Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 142200
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
300 PM MST SUN DEC 14 2014

.SYNOPSIS...HIGH PRESSURE WILL BUILD INTO THE REGION TONIGHT
THROUGH MONDAY. WEAK WEATHER SYSTEMS WILL CROSS THE AREA MONDAY
NIGHT THROUGH THURSDAY.

&&

.SHORT TERM (UNTIL 12Z WED)...THE WEAKENING REMAINS OF THE COOL
UPPER TROF ACROSS THE NORTHERN CWA THIS EVENING WILL CONTINUE TO
GRADUALLY LIFT NORTH AND OUT OF THE AREA OVERNIGHT AS RIDGING
BUILDS IN FROM THE SOUTHWEST.

INSTABILITY ASSOCIATED WITH THIS TROF HAS KEPT SNOW SHOWERS GOING
OVER NRN UT INTO THE AFTN. THE LAKE IS ENHANCING THESE BUT THEY
ARE NOT LIMITED TO AREAS DOWNWIND FROM THE LAKE. EXPECT THESE SNOW
SHOWERS TO PERSIST INTO THIS EVENING NORTH OF THE TROF AXIS THEN
END AS THE AXIS LIFTS NORTH AROUND MIDNIGHT.

A FEW OF THESE SHOWERS WILL BE BRIEFLY HEAVY AND SNOW PELLETS
COULD BRIEFLY SLUSH UP ROADS IN SPOTS UNDER THE HEAVIER SHOWERS.

FOG THAT FORMED ACROSS THE SRN AND SWRN VALLEYS HAS BURNED OFF BUT
STRATUS HAS FORMED OVER MANY OF THE WESTERN VALLEYS FROM ABOUT
DELTA SOUTH. EXPECT THIS TO DISSIPATE WITH THE LOSS OF DAYTIME
HEATING THIS EVE WITH SKIES BECOMING MOSTLY CLEAR OUTSIDE OF THE
NRN UT AREAS UNDER THE REMAINS OF THE UPPER TROF. FOG IS POSSIBLE
AS SKIES CLEAR LATER TONIGHT IN SOME OF THE NRN VALLEYS WHERE
PRECIP WILL LINGER INTO THE EVE AND HAVE IT MENTIONED THERE
TONIGHT INTO MON MORNING.

HIGH CLOUDS INCREASE FROM THE SW MON AND A WARM FRONT IS FORECAST
TO BRING A LITTLE SNOW MON NIGHT INTO EARLY TUE ACROSS THE
CENTRAL AND NRN CWA.

THE NEXT UPPER TROF BEGINS TO SPREAD DEEPER MOISTURE INTO THE CWA
TUE AFN INCREASING TUE NIGHT. LIFT IS WEAK WITH THIS NEXT WAVE BUT
MOISTURE IS FORECAST TO BE ABUNDANT SO FAIRLY WIDESPREAD BUT
LIGHT PRECIP IS POSSIBLE TUE NIGHT. THIS COULD BE RAIN IN THE
LOWER VALLEYS AS COLDER AIR IS NOT FORECAST TO SPREAD INTO THE CWA
UNTIL LATE TUE NIGHT.

&&

.LONG TERM (AFTER 12Z WEDNESDAY)...THE INITIAL WAVE OF THE SPLITTY
AND DISORGANIZED PACIFIC TROUGH IS PROGGED TO EXIT THE AREA
WEDNESDAY MORNING...BUT A MOIST AND UNSTABLE AIRMASS WILL REMAIN IN
PLACE AS THE SECOND AND LARGER WAVE DIVES SOUTH INTO SOUTHERN
ARIZONA/NORTHERN MEXICO THROUGH THURSDAY. LATEST MODELS BRING THE
CENTER OF THIS WAVE THROUGH NEVADA LATE WEDNESDAY/EARLY
THURSDAY...WHICH SHOULD BRING A DECENT SHOT OF PRECIP TO AT LEAST
SOUTHWEST AND SOUTH CENTRAL UTAH. PRECIP IS PROGGED TO LINGER OVER
AT LEAST SOUTHEAST UTAH THURSDAY EVENING.

THE TROUGH EXITS THURSDAY NIGHT...ALLOWING BRIEF RIDGING TO RETURN
ON FRIDAY. PROGRESSIVE PATTERN CONTINUES WITH THE NEXT PACIFIC
TROUGH PROGGED TO IMPACT UTAH AND SOUTHWEST WYOMING SATURDAY THROUGH
EARLY MONDAY. MODELS HAVE BEEN CONSISTENT IN DIVING THIS SYSTEM
SOUTH INTO ARIZONA AS WELL. HOWEVER...IN THE LAST COUPLE OF RUNS OF
THE GFS THE SYSTEM TRAVELS FARTHER EAST...INTO WESTERN UTAH...BEFORE
SPLITTING AND CAUSING THE LARGER WAVE TO DROP SOUTH. THIS WOULD
RESULT IN A GREATEST POTENTIAL FOR SIGNIFICANT PRECIP THAN EARLIER
RUNS...WHICH HAD THIS SPLIT OCCURRING OVER CALIFORNIA AND NEVADA.
00Z ECMWF LOOKED SIMILAR TO THE EARLIER GFS RUNS BUT HAS NOW TRENDED
A BIT EASTWARD WITH THE SPLIT AS WELL. HAVE TWEAKED POPS TO MORE
CLOSELY FOLLOW THE GFS SOLUTION. HIGH PRESSURE IS EXPECTED TO RETURN
BEHIND THIS SYSTEM FOR THE EARLY PART OF NEXT WEEK.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL THROUGH THE EVENING. HOWEVER...THERE IS A 40 PERCENT CHANCE
OF BRIEF MVFR CONDITIONS DEVELOPING IN SNOW SHOWERS THROUGH ABOUT
02Z. NORTHERLY WINDS ARE EXPECTED TO SHIFT TO THE SOUTHEAST BETWEEN
03Z AND 05Z.

&&

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

$$

SHORT TERM...WILENSKY
LONG TERM/AVIATION...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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