910
FXUS65 KBOI 151755
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1155 AM MDT WED APR 15 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- RAIN, MOUNTAIN SNOW AND GUSTY WINDS ON WEDNESDAY, THEN SNOW
LEVEL LOWERING TO VALLEY FLOORS TONIGHT AND THURSDAY MORNING.
- SUBFREEZING MORNING TEMPERATURES FRIDAY AND SATURDAY IN THE
AGRICULTURAL AREAS.
- WARMER AND DRIER OVER THE WEEKEND, WITH ANOTHER CHANCE OF
PRECIPITATION EARLY NEXT WEEK.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED 322 AM MDT WED APR 15 2026
THE NEXT STRONG UPPER TROUGH FROM THE GULF OF ALASKA AND
SURFACE COLD FRONT WERE APPROACHING OUR AREA THIS MORNING
WITH ANOTHER ROUND OF MODERATE TO HEAVY RAIN AND SNOW TODAY
AND TONIGHT. AT 2 AM MDT THE EASTWARD-MOVING COLD FRONT WAS
ALREADY ONSHORE IN WESTERN WA AND OR, EXTENDING OUT INTO THE
PACIFIC ALONG 42N. THE SUPPORTING UPPER LOW WAS NEAR 50/130
NEAR THE BC COAST AND MOVING SOUTHEASTWARD. RADAR WAS ALREADY
SHOWING AREAS OF LIGHT RAIN AND SNOW IN EASTERN OR AND WESTERN-
MOST IDAHO BUT LITTLE WAS REACHING THE GROUND. BUT PCPN WILL
INCREASE AROUND SUNRISE AND CONTINUE THROUGH THE DAY AND THIS
EVENING. THIS SYSTEM IS COLDER THAN THE PREVIOUS ONE AND WILL
LOWER THE SNOW LEVEL TO VALLEY FLOORS LATE TONIGHT AND EARLY
THURSDAY MORNING, BUT BY THEN MOST OF THE PCPN WILL BE ENDING.
THE SURFACE COLD FRONT IS SLATED TO PASS THROUGH EASTERN OR
THIS AFTERNOON AND WESTERN IDAHO THIS EVENING. AHEAD OF THE
FRONT, HEAVIEST PCPN WILL FALL IN THE BOISE MOUNTAINS AND WEST
CENTRAL IDAHO MOUNTAINS WITH SNOW LEVEL NEAR 6000 FEET, WITH
RAIN HEAVY ENOUGH TO LOOSEN ROCKS AND MUD ON STEEP SLOPES, SO
TRAVELERS SHOULD AVOID THE BANKS-LOWMAN ROAD AND SIMILAR ROADS
UNTIL RAIN CHANGES TO SNOW THIS EVENING. TOTAL PCPN TODAY
THROUGH THURSDAY SHOULD BE 0.75 TO 1.25 INCH IN OUR NORTHERN
MOUNTAINS, AND GENERALLY 0.25 TO 0.75 INCH ELSEWHERE, EXCEPT
0.15 TO 0.25 INCH IN RAIN-SHADOWED SOUTHERN AREAS. TOTAL
SNOWFALL WILL BE 8 TO 15 INCHES ABOVE 6000 FEET LATE TODAY
THROUGH TONIGHT BUT ONLY 1-3 INCHES NEAR 5000 FEET, INCLUDING
MCCALL/ID. PRE-FRONTAL SOUTHWEST TO WEST WINDS WILL INCREASE TO
ADVISORY SPEEDS IN THE SOUTHWEST IDAHO HIGHLANDS, SOUTHERN TWIN
FALLS COUNTY, AND IN SOUTHERN MALHEUR AND HARNEY COUNTIES. A
WIND ADVISORY HAS BEEN POSTED FOR THOSE AREAS THIS AFTERNOON AND
EARLY EVENING. THE FRONTAL PASSAGE ITSELF WILL BE MARKED BY A
SHORT PERIOD OF HEAVY SHOWERS AND ISOLATED THUNDERSTORMS. AFTER
THAT THE SNOW LEVEL WILL LOWER RAPIDLY AND RAIN WILL CHANGE TO
SNOW, WITH UP TO AN INCH ACCUMULATION OVERNIGHT IN THE MAGIC
VALLEY BUT LITTLE OR NONE IN THE TREASURE VALLEY.
