289
FXUS65 KBOI 271604
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1004 AM MDT MON OCT 27 2025
DISCUSSION
WE'RE STARTING WITH MOSTLY CLEAR SKIES THIS
MORNING ON THE BACKSIDE OF THE UPPER TROUGH. AFTERNOON
INSTABILITY WILL LEAD TO CUMULUS OVER HIGHER TERRAIN, AND A
SLIGHT CHANCE OF SHOWERS IN THE MTNS NORTH OF BAKER CITY,
MCCALL AND WARM LAKE. WINDS WILL REMAIN LIGHT FOR MOST
LOCATIONS, WITH THE WESTERN MAGIC VALLEY AND CAMAS PRAIRIE
KEEPING A STEADY 10-15 MPH, GUST TO 20 MPH WIND THROUGH THE DAY.
HARD FREEZE STILL ON TAP FOR TONIGHT ACROSS ALL ZONES. CURRENT
FORECAST IS ON TRACK SO NOW UPDATE.
AVIATION
LINGERING MVFR IN ISOLATED SNOW SHOWERS IN THE
MOUNTAINS, WITH SNOW LEVELS OF 3.5-4.5 KFT MSL THROUGH THE DAY.
OTHERWISE, VFR TODAY WITH A FEW MID LEVEL CLOUDS. SURFACE WINDS:
N-W 5-12 KT. WINDS ALOFT AT 10KFT MSL: W-NW 10-20 KT.
KBOI...VFR. SURFACE WINDS NW 5-10 KT TODAY, BECOMING SE 4-8 KT
TONIGHT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...RAIN AND SNOW
SHOWERS IN ID EARLY THIS MORNING WILL BE THE LAST PCPN FOR
SEVERAL DAYS, EXCEPT FOR POSSIBLE FLURRIES IN NORTHERN-MOST
MOUNTAINS WEDNESDAY MORNING. THE MAIN UPPER TROUGH WILL EXIT
EAST THIS MORNING AS AN UPPER RIDGE COMES IN FROM THE PACIFIC.
A FASTER-MOVING UPPER TROUGH FROM THE GULF OF ALASKA WILL RACE
INLAND ALONG THE CANADIAN BORDER WEDNESDAY WHILE THE SLOWER-
MOVING UPPER RIDGE STAYS OVER OUR CWA. THE TROUGH IS THE REASON
FOR THE POSSIBLE FLURRIES FAR NORTH WEDNESDAY. WEST WINDS WILL
INCREASE TO 15 TO 25 MPH WITH GUSTS TO 30 MPH IN SOUTH-CENTRAL
IDAHO BEHIND TODAY'S DEPARTING UPPER TROUGH, BUT WILL DECREASE
TONIGHT IN ALL AREAS AS SKIES CLEAR. STRONG RADIATIONAL COOLING
WILL THEN TAKE PLACE AND TUESDAY MORNING WILL BE THE COLDEST OF
THE SEASON SO FAR. PATCHY FOG WILL DEVELOP IN THE VALLEYS
OVERNIGHT AND LAST INTO MID-MORNING TUESDAY AS A MILD INVERSION
SETS UP. THE INCOMING UPPER RIDGE WILL ALLOW DAYTIME HIGH TEMPS
TO WARM FASTER IN THE MOUNTAINS THAN IN THE VALLEYS STARTING
TUESDAY, AND PATCHY VALLEY FOG MAY BE SLOW TO CLEAR AFTER THE
COLD NIGHTS AND LOW SUN ANGLE OF LATE OCTOBER.
LONG TERM...THURSDAY THROUGH MONDAY...THE LONG TERM WILL START
OUT DRY WITH OUR AREA UNDER NEAR ZONAL FLOW, RESULTING FROM A
DEEPENING ALASKAN LOW AND HIGH PRESSURE OVER SOCAL. THROUGHOUT
THE DAY FRIDAY, A MOIST PLUME OF PACIFIC MOISTURE WILL BEGIN TO
ADVECT OVER OUR AREA AHEAD OF AN UPPER LEVEL SHORTWAVE AND
SURFACE COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED LOW. HIGH
CLOUDS WILL INCREASE ACROSS OUR AREA FRIDAY AS A RESULT OF THIS
MOISTURE ADVECTION. WHILE THE BULK OF THE MOISTURE IS LOOKING
TO REMAIN TO OUR NORTH, THERE WILL BE ENOUGH RESIDUAL MOISTURE
TO SUPPORT PRECIPITATION IN OUR AREA. ENSEMBLE MEAN PWATS ARE
PROGGED TO REACH THE AROUND THE 90TH PERCENTILE. THIS WILL
SUPPORT ELEVATED PRECIPITATION CHANCES NORTH OF A LINE FROM
(ROUGHLY) FAIRFIELD/ID TO WAGONTIRE/OR. PRECIPITATION CHANCES
WILL RANGE FROM 20% TO 50%, INCREASING AS YOU MOVE NORTH FROM
THAT LINE. THE WEEKEND WILL ALSO BE BREEZY AS THE PRESSURE
GRADIENT TIGHTENS. OUR AREA WILL BEGIN TO DRY OUT THROUGH
SUNDAY AS WEAK RIDGING BEGINS TO BUILD IN AGAIN. TEMPERATURES
WILL BE SEASONABLE FOR THIS TIME OF YEAR, ALTHOUGH WILL LEAN
ABOVE NORMAL OVER THE COMING WEEKEND. ALSO, WITH OUR AREA ON
THE PERIPHERY OF RIDGING SOME UNCERTAINTY IS INTRODUCED
REGARDING LATE WEEK TEMPERATURES.
PRELIMINARY POINT TEMPS/POPS
BAKER CITY 21 51 24 55 / 0 0 0 0
BOISE 32 55 34 56 / 0 0 0 0
BURNS 16 53 21 58 / 0 0 0 0
CALDWELL 29 56 32 57 / 0 0 0 0
FAIRFIELD 12 46 17 54 / 0 0 0 0
IDAHO CITY 17 53 21 57 / 0 0 0 0
JEROME 26 48 31 54 / 0 0 0 0
MCCALL 16 44 21 48 / 0 0 0 0
MOUNTAIN HOME 27 54 30 58 / 0 0 0 0
ONTARIO 27 56 28 57 / 0 0 0 0
ROME 21 57 25 59 / 0 0 0 0
TWIN FALLS 27 48 29 54 / 0 0 0 0
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...DG
AVIATION.....JM
SHORT TERM...LC
LONG TERM....NF
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