Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 260820
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
220 AM MDT Thu Apr 26 2018

.SHORT TERM...Today through Saturday night. High pressure builds
and shifts in the next 36 hours. As the ridge shifts east, this
will allow the leading edge of moisture from the weekend storm to
move in. The models continue to try and kick off a few showers and
storms over various parts of eastern Idaho Friday afternoon and
evening. Right now, it looks like any real risk of develop would
be over the central mountains south into the Albion
Mountains/South Hills. There COULD be a couple of showers/storms
farther east but that may be even a stretch. Don`t expect much a
lot of rain with dry air in place closer to the ground. It`s
likely most of the moisture evaporates before hitting the ground.
Temperatures will continue to warm, with tomorrow still looking
like the warmest as we push 80 in some locations.

The low makes slow progress east on Saturday, with all of the
models showing something a bit different. Those differences are
creating some doubt (lower confidence) in how far east showers and
storms develop by the afternoon and nighttime hours. We have
higher chances where confidence is higher at the moment, which is
over the central mountains. There is a consistent signal for
precipitation as it will be closer to the center of the storm and
any offshoot from it during that timeframe. We also included a
higher chance over the eastern highlands (compared to areas
outside of the central mountains) as there is another consistent
signal for something to form in those areas. Rain amounts will be
light until late Saturday afternoon onward. The current forecast
shows a blend, based on some the really high amounts indicated by
models likely "feedback" and overdone. Does it means that we can
ignore it? No but confidence is really, really low on those
scenarios. Right now, we are also not looking for severe storms.
However, closed lows like this tend to surprise everyone so we
could see some "strong Storms" producing small hail and most
likely gusty winds. Cooler temperatures begin to creep in this
weekend, with snow levels Saturday night dropping low enough for
some wet snow/slush in areas above 7500ft in the central mountains
and Albion Mountains/South Hills.  Keyes

.LONG TERM...Sunday through Thursday.

First half of next week looks very unsettled as a large low pressure
system over the region will slowly move east. Models show strong
indications for showers for the mountains and highlands, less so for
the Snake Plain and Magic Valley which is creating a fair degree of
uncertainty still. Models then diverge around midweek with the GFS
keeping more showers around, especially for the high country while
the European is drier. Snow levels are relatively high for Sunday,
generally around 7000 ft. But those levels will fall in the wake of
the low to around 6000 ft for Monday and Tuesday.

Valle

&&

.AVIATION...
High pressure will produce dry weather and mainly light winds today.

Valle

&&

.HYDROLOGY...Warming temperatures through the week will help to
enhance snowmelt at mid and upper levels. A chance of showers
heading into the weekend will add to runoff while cooler
temperatures help to relieve some pressure. For now, it looks as if
the Portneuf, Blackfoot, Big Lost, Henry`s Fork and Snake Rivers
will all see high flows at some point during the next week. Huston

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Flood Advisory continues for the Blackfoot River above the Reservoir
until noon Thursday.

&&

$$



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