Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 301552

Area Forecast Discussion
National Weather Service Boise ID
952 AM MDT SAT JUL 30 2016

.DISCUSSION...Early morning visible satellite imagery revealed a
field of high based cumulus clouds over southern Idaho extending
into portions of southern Malheur County. Radar indicates that
some of these clouds are producing virga which is likely causing
gusty surface winds under these clouds. There have also been a
few lightning strikes this morning in southern Idaho. This
activity will increase in coverage this afternoon with isolated
thunderstorms expected from southern Malheur County into portions
of southern Idaho and scattered thunderstorms south of the Snake
River. Otherwise, the forecast is on track for another hot day
with temperatures similar to what we have seen for the last
several days.


.AVIATION...VFR. Isolated thunderstorms today mainly south of a KREO-
KBOI-KSNT line. Scattered thunderstorms expected along the ID-NV
border and north to the Snake River. Thunderstorms expected to
taper off before 06Z. Smoke layers with MVFR visibilities will
continue in the Lowman area and surrounding valleys. Also expect
smoke in the Snake River Plain with local MVFR visibilities
through 18Z, filtering in again overnight. Surface winds generally
W-NW 12 kts or less, with gusts to 40 kts near thunderstorms.
Winds aloft west 15-25 kts through 10K feet MSL.

Outlook for Sunday...Mainly VFR. Smoke will continue in the Boise
mountains, filtering into the Snake River Plain overnight through
the morning hours. Otherwise expect mostly clear skies and breezy
northwest winds.



SHORT TERM...Today through Sunday...Monsoon moisture that has
been over Nevada will creep north into the forecast area today.
But increasing westerly flow around an upper-level trough over
British Columbia will quickly push it back out of the area
tonight. Models appear slightly faster with the dry air pushing in
from the west, and have further limited thunderstorm coverage
today further south and east. Low level moisture is fairly
limited, and any storms that develop will be moving rather quickly
from the west at 20-30 mph, so main threats will be lightning and
gusty winds. This still supports the fire weather watch now in
effect. Temperatures 5 to 10 degrees cooler on Sunday, but still
near seasonal normals. Upper level westerly winds increase on
Sunday, so should see breezy conditions in the Snake Plain, and
over the ridgetops.

LONG TERM...Sunday night through Friday...Dry westerly flow aloft
will shift into the southwest Monday and Monday night ahead of an
approaching upper level trough. This system will move east across
Washington and northern Idaho Tuesday and Tuesday night, with
precipitation staying along and north of the Canadian border. The
main effects on our area will be breezy northwest winds and cooler
temperatures, with highs Tuesday and Wednesday 10 to 15 degrees
lower than Monday. A warming trend Thursday and Friday will precede
the next upper level trough. Models show the center of this system
over the British Columbia coast Friday morning, with southwest flow
aloft remaining dry over southeast Oregon and southwest Idaho. It is
still uncertain whether monsoon moisture will will cross the Nevada
border on Friday.

ID...Red Flag Warning until midnight MDT tonight IDZ423-426.



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