000 
FXUS65 KBOI 080327
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
930 PM MDT TUE APR 7 2009

.DISCUSSION...MID AND HIGH CLOUDS CONTINUE TO ADVANCE NORTHWARD 
AHEAD OF PARENT UPPER LOW OVER THE NORTHERN CALIFORNIA COAST...BUT 
THUS FAR ONLY SPOTTY PRECIPITATION REPORTS. NEVERTHELESS...THE 
LATEST 00Z MODEL GUIDANCE SHOWS SHOWER ACTIVITY BREAKING OUT OVER 
EASTERN OREGON AROUND DAYBREAK...THEN DRIFTING EASTWARD ACROSS 
SOUTHERN IDAHO DURING THE DAY WEDNESDAY. EXPECTING SHOWERS OVER MOST 
SOUTHWEST IDAHO ZONES DURING THE DAY AND FAVORING HIGHER TERRAIN.  
VALLEYS MAY SEE LITTLE OR NOTHING. CONVECTIVE INSTABILITY ALTHOUGH 
NOT VERY IMPRESSIVE...WILL BE THERE...ESPECIALLY ON THE EAST SIDE OF 
THE CLOSED LOW WHERE IT WILL BE WARMER AND HAVE DECENT JET DYNAMICS 
TO WORK WITH. WITHOUT MUCH SHEAR HOWEVER...ANY STORMS THAT DO DEVELOP 
ARE EXPECTED TO BE WEAK.  THIS HAS ALREADY BEEN INDICATED BY SPC IN 
THEIR LATEST GENERAL THUNDER OUTLINE FOR WEDNESDAY. TEMPERATURES OF 
COURSE MUCH COOLER THAN TODAY WITH EXTENSIVE CLOUDS AND SCATTERED 
SHOWERS SCATTERED AROUND.     

&&

.AVIATION...CEILINGS AOA 15K FEET MSL FOR MOST LOCATIONS TONIGHT. 
LOWER CEILINGS AND PRECIP WILL DEVELOP FROM KBNO-KREO SOUTH AND WEST 
BY WEDNESDAY MORNING...AND OVER SW ID DURING THE AFTERNOON. EXPECT 
WIDESPREAD MTN OBSCURATION AND LOCAL IFR CONDITIONS OVER HIGHER 
TERRAIN OF SE ORE AFTER 15Z AND SW ID AFTER 21Z. A COLD FRONT WILL 
BRING GUSTY NW WINDS AND A PERIOD OF LOWER CEILINGS /POSSIBLY MVFR/ 
TO THE TREASURE AND MAGIC VALLEYS WEDNESDAY AFTERNOON.

&&

.PREV DISCUSSION...TONIGHT THROUGH THURSDAY...HIGH TEMPERATURES HAVE 
JUMPED 10-15 DEGREES ABOVE NORMAL TODAY WITH ABUNDANT SUNSHINE AND 
DOWNSLOPE SE WINDS HELPING TO WARM THE VALLEYS. AS OF 21Z KBOI HAS 
RECORDED A HIGH OF 74 DEGREES WHICH IS 5 DEGREES BELOW THE RECORD 
HIGH OF 79 DEGREES SET BACK IN 1977. OCCLUDED UPPER LEVEL LOW IS 
SLOWLY MOVING EASTWARD WITH ITS CENTER ABOUT 250 MILES OFF THE SF 
BAY AREA COAST AS OF 20Z. CLOUD BANDS ARE EXTENDING NORTHEASTWARD 
INTO OREGON AND ARE JUST BEGINNING TO BRING CIRRUS INTO IDAHO. 
CONTRAILS ARE ALSO VISIBLE THROUGHOUT SE OREGON AND SW IDAHO DUE TO 
THE FLOW PATTERN AND MOISTURE MOVING IN ALOFT. AS EXPECTED ...MODELS 
HAVE CONTINUED TO SLOW THE PROGRESSION OF THE LOW INLAND SO HAVE 
BACKED OFF ON POPS THIS EVENING AND REMOVED ALL MENTION OF THUNDER. 
BEST CHANCES FOR PRECIP WILL BE ON WEDNESDAY WITH MODELS INDICATING 
PW VALUES 120-170 PERCENT OF NORMAL. COLD/OCCLUDED FRONT SHOULD PASS 
THROUGH SE OREGON LATE TONIGHT REACHING BOISE AROUND 12Z TOMORROW 
MORNING. CONVECTIVE PARAMETERS INDICATE A SLIGHT CHANCE FOR 
THUNDERSTORMS WEDNESDAY AFTERNOON AND EARLY EVENING IN A LINE 
EXTENDING FROM KBKE-KBOI-KTWF EASTWARD. SYSTEM BEGINS TO EXIT 
CENTRAL IDAHO THURSDAY MORNING AS A SECOND SPLITTING TROUGH BEGINS 
TO PUSH INTO SE OREGON. THERE WILL BE A BRIEF BREAK IN THE 
PRECIPITATION BETWEEN SYSTEMS. TEMPERATURES WILL RETURN TO NEAR 
NORMAL TOMORROW AND THURSDAY.

LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...NEXT SYSTEM POISED TO 
MOVE INTO THE WEST WILL SPLIT...WITH THE BULK OF THE 
MOISTURE/DYNAMICS ACCOMPANYING A CLOSED UPPER LOW WHICH TRACKS SOUTH 
OF THE AREA FRIDAY-SATURDAY. THERE IS SOME MOISTURE AVAILABLE FOR 
SHOWERS WITH THE NORTHERN PORTION OF THE TROUGH WHICH EXTENDS ACROSS 
THE PACNW...INCLUDING SE OREGON/SW IDAHO. THE ECMWF/GFS ARE IN GOOD 
AGREEMENT WITH THIS SCENARIO. ON SUNDAY...UPPER LEVEL RIDGE AND 
DRIER AIR MOVES INTO THE AREA AS SYSTEM DEPARTS TO THE EAST AND 
ANOTHER TROUGH APPROACHES THE PACNW. THIS NEXT SYSTEM DROPS INTO THE 
PACNW MON-TUE...SPREADING PRECIP BACK INTO THE AREA...FASTER IN THE 
GFS THAN THE ECMWF. A BLEND OF THE TWO SOLUTIONS IS PREFERRED. WENT 
ABOVE CLIMO FOR POPS/NEAR CLIMO FOR TEMPS LATE THIS WEEK...THEN A 
BLEND OF THE ECMWF/GFS/CLIMO FOR POPS AND COOLER THAN CLIMO ON TEMPS 
EARLY NEXT WEEK.

&&

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

$$

WEATHER.GOV/BOISE

DISCUSSION...GS
PREV DISCUSSION...DF
LONG TERM....BW/JT
AVIATION.....DG