000
FXUS65 KBOI 152151
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
251 PM MST THU JAN 15 2009

.SHORT TERM...TONIGHT THROUGH SATURDAY...DIFFERENTIATING BETWEEN
AREAS OF FOG AND AREAS OF LOW STRATUS UNDER THE INVERSION IS THE
BIGGEST CONCERN OF THE SHORT TERM FORECAST. SATELLITE IMAGERY AS
OF 2130Z CLEARLY SHOWS FOG AND STRATUS STRETCHING FROM THE VALLEYS
OF BAKER COUNTY OREGON THROUGH THE LOWER AND UPPER TREASURE VALLEY
JUST REACHING THE EDGE OF THE WESTERN MAGIC VALLEY. THE
FOG/STRATUS THROUGH THE WESTERN MAGIC VALLEY HAS ERODED
THROUGHOUT THE DAY BUT IS EXPECTED TO RETURN TO THE AREA
OVERNIGHT. BELIEVE THAT LOW STRATUS AND FOG WILL REMAIN THROUGHOUT
ALL OF THE ABOVE MENTIONED AREAS OVERNIGHT BUT FEEL THE MOST
LIKELY PLACE FOR DENSE FOG TO FORM WILL BE THROUGH THE LOWER
TREASURE VALLEY. HAVE ISSUED A DENSE FOG ADVISORY FOR THE LOWER
TREASURE VALLEY FROM 02Z-19Z BUT WILL LEAVE IT UP TO THE EVENING
SHIFT TO DETERMINE IF THIS WILL NEED TO BE EXPANDED INTO OTHER
AREAS. THERE IS A SLIGHT CHANCE THE FOG WILL PRODUCE LIGHT
FREEZING DRIZZLE OR SNOW FLURRIES MAKING FOR SLICK ROAD
CONDITIONS. STAGNANT INVERTED PATTERN WILL CONTINUE TO KEEP VALLEY
TEMPERATURES AT OR BELOW NORMAL WITH ABOVE NORMAL TEMPERATURES
THROUGH ELEVATIONS ABOVE 4500 FEET.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...STRONG INVERSION WILL
CONTINUE UNDER A RIDGE OF HIGH PRESSURE THAT WILL SLOWLY SHIFT ITS
AXIS OVER THE FORECAST AREA THROUGH WEDNESDAY. THE FOG AND LOW
STRATUS WILL CONTINUE TO BE A HINDRANCE AND A FORECAST CHALLENGE
DURING THIS PERIOD. BY WEDNESDAY NIGHT A SHORT WAVE TROUGH OF LOWER
PRESSURE WILL MOVE SOUTH OF THE IDAHO AND NEVADA BORDER...WHICH IS
A BIT LATER THAN PREVIOUS MODEL RUNS SUGGESTED. SOME DISAGREEMENT REMAINS
AS TO WHETHER THIS WILL SPLIT THE FLOW FOR A DRY FORECAST OR NOT...BUT
THERE WILL AT LEAST BE SOME SIGNIFICANT TEMPERATURE CHANGES IN STORE FOR
THE HIGHER ELEVATIONS WITH THE INVERSION WEAKENING UNDER SOMEWHAT
LESS STABLE CONDITIONS.


&&

.AVIATION...MVFR TO LOCAL LIFR CONDITIONS IN FOG AND LOW STRATUS
WILL REDEVELOP OVERNIGHT UNDER CLEAR SKIES AND CALM WINDS
THROUGH THE VALLEYS OF BAKER COUNTY THE LOWER AND UPPER TREASURE
VALLEY INTO THE WESTERN MAGIC VALLEY. SHELTERED MOUNTAIN VALLEYS
WILL ALSO SEE FOG AND LOW STRATUS. ELSEWHERE AND LOCATIONS ABOVE
4500 FEET WILL REMAIN VFR.


&&

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

$$

WEATHER.GOV/BOISE

SHORT TERM...DF
LONG TERM....CD/JT
AVIATION.....CD/DF