045 
FXUS65 KBOI 070947
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
347 AM MDT TUE OCT 7 2008

.SHORT TERM...TODAY THROUGH WEDNESDAY...COLD FRONTAL PASSAGE TODAY
WILL FIRST BRING MILD PACIFIC AIR AND BREEZY WINDS ACROSS THE
REGION AS THE PARENT SURFACE LOW MOVES THROUGH SW CANADA. A
SECONDARY FRONT APPEARED IN THE IR TO EXTEND AS FAR E AS 55/135W
IN A BACKWARDS-C SHAPE IN THE CU FIELD /OVER MID 50S WATER
TEMPERATURES/ AT 745Z. NORTHWEST FLOW TONIGHT AND WEDNESDAY WILL
SEND THAT REINFORCING COLD AIR /BUT LESS WIND/ ACROSS THE REGION
FOR COLDER CONDITIONS WEDNESDAY. MAX/MEX/MOSGUIDE HIGHS WERE ABOUT
5F WARMER THAN THE PREFERRED GS40BC/ECMWFBC/N12BC/SREFBC BLENDED
WITH A METNAM12 ANALOG COMBINATION. THE COOLING TREND HAS JUST
BEGUN THOUGH...

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...MODELS IN BETTER 
AGREEMENT WITH THE NEXT UPPER LEVEL SYSTEM.  THERE IS STILL SOME 
UNCERTAINTY AS TO THE PLACEMENT OF THE UPPER LEVEL TROUGH AND ALSO 
WHERE A CLOSED LOW ASSOCIATED WITH THIS TROUGH WILL END UP.  LATEST 
MODEL RUNS NOW HAVE THE GFS COMING MORE IN LINE WITH WHAT THE ECMWF 
HAD SEVERAL DAYS AGO BUT GUIDANCE FROM HPC STILL THINKS THE GFS IS 
TO FAST TO MOVE THE SYSTEM OUT.  WITH THE UNCERTAINTY IN THE 
PLACEMENT OF THE UPPER LEVEL TROUGH AND ASSOCIATED LOW DID NOT MAKE 
ANY MAJOR CHANGES TO THE FORECAST.  DRY CONDITIONS OVER THE AREA 
WEDNESDAY NIGHT AND EARLY THURSDAY MORNING AS A WEAK RIDGE OF HIGH 
PRESSURE MOVES OVER THE AREA.  THE UPPER LEVEL SYSTEM THAT HAS BEEN 
IN QUESTION WILL BEGIN TO MOVE INTO THE PACIFIC NORTHWEST THURSDAY 
NIGHT AND CONTINUE TO DIG TO THE SOUTH THROUGH AT LEAST SATURDAY.  
ONLY CHANGE TO THE FORECAST WAS TO INCREASE POPS SLIGHTLY ON 
THURSDAY AFTERNOON WITH BETTER TIMING OF THE SYSTEM DROPPING TO THE 
SOUTH.  DEPENDING ON HOW FAST THE COLD AIR MOVES INTO THE AREA WITH 
THIS UPPER LEVEL TROUGH MAY NEED TO DECREASE MAX TEMPERATURES FOR 
FRIDAY.  FOR NOW WILL NOT MAKE ANY CHANGES TO FRIDAY AND LET DAY 
SHIFT LOOK AT ANOTHER MODEL RUN.  UNSETTLED WEATHER WILL CONTINUE 
OVER THE WEEKEND WITH SLIGHT CHANCE TO CHANCE POPS AND BELOW NORMAL 
TEMPERATURES.  ONLY CHANGE TO THE WEEKEND FORECAST WAS TO INCREASE 
POPS OVER EASTERN ZONES AND INCREASE CLOUD COVER.  LATE SUNDAY INTO 
MONDAY UPPER LEVEL TROUGH BEGINS TO MOVE TO THE EAST FOR DECREASING 
POPS AND SLOWLY WARMING TEMPERATURES.

&&

.AVIATION...A COLD FRONT WILL SLOWLY MOVE OVER THE FORECAST AREA 
TODAY.  THIS WILL BRING ISOLATED RAIN SHOWERS AND BRIEF MVFR 
CEILINGS AND MOUNTAIN OBSCURATION.  SURFACE WINDS WILL BE LIGHT FROM 
THE SOUTHEAST BECOMING WEST TO NORTHWEST THIS AFTERNOON AND THIS 
EVENING BEHIND THE COLD FRONT.  ESTIMATED TIMING OF THE COLD FRONT 
WILL PASS THROUGH KBKE...KBNO AND KMYL AROUND 15Z...KBOI AROUND 18Z 
AND KTWF/KJER AROUND 21Z.  MODERATE TO STRONG WESTERLY WINDS ALOFT.  

&&

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

$$

WEATHER.GOV/BOISE

SHORT TERM...VM
LONG TERM....JA
AVIATION.....JA