065
FXUS65 KBOI 271751
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1151 AM MDT SUN SEP 27 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- VIRGA AND LIGHT RAIN TODAY THROUGH EARLY MONDAY, WITH HIGHEST
RAIN CHANCES ACROSS EAST OREGON AND THE WEST-CENTRAL IDAHO
MOUNTAINS.
- WARM AND DRY CONDITIONS EXPECTED TUESDAY THROUGH NEXT
WEEKEND, WITH MAX TEMPERATURES PEAKING WEDNESDAY AND THURSDAY.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED 230 AM MDT SUN SEP 27 2026
SOUTHEAST OREGON AND SOUTHWEST IDAHO RESIDE UNDER SOUTHWEST
FLOW ALOFT THIS MORNING AHEAD OF A WEAK TROUGH OVER THE WEST
COAST. THIS TROUGH IS SPREADING A SWATH OF MID-LEVEL MOISTURE
ACROSS THE AREA TODAY THROUGH EARLY MONDAY, BRINGING CLOUDY
SKIES, WIDESPREAD VIRGA, AND LIGHT RAIN. WHILE PRECIPITATION IS
EXPECTED TO BE SPORADIC AS MOISTURE EXPANDS NORTHWARD, THE
HIGHEST PROBABILITIES OF MEASURABLE RAINFALL ARE OVER EAST
OREGON AND WEST-CENTRAL IDAHO (20-40%) MAINLY IN THE AFTERNOON
AND EVENING...WITH LOWER CHANCES (5-15%) ELSEWHERE. SOUTHWEST TO
NORTHWEST SURFACE WINDS WILL BECOME BREEZY THIS AFTERNOON
ACROSS SOUTHEAST OREGON AND PORTIONS OF THE WESTERN SNAKE PLAIN.
AS THE TROUGH HEADS EASTWARD OVERNIGHT INTO EARLY MONDAY, THE
MOISTURE WILL ALSO DEPART TOWARD THE EAST. AS A RESULT, SKIES
WILL BEGIN TO CLEAR AND TEMPERATURES WILL TREND WARMER FOR
MONDAY COMPARED TO PREVIOUS DAYS. WESTERLY FLOW ALOFT WILL
ESTABLISH OVER THE REGION BEGINNING TUESDAY, WITH DRY AND WARM
CONDITIONS ANTICIPATED.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED 230 AM MDT SUN SEP 27 2026
FORECAST MODELS DEPICT A BUILDING RIDGE OVER THE SOUTHWESTERN
U.S. FROM TUESDAY THROUGH THURSDAY, DRIVING LOWER-ELEVATION
TEMPERATURES INTO THE UPPER 70S/LOW 80S BY WED AND THU.
THEREAFTER, A WEAK SHORTWAVE TROUGH WILL ENTER THE PACIFIC
NORTHWEST ON FRIDAY, BRIEFLY FLATTENING THE RIDGE AND DROPPING
TEMPERATURES BY A FEW DEGREES FRIDAY THROUGH SATURDAY. MOISTURE
ASSOCIATED WITH THIS TROUGH IS LIKELY TO REMAIN NORTH, KEEPING
SOUTHEAST OREGON AND SOUTHWEST IDAHO IN A DRIER AIRMASS. THE
RIDGE IS EXPECTED TO REBOUND ON SUNDAY AS THE TROUGH CONTINUES
EAST, SUPPORTING THE RETURN OF ABOVE NORMAL TEMPERATURES.
AVIATION /18Z SUNDAY THROUGH MONDAY/
ISSUED 1140 AM MDT SUN SEP 27 2026
GENERALLY VFR. VIRGA AND ISOLATED RAIN SHOWERS MAINLY OVER SE
OREGON AND THE CENTRAL ID MOUNTAINS. PATCHY FOG IN SHELTERED
MOUNTAIN VALLEYS OVERNIGHT THROUGH MONDAY MORNING. SURFACE
WINDS: SW- NW 5-15 KT, WITH GUSTS TO 25 KT SOUTH/EAST OF KBOI
THIS AFTERNOON AFTER 21Z. WINDS ALOFT AT 10KFT MSL: SW 10-20 KT.
KBOI...VFR WITH DENSE MID-HIGH CLOUD COVERAGE. VIRGA/LIGHT
SHOWERS IN THE VICINITY THIS AFTERNOON.
SURFACE WINDS: NW 7-14 KT THIS AFTERNOON, WITH GUSTS TO AROUND
20 KT LATE AFTERNOON THROUGH EARLY EVENING.
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
AVIATION.....JY
SHORT TERM...SH
LONG TERM....SH
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