Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 280951 CCA
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
252 AM MDT THU JUL 28 2016

...CORRECTED TO ADD AVIATION DISCUSSION...

.Discussion...The forecast for Southeast Idaho Thursday and Friday
is generally dry and void of thunderstorms. Satellite imagery this
morning shows some westward movement of high pressure over the Great
Basin and moist air that has been pooling over Old Mexico is
beginning to expand into California. Even some moisture streaming
off TS Frank located west of Baja California is drifting up the
coast. Models have been suggesting Saturday for this moist air to
slip into Southeastern Idaho. The GFS this morning even brings some
unstable air into the area between Oakley and Rogerson Friday
evening, hinting at possible thunderstorms, some low pops were
introduce in that area. Overall, finding the models are inconsistent
with how much monsoon moisture comes into this area. Think our over
all forecast trend is still good and have decided to keep it
consistent with isolated to scattered potential across this area
Saturday into Sunday. There still appears to be a cold front
Saturday afternoon, but MOS guidance is just beginning to pick up
on some winds in the Snake Plain for Saturday and Sunday, winds
should increase next model run. For fire concerns, forecast minimum
RH is walking the line on Saturday for watch/warning criteria. A
new disturbance enters the Pacific Northwest Sunday night and
Monday, tracking across the panhandle into Montana by Wednesday.
Another cold front and strong gusty winds are anticipated for
Tuesday. Some monsoon air remains across the South Central Caribou
Highlands Monday night and Tuesday with thunderstorms possible.
Wednesday through Friday looks dry while the monsoon moisture
temporarily is pushed out of state and may slip back in by next
weekend. RS

&&

.AVIATION...Increasing west to southwesterly winds briefly
expected during the late afternoon which will persist into the
evening hours for the three Snake Plain locations, otherwise expect
another VFR day. NP/RS

&&

.FIRE WEATHER...Weak high pressure to be centered over Western
Wyoming at the surface today. A more dominant high is overhead in
the upper atmosphere to the south with weak waves of low pressure
passing to its north across Idaho - creating periods of some
increased winds. A gradual increase in monsoonal moisture is
forecast beginning Friday and continuing through Sunday. Humidities
are expected to increase for most of the region, particularly across
the Eastern and Caribou Highland locations and for portions of the
Southern Highlands and into the Snake River Plain as well. At this
same time, increased winds speeds are likely across the Central
Mountain and Snake Plain locations. Gusts in excess of 25 to 30 mph
are likely on Sunday afternoon and evening. There is also the
possibility of these same gusts on Saturday across these same
locations. Finally, due to the increase in moisture expect
thunderstorm potential to increase by Saturday and continue into
Sunday across Southeast Idaho. Therefore, highlights are possible in
the coming days - primarily for Snake Plain and Central Mountain
zones.

Monday will continue to be breezy in advance of an approaching low
pressure trough. Forecast models continue to show differences
regarding the progression of this trough therefore forecasts in the
winds on Tuesday could be a bit aggressive right now. Right now, the
GFS is the only model that is showing any precip for Tuesday as
well.
NP/RS

&&

.PIH Watches/Warnings/Advisories...None.

&&

$$



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