870
FXUS65 KBOI 211541
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
ISSUED BY NATIONAL WEATHER SERVICE POCATELLO ID
941 AM MDT MON APR 21 2025
DISCUSSION
SKIES ARE MOSTLY CLEAR THIS MORNING AFTER LAST
NIGHT'S COLD FRONT WITH CLOUDS MAINLY LIMITED TO THE MOUNTAINS.
EXPECT MOSTLY SUNNY SKIES IN MOST AREAS WITH TEMPERATURES NEAR
NORMAL TODAY. THE EXCEPTION WILL BE IN THE NORTHERNMOST PORTIONS
OF THE WEST-CENTRAL MOUNTAINS WHERE THERE WILL BE A 20% CHANCE
OF SNOW SHOWERS AS A TROUGH MOVES BY TO OUR NORTH. WINDS WILL BE
BREEZY THIS AFTERNOON WITH GUSTS 15-25 MPH, EXCEPT IN THE MAGIC
VALLEY WHERE GUSTS UP TO 35 MPH WILL DEVELOP. FORECAST REMAINS
ON TRACK AND NO UPDATES ARE EXPECTED AT THIS TIME.
AVIATION
VFR. LARGELY CLEAR SKIES WITH LOW CLOUDS CLEARING THIS
MORNING/AFTERNOON OVER KMYL/KBKE, TEMPORARY MTN OBSCURATION. SNOW
LEVELS: 4.5-6 KFT MSL DECREASING TO 3.5-5 KFT. SURFACE WINDS: W/NW 5-
10 KT GUSTING 15 KTS; MAGIC VALLEY AND SE TREASURE VALLEY TO SEE
W/NW 10-20 GUSTING 20-30 KT. BECOMING VARIABLE UNDER 10 KT TONIGHT.
WINDS ALOFT AT 10KFT: W-NW 10-25 KT.
KBOI...VFR. SURFACE WINDS W-NW 8-12 KT, GUSTING TO 15-20 KT THIS
AFTERNOON. WINDS CALM AND VARIABLE TONIGHT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...WEAK PACIFIC COLD
FRONT BROUGHT SCATTERED LIGHT RAIN SHOWERS TO SOUTHWEST IDAHO
DURING THE NIGHT. AT 3AM MDT KCBX RADAR STILL SHOWED WEAK ECHOES
IN OWYHEE COUNTY BUT SHOULD END BY SUNRISE AS THE COLD FRONT
COMPLETES ITS PASSAGE THROUGH OUR CWA. POST-FRONTAL WEATHER
TODAY WILL INCLUDE CLEARING SKIES, 4 TO 8 DEGREES COOLER TEMPS,
AND STRONGER AFTERNOON WEST/NORTHWEST WINDS THAN OCCURRED
YESTERDAY. STRONGEST GUSTS, UP TO 35 MPH, WILL BE FOUND IN THE
MAGIC VALLEY AND CAMAS PRAIRIE. CLEAR SKIES AND DECREASING WINDS
TONIGHT WILL ALLOW LOW TEMPS TUESDAY MORNING TO DIP INTO THE
20S IN EASTERN OREGON AND THE MOUNTAINS OF WESTERN IDAHO, AND
LOWER TO MID 30S IN THE IDAHO VALLEYS, COLD ENOUGH FOR FROST
NEAR SUNRISE IN THE AGRICULTURAL VALLEYS. TUESDAY LOOKS SUNNY
AND 2 TO 5 DEGREES WARMER THAN TODAY AS THE UPPER TROUGH
SHIFTS EASTWARD OUT OF OUR AREA. AFTER ZONAL FLOW ALOFT EARLY
WEDNESDAY, A NEW UPPER TROUGH WILL DEVELOP IN WESTERN WA AND
OR LATER WEDNESDAY AND FLOW ALOFT IN OUR CWA WILL BACK TO
SOUTHWESTERLY. MOISTURE IN THE SOUTHWEST FLOW WILL CREATE A
20 PERCENT CHANCE OF RAIN SHOWERS IN THE IDAHO MOUNTAINS
WEDNESDAY AFTERNOON AND EVENING, WHILE EASTERN OREGON STAYS
MOSTLY CLEAR. CLOUDS IN IDAHO WILL DECREASE LATER WEDNESDAY
NIGHT, ALLOWING LOW TEMPS THURSDAY MORNING TO AGAIN DIP TO
25 TO 30 DEGREES IN THE MOUNTAINS AND HIGHER BASINS, AND 30S
ELSEWHERE.
LONG TERM...THURSDAY THROUGH MONDAY...WARM AND DRY TO END THE
WORK WEEK, AS AN UPPER LEVEL RIDGE SITS OVER OUR AREA. HOWEVER,
THAT PATTERN WILL BEGIN TO CHANGE FRIDAY AFTERNOON. WHILE THERE
IS GOOD MODEL CONSENSUS ON AN UPPER LEVEL TROUGH MAKING ITS WAY
OVER OUR AREA LATE FRIDAY/EARLY SATURDAY, THE STRENGTH AND
ASSOCIATED PRECIPITATION IS STILL UNCERTAIN. THE GFS SOLUTION
ALLOWS FOR BETTER MOISTURE AND DYNAMICS, WHILE THE EURO/CANADIAN
KEEPS OUR AREA DRIER WITH WEAKER FORCING OVER OUR AREA.
ENSEMBLES ARE SHOWING INSTABILITY BUILDING IN OVER THE AREA
FRIDAY AFTERNOON/EVENING (THE GFS ENSEMBLE MEMBERS ARE MORE ON
BOARD GIVEN THE SCENARIO LISTED PRIOR). DUE TO THIS, THERE IS A
SLIGHT CHANCE (UNDER 20%) FOR THUNDER FRIDAY AFTERNOON/EVENING
MAINLY OVER THE SOUTHWEST HIGHLANDS. PRECIPITATION CHANCES
FRIDAY AFTERNOON THROUGH SUNDAY WILL RANGE FROM 15-30% IN LOWER
ELEVATIONS (30-60% IN HIGHER TERRAIN). THOSE CHANCES TAPER OFF
SUNDAY AFTERNOON THROUGH MONDAY AS THE TROUGH MOVES OFF TO THE
EAST. WINDS WILL INCREASE OUT OF THE NORTHWEST FRIDAY AFTERNOON
FOLLOWING A COLD FRONT AND REMAIN BREEZY THROUGH MONDAY.
TEMPERATURES 5-10 DEGREES ABOVE NORMAL TO END THE WORK WEEK ON
THURSDAY AND FRIDAY, DROPPING TO MORE SEASONABLE LEVELS SATURDAY
AND MONDAY. SNOW LEVELS START AT 7-8.5 KFT THURSDAY AND FRIDAY,
LOWERING TO 4.5-6 KFT FOLLOWING THE COLD FRONTAL PASSAGE.
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...ST
AVIATION.....CH
SHORT TERM...LC
LONG TERM....NF
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