE
NORTHERN STREAM EXPECTED TO CLIP NORTHERN UTAH TODAY.
MEANWHILE...THE SOUTHERN BRANCH WAVE IS MERGING WITH THE REMNANTS OF
THE PREEXISTING CLOSED LOW OVER SOUTHERN CALIFORNIA AND WILL TRACK
ACROSS ARIZONA TODAY AS AN OPEN WAVE. A COLD FRONT IS CURRENTLY
DRAPED ACROSS CENTRAL IDAHO AND INTO NORTH-CENTRAL NEVADA AND IS
EXPECTED TO ENTER NORTHWEST UTAH TODAY...ALTHOUGH IT WILL BE QUITE
SHALLOW AND WEAK.

SHOWERS ARE CONTINUING ACROSS NORTHERN UTAH THIS MORNING...NEAR WHAT
IS LEFT OF THE DEFORMATION AXIS THAT LIFTED NORTH THROUGH UTAH
YESTERDAY. THESE SHOULD DECREASE A BIT DURING THE MORNING
HOURS...ONLY TO LIGHT UP AGAIN AS THE AFOREMENTIONED COLD FRONT
APPROACHES. ENOUGH MOISTURE REMAINS IN PLACE TO GENERATE CONVECTION
THROUGHOUT THE AREA TODAY...MOSTLY OVER THE HIGH TERRAIN.
HOWEVER...DUE TO THE PASSAGE OF THE NORTHERN STREAM WAVE AND
ASSOCIATED COLD FRONT...FAVOR WILL BE GIVEN TO THE MOUNTAINS AND
VALLEYS OF NORTHERN UTAH. SINCE THE LOW LEVELS ARE STILL FAIRLY
DRY...GUSTY WINDS BUT LITTLE RAINFALL WILL LIKELY ACCOMPANY SOME OF
THE SHOWERS.

MODELS CONTINUE TO SPREAD MOISTURE INTO THE AREA TOMORROW AS
SOUTHWEST FLOW INCREASES AHEAD OF THE NEXT APPROACHING TROUGH...WITH
FORECAST PWAT INCREASING A BIT WITH EACH MODEL RUN. THE TROUGH IS
PROGGED TO EJECT NORTHEAST TOMORROW...JUST GRAZING NORTHERN UTAH
AS A SECOND AND STRONGER TROUGH CARVES SOUTH ALONG THE WEST COAST
STATES. THE INITIAL WAVE WILL PUSH A COLD FRONT...A BIT STRONGER
THAN THE ONE TODAY...INTO NORTHERN UTAH TOMORROW. THE COMBINATION OF
INCREASED MOISTURE AND LARGE-SCALE LIFT WILL RESULT IN MORE
WIDESPREAD SHOWERS AND A BETTER CHANCE OF MEASURABLE PRECIPITATION.
THE COLD FRONT IS EXPECTED TO STALL IN THE VICINITY OF
CENTRAL/SOUTHERN UTAH TOMORROW NIGHT...WITH NOCTURNAL SHOWERS
FOCUSING IN THAT GENERAL AREA.

MOISTURE WILL REMAIN IN ABUNDANCE ON SATURDAY AHEAD OF THE NEXT
TROUGH. WIDESPREAD PRECIPITATION IS EXPECTED TO DEVELOP AHEAD OF AND
ALONG THE COLD FRONT SATURDAY THROUGH SATURDAY NIGHT. EVEN WITH THE
LATE-DAY TIMING OF THE COLD FRONT...MAX TEMPERATURES ON SATURDAY ARE
EXPECTED TO BE NOTICEABLY COOLER THAN FRIDAY...ESPECIALLY ACROSS THE
NORTH AND WEST...DUE TO THE LINGERING COOL AIRMASS BROUGHT INTO THE
AREA WITH THE FRIDAY FRONT AND THE INCREASED CLOUDS AND
PRECIPITATION. HOWEVER...SNOW LEVELS WILL REMAIN ABOVE 7000FT MOST
AREAS BEFORE FALLING TO NEAR 6000FT OVER MUCH OF NORTHERN AND
WESTERN UTAH LATE SATURDAY NIGHT BEHIND THE FRONT. ALSO SHOULD NOTE
THAT LOCALLY GUSTY WINDS MAY ACCOMPANY THE FRONT ESPECIALLY IN
FAVORED DOWNSLOPE REGIONS SUCH AS THE NORTHWEST DESERTS.

