701
FXUS65 KBOI 081528
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
928 AM MDT THU MAY 8 2025
DISCUSSION
WEAK COLD FRONT MOVED THROUGH OUR CWA OVERNIGHT,
AND TODAY WILL BE SUNNY WITH BREEZY NORTHWEST WINDS THIS
AFTERNOON. THE WARMING TREND IS HALTED FOR TODAY ONLY, WITH
FORECAST HIGH TEMPS TODAY SIMILAR TO HIGHS YESTERDAY. BUT
FRIDAY WILL BE 8 TO 10 DEGREES WARMER, AND SATURDAY EVEN
ANOTHER 1-3 DEGREES WARMER ON THE IDAHO SIDE, WHILE OREGON
BEGINS TO COOL. A PACIFIC UPPER TROUGH/LOW WILL APPROACH THE
NORTHWEST COAST SATURDAY, WITH BIG WEATHER CHANGES IN OUR CWA
SUNDAY AND MONDAY AS THE UPPER LOW MOVES INLAND. THESE CHANGES
INCLUDE SHOWERS, THUNDERSTORMS, GUSTY WINDS, AND 20 TO 25
DEGREES COOLING, WITH TUESDAY THE COOLEST DAY. CURRENT FORECAST
COVERS ALL THIS. NO UPDATES.
AVIATION
VFR WITH HIGH CLOUDS FILLING IN THIS EVENING.
SURFACE WINDS: W-NW 5-15 KT BECOMING VARIABLE LESS THAN 10 KT
BY FRI/03Z. WINDS ALOFT AT 10KFT MSL: SW 15-25 KT.
KBOI...VFR. NW WINDS 8-10 KT, SHIFTING TO E-SE 4-8 KT OVERNIGHT.
WEEKEND OUTLOOK...SATURDAY WILL BE WARM AND DRY WITH INCREASING
CLOUDS. SHOWERS AND THUNDERSTORMS POSSIBLE (15-30%) OVER THE BOISE
MOUNTAINS AND ID/NV BORDER LATE AFTERNOON INTO EVENING. ON SUNDAY
AFTERNOON, A COLD FRONT WILL MOVE FROM SE OR INTO SW ID, BRINGING
A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WITH GUSTY WESTERLY
WINDS, LOWERING CEILINGS, AND MOUNTAIN OBSCURATION.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH SATURDAY NIGHT...WARM AND DRY
CONDITIONS WILL CONTINUE ACROSS THE REGION TODAY, WITH
TEMPERATURES RUNNING ABOUT 10 DEGREES ABOVE NORMAL. A WEAK
FRONTAL PASSAGE EARLY THIS MORNING TEMPORARILY FLATTENED THE
RIDGE, KEEPING TODAY’S HIGHS NEAR YESTERDAY’S LEVELS—GENERALLY
IN THE UPPER 70S ACROSS THE LOWER VALLEYS.
ON FRIDAY, THE RIDGE WILL EXPAND NORTHWARD OVER THE NORTHERN
ROCKIES, ALLOWING TEMPERATURES TO RISE ANOTHER 8 TO 10 DEGREES,
WITH HIGHS REACHING THE UPPER 80S IN THE VALLEYS. BY SATURDAY,
A DEEPENING UPPER-LEVEL LOW WILL APPROACH THE PACIFIC NORTHWEST
COAST, INCREASING SOUTHWESTERLY FLOW AND DRAWING IN ADDITIONAL
MOISTURE ALOFT. THIS WILL TIGHTEN THE PRESSURE GRADIENT,
RESULTING IN BREEZY SOUTHERLY WINDS ACROSS THE AREA. THE
COMBINATION OF WARM AIR AND DOWNSLOPE FLOW WILL HELP PUSH VALLEY
TEMPERATURES TO NEAR RECORD LEVELS, WITH HIGHS IN THE LOW 90S.
THERE ALSO APPEARS TO BE SUFFICIENT HIGH-LEVEL MOISTURE
(PRECIPITABLE WATER VALUES IN THE 60TH PERCENTILE) AND
INSTABILITY (CAPE) TO SUPPORT THUNDERSTORM DEVELOPMENT SATURDAY
AFTERNOON. INVERTED-V SOUNDINGS SUGGEST THAT STRONGER STORMS MAY
PRODUCE GUSTY OUTFLOW WINDS. STORMS ARE MOST LIKELY TO INITIATE
OVER THE HIGHER TERRAIN OF SOUTHWEST IDAHO, WHERE OROGRAPHIC
LIFT WILL AID CONVECTION.
LONG TERM...SUNDAY THROUGH THURSDAY...INCOMING UPPER-LEVEL
TROUGH PENDING, A COOL AND CLOUDY LONG TERM IS ON THE WAY. A COLD
FRONT WILL MOVE THROUGH THE REGION SUNDAY AFTERNOON INTO MONDAY,
BRINGING GUSTY WINDS, COOLER TEMPS, AND SHOWERS AND THUNDERSTORMS.
SHOWER AND THUNDERSTORM CHANCES SUNDAY WILL BE GREATEST IN BAKER,
ADAMS, AND VALLEY COUNTIES WITH CHANCE RANGING FROM 30-50%. THE REST
OF THE REGION CURRENTLY IS SITTING 15-30% CHANCE. GUSTY WINDS WILL
BE GREATEST SUNDAY AFTERNOON INTO EVENING, PARTICULARLY IN SOUTHERN
HARNEY, MALHEUR, AND OWYHEE COUNTIES WHERE GUSTS MAY REACH 40 KTS.
SNOW LEVELS WILL DECREASE FROM 8,000-9,500 FEET SUNDAY AFTERNOON
TO 5,500-7,000 FEET THROUGH THE EXTENDED PERIOD, WITH HIGHEST
LEVELS OCCURRING IN THE WESTERN MAGIC VALLEY. SHOWER CHANCES
REMAIN INTO MONDAY AT 50-70% IN THE WEST-CENTRAL MOUNTAINS,
DECREASING TO 30-45% ELSEWHERE. THE COLD FRONT WILL BRING HIGH
TEMPS MONDAY AND TUESDAY 15-20 DEGREES COOLER THAN THE WEEKEND.
SHOWERS REMAIN POSSIBLE TUESDAY AND WEDNESDAY, DIMINISHING IN
SE OR WEDNESDAY, AND THUNDERSTORMS REMAIN POSSIBLE IN THE
WESTERN MAGIC VALLEY BOTH DAYS AS WELL. THE UPPER-LEVEL TROUGH
WILL MEANDER OVERHEAD UNTIL LATE TUESDAY INTO WEDNESDAY. FROM
WEDNESDAY INTO THURSDAY, THE GFS PUTS US UNDER NW FLOW ALOFT,
WHILE THE ECMWF AND CANADIAN BUILD A HIGH AMPLITUDE SHORTWAVE
RIDGE. ALTHOUGH THE SOLUTIONS DIFFER, THE NET RESPONSE WILL BE A
DRIER PATTERN, PROVIDING SOME RELIEF FROM PRECIPITATION FOR THE
TIME.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...LC
AVIATION.....SA
SHORT TERM...JDS
LONG TERM....CH
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