FXUS65 KBOI 090408
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
908 PM MST TUE DEC 8 2009
.DISCUSSION...VERY COLD NIGHT ON TAP FOR THE AREA. WILL UPDATE TO
LOWER TEMPS MOST AREAS BASED ON LATEST OBS...CLEAR SKIES...LIGHT
WINDS...AND EXPECTED TRENDS. NEW FORECAST FOR KBOI IS -10. THEY
ARE AT 2 DEGREES ABOVE ZERO AT 9:02 PM MST. KUNA GOT TO -12 LAST
NIGHT AND APPEARS TO BE HEADED EVEN A LITTLE COLDER FOR TONIGHT.
FAIRFIELD SHOULD HIT -21 OR SO. MOUNTAIN HOME APPEARS TO BE
HEADED FOR -13. IT IS IMPORTANT TO REMEMBER ON NIGHTS LIKE THIS
THAT THERE ARE VERY LARGE VARIANCES IN TEMPERATURE OVER VERY
SHORT DISTANCES. THESE DIFFERENCES ARE DUE TO TOPOGRAPHY AND
MICROSCALE WIND PATTERNS. FOR EXAMPLE...MUCH OF THE BOISE AREA
WILL NOT GET DOWN AS LOW AS -10. HOWEVER...THE AIRPORT SITS IN A
LOCATION FAVORABLE FOR RADIATIONAL COOLING AND WILL BE ONE OF THE
COLDEST LOCATIONS IN THE ENTIRE METRO AREA. IN THE WEST CENTRAL
AND BOISE MTNS TONIGHT...SOME HIGH CLOUDS WILL MOVE RAPIDLY SOUTH
AND LIMIT THE VERY LATE NIGHT COOLING...RESULTING IN TEMPS MUCH
LIKE YDAY INSTEAD OF SIGNIFICANTLY COLDER...WHICH WOULD HAVE
LIKELY RESULTED IF THE CLOUDS WERE NOT HEADED IN.
CONDITIONS WILL START TO SLOWLY WARM DAY BY DAY AS OF TOMORROW.
WE SHOULD BE BACK TO NEAR OR ABOVE NORMAL TEMPERATURES BY
SATURDAY.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH WEDNESDAY UNDER
MOSTLY CLEAR SKIES. ALTHOUGH THE AIR IS QUITE DRY LOCAL POCKETS OF
FOG ARE STILL POSSIBLE AFTER 06Z. SURFACE WINDS WILL BE LIGHT. WINDS
ALOFT WILL BE MODERATE NORTHWEST.
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH THURSDAY...BUBBLE SURFACE HIGH
PRESSURE CENTER NOSING INTO IDAHO THIS AFTERNOON WILL OVERSPREAD
THE REGION TONIGHT. AN UPPER LEVEL WAVE WITH CLOUDS IN WESTERN
CANADA WILL BRUSH NORTHERN ZONES WITH SOME HIGH CLOUDS LATE
TONIGHT. MUCH VALLEY SNOW COVER TREASURE/MAGIC VALLEYS AND
ELSEWHERE TO COMBINE WITH ANOTHER NIGHT OF MOSTLY CLEAR SKIES AND
LIGHT WINDS FOR WIDESPREAD SINGLE DIGIT TO SUB- ZERO (F)
TEMPERATURES. LOCALIZED FREEZING FOG A POSSIBILITY EARLY
WEDNESDAY. AFOREMENTIONED UPPER WAVE LOOKS TO HAVE ENOUGH LIFT
TO WRING OUT LIGHT SNOW SHOWERS/FLURRIES ACROSS NE VALLEY COUNTY
WEDNESDAY INTO THE EVENING. CLOUDS LOOK TO LINGER THERE THROUGH
THURSDAY. BUBBLE HIGH CONTINUES OVER SW IDAHO THROUGH THURSDAY
WITH SOME INCREASE IN E-W SURFACE PRESSURE GRADIENT OVER OREGON AS
A SYSTEM DEVELOPS OFFSHORE. LOW TEMPERATURES AVERAGE 10-20F BELOW
NORMAL AND HIGHS MODERATING FROM AROUND 20 BELOW THROUGH WEDNESDAY
TO AROUND 15 BELOW NORMAL THURSDAY. DROPPED HIGHS THURSDAY BY
5-10F AS DEEP FREEZE DOMINATES THE SHORT TERM. SO NOW IT LOOKS TO
BE FRIDAY BEFORE EVEN THE BOISE TO MOUNTAIN HOME AREA EDGES UP TO
NEAR THE FREEZING MARK AND NOT UNTIL SATURDAY FOR THE ENTIRE
VALLEY AS MENTIONED NEXT.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODELS STILL IN GOOD
AGREEMENT FOR THE FRIDAY TIME PERIOD BY HAVING THE FLOW BACK TO THE
NORTHWEST WHICH WILL SLOWLY BRINGING A LITTLE WARMER TEMPERATURES
INTO THE AREA BY PUSHING THE MODIFIED ARCTIC AIRMASS OUT OF THE AREA.
TEMPERATURES THOUGH WILL REMAIN MUCH BELOW NORMAL. DIFFERENCES IN
THE MODELS CREEP INTO PLAY BY SATURDAY AND SUNDAY. GFS CONTINUES
ITS THINKING THE PAST FEW DAYS BY PUSHING THE SUBTROPICAL JET
NORTHWARD INTO THE PACIFIC NORTHWEST. THIS WOULD BRING IN WETTER
AND WARMER CONDITIONS BOTH THOSE DAYS. THE ECM DID SHOW THIS SAME
TREND THE LAST FEW DAYS BUT NOW THE 12Z RUN SHOWS THAT THE
NORTHWESTERLY FLOW CONTINUES THROUGH THE WEEKEND. THIS WOULD KEEP
TEMPERATURES COOLER AND CONDITIONS DRIER THROUGH SUNDAY. FOR NOW
HAVE DONE A BLEND OF THOUGHTS FROM THE LAST FEW DAYS AND THE
LATEST EC MODEL. THIS STILL LEAVES CHANCE POPS ACROSS THE FORECAST
AREA WHICH IS STILL ABOUT 10-15 PERCENT HIGHER THAN CLIMO.
FOR THE FIRST OF THE WEEK...TEMPERATURES AND POPS WILL REMAIN
AROUND CLIMO AS WE NEED TO SEE WHAT HAPPENS WITH THE WESTERLIES
OFF THE COAST OVER THE WEEKEND.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION.....JT
PREV SHORT TERM...VM
PREV LONG TERM....CR/DD
