FXUS65 KSLC 101744
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1044 AM MST THU DEC 10 2009

.SYNOPSIS...GENERALLY DRY AND COLD CONDITIONS WILL EXIST THROUGH
THE REMAINDER OF THE WEEK. MOISTURE WILL INCREASE OVER THE
WEEKEND AS A SERIES OF PACIFIC STORM SYSTEMS IMPACT THE AREA.

&&

.DISCUSSION...CYCLONIC NORTHWESTERLY FLOW ALOFT RESIDES ACROSS
THE FORECAST AREA THIS MORNING...ALONG THE BACKSIDE OF A DEEP
LONGWAVE TROUGH ENCOMPASSING MUCH OF THE NORTHERN AND CENTRAL
CONUS. AT THE SURFACE HIGH PRESSURE REMAINS CENTERED ACROSS THE
INTERIOR WEST ALLOWING FOR ANOTHER COLD START...WITH MIN TEMPS
RANGING FROM SUB ZERO TO THE SINGLE DIGITS ACROSS MOST NORTHERN
AND CENTRAL UT VALLEYS. GOING TEMPERATURE FORECAST LOOKS
REASONABLE BUT WILL MONITOR HOURLY TRENDS AND UPDATE IF
NECESSARY.

LONGWAVE TROUGH FORECAST TO SLOWLY PULL AWAY FROM THE REGION
DURING THE NEXT 24 HOURS ALLOWING A BELT OF WESTERLIES EXTENDING
ACROSS THE EASTERN PACIFIC TO SPREAD INLAND. THIS WILL BRING A
RELATIVELY MILD BUT MOIST PATTERN TO THE REGION WITH SEVERAL
EMBEDDED SHORTWAVE FEATURES PASSING THROUGH BEGINNING FRIDAY
AFTERNOON...AND CONTINUING THROUGHOUT THE WEEKEND.

INITIAL SHORTWAVE TROUGH AND ASSOCIATED PLUME OF MOISTURE IS
EXPECTED TO PASS THROUGH THE REGION FRIDAY AFTERNOON/NIGHT. THIS
WAVE WILL BE WEAKENING AS IT MOVES INTO A REGION OF UPPER LEVEL
CONFLUENCE. ANTICIPATE A HIGH POP/LOW QPF EVENT PRIMARILY
IMPACTING THE NORTHERN AND CENTRAL MOUNTAINS. 

SOUTHWESTERLY FLOW ALOFT EXPECTED TO STRENGTHEN CONSIDERABLY
SATURDAY AHEAD OF A SOMEWHAT STRONGER SYSTEM FOR SATURDAY
NIGHT/SUNDAY. GFS/NAM ARE BOTH SUGGESTING A CONVERGENCE ZONE AND
ATTENDANT BAND OF HEAVIER PRECIPITATION TO SET UP ACROSS PORTIONS
OF NORTHERN AND CENTRAL UT SATURDAY NIGHT INTO SUNDAY. WITH
STRENGTHENING FLOW AHEAD OF THIS WAVE AND WARMING TEMPERATURES
ALOFT CONCERNS WILL FOCUS ON HOW MUCH MIXING OCCURS AND RESULTANT
P-TYPE ISSUES. SUSPECT MOST NORTHERN AND CENTRAL VALLEYS WILL
EFFECTIVELY MIX BY SOMETIME SATURDAY EVENING POSSIBLY ALLOWING FOR
A CHANGEOVER TO RAIN ALONG THE VALLEY FLOORS...ALTHOUGH MORE
PROTECTED VALLEYS SUCH AS THE CACHE AND UINTA BASIN MAY SEE COLD
AIR REMAIN TRAPPED. WILL TAKE A CLOSER LOOK AT 12/18Z MODEL RUNS
BEFORE MAKING ANY CHANGES TO GOING FORECAST.

&&

.AVIATION...WINDS AT THE SLC TERMINAL ARE EXPECTED TO SHIFT TO THE 
NORTHWEST BETWEEN 19Z AND 21Z. VFR CONDITIONS WITH GENERALLY CLEAR 
SKIES WILL PREVAIL. 

&&

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

&&

$$

SEAMAN/HOSENFELD

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