Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 290258

Area Forecast Discussion
National Weather Service Boise ID
858 PM MDT THU JUL 28 2016

.DISCUSSION...A west-northwest flow aloft will continue through
Friday. Monsoon moisture in Nevada may creep just far enough
northward for a slight chance of thunderstorms along the Nevada
border Friday afternoon. Otherwise, expect dry and very warm
conditions (highs around 100F in the lowest valleys) with mostly
clear skies and light winds. Forecast is on track.


.AVIATION...VFR with clear skies. Smoke from the Pioneer fire
still present. Expect MVFR conditions in and around Lowman.
Surface winds, variable, mostly 10 kts or less. Winds aloft to 10k
feet MSL, westerly 10-20 kts.


SHORT TERM...Tonight through Saturday...Upper level high pressure
centered over the southern Great Basin continues to dominate the
weather across southeast Oregon and southwest Idaho. Little change
in the pattern through Friday with hot and dry conditions and generally
light winds.

Main forecast concern is moisture moving into the area from the
south Friday evening through Saturday. Models have been consistent
in bringing an upper level trough and associated cold front into
the Pacific Northwest on Saturday. Ahead of this system the flow
aloft will turn more west to southwest and allow monsoon moisture
to creep into the area. Confidence is not great on when moisture
will arrive so kept just a slight chance of thunderstorms near the
Nevada border late Friday afternoon and evening. Greater confidence
for sufficient moisture and instability for thunderstorms on
Saturday. Most favorable areas will be across southern Harney and
Malheur Counties and on the Idaho side with storms favoring
higher terrain. Models are showing precipitable water increasing
to near 1 inch Saturday but the forecast soundings are dry in the
low levels, so little precipitation and gusty outflow winds are
expected with thunderstorms. Pressure gradient will start to
tighten on Saturday as well bringing an uptick in winds with
temperatures in the lower valleys around 100 degrees again.

LONG TERM...Saturday night through Thursday...Trough and associated
cold front will push monsoon moisture out of the region Sunday
morning and bring a cooler and drier airmass in its wake.
Temperatures Sunday will be near normal. Winds overnight will be
quite breezy with the frontal passage and breezy again Sunday post-
frontal. Monday will warm slightly under a southwesterly flow and
light winds. Models have come in line in developing another, deeper
trough expected to pass through the region Tuesday. For now, frontal
passage associated with Tuesday`s trough is expected to pass trough
the region Monday night for breezy overnight conditions.
Temperatures Tuesday will be 5 to 10 degrees below normal and will
then begin a slow climb through the end of the period bouncing back
to normal by Thursday under a light southwesterly flow.





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