Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 260952

Area Forecast Discussion
National Weather Service Pocatello ID
352 AM MDT Sat May 26 2018

.SHORT TERM...Today through Tuesday. An Upper Level low is
currently over Central California bringing moisture and
instability over our area in Southerly flow. Models continue to
show this low move over Nevada by later this afternoon. Expect
Scattered thunderstorms and showers over the western Central
mountains and the western Southern Highlands. Expect isolated
thunderstorms and showers mainly in the mountains elsewhere. These
storms will likely produce hail and gusty outflow winds. SPC has
a marginal outlook for the Eastern Magic valley, the Snake River
plain, the Big Lost/Pahsimeroi Range/mountains and the Upper Snake
Highlands. This marginal risk area may shift away from the valley
and plain areas with the new update later this morning. On Sunday
models continue to show this Upper Level low move over extreme
southeast Idaho bringing more widespread precipitation over the
Upper Snake Highlands, Upper Snake River plain and the Southern
Central/Lost River/Pahsimeroi mountains/ranges before bringing
widespread precipitation to our Southern areas in return, upslope
flow late Sunday into Memorial day. Expect a wet/cold Memorial
day, particularly for the mountains. This precipitation will
increase flows for rivers and streams. Some river flows will
intensify. Please see the hydro discussion for additional
information. Tuesday weak high pressure starts to build in from
the west. Expect afternoon thunderstorms mainly over our Eastern
areas. Expect slightly above normal temperatures today before
dropping below normal Sunday and Memorial Day and then rising
slightly above normal on Tuesday. Wyatt

.LONG TERM...Wednesday through next Saturday.  Another system
moves through area Wednesday through Friday night bringing light
to moderate precipitation. High pressure tries to build in on
Saturday but models still show a chance of afternoon precipitation
particularly for our Northern ares. Look for slightly above
normal temperatures Wednesday and Thursday before dropping to near
normal to slightly below normal on Friday and Saturday. Wyatt


.AVIATION...Thunderstorm activity will increase this afternoon as an
upper low drops into NV. The favored areas will be in the Central
Mountains and the South Central Highlands, targeting KBYI and KSUN
mainly. Some of the storms could become severe with gusty outflows
and hail. Drier air remains over the Snake Plain and Eastern
Highlands through the afternoon. This evening, expect to see another
round of showers moving up out of Utah along and east of Interstate
15. These showers should taper off around midnight. Hinsberger


.FIRE WEATHER...Main threat today will be from thunderstorms
developing over the Central Mountains and South Central highlands
this afternoon. These storms could become severe with gusty outflow
winds and hail. Dry weather should prevail over the Snake Plain this
afternoon, but showers are expected to move in from Utah this
evening. Rainfall could be heavy at times on Sunday afternoon.
Moisture will work its way in from the east. Showers remain in the
forecast through Monday with drier air making its way into the area
on Tuesday, but only briefly. A cold front will make its way into
the region on Wednesday, and may trigger more showers and
thunderstorms. Hinsberger


.HYDROLOGY...Rain over the last couple of days combined with
snowmelt have caused some minor flooding for a couple of local
rivers. The Henry`s Fork near Rexburg has reached minor flood stage
and forecasted to remain in flood through the middle of next week
with warmer temperatures and rain later this weekend. The Big Wood
river has just reached flood stage this morning. The Big Wood will
likely drop below flood stage today but expect the Big Wood to
peak again next Monday and Tuesday after the next storm system.
Currently the Big Wood river is not expected to reach flood stage
in the next peak. However, it won`t take much more rain than is
currently forecasted for the river to reach minor flood stage next
Monday or Tuesday. The Big Lost at Howell, Antelope Creek near
Darlington, and the Teton river at St Anthony all have flood
advisories out now for being either near or slightly at minor
flood stage. Overall flooding is minimal with mainly field
flooding. The Snake River at Menan has exceeded minor flood stage
and will likely remain there through the weekend as the Henry Fork
continues to slightly rise. Use caution around fast flowing
water. Wyatt



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