938
FXUS65 KBOI 201002
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
302 AM MST MON JAN 20 2025
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
A COLD MORNING
PERSISTS ACROSS THE REGION AS A MODIFIED ARCTIC AIR MASS REMAINS
IN PLACE. LIGHT SNOW WAS OBSERVED THIS MORNING IN THE HIGHLANDS
SOUTH OF THE SNAKE PLAIN, LINKED TO A WEAK CONVERGENCE ZONE.
HOWEVER, NO SNOW ACCUMULATION HAS BEEN SEEN ON WEBCAMS AT
ROGERSON AND JACKPOT. LIGHT SNOW MAY CONTINUE IN THAT AREA UNTIL
SUNRISE.
ELSEWHERE, EXPECT COLD TEMPERATURES AND MOSTLY CLEAR SKIES
TODAY. HIGHS IN THE WESTERN SNAKE RIVER PLAIN WILL HOVER NEAR
FREEZING. SOUTHEASTERLY WINDS OF 10 TO 15 MPH WILL MAKE IT FEEL
EVEN COLDER. TONIGHT WILL BRING ANOTHER FRIGID EVENING, WITH
LOWS RANGING FROM THE UPPER TEENS TO THE LOW 20S. AREAS WITH
SIGNIFICANT SNOW COVER, SUCH AS THE CAMAS PRAIRIE AND LONG
VALLEY, MAY EXPERIENCE LOWS RANGING FROM JUST ABOVE ZERO TO AS
COLD AS 15 DEGREES BELOW ZERO.
ON TUESDAY, AN UPPER-LEVEL RIDGE WILL MOVE EASTWARD,
INTRODUCING WARMER TEMPERATURES TO THE REGION, PARTICULARLY IN
SOUTHEAST OREGON, WHERE HIGHS ARE EXPECTED TO REACH THE UPPER
30S TO LOW 40S. HOWEVER, MUCH OF SOUTHWEST IDAHO, ESPECIALLY
THE VALLEYS, WILL REMAIN BELOW NORMAL TEMPERATURES AS COLD AIR
REMAINS TRAPPED. THE RIDGE WILL PERSIST TO THE WEST THROUGH
WEDNESDAY, KEEPING TEMPERATURES LARGELY UNCHANGED. A SURFACE
INVERSION IS LIKELY TO DEVELOP IN THE VALLEYS, POTENTIALLY
LEADING TO STAGNANT CONDITIONS.
LONG TERM...THURSDAY THROUGH MONDAY
A RIDGE ALONG THE WEST
COAST WILL BUILD INTO OR/ID THURSDAY AHEAD OF A COLD FRONT,
WARMING MOST AREAS BY A FEW DEGREES FROM WED. A TROUGH WILL
ARRIVE FROM THE NORTH AND BRING THE COLD FRONT THROUGH SOUTHEAST
OR AND SOUTHWEST ID BY FRIDAY MORNING. THIS TROUGH WILL
INCREASE THE CHANCE OF SNOW SHOWERS TO AROUND 20-40 PERCENT,
WITH HIGHEST VALUES OVER THE MOUNTAINS AND LOWER ELSEWHERE.
SHOWER CHANCES WILL CONTINUE INTO SATURDAY MORNING BEFORE DRY
AIR ARRIVES BEHIND THE TROUGH BY THE AFTERNOON. HIGH PRESSURE
WILL BUILD ON SUNDAY AND INTO EARLY NEXT WEEK, STRENGTHENING
TEMPERATURE INVERSIONS AND SUPPORTING STAGNANT VALLEY
CONDITIONS. OVERALL, TEMPERATURES ARE EXPECTED TO LOWER A FEW
DEGREES BELOW NORMAL BEHIND THE COLD FRONT, THEN RETURN TO NEAR-
NORMAL BY MONDAY.
AVIATION
GENERALLY VFR. LIGHT SNOW NEAR KMUO AND SOUTH
TOWARD THE ID/NV BORDER, TAPERING OFF AFTER 20/12Z. SURFACE
WINDS: VARIABLE LESS THAN 10 KT, EXCEPT E-SE 5-15 KT IN WESTERN
SNAKE PLAIN.
KBOI...VFR. SCATTERED LOW CLOUDS BETWEEN 3500-4500 FEET AGL
THROUGH MORNING, THEN MOSTLY CLEAR. SURFACE WINDS: SE 5-12 KT.
AIR STAGNATION
THE RIDGE OF HIGH PRESSURE WILL CONTINUE TO
BUILD ALONG THE WEST COAST, BUT HIGHER DIURNALLY DRIVEN WINDS
WILL PREVENT EXTENSIVE STAGNANT CONDITIONS THROUGH TUESDAY.
SHELTERED VALLEYS WILL SEE MIXING HEIGHTS AROUND 1,000-1,500
FEET ON WEDNESDAY AND THURSDAY, WHICH COULD ALLOW FOR SOME
SIGNIFICANT COLD POOLS AND FOG TO FORM. HOWEVER, CONFIDENCE IS
LOW ON THE EXTENT OF THE INVERSION AND STRENGTH OF THE STABLE
SURFACE LAYER. THE SYSTEM ON FRIDAY SHOULD SCOUR OUT THE
INVERSION AND RELATED STAGNANT CONDITIONS.
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
SHORT TERM...JDS
LONG TERM....SH
AVIATION.....SH
AIR STAGNATION...SA
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