165
FXUS65 KBOI 182125
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
225 PM MST WED DEC 18 2024
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
WE HAVE MIXED OUT
TODAY MORE THOROUGHLY THAN EXPECTED, WITH TEMPERATURES RISING
ABOVE FORECAST HIGHS. THIS HAS IMPLICATIONS FOR THE FORECAST
GOING FORWARD, SUCH AS LOWERED EXPECTATIONS FOR FOG TONIGHT, AND
A SLOWER RE-DEVELOPMENT OF AN INVERSION. WE STILL SEE AN
INVERSION FORMING, BUT HAVE REDUCED THE AMOUNT OF COOLING IN THE
LOWER TREASURE VALLEY AND SURROUNDING AREAS FOR THU AND FRI.
OTHERWISE, AN UPPER LEVEL RIDGE WILL MOVE ACROSS THE AREA
THURSDAY, BRINGING MOSTLY CLEAR SKIES TO MOST AREAS. SW FLOW
ALOFT WILL MOVE IN BEHIND THIS, WITH WARMER AIR ADVECTING INTO
THE REGION ALOFT WHILE THE INVERSION FORMS AT THE SURFACE. AFTER
A VERY WEAK AND DRY TROUGH SLIDES ACROSS OUR NORTHERN AREA THU,
A SECOND RIDGE AXIS WILL RACE OVERHEAD EARLY FRIDAY. WINDS WILL
INCREASE FRIDAY AFTERNOON GENERALLY FROM THE WESTERN MAGIC
VALLEY WEST INTO THE UPPER TREASURE VALLEY. FRIDAY NIGHT WILL BE
DRY WITH AN INCREASING CHANCE OF LOW CLOUDS AND FOG IN LOWER
ELEVATIONS.
LONG TERM...SATURDAY THROUGH WEDNESDAY
THE BREAKDOWN OF A
PERSISTENT LOW OVER THE HUDSON BAY HAS FINALLY ALLOWED THE STORM
TRACK TO MOVE OVER OUR AREA, KEEPING THINGS WET AND ACTIVE IN THE
LONG TERM. EACH LOW WILL BE WORKING TO BREAK DOWN A RIDGE IN THE
SHORT TERM, SO THE FIRST FEW SYSTEMS, THIS WEEKEND AND MONDAY, ARE
LIKELY TO BE ON THE WEAKER SIDE. ONLY A FEW HUNDREDTHS EXPECTED TO
FALL WITH A SYSTEM LATE SATURDAY INTO EARLY SUNDAY IN THE VALLEYS AS
RAIN. IN THE MOUNTAINS 0.1-0.3 INCHES OF RAINFALL BECOMING A FEW
INCHES OF SNOW ABOVE 5-6 KFT MSL. LATER SUNDAY INTO MONDAY ANOTHER
TROUGH ANOTHER SYSTEM MOVES IN. THIS ONE APPEARS A BIT WETTER,
LIKELY KEYING INTO SOME WEAKENING OF THE POSITIVE HEIGHT
ANOMALIES AFTER SATURDAY, WITH ABOUT 0.1 INCHES OF RAINFALL FOR
VALLEYS AND AGAIN 0.1-0.3 INCHES OF RAIN IN MOUNTAINS WITH A
FEW INCHES OF SNOW ABOVE 5-7 KFT MSL. A THIRD TROUGH IS SLATED
TO MOVE THROUGH TUESDAY EVENING THROUGH CHRISTMAS MORNING, AGAIN
TRENDING WETTER. IN THE VALLEYS 0.1 TO 0.4 INCHES OF RAINFALL,
AND 0.5 TO 1 INCH OF RAINFALL IN THE MOUNTAINS BECOMING 2-8
INCHES OF SNOW ABOVE 5-6 KFT MSL. TEMPS HOLD FAIRLY STEADY
AROUND 5 DEGREES ABOVE NORMAL, WITH SLIGHT COOLING AFTER EACH
TROUGH. UNLESS THE TUESDAY NIGHT TROUGH BECOMES VERY COLD IN THE
NEXT FEW MODEL RUNS, A WHITE CHRISTMAS FOR SNAKE PLAIN
LOCATIONS IS LOOKING UNLIKELY.
AVIATION
VFR WITH MID-HIGH CLOUDS. MOUNTAIN OBSCURATION DUE TO
OROGRAPHIC CLOUDS. FOG/LOW STRATUS DEVELOPMENT EXPECTED IN VALLEYS
TONIGHT, THOUGH LOWER CONFIDENCE DUE TO WARMER THAN EXPECTED SURFACE
TEMPERATURES TODAY. SURFACE WINDS: LIGHT AND VARIABLE. WINDS ALOFT
AT 10KFT MSL: W 35-45 KT.
KBOI...VFR AND MID-HIGH CLOUDS. FOG WILL DEVELOP IN LOWER TREASURE
VALLEY (KONO/KEUL) TONIGHT WITH A 10% CHANCE OF LIFR FOG REACHING
KBOI. SURFACE WINDS: SE 5-10 KT, THEN SE/VARIABLE UP TO 5 KT THIS
EVENING AND TONIGHT.
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...SP
LONG TERM....JM
AVIATION.....JM
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