FXUS65 KBOI 252147
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
247 PM MST FRI DEC 25 2009

.SHORT TERM...STRATUS HAS THINNED OUT IN THE AFTERNOON SUN AS IT 
MOVED WWD INTO THE TREASURE VALLEY BUT WE EXPECT STRATUS TO INCREASE
AGAIN AROUND SUNSET OR SHORTLY AFTER. PREFERRED NAM SHOWS IT MOVING 
SLOWLY NWWD INTO THE LOWER TREASURE VALLEY OVERNIGHT AND SETTLING 
INTO THE LOWER MALHEUR VALLEY SATURDAY...WHILE SLOWLY DECREASING IN 
THE WRN MAGIC VALLEY AND UPPER TREASURE VALLEY.  ALONG WITH THIS...
MIN TEMPS TONIGHT WILL BE HELD NEAR LAST/S MINS BY SKY COVER...AND 
MAX TEMPS SATURDAY WILL BE A COUPLE DEGS COLDER THAN THEY WOULD BE 
UNDER BRIGHT SUN.  ALOFT...NLY COMPONENT WILL END AS THE UPPER RIDGE 
OVER OUR AREA BECOMES AN UPPER HIGH CELL THAT DRIFTS NEWD INTO 
ALBERTA...LEAVING LIGHT WINDS ALOFT OVER OUR AREA.  COLD AIR WILL 
REMAIN ENTRENCHED IN OUR VALLEYS THROUGH SUNDAY.  WITH LIGHT WINDS 
CONTINUING AT THE SURFACE THE CURRENT AIR STAGNATION ADVISORY FOR 
THE VALLEYS OF HARNEY AND BAKER COUNTIES WILL CONTINUE THROUGH 
SATURDAY.  ON SUNDAY THE FIRST PACIFIC MOISTURE WILL MOVE FAR ENOUGH
INLAND FOR A SLIGHT CHANCE OF SNOW SHOWERS IN SOUTHERN HARNEY COUNTY 
SUNDAY AFTERNOON.  DRY ELSEWHERE.  LITTLE DAY-TO-DAY TEMPERATURE 
CHANGE THROUGH SUNDAY.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY...SPLIT FLOW WILL KEEP 
CONDITIONS DRY THROUGH MONDAY. THEN A SHORTWAVE TROUGH WILL BEGIN TO 
MOVE FROM NORTHERN CALIFORNIA INTO SOUTHERN OREGON. THE LEADING EDGE 
OF THIS SYSTEM PROBABLY WON/T DO MUCH OTHER THAN PROVIDE BETTER 
MIXING OF THE ATMOSPHERE AND BRING IN A MID LEVEL CLOUD DECK. NOT 
UNTIL TUESDAY THAT THE PATTERN LOOKS TO BECOME MORE PROGRESSIVE FOR 
A CHANCE OF SNOW. THERE IS DECENT AGREEMENT BETWEEN MODELS WITH THIS 
TRANSITION BUT CONSIDERABLY MORE DIFFERENCES FOR THE LATTER PERIODS. 
THIS IS BECAUSE THE ECMWF TRIES TO RE-AMPLIFY THE RIDGE OF HIGH 
PRESSURE WHILE THE GFS ADVERTISES A MORE OPEN WESTERLY FLOW WITH A 
SERIES OF EMBEDDED SHORTWAVES. AS SUCH...I BLENDED CLIMATOLOGY WITH 
ANALOG PATTERNS FROM PREVIOUS EVENTS IN SIMILAR FLOW. THE GFS IS 
STILL THE WARMEST OF SOLUTIONS WITH TEMPERATURES SLIGHTLY BELOW 
NORMAL SO DIDN/T MAKE ANY DRAMATIC CHANGES TO EXISTING TEMPERATURE 
AND DEW POINT FORECASTS.

&&

.AVIATION....STRATUS IS ADVANCING WESTWARD THROUGH THE TREASURE 
VALLEY THIS AFTERNOON AND WILL CONTINUE THIS TREND WITH MVFR 
CEILINGS AND VISIBILITY THIS EVENING. OVERNIGHT AND SATURDAY THE 
STRATUS WILL MAKE ADDITIONAL GAINS TOWARD KONO...AND KBKE BY 
TOMORROW AFTERNOON. SHELTERED VALLEYS WILL SEE DETERIORATING 
CIGS/VIS AFTER 03Z TONIGHT WITH LOCAL LIFR. ELSEWHERE CONDITIONS 
WILL BE VFR WITH NO SIGNIFICANT CHANGES THROUGH SUNDAY. SURFACE 
WINDS WILL BE LIGHT. WINDS ALOFT WILL BE MODERATE NORTHERLY 15 TO
30 KTS.

&&

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

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...LC
LONG TERM....CD/BB
AVIATION.....CD