455
FXUS65 KBOI 231701
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1001 AM MST TUE DEC 23 2025
DISCUSSION
SURFACE OBSERVATIONS AND RADAR IMAGERY DEPICT
LIGHT RAIN NORTH OF A WARM FRONT CROSS BAKER COUNTY OREGON AND
THE WEST CENTRAL MOUNTAINS OF IDAHO. LIVE WEB CAMERAS SHOW THAT
THE PRECIP TYPE IS RAIN, EVEN IN THE MOUNTAINS, WITH SNOW
LEVELS ESTIMATED AT AROUND 7000 FEET THIS MORNING. DRY AND MILD
CONDITIONS ARE EXPECTED THIS AFTERNOON SOUTH OF THE WARM FRONT
WITH TEMPERATURES ABOUT 15 DEGREES ABOVE SEASONAL NORMALS.
AVIATION
PRECIPITATION CONTINUING TO MOVE NORTH NEAR KBKE/KMYL,
EXITING OUR AREA BY TUE/19Z. FOG/LOW STRATUS CONTINUING IN THE LOWER
TREASURE VALLEY THROUGH THE MORNING. VFR/IFR IN PRECIPITATION,
MVFR/LIFR IN FOG/LOW STRATUS. CONDITIONS IMPROVING TO VFR UNDER
OVERCAST SKIES BY EARLY AFTERNOON. SNOW LEVELS: 7 KFT MSL OR
HIGHER. SURFACE WINDS: SW-SE 5-15 KT WITH GUSTS TO 20-30 KT
THIS EVENING. WINDS ALOFT AT 10KFT MSL: SW 25-45 KT.
KBOI....VFR UNDER OVERCAST HIGH CLOUDS. SURFACE WINDS: SE 8-12 KT,
INCREASING TO SE 12-17 KT WITH GUSTS TO 27 KT OVERNIGHT INTO
WEDNESDAY MORNING.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...A BROAD WARM
FRONTAL ZONE CONTINUES TO SHIFT NORTHWARD ACROSS THE REGION THIS
MORNING. PRECIPITATION REMAINS LIMITED WITH THE FRONT AT THIS
HOUR AS THE PRIMARY MOISTURE PLUME IS STILL DISPLACED TO THE
SOUTHWEST. AS THE FRONT ADVANCES NORTHWARD LATER THIS MORNING,
DEEPER MOISTURE FROM THE LANDFALLING ATMOSPHERIC RIVER WILL
REACH THE AREA, INTENSIFYING PRECIPITATION ACROSS WEST CENTRAL
IDAHO AND BAKER COUNTY. SNOW LEVELS REMAIN SEASONABLY HIGH,
GENERALLY BETWEEN 6000 AND 8000 FEET MSL, KEEPING VALLEY
PRECIPITATION AS RAIN. LARGE PORTIONS OF THE FORECAST AREA SOUTH
OF THE FRONT WILL REMAIN DRY FOR THE REMAINDER OF THE DAY.
THE IMMEDIATE CONCERN FOR THE TUESDAY MORNING COMMUTE IS THE
PRESENCE OF PATCHY FOG AND LOW STRATUS, PARTICULARLY IN THE
LOWER TREASURE VALLEY AND SHELTERED BASINS WHERE SURFACE
MOISTURE IS INCREASING. CONDITIONS ARE EXPECTED TO IMPROVE BY
LATE TUESDAY MORNING AS THE WARM FRONTAL ZONE MOVES NORTH OF THE
AREA. ONCE THE FRONT CLEARS, THE REGION WILL RESIDE IN THE WARM
SECTOR AHEAD OF AN APPROACHING COLD FRONT. THIS WILL ALLOW
TEMPERATURES TO CLIMB WELL ABOVE NORMAL, REACHING THE 50S IN
MANY SOUTHERN VALLEYS.