.LONG TERM (AFTER 12Z SUNDAY)...FOLLOWING THE COLD FRONTAL PASSAGE
LATE SATURDAY OR EARLY SUNDAY MORNING...A MOIST NORTHWESTERLY FLOW
LOOKS TO REMAIN OVER THE CWA THROUGH THE DAY SUNDAY. THIS WILL
LIKELY ALLOW SOME PRECIPITATION TO LINGER ACROSS MUCH OF THE
STATE...PARTICULARLY OVER THE HIGHER TERRAIN. HAVE INCREASED POPS
THROUGH THE DAYTIME HOURS SUNDAY...AND HAVE ALSO INCREASED NORTHERLY
WIND SPEEDS A BIT BEHIND THE FRONT. WITH ADDITIONAL CLOUD COVER AND
PRECIPITATION LINGERING SUNDAY...ALSO LOWERED MAX TEMPERATURES FOR
MUCH OF THE AREA.

THE 12Z MODEL RUNS ARE IN GOOD AGREEMENT THAT THE UPPER LEVEL TROUGH
CLOSES OFF AND EXITS THE REGION TO THE SOUTHEAST ON SUNDAY
NIGHT...WITH A MUCH DRIER AND MORE STABLE AIRMASS MOVING OVERHEAD
THROUGH THE DAY MONDAY. THIS WILL BE THE BEGINNING OF A SIGNIFICANT
WARMING TREND...WITH A LARGE UPPER LEVEL RIDGE MOVING OVER THE GREAT
BASIN MONDAY THROUGH WEDNESDAY. TEMPERATURES HAVE TRENDED WARMER
WITH THE CURRENT RUNS...WITH 700MB TEMPS RISING TO 7 TO 10 DEGREES
CELSIUS BY WEDNESDAY AND THURSDAY. HAVE RAISED BOTH MAX AND MIN
TEMPERATURES THROUGH THIS PERIOD TO ACCOUNT FOR THIS TREND...WITH
WASATCH FRONT TEMPERATURES PERHAPS REACHING THE 80 DEGREE FAHRENHEIT
MARK FOR THE FIRST TIME THIS CALENDAR YEAR.

&&

.AVIATION...THE SALT LAKE CITY TERMINAL COULD BE IMPACTED BY
SCATTERED SHOWERS ACROSS NORTHERN UTAH TODAY...WITH ISOLATED
THUNDERSTORMS ALSO POSSIBLE THIS AFTERNOON. THE MOST LIKELY IMPACT
FROM THESE STORMS IS GUSTY ERRATIC WINDS...WITH CEILINGS BELOW
7000FT OR EVEN BRIEF MVFR CONDITIONS ALSO POSSIBLE IF A HEAVIER
SHOWER MOVES DIRECTLY OVERHEAD. THE TIMING AND STRENGTH OF WIND
DIRECTION CHANGES ARE RELATIVELY LOW CONFIDENCE DUE TO THESE
SHOWERS...BUT THE MOST LIKELY SCENARIO IS FOR SURFACE WINDS TO
RETURN TO THE SOUTH BETWEEN 11Z AND 13Z...BEFORE SWITCHING TO THE
NORTHWEST BETWEEN 19Z AND 22Z.

&&

.FIRE WEATHER...INCREASING MOISTURE ACROSS UTAH WILL ONCE AGAIN LEAD
TO SHOWER AND THUNDERSTORM DEVELOPMENT TODAY...THOUGH THE CHANCE OF
WETTING RAIN TODAY WILL BE FAIRLY LOW WITH THESE HIT-OR-MISS
SHOWERS. THE CHANCE OF WETTING RAIN WILL INCREASE A BIT ON
FRIDAY...AND THEN SIGNIFICANTLY ON SATURDAY INTO SUNDAY...AS A
LARGER STORM SYSTEM MOVES THROUGH THE REGION. ACCUMULATING SNOW IS
EXPECTED IN THE MOUNTAINS WITH THIS SATURDAY/SUNDAY STORM...WITH
SNOW LEVELS DROPPING AS LOW AS 5000-6000 FEET. GUSTY SOUTHWEST WINDS
WILL DEVELOP ACROSS MUCH OF THE AREA THE NEXT COUPLE DAYS...BEFORE
THE COLD FRONT LATE SATURDAY INTO SUNDAY BRINGS BREEZY NORTHERLY
WINDS.

THE STORM IS EXPECTED TO EXIT SUNDAY NIGHT...WITH HIGH PRESSURE
BUILDING OVER THE REGION MONDAY THROUGH THURSDAY. THIS WILL LEAD TO
SIGNIFICANTLY DRIER AND WARMER CONDITIONS...WITH WINDS EXPECTED TO
BE LARGELY TERRAIN DRIVEN THROUGH AT LEAST MONDAY AND TUESDAY.

&&

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

$$

CHENG/SCHOENING

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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