000 
FXUS65 KBOI 071730
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1030 AM MST MON DEC 7 2009

.DISCUSSION...AREAS OF SNOW ACROSS THE TREASURE VALLEY BROUGHT 0.5
TO 1.6 INCHES OF MEASURABLE SNOW TO CALDWELL/ NAMPA/ KUNA...AND A
TRACE TO BUHL AND TWIN FALLS. IN BOISE ACCUMULATIONS WERE LOCALLY
HIGHER FROM NIFC AND THE AIRPORT...AND SOUTHEAST BOISE 2 TO 3.7
INCHES. LOOK FOR LIGHT TO MODERATE SNOW ACCUMULATIONS OF 1 TO
LOCALLY 3 INCHES THROUGH THE EVENING HOURS FROM KMUO SOUTHEASTWARD
THROUGH SOUTHERN TWIN FALLS COUNTY. MAY NEED AN ADVISORY FOR SNOW
SOUTHERN TWF COUNTY ZONE 30 AS VERY COLD TEMPERATURES RESULT IN
30:1 SNOW RATIOS - WILL DECIDE BASED ON ACCUMS/SPOTTER REPORTS
FROM MOUNTAIN HOME AREA. CLEAR AND VERY COLD TONIGHT WITH A GOOD
CHANCE OF FOG SNOWIER AREAS LAKE LOWELL-BOISE. GUSTY NE WINDS LOOK
TO KEEP FOG AWAY FROM THE MAGIC VALLEY TONIGHT. COLDEST NIGHT
TONIGHT AND COLDEST DAYS TODAY AND TUESDAY /IDAHO/ THEN A WARMING
TREND IS EXPECTED. HIGHS AROUND 10F BELOW NORMAL AND LOWS TO 20F BELOW
NORMAL EARLY THIS WEEK. NEAR NORMAL IS EXPECTED WEDNESDAY THEN
GOING TO ABOVE NORMAL THURSDAY. MOISTURE LOOKS TO SPREAD ACROSS
THE AREA SATURDAY THROUGH SUNDAY WITH SNOW LEVELS RISING FROM 3K
FT EARLY SATURDAY TO 4500 FEET SUNDAY AFTERNOON. 

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL GENERALLY NORTH 
OF I-84 AND ACROSS EASTERN OREGON THROUGH THIS EVENING. FROM I-84 
SOUTHWARD TO THE NEVADA BORDER VFR WITH POCKETS OF MVFR CONDITIONS 
IN LOW CLOUDS AND -SN EXPECTED THROUGH THIS AFTERNOON. AS LOW KICKS 
OUT TO THE EAST OVERNIGHT...EXPECTING VFR CONDITIONS AFTER MIDNIGHT. 
WITH THE FRESH SNOW ACROSS KBOI THERE IS A SLIGHT THREAT OF MORNING 
FOG DEVELOPING AFT 12Z. STRONG EAST TO NORTHEAST WIND CONTINUE 
MAINLY EAST OF BOISE. 

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH TUESDAY...BANDS OF LIGHT SNOW CONTINUE 
ACROSS PORTIONS OF THE TREASURE VALLEY...MAINLY SOUTH OF INTERSTATE 
84 BETWEEN CALDWELL AND MOUNTAIN HOME...INCLUDING THE BOISE METRO. 
THERE HAVE BEEN NO SIGNS OF LETTING UP AND IN FACT...THE RADAR 
COVERAGE HAS INCREASED IN THE PAST COUPLE HOURS. NOT SURE EXACTLY 
WHEN THE SNOW WILL QUIT...BUT THE LATEST NAM12 INDICATES THAT IT 
WILL CONTINUE THROUGH MID-MORNING. QPF AMOUNTS WILL BE LIGHT...BUT 
BECAUSE TEMPS ARE COLD EVEN A COUPLE HUNDREDTHS OF AN INCH WOULD 
RESULT IN A HALF INCH OF POWDERY SNOWFALL. SINCE THE ROADS ARE 
ALREADY SNOW-COVERED AND EXPECTING MORE LIGHT SNOW THROUGH THE 
MORNING COMMUTE...WILL HOIST A WINTER WEATHER ADVISORY FOR THE 
TREASURE VALLEY UNTIL 9 AM MST. SNOW SHOWERS EXTEND EAST INTO THE 
WESTERN MAGIC VALLEY AND SOUTH TO THE NEVADA BORDER...AND WILL 
LIKELY CONTINUE IN THOSE AREAS AS WELL THIS MORNING. BITTER COLD 
WIND CHILLS HAVE NOT MATERIALIZED IN THE CAMAS PRAIRIE...SO WILL 
CANCEL THE WIND CHILL WARNING...ALTHOUGH WIND CHILLS DOWN TO 10 
BELOW ZERO WILL CONTINUE FOR THE NEXT SEVERAL HOURS. UPPER TROUGH 
RESPONSIBLE FOR THE SNOW WILL SLOWLY WORK EAST TONIGHT WITH DRIER 
AIR MOVING IN FROM THE NORTH AND WEST. SKIES ARE EXPECTED TO CLEAR 
IN MOST AREAS BY TUESDAY MORNING RESULTING IN SOME OF THE COLDEST 
TEMPS IN A LONG TIME. TEMPS COULD BE EVEN COLDER IN THE TREASURE 
VALLEY TONIGHT IF THE SNOW STICKS AROUND THROUGH TONIGHT. 

LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...MODELS REMAIN IN GOOD 
AGREEMENT WITH EACH OTHER FOR THE EARLY PORTION OF THE EXTENDED.  
MAIN UPPER LEVEL TROUGH WILL SLOWLY EXIT THE REGION BEGINNING 
WEDNESDAY AS THE UPPER LEVEL RIDGE OFF THE WEST COAST PUSHES FURTHER 
TO THE EAST.  THIS WILL GRADUALLY SHIFT THE FLOW ALOFT FROM A COLD 
NORTHERLY FLOW TO A MODERATING NORTHWESTERLY FLOW.  MODELS STILL 
KEEP THE MOIST SUBTROPICAL FLOW SOUTH OF THE FORECAST AREA BUT COULD 
SEE A SMALL CHANCE OF PRECIPITATION ALONG THE NEVADA BORDER.  POPS 
FOR WEDNESDAY THROUGH FRIDAY WILL REMAIN LOW WITH SLOWLY WARMING 
TEMPERATURES.  FOR THE WEEKEND MODELS ARE IN BETTER AGREEMENT BUT 
ENOUGH DIFFERENCE IN TIMING OF THE WEATHER SYSTEM FOR UNCERTAINTY IN 
THE FORECAST.  MODELS AGREE ON A MOIST SOUTHWEST FLOW ALOFT 
DEVELOPING OVER THE REGION FOR THE WEEKEND BUT DIFFER ON THE TIMING 
OF WHEN THE PRECIPITATION WILL MOVE INTO THE FORECAST AREA AND HOW 
MUCH PRECIPITATION WILL FALL.  FOR NOW WILL HAVE POP ABOVE 
CLIMATOLOGY AND WITH THE WARMER SOUTHWEST FLOW WILL WARM 
TEMPERATURES TO NEAR NORMAL.

&&

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

$$

WEATHER.GOV/BOISE

DISCUSSION...VM
AVIATION.....CR
PREV SHORT TERM...BW
PREV LONG TERM....JA