Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 270412
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
912 PM MST MON JAN 26 2015

.SYNOPSIS...A STORM SYSTEM OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING WILL CONTINUE NORTH INTO THE WESTERN GREAT ON TUESDAY.
THIS STORM WILL WEAKEN AS IT TURNS EAST ACROSS NORTHERN UTAH
ON TUESDAY NIGHT THROUGH EARLY WEDNESDAY.

&&

.SHORT TERM (UNTIL 00Z FRIDAY)...THE UPPER LOW CURRENTLY ALONG THE
SOUTHERN CALIFORNIA COAST WILL CONTINUE ON A NORTHWARD TRACK INTO
THE WESTERN GREAT BASIN ON TUESDAY. THE TROUGH EXTENDING EAST FROM
THE LOW CENTER WILL LIFT NORTH THROUGH WESTERN ARIZONA...THEN INTO
SOUTHWEST UTAH FOR LATE TONIGHT THROUGH EARLY TUESDAY.

MOIST LOW-LEVEL WARM ADVECTION WILL BRING SOME LIGHT PRECIP INTO
FAR SOUTHWEST UTAH SHORTLY AFTER MIDNIGHT. THIS PRECIP WILL BECOME
BETTER ORGANIZED AND EXPAND NORTH LATE TONIGHT AS THE ADVANCING
TROUGH AXIS AND THE ASSOCIATED MID-LEVEL COLD AIR CREATE A MORE
UNSTABLE AIR MASS AND INCREASED DYNAMIC LIFT.

PRECIP WILL LIKELY BECOME LIGHT AND LESS ORGANIZED ACROSS NORTHERN
UTAH AS THE TROUGH AXIS WEAKENS TUESDAY MORNING. LOOKING AT A
REJUVENATION OF VALLEY RAIN/MOUNTAIN SNOW TUESDAY/EARLY WEDNESDAY
AS THE REMNANT OF THE UPPER LOW OVER NEVADA TRACKS EAST ACROSS
NORTHERN UTAH AS AN OPEN WAVE LATE TUESDAY NIGHT. MODEL QPFS AT
THIS POINT ARE NOT THAT IMPRESSIVE WITH THIS FEATURE. SUSPECT THAT
THE GUIDANCE MAY BE A LITTLE ON THE LOW SIDE AS THE WEAK DYNAMICS
WILL BE WORKING ON MOISTURE WITH A TROPICAL ORIGIN AND WILL HAVE
ADEQUATE THERMAL SUPPORT TO GENERATE DECENT LIFT.

&&

.PREVIOUS LONG TERM (AFTER 00Z FRIDAY)...THURSDAY NIGHT AND
FRIDAY THE LOW CONTINUES TO SPIN SOUTHWEST OF THE FORECAST
AREA...WITH CHANCES OF PRECIPITATION INCREASING ACROSS THE CWA AS
THE LOW SLOWLY MEANDERS EASTWARD. THE BEST CHANCE FOR SIGNIFICANT
PRECIP WILL BE ACROSS CENTRAL AND SOUTHERN UTAH...BUT SOME SHOWERS
COULD ALSO BE POSSIBLE ACROSS THE WASATCH FRONT AND UINTA COUNTY
WY. HAVE SLIGHTLY RAISED POPS IN SOME AREAS...BUT IN GENERAL LEFT
THE ONGOING FORECAST IN PLACE.

PRECIP LOOKS TO LINGER INTO SATURDAY...BEFORE THE LOW EXITS INTO
MEXICO AND DRIER AIR MOVES INTO UTAH FROM THE NORTHWEST. A COOL AND
STABLE NORTHWEST FLOW THEN ESTABLISHES ITSELF OVER THE AREA FOR
SUNDAY...WITH THE MEAN WESTERN CONUS RIDGE CENTERED OVER CALIFORNIA.

THE RIDGE FLATTENS A BIT FOR SUNDAY NIGHT AND MONDAY...ALLOWING SOME
LOW LEVEL MOISTURE TO APPROACH THE UTAH/IDAHO BORDER FROM THE NORTH.
HAVE SLIGHTLY INCREASED POPS IN THE NORTHERN MOUNTAINS TO ACCOUNT
FOR THE CHANCE OF SOME OROGRAPHIC PRECIP. LOOKING BEYOND DAY
7...UNCERTAINTY BEGINS TO INCREASE...AS THE GFS AND ECMWF DISAGREE
ON WHETHER THE RIDGE RE-AMPLIFIES OVER THE WEST HEADING INTO THE
MIDDLE OF NEXT WEEK. THAT SAID...GOOD MODEL AGREEMENT THROUGH DAY 7
LED TO MORE CONFIDENCE IN THE EXTENDED FORECAST THAN HAS BEEN THE
NORM RECENTLY...WITH THE MAIN SOURCE OF UNCERTAINTY BEING THE
PLACEMENT/MOVEMENT OF THE CLOSED LOW THURSDAY NIGHT THROUGH
SATURDAY.

&&

.AVIATION...NORTH TO NORTHWESTERLY WINDS AROUND 5 KTS AT THE SLC
TERMINAL WILL CONTINUE THROUGH 02-04Z TONIGHT. OTHERWISE...CLOUDS
WILL BEGIN TO INCREASE TUESDAY MORNING AHEAD OF WEATHER DISTURBANCE
THAT WILL IMPACT THE AREA THROUGH WEDNESDAY.

&&

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

$$

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