368
FXUS65 KBOI 180337
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
837 PM MST SUN NOV 17 2024
DISCUSSION
AS OF 2030 MST, THE COLD FRONT IS CURRENTLY
ARCING FROM THE ID-OR BORDER NEAR ONTARIO, DOWN INTO SOUTHEAST
OREGON NEAR THE STEENS MOUNTAINS, WITH HEAVY PRECIPITATION AND
GUSTY NORTHWEST WINDS BEHIND THE FRONT. SNOW WILL CONTINUE ABOVE
4000 FEET THIS EVENING, WITH SNOW LEVELS DROPPING TO 3000 FEET
TONIGHT. THERE IS A MODERATE CHANCE (30% CHANCE) OF SNOW AT
VALLEY FLOORS NEAR BOISE TONIGHT, WITH MINIMAL ACCUMULATION
MELTING QUICKLY. SHOWERS WILL DISSIPATE RIGHT AROUND SUNRISE,
WITH ISOLATED SNOW SHOWERS LINGERING THROUGH THE DAY IN THE
COLDER AIR MASS. THE FORECAST HAS BEEN UPDATED TO REFLECT
SLIGHTLY HIGHER SNOW AMOUNTS IN THE MOUNTAINS.
AVIATION
COLD FRONT TO GENERATE A PERIOD OF MVFR/IFR/LIFR FROM
03Z-07Z ACROSS THE AREA. LOW CEILING AND VISIBILITY REDUCTIONS IN
RA/SN. SURFACE WINDS 12 TO 24 KT FROM S/SE SWITCHING TO W/NW
WITH THE FRONT. WINDS ALOFT SW 30-40 KT.
KBOI...COLD FRONT TO IMPACT THE TERMINAL BETWEEN 0330Z AND 0430Z
WITH A WIND SHIFT TO THE NW AND CONTINUED STRONG GUSTS IN EXCESS OF
30 KT. PERIOD OF MVFR POSSIBLE IN LOW CEILINGS AND PRECIPITATION
DURING FRONTAL PASSAGE. PRECIPITATION FALLING MAINLY IN THE FORM OF
RA.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...WARM FRONT IS
TRACKING ACROSS SOUTHWEST ID THIS AFTERNOON. SNOW LEVELS HAVE
RISEN TO 5000 FEET ACROSS MUCH OF THE AREA WITH THE EXCEPTION
OF THE WEST CENTRAL ID MOUNTAINS WHERE SNOW LEVELS REMAIN AROUND
4000 FEET. SURFACE WINDS CONTINUE TO INCREASE THIS AFTERNOON
AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH THE AREA LATER THIS
EVENING. THE COLD FRONT WILL MOVE ACROSS EASTERN OR THIS
EVENING, AROUND 6-7PM PST IN BAKER CITY AND BURNS, AND THROUGH
THE BOISE METRO AROUND 10-11PM MST, AND TWIN FALLS AROUND 1-2AM
MST. WOULD NOT BE SURPRISED TO SEE THUNDERSHOWERS ALONG THE
COLD FRONT LATE THIS EVENING. SNOW LEVELS FALL TO THE VALLEY
FLOORS BEHIND THE FRONT, BUT PRECIPITATION QUICKLY TAPERS OFF AS
DRIER AND COOLER AIR MOVES INTO THE REGION. THE EASTERN OR
BASINS AND AREAS BELOW 4000 FEET WILL SEE A DUSTING OF SNOW
BEHIND THE COLD FRONT, WITH 1 TO 3 INCHES OF SNOW IN THE LONG
VALLEY AND OWYHEE MOUNTAINS, AND 5 TO 10 INCHES OF SNOW ABOVE
6500 FEET MSL. PRECIPITATION BRIEFLY TAPERS OFF MIDDAY MONDAY,
BEFORE THE SURFACE HEATING OF THE DAY CAUSES SCATTERED SNOW
SHOWERS TO DEVELOP DURING THE AFTERNOON WITH THE COLD AIR ALOFT.
TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL ON MONDAY.
THEN THE FORECAST TURNS TO THE NEXT SYSTEM ON TUESDAY INTO
WEDNESDAY. A WARM FRONT BRINGS LIGHT SNOW TO MUCH OF THE AREA ON
TUESDAY NIGHT, AS SNOW LEVELS WILL BE NEAR THE VALLEY FLOORS.
MODELS CURRENTLY HAVE A TROUGH GAINING RECORD BREAKING STRENGTH
(945-955 MILLIBARS) OFF THE PACIFIC NW COAST ON TUESDAY AND
WEDNESDAY THAT WILL NEED TO BE MONITORED. WHILE THE ENERGY WILL
STAY NORTH AND WEST OF OUR AREA, IT WILL STILL BRING WINDY
CONDITIONS AS THE PRESSURE GRADIENT INCREASES SIGNIFICANTLY.
LONG TERM...WEDNESDAY THROUGH SUNDAY...MODELS REMAIN IN EXCELLENT
AGREEMENT ON THE DEVELOPMENT AND ARRIVAL OF AN ATMOSPHERIC RIVER
WEDNESDAY. THIS WILL BRING SIGNIFICANT PRECIPITATION TO THE REGION
THROUGH THE WEEKEND. DETAILS DIFFER IN IMPORTANT WAYS, AS THEY OFTEN
DO, BY DAY 5 (FRIDAY), AS SOME MODELS CONTINUE TO SHOW A BRIEF BREAK
IN PRECIP FOR MOST OF THE AREA, WHILE OTHERS SHOW LITTLE TO NO
BREAK. THE NBM HAS KEPT "MENTIONABLE" POP (>15% CHANCE) OVER
ALMOST THE ENTIRE AREA THROUGH THE LONG TERM, IN LINE WITH THE
SPREAD OF POTENTIAL SOLUTIONS. AT THIS TIME, CONFIDENCE IN
PRECIPITATION IS LOWEST IN/NEAR THE WESTERN MAGIC VALLEY.
TEMPERATURES WILL BE COLD TO START THE LONG TERM, AND THIS
BRINGS THE CHANCE OF LIGHT SNOW IN THE VALLEYS WEDNESDAY
MORNING. HOWEVER, AS WARM AIR ADVECTION CONTINUES THROUGH AT
LEAST FRIDAY, SNOW LEVELS WILL RISE AND ANY BRIEF LOW LEVEL SNOW
WILL QUICKLY CHANGE OVER TO RAIN. THE PEAKS OF THE MOUNTAINS
MAY BE IN LINE FOR OVER A FOOT OF NEW SNOW, BUT AREAS UNDER
AROUND 7000 FT WILL CHANGE TO RAIN BY THURSDAY, ENDING THE SNOW
THREAT UNTIL SATURDAY. ALONG WITH PRECIPITATION, GUIDANCE IS
STILL INDICATING A GOOD CHANCE FOR RELATIVELY STRONG WINDS IN
HIGHER ELEVATIONS THROUGH MUCH OF THIS PERIOD. TEMPS ARE
EXPECTED TO BE ABOVE NORMAL (HIGH CONFIDENCE) THU- SAT, WITH SUN
NOW FORECAST TO BE NEAR NORMAL.
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...SA
AVIATION.....SA
SHORT TERM...KA
LONG TERM....SP
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