845
FXUS65 KBOI 181648
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
948 AM MST SAT JAN 18 2025
DISCUSSION
THE COLDEST AIR MASS OF THE WINTER SEASON SETTLED
INTO THE REGION, INCLUDING THE BOISE AIRPORT WHERE THE LOW WAS
16F. HOWEVER, THIS IS NOT EVEN CLOSE TO THE BOISE DAILY RECORD
VALUE OF -27F SET IN 1883! DRY CONDITIONS AND LIGHT WINDS PREVAIL
TODAY WITH AFTERNOON HIGHS IN THE 30S VALLEYS AND TEENS/20S
MOUNTAINS. NO UPDATES.
AVIATION
LOW CLOUDS WITH LOCALIZED MVFR AND MTN OBSCURATION
IN W-CENTRAL ID MTNS EAST AND NORTH OF KMYL THIS MORNING. PATCHY
IFR FOG IN THE LONG VALLEY (INCLUDING KMYL) THIS MORNING.
OTHERWISE, VFR. WINDS: VARIABLE 10 KT OR LESS. WINDS ALOFT AT
10KFT MSL: NW-N 10-25 KT.
KBOI...VFR. WINDS: VARIABLE OR NW 3-8 KT.
SUNDAY OUTLOOK...MAINLY VFR. ISOLATED AFTERNOON MVFR/IFR SNOW
SHOWERS AND MOUNTAIN OBSCURATION IN THE W-CENTRAL ID MTNS.
SURFACE WINDS: VARIABLE 10 KT OR LESS.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH MONDAY NIGHT...A MODIFIED ARCTIC
AIR MASS WILL SETTLE INTO THE REGION AND PERSIST THROUGH MONDAY,
ACCOMPANIED BY A STEADY NORTHERLY FLOW. THIS PATTERN WILL BRING
THE COLDEST TEMPERATURES OF THE WINTER SO FAR, ESPECIALLY IN
AREAS WITH EXISTING SNOW COVER. HOWEVER, INCREASED HIGH CLOUDS
THIS AFTERNOON THROUGH SUNDAY COULD MODERATE THE COLD,
PARTICULARLY IN SOUTHWEST IDAHO, WHERE THERE IS A 50% CHANCE
THAT LOW TEMPERATURES WILL REMAIN 3 TO 7 DEGREES HIGHER THAN THE
CURRENT FORECAST.
IN THE WESTERN SNAKE RIVER PLAIN, HIGH TEMPERATURES THROUGH
MONDAY WILL HOVER SLIGHTLY ABOVE FREEZING, WITH MORNING LOWS
RANGING FROM THE UPPER TEENS TO THE LOW 20S. AREAS WITH
SIGNIFICANT SNOW COVER, SUCH AS THE CAMAS PRAIRIE AND LONG
VALLEY, COULD EXPERIENCE MORNING LOWS RANGING FROM JUST ABOVE
ZERO TO AS COLD AS 20 DEGREES BELOW ZERO.
A WEAK SHORTWAVE IS EXPECTED TO PASS ACROSS WESTERN MONTANA AND
EASTERN IDAHO LATE SUNDAY INTO EARLY MONDAY, BRINGING A 20%
CHANCE OF LIGHT SNOW TO THE CENTRAL IDAHO MOUNTAINS, WHICH MAY
RESULT IN A LIGHT DUSTING. THERE IS ALSO A LOW 10% CHANCE OF
SNOW SHOWERS REACHING THE WESTERN MAGIC VALLEY AND SOUTHERN TWIN
FALLS COUNTY EARLY MONDAY MORNING, AS INDICATED BY A MINORITY OF
HIGH-RESOLUTION MODELS. CONFIDENCE IN THIS SCENARIO REMAINS LOW
BUT SNOW MAY NEED TO BE ADDED TO THE FORECAST SHOULD THIS TREND
CONTINUE IN THE GUIDANCE OVER THE NEXT 24 HOURS.
LONG TERM...TUESDAY THROUGH SATURDAY...A RIDGE ALONG THE WEST
COAST WILL STRENGTHEN AND BUILD TOWARD THE FORECAST AREA TUESDAY.
THE INCREASING HEIGHTS WILL ASSIST THE PROMINENT COLD AIR MASS
EASTWARD AND ALLOW TEMPERATURES TO MODIFY OVER E OREGON AND SW
IDAHO. WHILE COLD, NORTH-NORTHWEST FLOW WILL REMAIN, TUESDAY TEMPS
SHOULD WARM SEVERAL DEGREES COMPARED TO MONDAY. THIS N-NW FLOW WILL
DOMINATE THROUGH THURSDAY, WITH GRADUAL WARMING EXPECTED EACH DAY
FOR MOST AREAS. THE EXCEPTION WILL BE IN LOWER OR SHELTERED VALLEYS
WHERE COLD POOLS ARE SLOW TO ERODE. BEGINNING FRIDAY, MODELS ARE IN
FAVOR OF ANOTHER COLD TROUGH INTRUSION THAT WILL INCREASE WINDS AND
THE CHANCE FOR SNOW SHOWERS (20-40%) ACROSS THE AREA FRIDAY AND
SATURDAY. THE TIMING AND WESTWARD EXTENT OF THIS TROUGH IS STILL
UNCERTAIN, AND THEREFORE FORECAST CONFIDENCE IN TEMPERATURES AND
TIMING OF SHOWERS IS STILL RELATIVELY LOW BOTH DAYS.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.TWITTER.COM/NWSBOISE
DISCUSSION...BW
AVIATION.....BW
SHORT TERM...JDS
LONG TERM....SH
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