STRENGTHENING SOUTH TO SOUTHWEST FLOW ALOFT WILL LEAD TO BREEZY
CONDITIONS IN OUR SOUTHERN ZONES THROUGH EARLY WEDNESDAY
AFTERNOON. WINDS ARE EXPECTED TO REACH ADVISORY CRITERIA IN THE
SOUTHERN HIGHLANDS OF IDAHO AND SOUTHERN TWIN FALLS COUNTY,
WHERE GUSTS UP TO 50 MPH ARE POSSIBLE. THE COLD FRONT IS TIMED
TO MOVE INLAND LATE WEDNESDAY, BRINGING A RESUMPTION OF
WIDESPREAD PRECIPITATION. THE HEAVIEST TOTALS ARE CURRENTLY
AIMED AT THE BOISE MOUNTAINS, THOUGH ALL AREAS CAN EXPECT A
PERIOD OF MODERATE RAIN AS THE FRONT PASSES THROUGH WEDNESDAY
NIGHT. BEHIND THE FRONT, COOLER AIR WILL BEGIN TO FILTER IN,
THOUGH THE CORE OF THE COLD AIR REMAINS TO THE NORTH. SNOW
LEVELS WILL GRADUALLY LOWER TO AROUND 5000 FEET IN THE NORTH AND
7000 FEET IN THE SOUTH BY CHRISTMAS MORNING. TRAVELERS SHOULD
REMAIN ALERT FOR POTENTIAL ROCK SLIDES IN STEEP TERRAIN DUE TO
THE COMBINATION OF RAIN AND SATURATED SOILS.
THURSDAY (CHRISTMAS DAY) WILL SEE A CONTINUATION OF SHOWERS AS A
SHORTWAVE TROUGH MOVES THROUGH THE REGION. HIGH TEMPERATURES
WILL REMAIN 10 TO 15 DEGREES ABOVE SEASONAL AVERAGES, BUT A MORE
NOTICEABLE COOLING TREND WILL BEGIN BY LATE THURSDAY NIGHT AS
SNOW LEVELS CONTINUE THEIR SLOW DESCENT. FOR THOSE LOOKING FOR A
WHITE CHRISTMAS IN THE WESTERN SNAKE PLAIN, THE PROBABILITY
REMAINS AT ZERO PERCENT FOR SNOW ON THE GROUND OR ANY FALLING
SNOW THROUGH THE HOLIDAY.
LONG TERM...FRIDAY THROUGH TUESDAY...THE UPPER LEVEL TROUGH
RESPONSIBLE FOR THE UNSETTLED WEATHER ON CHRISTMAS WILL SHIFT
EASTWARD ON FRIDAY. AS THE LOW PASSES, PRECIPITATION CONTINUES
AS MOISTURE AND DYNAMICS TAPER OFF. OROGRAPHY IS EXPECTED TO BE
THE MAIN PRECIP INDUCER. SNOW LEVELS DROP FROM 3-4 KFT MSL
FRIDAY TO VALLEY FLOORS SATURDAY MORNING. PRECIPITATION DURING
THIS TIME DECREASES, WITH A TOTAL RAINFALL/LIQUID EQUIVALENT OF
LESS THAN 0.1" IN LOW ELEVATIONS AND ABOUT 0.25" IN MOUNTAINS.
SNOWFALL OF 1-5" IN MOUNTAIN TOWNS AND RIDGES IS EXPECTED.
SATURDAY, DRYING CONDITIONS SPREAD WEST TO EAST AS A RIDGE
BUILDS, BRINGING NORTHWEST FLOW ON SATURDAY. THE RIDGE CONTINUES
TO BUILD THROUGH TUESDAY, PUSHING THE STORM TRACK NORTH WITH A
CUT OFF LOW OFF THE SOCAL COAST. THIS SETUP WILL SUPPORT STRONG
SUBSIDENCE, CLEAR SKIES, AND LIGHT WINDS. SO WITH RECENT RAINS,
INVERSIONS THAT BUILD DURING THIS TIME WILL HAVE FAVORABLE
CONDITIONS TO BECOME LONG LASTING WITH STRATUS/FOG. THIS MEANS
FORECAST MAX TEMPS MAY BE TOO HIGH DURING THE LONG TERM. A
POTENTIAL RETURN TO UNSETTLED WEATHER SEEMS LESS LIKELY THAN
PREVIOUS MODEL RUNS, ESPECIALLY GIVEN DETERMINISTIC MODEL
CONSENSUS ON THE CUT OFF LOW REJOINING THE FLOW IN THE EXTENDED.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WIND ADVISORY FROM 8 AM TO 2 PM MST WEDNESDAY IDZ015-030.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...JB
AVIATION.....NF
SHORT TERM...JDS
LONG TERM....JM
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