Area Forecast Discussion
Issued by NWS Pocatello, ID

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478
FXUS65 KPIH 240817
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
217 AM MDT SUN JUL 24 2016

.SHORT TERM...Today through Tuesday.
Expect dry and mild conditions today with high temperatures again
very close to late July normals for southeast Idaho. A warming
trend will kick in Monday and above normal temperatures are
expected the remainder of the week. No convective activity is
expected Monday but a weak upper level system combined with
instability may produce isolated thunderstorms Tuesday afternoon
in the central mountains and Upper Snake River Highlands.
GK

.LONG TERM...Wednesday through Sunday.
Very warm conditions are expected in the long term period with
well above normal temperatures expected to continue into next
weekend. It should be mainly dry and kept it that way in the grids
but could see an increase in convective activity by next weekend
as some more moisture may finally work back into southeast Idaho.
GK

&&

.AVIATION...A dry NW flow aloft this morning will transition
to SW flow late this afternoon and tonight with little or no
impactful weather anticipated at the terminals. Huston
&&

.FIRE WEATHER...A dry NW flow aloft early this morning is expected
to transition to SW flow later this afternoon and tonight as a
transient ridge of high pressure builds over the region bringing
light winds and warming temperatures. The ridge begins to break down
late Monday afternoon and continues to weaken through Tuesday as a
flat trough gradually migrates east through the region opening the
door for isolated afternoon and evening thunderstorms near Lost
Trail Pass Monday and then over ERN Lemhi county and SW Montana
Tuesday. The NAM model is flashing enough thunderstorm coverage to
warrant a Red Flag Warning for Lemhi County/Fire Zones 475 and 476
Tuesday afternoon and evening whereas the GFS model is mostly
stable. We will continue to monitor this development to see how
things shake out over the next several model runs. With the passing
system Monday and Tuesday we will see some wind mixing down from
aloft into the CNTRL mountains and Snake River Plain each afternoon
but remaining below warning criteria. A second weaker feature slides
east through the region Wednesday with perhaps enough instability to
support a thunderstorm or two along the Montana border near Island
Park otherwise the region remains largely dry. The flow aloft within
the mixed layer may be strong enough here to support near Red Flag
wind gusts within the CNTRL mountains. More on that as the event
draws near. For Thursday into Friday, the ridge over the SW states
expands northward across California and Nevada into Oregon with
accompanying sub-tropical moisture migrating north over the Sierra
and WRN Nevada. By Saturday, this moisture advances east across SRN
and CNTRL Idaho ahead of a weak Pacific disturbance shearing east
through NRN California and ahead of a deeper low pressure trough
rotating into WRN Canada. Resident moisture, coupled with the break
down of the ridge as the Canadian trough axis sweeps inland across
the NW states should be all it takes for widespread isolated to
scattered afternoon and nighttime thunderstorm activity Saturday
afternoon into Sunday afternoon. In addition to the thunderstorm
activity, stronger west winds will sweep across SRN Idaho behind the
accompanying cold front Sunday. So it appears that next weekend may
be shaping up to be a fairly active weekend for fires. We will
continue to watch this closely as the week progresses. Huston
&&

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

$$



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