834
FXUS65 KBOI 211556
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
956 AM MDT TUE OCT 21 2025
DISCUSSION
BELOW FREEZING TEMPERATURES WERE EXPERIENCED LAST
NIGHT ACROSS MOST OF THE TREASURE VALLEY AND MAGIC VALLEY
AGRICULTURAL AREAS WHICH BRINGS THE 2025 GROWING SEASON TO AN
END. GIVEN THAT THE GROWING SEASON NORMALLY ENDS IN MID TO LATE
OCTOBER, NO ADDITIONAL FROST OR FREEZE WARNINGS WILL BE ISSUED
IN 2025. VERY DRY AIR WITH CLEAR SKIES WILL ALLOW TEMPERATURES
TO RAPIDLY WARM TO NEAR NORMAL ACROSS THE AREA FOR A PLEASANT
AFTERNOON WITH LIGHT WINDS. TONIGHT'S TEMPERATURES WILL NOT BE
QUITE AS COLD AS THEY WERE EARLY THIS MORNING, BUT TEMPERATURES
WILL DROP QUICKLY AGAIN AFTER SUNSET FALLING TO NEAR OR BELOW
FREEZING IN MOST AREAS. FOG IS LIKELY AGAIN TONIGHT IN PORTIONS
OF VALLEY COUNTY, ESPECIALLY IN THE VICINITY OF LAKE CASCADE.
AVIATION
VFR. PATCHY MOUNTAIN VALLEY FOG THIS MORNING. SURFACE
WINDS: VARIABLE LESS THAN 10 KT. WINDS ALOFT AT 10KFT MSL: SW-W 10-
20 KT.
KBOI...VFR. SURFACE WINDS: LIGHT AND VARIABLE, AFTER SUNSET BECOMING
SE 4-9 KT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...WEAK RIDGING IS
BUILDING ACROSS THE REGION, WITH A WARMING AND DRYING TREND
TAKING OVER THROUGH THE SHORT TERM PERIOD. LIGHT SOUTHEAST
WINDS AND WARMER DAYTIME HIGH TEMPERATURES WILL KEEP
TEMPERATURES SLIGHTLY WARMER TOMORROW NIGHT, BUT LIGHT WINDS
THIS MORNING WILL ALLOW FOR TEMPERATURES NEAR FREEZING IN LOWER
ELEVATION VALLEYS. THEREFORE, THE FREEZE WARNING IS STILL IN
EFFECT FOR THE SNAKE RIVER VALLEY. AREAS IN BOISE AND ALONG THE
FOOTHILLS WILL STAY ABOVE FREEZING THANKS TO SLIGHTLY ELEVATED
SOUTHEAST WINDS, BUT LOWER ELEVATION AND SHELTERED AREAS WILL
SEE TEMPERATURES DIP TO THE UPPER 20S AND LOW 30S. TEMPERATURES
NEAR ONTARIO AND CALDWELL ARE ALREADY NEAR 33-36F AS OF 3:00AM
MDT.NO ADDITIONAL FROST OR FREEZE WARNINGS WILL BE ISSUED
IN 2025.
A LOW PRESSURE SYSTEM WILL MOVE TO OUR SOUTH ON WEDNESDAY,
BRINGING SOME CLOUD COVER TO SOUTHERN PORTIONS OF THE REGION.
THE RISK OF PRECIPITATION IS NEARLY NONEXISTENT, AS THE LOW
CENTER IS PROJECTED TO STAY FAR TO OUR SOUTH.
LONG TERM...FRIDAY THROUGH TUESDAY...A DEEP TROUGH OVER THE
GULF OF ALASKA WILL HELP ADVECT A PLUME OF MOISTURE INTO THE
NORTHWEST BEGINNING LATE FRIDAY. THIS ATMOSPHERIC RIVER WILL
BRING PRECIPITATION TO THE AREA BY EARLY SATURDAY, BUT WARM
SOUTHWEST FLOW AHEAD OF THE MAIN COLD AIR MASS WILL KEEP
TEMPERATURES ABOVE NORMAL ON FRIDAY AND SATURDAY. TEMPERATURES
WILL THEN PLUMMET 10 TO 15 DEGREES ON SUNDAY AS COLD AIR, GUSTY
WINDS, AND SIGNIFICANT MOISTURE MOVES INTO THE REGION. SNOW
LEVELS WILL BE AROUND 7000-8000 FEET MSL THROUGH SATURDAY,
DROPPING TO 4000-5000 FEET MSL ON SUNDAY AND MONDAY. WIDESPREAD
VALLEY RAIN AND HEAVY MOUNTAIN SNOW IS ANTICIPATED, WITH 2 DAY
SNOWFALL TOTALS REACHING UP TO 8 TO 12 INCHES FOR HIGHER SUMMITS
WITH 1-3 INCHES FOR MOUNTAIN VALLEYS BY MONDAY MORNING. MODELS
REMAIN IN LOCKSTEP WITH THIS SYSTEM, WITH ONLY SLIGHT VARIATIONS
ON TIMING OF THE INITIAL PRECIPITATION ON SATURDAY.
BY LATE MONDAY, THE TROUGH LOOKS TO MOVE TO OUR EAST AND DEEPEN
OVER THE GREAT PLAINS. THIS WILL KEEP US IN COOL NORTHWEST FLOW
LATE MONDAY INTO TUESDAY, WITH SOME LINGERING MOISTURE OVER
HIGH TERRAIN PRODUCING SOME STRAY SHOWERS. A RIDGE OF HIGH
PRESSURE LOOKS TO THEN DEVELOP ACROSS THE WESTERN US BY TUESDAY,
BRINGING ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS.
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...JB
AVIATION.....CH
SHORT TERM...SA
LONG TERM....SA
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