FXUS65 KBOI 241606
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
906 AM MST THU DEC 24 2009

.DISCUSSION...FOG DID NOT MATERIALIZE IN THE SNAKE BASIN AS 
FORECAST YESTERDAY BY MOS PRODUCTS...BUT THE WRN END OF STRATUS
DECK PERSISTED IN JEROME AND GOODING COUNTIES THROUGH THE NIGHT.  
TODAY/S MOS PRODUCTS...ESPECIALLY MET MOS...AGAIN SUGGEST A 
FOG/STRATUS EVENT FOR LATE TONIGHT INTO CHRISTMAS MORNING BUT
THIS TIME WE WON/T FORECAST IT UNLESS NEW MODELS MAKE DEFINITE 
CHANGES FROM CURRENT CONDITIONS REGARDING SURFACE RH AND WIND 
FIELDS.  WITHOUT THOSE CHANGES PERSISTENCE WILL BE FORECAST
INTO CHRISTMAS.  EARLY MORNING UPDATE ALREADY ADJUSTED TOWARD 
PERSISTENCE AND NO FURTHER UPDATES NEEDED FOR NOW.

&&

.AVIATION...VFR CONDITIONS WITH SCATTERED HIGH CLOUDS. SURFACE WINDS 
LIGHT TO MODERATE FROM THE NORTHWEST THROUGH 00Z THIS AFTERNOON WITH 
LIGHT TO MODERATE NORTHERLY WINDS ALOFT 15 TO 25 KTS.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH FRIDAY...HIGH PRESSURE SURFACE AND ALOFT 
WILL PRODUCE LIGHT DIURNAL WINDS TODAY. SURFACE HIGH CENTER TO THE 
EAST FRIDAY WILL TRANSITION TO EAST LOW LEVEL ENHANCEMENT ON WINDS 
FOR BETTER CHANCES OF STRATUS WORKING IN FROM SE AND SOUTH CENTRAL 
IDAHO INTO SOUTHWEST IDAHO BY FRIDAY. PATCHY STRATUS COULD ALSO FORM 
AROUND LAKE LOWELL AREA. MET AND ANALOG/GFSBC BLENDS PREFER ED FOR 
TEMPERATURES.

STAGNANT CONDITIONS LOOK TO PROMOTE PATCHY MORNING FOG AND
DEVELOPMENT OF HAZY CONDITIONS IN LOWER ELEVATIONS AND BASINS
WHERE LIMITED FLOW ALLOWS A BUILD-UP OF PARTICULATES. THIS LOOKS
TO LAST INTO THE MID-RANGE AS MENTIONED NEXT.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...FORECAST AREA REMAINS 
UNDER THE INFLUENCE OF A HIGHLY AMPLIFIED WRN CONUS RIDGE THROUGH 
SATURDAY - FOR A CONTINUATION OF INVERTED TEMPERATURE PROFILES AND 
STAGNANT VALLEY CONDITIONS. BY SUNDAY...MODELS ATTEMPT A BREAKDOWN 
OF THE RIDGE AS AN UPPER LOW OFF THE NRN CALIFORNIA COAST EJECTS 
SHORTWAVE ENERGY NORTHEAST /INTO SE OREGON/ BEFORE DIGGING 
SOUTHWARD. THE STRENGTH OF THIS SHORTWAVE AND SUBSEQUENT WAVES /IN 
PREDOMINANTLY SPLIT FLOW/ REMAIN IN QUESTION THROUGH EARLY NEXT 
WEEK. THEREFORE...HAVE KEPT MID-RANGE TEMPERATURES AT OR BELOW 
NORMAL AND TRENDED POPS DRIER THAN NORMAL DUE TO LACK OF UPPER LEVEL 
DYNAMICS. BY WEDNESDAY...MODELS INDICATE A SHIFT TOWARD WESTERLY 
FLOW AND ANOTHER WEAK WAVE TARGETED FOR THE FORECAST AREA. STILL - 
TIMING AND PLACEMENT REMAIN UNCERTAIN. THUS...HAVE TRENDED POPS 
HIGHER /TOWARD CLIMATOLOGY/ BY THURSDAY. 

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...AIR STAGNATION ADVISORY UNTIL 4 PM PST SATURDAY FOR ORZ061-
        ORZ062.
&&

$$

WEATHER.GOV/BOISE

DISCUSSION...LC
AVIATION.....CD
PREV SHORT TERM...VM
PREV LONG TERM....MT