FXUS65 KBOI 031652
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
952 AM MST THU DEC 3 2009

.DISCUSSION...SKIES WERE CLEAR THIS MORNING THROUGHOUT THE BULK OF 
SE OREGON/SW IDAHO. HOWEVER...PATCHY FOG IN THE VALLEYS OF SOUTHERN 
HARNEY/WESTERN MALHEUR COUNTIES IS EXPECTED TO DISSIPATE BY THE 
AFTERNOON. AIRMASS WILL REMAIN DRY AND COLD THROUGH TODAY. NO 
UPDATES.

&&

.AVIATION...VFR UNDER CLEAR SKIES...EXCEPT FOR PATCHY MVFR/IFR 
VALLEY FOG AND STRATUS. STRATUS DECK OVER SOUTHERN TWIN FALLS COUNTY 
EXTENDING NORTH INTO KTWF AND MAGIC VALLEY THIS EVENING MAY PUSH 
EAST AROUND 04Z BUT RETURN AROUND 09Z WITH WIND SWITCHING TO THE 
EAST. ALSO EXPECT FOG/STRATUS TO FORM MAINLY ALONG THE SNAKE RIVER 
SOUTH OF KBOI...IN THE LOWER TREASURE VALLEY WEST OF KBOI...AND IN 
THE KMYL AREA AND LONG VALLEY EARLY THURSDAY MORNING. FOG/STRATUS 
DISSIPATING BY 18Z. VFR CONDITIONS WILL CONTINUE UNDER MOSTLY CLEAR 
SKIES THURSDAY. SURFACE WINDS WILL BE LIGHT. WINDS ALOFT WILL BE 
NORTHERLY 20-40 KTS.

&&

.PREV DISCUSSION...
SHORT TERM...CONTINUED CLEAR COLD AND DRY TODAY UNDER STRONG NORTH 
WINDS ALOFT AND SURFACE HIGH PRESSURE CENTERED NEAR YELLOWSTONE. 
SHORT WAVE TROUGH CURRENTLY IN NORTHERN GULF OF ALASKA WILL DIG SEWD 
INTO BC TONIGHT PUSHING A NARROW SHORT WAVE RIDGE AHEAD OF IT INTO 
OUR CWA FRIDAY MORNING.  THIS RIDGE WILL TURN OUR NORTHERLY FLOW 
ALOFT TO NWLY RESULTING IN SLIGHT WARMING FRIDAY.  SOME OF THE 
CLOUDS CURRENTLY OFF VANCOUVER ISLAND WILL COME INTO OUR NRN-MOST 
ZONES FRIDAY BUT NO PCPN IS EXPECTED.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...GOOD MODEL AGREEMENT ON 
LARGE-SCALE PATTERN THROUGH THE PERIOD...THOUGH LESS CONFIDENT ON 
SOME DETAILS. FIRST PUSH OF COLD AIR ARRIVES FRIDAY NIGHT BACKED BY 
A 1060 MB HIGH OVER NORTHERN BC. THE UPPER LEVEL DYNAMICS WILL TRACK 
THROUGH CENTRAL IDAHO BRINGING LIGHT SNOW TO THE SW IDAHO MTNS. SOME 
DIFFERENCES IN TIMING AND TRACK OF A SECONDARY LOW THAT DROPS INTO 
THE PAC NW LATE SAT/SUN. THE ECMWF IS THE DRIER SOLUTION TRACKING 
THE LOW CENTER ALONG THE NW COAST WHILE THE GFS DROPS THE LOW CENTER 
SOUTH ALONG THE ID/ORE BORDER. GIVEN EITHER TRACK DRY AIRMASS WILL 
LIMIT SNOW AMOUNTS WITH VALLEYS LIKELY NOT SEEING MORE THAN A 
DUSTING BY SUNDAY EVENING. CORE OF MODIFIED ARCTIC AIR REMAINS EAST 
OF THE DIVIDE AS IT SLIPS INTO MT AS A 1040 MB HIGH LATE SUNDAY. 
COLDEST DAYS ARE SUNDAY THROUGH TUESDAY DURING WHICH MOST LOCATIONS 
WILL NOT MAKE IT ABOVE FREEZING. GOOD MODEL AGREEMENT ON MOIST 
WESTERLY FLOW DEVELOPING BY WED NEXT WEEK BRINGING OVERRUNNING 
PRECIP AND MODERATING TEMPS BACK TO NEAR NORMAL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&

$$

WEATHER.GOV/BOISE

DISCUSSION...BW
AVIATION.....JT
PREV SHORT TERM...LC
PREV LONG TERM....DG