FXUS65 KBOI 022149
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
250 PM MST WED DEC 2 2009

.SHORT TERM...UPPER RIDGE JUST OFF THE WEST COAST WITH COLD DRY 
NORTHERLY FLOW OVER IDAHO. UPPER RIDGE WILL COLLAPSE AND MOVE EAST 
THURSDAY AND FRIDAY. TEMPERATURES WILL REMAIN FAIRLY CONSTANT 
THURSDAY THEN WARM A BIT FRIDAY. STRONG NORTH PACIFIC STORM WILL 
MOVE ACROSS THE NORTHERN GULF OF ALASKA TONIGHT AND THURSDAY HEADING 
INLAND INTO WESTERN BC FRIDAY. THIS WILL BE THE STORM THAT BRINGS 
POSSIBLE LIGHT SNOW TO THE AREA SATURDAY. 

.LONG TERM...FRIDAY NIGHT THROUGH MONDAY...MODELS ARE IN GOOD 
AGREEMENT DURING THIS PORTION OF THE LONG TERM. A VERY COLD UPPER 
LEVEL TROUGH WITH AXIS ORIENTED EAST WEST REMAINS OVER THE NORTHWEST 
STATES. AT THE SURFACE OUR AREA IS UNDER THE EDGE OF MODIFIED ARCTIC 
AIR FLOWING SOUTH OUT OF BRITISH COLUMBIA...WHILE THE COLDEST AIR 
STAYS WELL TO OUR NORTH AND EAST WITH CENTERS IN CENTRAL BRITISH 
COLUMBIA AND MONTANA. ONLY LIGHT AMOUNTS OF SNOW ARE EXPECTED. 
TEMPERATURES WILL BE 5 TO 10 DEGREES BELOW NORMAL...BUT WELL ABOVE 
RECORD LOWS. 

TUESDAY AND WEDNESDAY...MODEL AGREEMENT FALTERS BY TUESDAY AS RECENT 
RUNS STRUGGLE WITH THE TIMING AND PLACEMENT OF THE UPPER LOW AS IT 
EXITS THE FORECAST AREA. ECMWF QUICKLY SHIFTS TO A MOIST ZONAL 
PATTERN...WHILE GFS PREFERS A SLOWER /AND THUS DRIER/ TRANSITION TO 
WESTERLY FLOW. BY LATE WEDNESDAY...BOTH INDICATE A WETTER OVERALL 
PATTERN BUT CONFIDENCE IN THE LATE PERIOD TEMPERATURE FORECAST 
REMAINS LOW. THEREFORE...HAVE INCREASED TUE/WED POPS BUT KEPT TEMPS 
AT OR BELOW DECEMBER NORMALS. 

&&

.AVIATION...PATCHY MVFR/IFR VALLEY FOG AND STRATUS WILL DEVELOP 
AFTER 06Z...MAINLY ALONG THE SNAKE RIVER SOUTH OF KBOI...IN THE 
LOWER TREASURE VALLEY WEST OF KBOI...AND IN THE KMYL AREA AND LONG 
VALLEY. OTHERWISE VFR CONDITIONS WILL CONTINUE UNDER MOSTLY CLEAR 
SKIES. SURFACE WINDS WILL BE LIGHT. WINDS ALOFT WILL BE NORTHERLY 
20-40 KTS.

&&

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

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...PRF
LONG TERM...JT/MT
AVIATION...JT