FXUS65 KSLC 262156
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
256 PM MST SAT DEC 26 2009

.SYNOPSIS...WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION
THROUGH THROUGH SUNDAY. A WEAK AND GENERALLY DRY DISTURBANCE FROM
THE PACIFIC WILL SLOWLY PASS THROUGH THE REGION EARLY NEXT WEEK.

&&

.DISCUSSION...MID LEVEL COL IN PLACE ACROSS THE FORECAST AREA THIS
AFTERNOON RESULTING IN VERY LIGHT FLOW ALOFT. LAYER OF STRATUS
WHICH RESIDED ACROSS THE NORTHERN WASATCH FRONT EARLIER HAS SLOWLY
ADVECTED WESTWARD ACROSS NORTHWEST UT...AND WILL LIKELY REMAIN IN
PLACE THROUGHOUT THE NIGHT. WILL SEE A PERIOD OF MOSTLY CLEAR
SKIES ACROSS THE VALLEYS OF NORTHERN UT THIS EVENING WHICH MAY
ALLOW TEMPS TO DROP QUICKLY. OTHERWISE ANTICIPATE LOW STRATUS TO
EXPAND ACROSS NORTHERN UT OVERNIGHT WHICH SHOULD LIMIT WIDESPREAD
FOG POTENTIAL. ADDITIONALLY...MODELS ARE SPREADING PLUME OF MID
AND HIGH LEVEL MOISTURE CURRENTLY ACROSS CA EASTWARD INTO
SOUTHERN AND CENTRAL UT OVERNIGHT. 

PRIMARY CONCERN THE NEXT FEW DAYS CONTINUES TO BE INCREASING
STAGNATION ACROSS NORTHERN VALLEYS AS FLOW ALOFT REMAINS QUITE
WEAK. ALTHOUGH COLD AIR WILL REMAIN TRAPPED ACROSS THE LOWER
ELEVATIONS OF NORTHERN UT...INVERSIONS DONT LOOK TO BE
PARTICULARLY STRONG AS LIMITING FACTOR STILL APPEARS TO BE
RELATIVELY COOL 700MB TEMPS...WHICH ARE FORECAST TO REMAIN IN THE
-8 TO -10C RANGE. FOG MAY ALSO BECOME AN INCREASING
CONCERN...ALTHOUGH COMBINATION OF STRATUS ALREADY IN PLACE AND
INCREASING MID AND HIGH LEVEL MOISTURE SHOULD KEEP FOG COVERAGE
FAIRLY LOCALIZED.

A SHORTWAVE TROUGH IS EXPECTED TO SPREAD ACROSS THE DESERT
SOUTHWEST AND NORTHERN MX EARLY NEXT WEEK...WITH LITTLE MORE THAN
A WEAK AND DIFFUSE MID LEVEL TROUGH AXIS PASSING THROUGH THE
FORECAST AREA. APPRECIABLE DYNAMIC FORCING AND ATTENDANT
PRECIPITATION THREAT LOOK TO REMAIN SOUTH OF THE AZ
BORDER...ALTHOUGH ENOUGH MOISTURE SPREADING INTO THE AREA COMBINED
WITH THIS WEAK TROUGH AXIS APPEARS SUFFICIENT TO WARRANT LOW POPS
MAINLY ACROSS THE HIGHER TERRAIN LATE MONDAY INTO TUESDAY.
ACCUMULATIONS...IF ANY...WOULD BE QUITE SMALL.

OTHERWISE BLOCKING CANADIAN HIGH EXPECTED TO BREAK DOWN EARLY NEXT
WEEK ALLOWING A NORTHWESTERLY FLOW ALOFT TO DEVELOP ACROSS THE
INTERMOUNTAIN WEST. A SERIES OF FAIRLY WEAK EMBEDDED SHORTWAVES
ARE EXPECTED TO PASS THOUGH THIS FLOW DURING THE MIDDLE TO LATTER
PORTION OF NEXT WEEK. IT REMAIN DIFFICULT AT THIS POINT TO SAY
WHETHER ANY OF THESE FEATURES WILL BE SUFFICIENT TO COMPLETELY
DISLODGE VALLEY INVERSIONS ACROSS NORTHERN UT AS 12Z RUNS FROM THE
GFS/EC/GEM CONTINUE TO EXHIBIT CONSIDERABLE SPREAD BETWEEN
RESPECTIVE SOLUTIONS. HOWEVER IT DOES APPEAR SOMEWHAT UNLIKELY ANY
OF THESE WAVES WILL BE SUFFICIENT TO COMPLETELY SWEEP OUT STAGNANT
AIR BEFORE AT LEAST NEXT WEEKEND.

&&

.AVIATION...PERIODS OF MVFR CONDITIONS AT THE SLC TERMINAL ARE 
LIKELY THROUGH THE EVENING AND OVERNIGHT HOURS IN HAZE AND PATCHY 
FOG. THERE IS ALSO A 20 PERCENT CHANCE THAT FOG OR LOW STRATUS COULD 
CAUSE IFR CONDITIONS OR WORSE...PARTICULARLY AFTER 06Z.

&&

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

&&

$$

SEAMAN/SCHOENING

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)