Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 161127
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
427 AM MST TUE DEC 16 2014

.SYNOPSIS...THE UPPER LEVEL TROUGH OVER THE EASTERN PACIFIC TODAY
WILL SEND A SERIES OF WEAK WEATHER SYSTEMS ACROSS THE REGION
THROUGH THURSDAY. HIGH PRESSURE WILL RETURN FOR FRIDAY.

&&

.SHORT TERM (UNTIL 00Z SATURDAY)...A MOIST SOUTHWEST FLOW ALOFT
EXISTS ACROSS THE GREAT BASIN AHEAD OF THE NEGATIVE-TILT SPLIT
TROUGH EXTENDING FROM THE GULF OF ALASKA TO THE CENTRAL
CALIFORNIA COAST. WEAK VORTICITY MAXES EJECTING NORTHEAST AHEAD
OF THE TROUGH WILL BRING AREAS OF LIGHT PRECIP TO MAINLY NORTHERN
UTAH TODAY.

ONE FEATURE WHICH IS SOMEWHAT LOST IN THE CLOUD FIELD OVER
SOUTHWEST UTAH WILL LIFT INTO NORTHEAST UTAH THIS MORNING. WEAK
DYNAMIC LIFT WORKING WITH ADEQUATE MOISTURE WILL GENERATE LIGHT
PRECIP ACROSS CENTRAL THEN NORTHEAST UTAH THIS MORNING.

A MORE ACTIVE VORTICITY MAX EXITING THE CENTRAL SIERRAS WILL TAKE
AIM ON NORTHEAST NEVADA/NORTHWEST UTAH LATER THIS MORNING THROUGH
EARLY THIS EVENING. ALREADY SEEING A FEW RADAR RETURNS MOVING OUT
OF WEST-CENTRAL UTAH...WITH MUCH GREATER AREAL COVERAGE NOTED TO
THE WEST OVER NEVADA. STRONGER DYNAMIC LIFT ALONG WITH COLDER AIR
ALOFT AND A DEEPER MOISTURE LAYER SHOULD BRING A GREATER AREA OF
PRECIP INTO NORTHERN UTAH BY THIS AFTERNOON...AND ON THROUGH THE
EARLY EVENING HOURS. THE HEAVIEST RAIN/SNOW WILL LIKELY STAY NEAR
THE COLD POOL ALOFT AND STRONGEST DYNAMIC LIFT OVER THE FAR
NORTHWEST PORTION OF THE STATE. DRIER AIR AND DYNAMIC SUBSIDENCE
TRAILING THIS FEATURE SHOULD BRING AN END TO MOST IF NOT ALL
PRECIP UP NORTH BY LATE TONIGHT.

THE NEXT VORTICITY MAX CURRENTLY NEAR 41/131 WILL FOCUS OVER
SOUTHERN UTAH ON WEDNESDAY. THIS SYSTEM WILL HOLD TOGETHER WELL AS
IT ENTERS CALIFORNIA...THEN WEAKEN A BIT AS IT SPLITS MOVING INTO
THE WESTERN GREAT BASIN TONIGHT. THE FEATURE WILL STILL HAVE SOME
KICK AS IT TRACKS EAST ACROSS SOUTHERN NEVADA AND THEN NORTHERN
ARIZONA. SUFFICIENT DYNAMIC LIFT AND COLD AIR ALOFT WILL FIND A
STILL FAIRLY MOIST AIRMASS ACROSS SOUTHERN UTAH WEDNESDAY THROUGH
EARLY THURSDAY. LOOKING AT THE DEVELOPMENT OF WIDESPREAD LIGHT TO
MODERATE PRECIP NORTH AND EAST OF THE VORTICITY MAX BEGINNING EARLY
WEDNESDAY. COLDER TEMPERATURES ALOFT ALONG WITH FAIRLY STRONG
SYNOPTIC-SCALE LIFT SHOULD PROMOTE SNOW AS THE MAIN PRECIP TYPE
OUTSIDE OF THE LOWER VALLEYS NEAR THE ARIZONA BORDER. SEVERAL
INCHES OF SNOW COULD FALL ACROSS THE SOUTHERN MOUNTAINS THROUGH
EARLY THURSDAY.

LINGERING SHOWER ACTIVITY SHOULD WIND DOWN THURSDAY AFTERNOON AS
HIGH PRESSURE ALOFT SHIFTS EAST INTO THE GREAT BASIN. THIS HIGH
WILL CENTER ACROSS UTAH FOR FRIDAY...MAINTAINING DRY/STABLE
CONDITIONS HEADING INTO THE WEEKEND.

&&

.LONG TERM (AFTER 00Z SATURDAY)...BOTH THE EC AND GFS START SATURDAY
OFF WITH THE CWA UNDER A FLAT RIDGE BUT THEN HAVE A WEAK DISTURBANCE
MOVING SOUTHEAST ACROSS NORTHERN UTAH BY 00Z SUNDAY. THE EC HAS BEEN
MORE CONSISTENT WITH THIS FEATURE AND THE GFS NOW HAS BOUGHT OFF ON
THIS DISTURBANCE AS WELL. HOWEVER...THE LATEST 06Z GFS IS ACTUALLY
STRONGER AND MOVES IT ACROSS SOUTHWESTERN WYOMING AND NORTHEAST UTAH
LATE SATURDAY VERSES THE EC WHICH HAS THE MAIN ENERGY MOVING INTO
WEST CENTRAL UTAH. FORECAST IS BASED ON A BLEND OF THE EARLIER GFS
AND EC SOLUTIONS...BUT LATEST GFS WOULD ARGUE FOR HIGHER POPS OVER
THE NORTHERN MOUNTAINS.

A RIDGE GRADUALLY BUILDS INTO CALIFORNIA AND NEVADA SUNDAY THROUGH
TUESDAY WITH UTAH ON THE EASTERN FRINGE WHICH MEANS ANY WEAK
DISTURBANCE RIDING OVER THIS RIDGE WILL KEEP NORTHERN UTAH UNDER A
SOMEWHAT ACTIVE WARM ADVECTION PATTERN. HAVE KEPT NEAR CLIMO POPS
FOR THE NORTHERN THIRD OF THE CWA FOR THIS REASON WHILE THE SOUTHERN
TWO THIRDS OF THE CWA SHOULD BE DRY WITH TEMPERATURES ABOVE NORMAL.
THE ACTIVE NORTHWEST FLOW ACROSS NORTHERN UTAH WILL KEEP A FAIR
AMOUNT OF CLOUDS AROUND WHICH WILL PREVENT ANY VALLEY INVERSION FROM
DEVELOPING...CONSEQUENTLY ABOVE NORMAL TEMPERATURES ACROSS THE NORTH
AS WELL. TEMPERATURES WILL TAKE A RUN INTO THE LOWER 50S ACROSS THE
CENTRAL AND SOUTHERN WASATCH FRONT MONDAY AND TUESDAY.

&&

.AVIATION...AT THE SLC TERMINAL VARIABLE LIGHT WINDS ARE EXPECTED TO
BECOME SOUTHEAST BY 13-14Z AND REMAIN SOUTHEAST THROUGHOUT THE DAY.
CIGS SHOULD REMAIN ABOVE BKN100 THROUGH ABOUT 00Z BUT THEN THEY WILL
LOWER TO NEAR BKN070 AFTER 02Z WITH A 30 PERCENT CHANCE OF LOWERING
BELOW BKN070 BY 06Z.

&&



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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...STRUTHWOLF

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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