FXUS65 KSLC 302212
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
312 PM MST MON NOV 30 2009

.SYNOPSIS...HIGH PRESSURE WILL SHIFT WESTWARD TONIGHT ALLOWING A
SYSTEM DROPPING THROUGH THE HIGH PLAINS TO SEND A DRY COLD FRONT
ACROSS UTAH ON TUESDAY. A COLD DRY NORTHERLY FLOW WILL FOLLOW FOR 
WEDNESDAY AND THURSDAY.

&&

.DISCUSSION...RIDGE OF HIGH PRESSURE OVER OREGON AND NEVADA WILL
MOVE WESTWARD TONIGHT AND BUILD ALONG THE PACIFIC NORTHWEST COAST
ON TUESDAY. THIS WILL ALLOW AN UPPER LEVEL SYSTEM TO DROP
SOUTHWARD ACROSS THE NORTHERN HIGH PLAINS AND BRING A DRY COLD
FRONT ACROSS UTAH TUESDAY AFTERNOON. THIS FRONT WILL MIX OUT THE
INVERSION ACROSS MOST AREAS BY TUESDAY AFTERNOON LENDING TO A
SOMEWHAT MILDER DAY THAN TODAY WHERE MOST VALLEYS HAVE BEEN STUCK
UNDER THE INVERSION. 

SINCE THE CORE OF THE COLD AIR REMAINS EAST OF THE CONTINENTAL
DIVIDE THE AIRMASS WILL REMAIN RATHER STABLE ALOFT SO NO PRECIP
OTHER THAN POSSIBLE FLURRIES ACROSS THE UINTAS ARE FORECAST FOR
TUESDAY NIGHT. BEHIND THE COLD FRONT A RELATIVELY COLD AIR MASS
WILL MOVE OVER THE ENTIRE CWA AND REMAIN IN PLACE THROUGH THURSDAY
UNDER A NORTHWESTERLY FLOW ALOFT. THE MAIN FORECAST CONCERN
THROUGH THE NEXT FOUR DAYS WILL BE IF AND WHEN AN INVERSION WILL
DEVELOP.

BY THURSDAY...THE MODELS BEGIN TO DIVERGE OVER THE GULF OF ALASKA
SUCH THAT BY FRIDAY THE EC HAS A CLOSED LOW OFF THE COAST OF
OREGON WHILE THE GEM HAS A CLOSED LOW OVER CENTRAL OREGON AND THE
OPERATIONAL GFS HAS AN OPEN WAVE OVER WYOMING AND MONTANA. THE GFS
ENSEMBLE IS FARTHER WEST NORTHWEST WITH THE OPEN WAVE WITH SOME
MEMBERS CLOSING THE WAVE OFF AS WELL. THE EVOLUTION OF THIS OPEN WAVE/CLOSED
LOW SYSTEM THROUGH THE WEEKEND VARIES GREATLY AND THEREFORE
CONFIDENCE IS LOW ON DETAILS BEYOND DAY 4. HAVE A HIGH DEGREE OF
CONFIDENCE THAT THE WEATHER PATTERN IS SHIFTING THIS WEEKEND BUT
HOW IT ALL PLAYS OUT IS YET TO BE DETERMINED. THE EC SUGGESTS A
MICRO RIDGE FORMS OVER UTAH ON SATURDAY WITH 700 MB TEMPERATURES
RISING TO ABOUT -5C AT SLC...WHILE THE GFS SUGGESTS THE BACKSIDE
OF A TROUGH WITH -18C AT 700 MB AT SLC. PLAYED THE MIDDLE OF THE
ROAD FOR NOW WITH SO MUCH UNCERTAINTY. 

&&

.AVIATION...VFR CONDITIONS TO REMAIN AT SLC THROUGH THE FORECAST 
PERIOD. NW LAKE BREEZE CONTINUES THROUGH EARLY EVENING BEFORE SE 
DRAINAGE WINDS PREVAIL BEGINNING BETWEEN 02-04Z.

&&

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

&&

$$

PUBLIC...STRUTHWOLF
AVIATION...ROGOWSKI

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