007
FXUS65 KBOI 201741
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1141 AM MDT MON APR 20 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- DRY, BREEZY AFTERNOONS AND WARM THROUGH TUESDAY.
- TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL THROUGH TUESDAY.
- SHOWERS AND THUNDERSTORMS, WINDY, AND MUCH COOLER TUESDAY
NIGHT THROUGH THURSDAY DECREASING FRIDAY, AS A COOL UPPER
LEVEL TROUGH AND SEVERAL FOLLOWING TROUGHS MOVE THROUGH.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED 329 AM MDT MON APR 20 2026
AN UPPER RIDGE WILL CONTINUE WARM, DRY WEATHER IN OUR CWA
THROUGH TUESDAY MORNING, WITH CLOUDS INCREASING FROM THE SOUTH
AND WEST FROM A DEEP PACIFIC UPPER LOW OFF CALIFORNIA NEAR
40/130. LATER TUESDAY THE LOW WILL COME INLAND AND BRING PCPN TO
OUR CWA. SHOWERS WILL MAXIMIZE TUESDAY NIGHT AND WEDNESDAY AS
THE LOW MOVES RIGHT OVER OUR AREA. WE HAVE A 20 PERCENT CHANCE
OF THUNDERSTORMS IN EASTERN OR TUESDAY AFTERNOON WHEN LAPSE
RATES ARE STEEPEST DUE TO WARM AIR STILL AT THE SURFACE, THEN
SHIFTING INTO WESTERN IDAHO TUESDAY EVENING AND CENTRAL IDAHO
WEDNESDAY ALONG AND AHEAD OF AN EASTWARD-MOVING COLD FRONT. HIGH
TEMPS TODAY AND TUESDAY WILL BE IN THE 60S-70S IN THE MOUNTAINS
AND LOWER 80S IN THE SOUTHERN VALLEYS, THEN COOL 20-30 DEGREES
BEHIND THE FRONT, TOO COLD TO SUPPORT FURTHER THUNDERSTORMS.
THE SNOW LEVEL WILL LOWER TO NEAR 5500 FEET WEDNESDAY WITH
SEVERAL INCHES ACCUMULATION. POST-FRONTAL WEST WINDS WILL
INCREASE WEDNESDAY TO NEAR ADVISORY SPEEDS IN SOUTHEAST
OREGON, AND IN THE SNAKE BASIN SOUTH TO THE NEVADA BORDER.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED 329 AM MDT MON APR 20 2026
BREEZY CONDITIONS AND SCATTERED SHOWERS WILL LINGER THROUGH
THURSDAY WHILE THE AREA REMAINS INFLUENCED BY A DEPARTING UPPER
LOW. BELOW- NORMAL TEMPERATURES WILL ALSO CONTINUE, WITH SNOW
LEVELS HOLDING BETWEEN 4500-6000 FT MSL. ON FRIDAY, THIS UPPER
LOW WILL MERGE WITH A STALLED CANADIAN TROUGH OVER THE NORTHERN
U.S., REINFORCING COOL, NORTHERLY FLOW OVER THE PACNW THROUGH
THE WEEKEND. WHILE INSTABILITY REMAINS, DIMINISHING MOISTURE
WILL LIMIT SHOWER CHANCES TO 10-30% FRIDAY-SUNDAY. SHOWER
CHANCES WILL PRIMARILY FAVOR THE HIGHER TERRAIN OF SW IDAHO,
WITH 4500-6500 FT SNOW LEVELS. BY MONDAY, THE CANADIAN TROUGH
WILL EVENTUALLY SHIFT EAST AS WEAK RIDGING BUILDS, RESULTING IN
MOSTLY DRY, SLIGHTLY WARMER CONDITIONS ACROSS SE OREGON AND SW
IDAHO.
AVIATION /18Z MONDAY THROUGH TUESDAY/
ISSUED 1140 AM MDT MON APR 20 2026
VFR. VIRGA DEVELOPING IN E OREGON. SURFACE WINDS: SW-SE 5-15 KT
WITH GUSTS TO 20-25 KT IN THE AFTERNOON. WINDS ALOFT AT 10KFT
MSL: S 10-20 KT.
KBOI...VFR. SURFACE WINDS: GENERALLY SE 5-12 KT.
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
AVIATION.....CH
SHORT TERM...LC
LONG TERM....SH
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