Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 300233
Area Forecast Discussion
National Weather Service Boise ID
833 PM MDT SUN MAY 29 2016
.DISCUSSION...One thunderstorm passed across southern Twin Falls
County this afternoon, but since then all the convective wx has
shifted to sern Idaho. Radar also indicated a few showers in the
west-central Idaho mountains this afternoon, but those were dying
out this evening. Upper trough passing eastward across Idaho
tonight will bring breezy, cooler, dry wx Monday. An upper ridge
will build strongly over the Intermountain West Tuesday, leading
to hot weather Thursday through Sunday, with the weekend the
hottest period. Lower Idaho valleys will reach 95 to 100 degs
next weekend, or about 20 degrees above normal. Moisture moving
north along the California Sierra Nevada may reach eastern Oregon
with potential for thunderstorms next Sunday. No thunderstorms
in our forecasts yet, however. No updates for now.
.AVIATION...VFR. Isolated showers and thunderstorms north of KMYL
southeast of KTWF this evening tapering off. Partial clearing
overnight. Surface winds becoming W to NW 10-15kt with gusts to 25kt
Monday afternoon. Winds aloft at 10KFT MSL: NW 10-20kt.
SHORT TERM...Tonight through Tuesday...Showers and thunderstorms
were moving northeast mainly across Twin Falls County as of 245
PM MDT. Additional showers and storms are forecast for much of our
southwest Idaho zones through the afternoon, with coverage moving
off to the east this evening. CAPE values forecast by the latest
NAM are higher than previously forecast, and some storms could
produce wind gusts to 40 mph and pea-size hail. This activity is
being forced largely by an upper-level trough that is moving from
west to east across the area this afternoon. A cold front is also
moving through, but it is weak and diffuse. A reinforcing cold
front will move through overnight, but it will be dry. After the
trough and cold front move out late tonight and tomorrow, we
will see the beginning of a large upper-level ridge building into
the region. After a brief cool-down tomorrow, we will warm up
considerably on Tuesday, with highs reaching the lower 80s in the
Treasure Valley and the lower elevations of southeast Oregon.
Overnight lows will be close to normal for the next two nights.
Northwest winds will be breezy tomorrow, averaging 15 to 20 mph in
the Upper Treasure and Western Magic Valleys in the afternoon.
Gusts will be near 30 mph in those areas. Tuesday`s winds will be
much lighter and average less than 10 mph as the influence of the
upper-level ridge begins to be felt.
LONG TERM...Tuesday night through Friday...A strong upper-level
ridge will move over the Intermountain West on Wednesday and
remain in place through Friday. The ridge axis moves east of the
forecast area on Thursday which should allow temperatures to
reach well above normal, in the low 90s in the lower valleys, by
Friday night through Sunday...Ridge axis still impacting the area
causing temperatures well above normal. A closed low off the
California coast will bring moisture into the area which could
cause some afternoon thunderstorms to develop, mostly in higher
terrain, through the period.
PREV SHORT TERM...SP
PREV LONG TERM....JDS/JC