337
FXUS65 KBOI 210321
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
821 PM MST MON JAN 20 2025
DISCUSSION
VERY COLD CONDITIONS CONTINUE ACROSS SOUTHWESTERN
IDAHO AND SOUTHEASTERN OREGON THIS EVENING. CLEAR SKIES AND
LIGHT WINDS ARE ALLOWING EXCELLENT RADIATIONAL COOLING AND
TEMPERATURES ARE RUNNING ABOUT 5 DEGREES COLDER THAN THEY WERE
AT THE SAME TIME LAST NIGHT. IN FACT, TEMPERATURES IN THE
MOUNTAINS HAVE ALREADY FALLEN BELOW ZERO IN MANY AREAS. THIS
WILL BE THE COLDEST NIGHT OF THE WINTER SO FAR. THE PREVIOUS FORECAST
DESCRIBES THE SITUATION PERFECTLY AND NO UPDATES ARE NEEDED
THIS EVENING.
AVIATION
VFR. MOSTLY CLEAR. SURFACE WINDS: VARIABLE UP TO 10 KTS.
WINDS ALOFT AT 10KFT MSL: N-NW 15-25 KTS BECOMING W-NW 35-45KT TUES
AFTERNOON.
KBOI...VFR. SURFACE WINDS: SE 5-10KT, BECOMING NW 5 KT TUES
AFTERNOON.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...LITTLE CHANGE IN
THE DRY STABLE WEATHER PATTERN WITH AN UPPER RIDGE OFF THE WEST
COAST AND A NORTH-NORTHWEST FLOW ALOFT ACROSS OUR REGION.
TEMPERATURES REMAIN COLD, BUT WITH A SLIGHT WARMING TREND. THE
AIR MASS IS TOO DRY TO SUPPORT FOG, BUT THERE MAY BE LOCALIZED
POCKETS OF EARLY MORNING FOG IN WIND-SHELTERED MOUNTAIN VALLEYS.
LONG TERM...THURSDAY THROUGH MONDAY...MODELS ARE IN DECENT
AGREEMENT WITH REGARD TO A DEVELOPING UPPER TROUGH MOVING FROM
FROM THE NORTH LATE IN THE WEEK. HOWEVER, THERE IS SOME
DISAGREEMENT WITH THE STRENGTH AND SOUTHWARD PROGRESSION OF IT.
A BLEND OF ENSEMBLE MEMBERS DEPICT A FASTER-MOVING SYSTEM WHICH
WOULD KEEP SNOWFALL AMOUNTS ON THE LIGHTER SIDE. THERE IS A
15-40 PERCENT CHANCE OF LIGHT SNOW IN THE VALLEYS AND A 40 TO 60
PERCENT CHANCE IN THE MOUNTAINS ON FRIDAY WITH THE TROUGH
PASSAGE, FOLLOWED BY A 15-30 PERCENT CHANCE OF LIGHT SNOW IN
S-CENTRAL IDAHO AND ALONG THE NEVADA BORDER ON SATURDAY. A COLD
FRONT WILL ACCOMPANY THE TROUGH, PROVIDING THE REGION WITH
BREEZY TO LOCALLY WINDY CONDITIONS - ESPECIALLY ON SATURDAY.
DRIER STABLE CONDITIONS WITH LIGHT WINDS FOLLOW EARLY NEXT WEEK
AS ANOTHER UPPER RIDGE DEVELOPS OFF THE COAST. NEAR-NORMAL
TEMPERATURES THURSDAY AND FRIDAY LOWER TO SEVERAL DEGREES BELOW
NORMAL OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
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...JB
AVIATION.....KA
SHORT TERM...BW
LONG TERM....BW
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