Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 301431
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
831 AM MDT FRI SEP 30 2016

.UPDATE...

Updated afternoon forecast to include isolated thunderstorms
across the Magic Valley where radar shows convection occurring
near Mountain Home moving east. Not sure if the convection will
hold together this morning, but could redevelop over the Magic
Valley during the afternoon instability.

Valle

&&

.PREV DISCUSSION... /issued 309 AM MDT FRI SEP 30 2016/

SHORT TERM...Today through Sunday. Broad southwest flow through
the depth of the atmosphere will remain in place today, with weak
embedded waves in this flow. The first such wave is located just
to our west this morning, and is aiding in the development of
showers over portions of the Magic Valley and Central Mountains.
As this wave works eastward today, it will interact with slightly
better moisture in place over SE Idaho, and thus expect scattered
showers with embedded isolated thunderstorms to develop this
afternoon, most numerous across the Eastern Highlands and Central
Mountains, with lesser coverage over the Snake Plain. Storms do
have the potential to produce gusty winds and small hail. This
activity will weaken overnight but an isolated shower chance
lingers through the night. On Saturday, an organized band of
precipitation is expected to develop across the Central Mountains
during the morning and advance eastward across SE Idaho through
the day and into the Eastern Highlands by evening. This will
impact put a potential damper on any outdoor activities. Winds
will become breezy Saturday afternoon, particularly across the
Upper Snake Plain and Central Mountains, but remain below advisory
levels. After some drying across much of SE Idaho Saturday night,
a wave of low pressure is expected to rotate northward across SE
Idaho Sunday, bringing renewed chances for isolated to scattered
showers along with isolated thunderstorms. Expect light snow
accumulations across the Central Mountains above 8,000 feet
Sunday. Temperatures will remain just above seasonal
climatological averages through Sunday in the presence of the
broad southwest flow.

LONG TERM...Monday through Friday. A seasonally strong closed low
pressure system remains forecast to track through the northern
Great Basin Monday into Tuesday, exiting eastward into Wyoming
late Tuesday into Wednesday. This is a favorable track for
widespread precipitation across SE Idaho, particularly for the
Southern and Eastern Highlands, and this is reflected in the
latest forecast. Precipitation should become more expansive and
steadier Monday, with this activity gradually shifting eastward
across the Eastern Highlands Tuesday. With the upper low around,
temperatures will fall sharply on Monday to below seasonal
averages, with cool temperatures persisting into mid-week. Snow
levels across much of the area fall to under 8,000 feet by Tuesday
morning, perhaps falling as low as around 6,500 feet elevation
across the Southern and Eastern Highlands. This will likely mean
some snow for mountain passes Monday night into Tuesday. This may
impact the Tuesday morning commute for these areas. Drier and
milder conditions build into the region Wed-Thu, with the next
storm system beginning to spread precipitation across the Central
Mountains by Friday. AD/GK

AVIATION...Expect VFR conditions throughout the day with only
isolated isolated thunderstorms expected this afternoon.   Have
nothing more than VCTS at all sites today.   Expect similar
conditions Saturday with showers and isolated afternoon
thunderstorms expected.
GK

FIRE WEATHER...Warm conditions will continue today on southwest
flow aloft. Expect nothing more than isolated thunderstorms this
afternoon. Cooling should begin Saturday with a better chance for
showers as an upper level low moves east with temperatures
expected to drop to well below normal readings Monday with
elevated humidity and showers continuing into the early part of
next week. GK

&&

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

$$



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