Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 260850

Area Forecast Discussion
National Weather Service Pocatello ID
250 AM MDT THU MAY 26 2016

.SHORT TERM...Today through Saturday...Areas of patchy fog possible
this morning with lingering moisture in the air, clear skies and
light winds. Fog is most likely to develop in the Upper Snake
Plain near Island Park extending into the valleys of the Central
Mountains. Additional patchy areas possible for the rest of the
Southeast Idaho through mid-morning.

Upper level pattern has become more disorganized over our region
which should mean less rain opportunity and warmer temperatures
today. Mountain snow, however, is expected to continue. Next
approaching upper low from the northwest remains on track for
early Friday which will mainly impact our northerly areas.
Scattered showers with rainfall amounts near 0.50 inches forecast
Friday into early Saturday in some areas. Other impacts for the
rest of the region from this low will be increasing southwest and
west winds in excess of 20mph with higher gusts. Expect winds to
begin increasing early morning and continue through late evening.
Advisories are likely to be issued for these conditions through
the Snake Plain and for American Falls Reservoir. NP/DMH

.LONG TERM...Sunday through Thursday...Unfortunately, the
forecast becomes difficult to predict by Sunday and Monday.
Weather models this latest run seem to be in consensus to provide
clear skies Sunday with the exception of some isolated showers in
the Central Mountains however climatology suggests an isolated to
scattered risk. Additionally, previous model runs show a trough
moving into the region quicker. The timing of this trough will
determine how the forecast will play out for Memorial Day. If we
believe the faster progression it will have a minimal impact for
outdoor activities Monday, and primarily affect our eastern areas
bordering Wyoming. However, if we believe the stronger progression
of the GFS model more widespread impacts across SE Idaho including
cloudy skies, a rainy day followed by increasing winds by the
afternoon would occur. Since this is the first occurance this
model has shown this trend and it is the only one showing it, it
is not officially in the forecast for Monday however it is
important to note its possibility.

Mid-week provides a ridge of high pressure and thus a brief break
from the daily precipitation chances. Temperatures should warm
nicely. NP/DMH


.AVIATION...Weak transitory upper ridge shifts across East Idaho
today. However, enough lingering surface moisture in place along
with shortwave trough dropping through PacNW states to help
influence additional convective development today. Best chances for
KSUN terminal today but outflows from convection in central mtns may
be enough to produce outside chance of development at KIDA/KPIH as
well. As in previous days, ceilings expected to remain VFR dropping
to MVFR within convective areas. DMH


.FIRE WEATHER...Weak upper ridge early today gives way to shortwave
feature dropping through Pac NW states, helping to reinforce broad
trough over western states. Weakly unsettled conditions today will
allow convection to develop mainly over higher elevations. Gusty
outflows the main threat. Continued unsettled conditions will
continue into the holiday weekend as conditions alternate between
broad flat flow/weak ridging and progression of northern stream
reinforcing shortwave features moving through the northern states.
Breezy to windy conditions return each day as mid level flow
strengthens along with surface pressure gradient. Ridge conditions
are still expected to return by midweek next week with warmer
temperatures. DMH

.PIH Watches/Warnings/Advisories...

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