THURSDAY WILL BE WINDY AND COLD WITH LINGERING SNOW SHOWERS AS
THE UPPER LOW MOVES THROUGH, THEN CLEARING AND QUITE COLD
THURSDAY NIGHT. A FREEZE WATCH HAS BEEN POSTED FOR THE TREASURE
VALLEY AND WESTERN MAGIC VALLEY AGRICULTURAL VALLEYS FOR FRIDAY
MORNING AND AGAIN SATURDAY MORNING, BUT FRIDAY LOOKS LIKE THE
COLDER DAY. LOW TEMPERATURES FRIDAY WILL DIP AS LOW AS 24
DEGREES IN THE WESTERN MAGIC VALLEY WHICH WOULD BE A HARD
FREEZE, WITH 27 TO 30 DEGREES IN THE TREASURE VALLEY, AGAIN
COLD ENOUGH TO DAMAGE YOUNG PLANTS UNLESS THEY ARE PROTECTED.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED 322 AM MDT WED APR 15 2026
A RIDGE BUILDING IN BEHIND THE SYSTEM IN THE SHORT-TERM PERIOD
WILL ALLOW FOR DRY AND MILDER CONDITIONS ON SATURDAY, WITH
TEMPERATURES NEAR NORMAL. SATURDAY MORNING WILL BE THE LAST
MORNING (IN THIS FORECAST PERIOD AT LEAST) WITH TEMPERATURES
NEAR OR BELOW FREEZING ACROSS THE AREA. TEMPERATURES COME
SUNDAY WILL WARM TO 5-10 DEGREES ABOVE NORMAL.
THIS NEXT WEEK, GUIDANCE CONTINUES TO RESOLVE A LOW DIGGING DOWN
FROM THE GULF ALASKA AND CLOSING OFF FROM THE MAIN JET STREAM,
BUT TIMING CONTINUES TO BE TRICKY. OVER THE PAST FEW RUNS,
ENSEMBLE GUIDANCE HAS CONTINUALLY SLOWED THE SYSTEM, DELAYING
ITS ARRIVAL INTO OUR AREA. WITH SOUTHERLY FLOW AHEAD OF THIS
LOW, A SLIGHT WARMING TREND WOULD BE ABLE TO SUSTAIN ITSELF INTO
EARLY NEXT WEEK WITH A SLOWER ARRIVAL. THE CURRENT FORECAST
CARRIES SLIGHT PRECIPITATION CHANCES COME MONDAY, INCREASING TO
20-40 PERCENT AREA-WIDE TUESDAY AND WEDNESDAY (WHERE THE
CONSENSUS IS STARTING TO LEAN ON THE LOW'S ARRIVAL). TEMPERATURES
SHOULD BE ABLE TO MAINTAIN THE SLIGHT WARMING TREND AND REMAIN
ABOVE NORMAL THROUGH TUESDAY IN THE SOUTHERLY FLOW, BEFORE
COOLING TO NEAR NORMAL BEHIND THE SYSTEM. BREEZY SOUTH/SOUTHWEST
WINDS ARE ANTICIPATED EARLY NEXT WEEK AS THE LOW INCHES CLOSER,
BECOMING W-NW FOLLOWING ITS PASSAGE.
AVIATION /18Z WEDNESDAY THROUGH THURSDAY/
ISSUED 1154 AM MDT WED APR 15 2026
LOW VFR/MVFR CEILINGS IN RAIN AND IFR/LIFR IN MTN SNOW. SNOW LEVELS
5-7KFT MSL. A COLD FRONT WILL BRING SHARP WIND SHIFTS AND INTENSIFY
PRECIP AFTER 20Z, WITH MVFR/IFR IN HEAVIER RAIN SHOWERS. A 25%
CHANCE OF THUNDER WITH SMALL HAIL/GRAUPEL ALONG THE FRONT. SNOW
LEVELS RAPIDLY LOWERING TO VALLEY FLOORS FOLLOWING THE FRONT.
SCATTERED LIGHT SNOW SHOWERS EXPECTED THURSDAY MORNING THROUGH
AFTERNOON. SURFACE WINDS: SE-SW 10-20 KT WITH GUSTS 20-35 KT, THEN W-
NW 15-30KT WITH GUSTS UP TO 40 KT THIS AFTERNOON WITH THE FRONTAL
PASSAGE. WINDS ALOFT AT 10KFT MSL: W-SW 25-40 KT.
KBOI...SHOWERS CONTINUING WITH PERIODS OF MVFR CEILINGS AND REDUCED
VISIBILITY THIS AFTERNOON. A STRONG COLD FRONT WILL ARRIVE THIS
AFTERNOON AROUND 22Z. THE FRONT WILL BRING A SHARP NW WIND SHIFT,
HEAVIER PRECIP, TEMPORARY MVFR/IFR, AND POTENTIAL FOR
GRAUPEL/LIGHTNING. CONDITIONS RETURNING TO VFR FOLLOWING THE FRONT.
SURFACE WINDS: SE 10-15 KT THIS MORNING, THEN NW 15-25 KT WITH GUSTS
UP TO 35 KT FOLLOWING FRONTAL PASSAGE THIS AFTERNOON/EVENING.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
FOR IDZ012-014-016.
WIND ADVISORY UNTIL 8 PM MDT THIS EVENING FOR IDZ015-030.
OR...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
FOR ORZ064.
WIND ADVISORY UNTIL 8 PM MDT /7 PM PDT/ THIS EVENING FOR
ORZ061-063.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....DG
SHORT TERM...LC
LONG TERM....NF
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