Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 190852
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
252 AM MDT Fri May 19 2017

.SHORT TERM...Today through Sunday night. The upper level low that
has been producing our late Winter-like weather over the region
the past couple of days will take up residence over Colorado
through the day today. The western fringes of this low`s broad
cyclonic circulation will be close enough to produce a few showers
and perhaps an isolated thunderstorm over the Eastern
Highlands/WY border region extending westward across the Southern
Highlands/UT border region. Activity should be most numerous
during peak heating, or late afternoon and early evening. An
isolated shower will be possible outside of these above-mentioned
areas as well. A disturbance will slide southeastward through the
area on Saturday which will act to kick the stubborn Upper Low
into the Great Plains while at the same time promoting the
development of scattered to numerous showers and thunderstorms
beginning Saturday afternoon and continuing through Sunday across
all of SE Idaho. Severe thunderstorms are not anticipated at this
time due to unfavorable parameters, however cannot rule out some
small hail and gusty winds Saturday afternoon/early evening with
some of the stronger storms. Precipitation with this system will
be spotty due to the convective nature of the activity -- however
a few locations may receive upwards of 0.25" of precipitation.

A Frost Advisory is in effect for the Snake Plain through 9AM this
morning. Thus far, cloud cover has been persistent and has
allowed temperatures to stay a bit warmer than earlier anticipated.
However, some breaks in the cloud canopy are beginning to form
over northern sections of the Snake Plain, and temperatures are
beginning to fall accordingly. Thus, will allow the Advisory to
continue. Temperatures will begin a gradual ascension towards
climatological averages through the short-term period, reaching
this threshold by Sunday, which means highs sneaking towards 70
across the Snake Plain. This will end a 7-day stretch of below
average temperatures. AD/Valle

.LONG TERM...Monday through Friday.

Extended forecast looks warmer and drier now than in previous runs.
The models have shifted the high pressure ridge that was located on
the coast further inland. This may have potential major impacts on
flooding by the end of next week as some of the guidance is
advertising mid 80s for highs and its possible we The stage on area rivers is expected to continue to
drop over the next couple of days due to recently cooler
temperatures. As temperatures warm over the weekend and into the
middle of next week, look for a resumption of snowmelt production
which will drive the stage up on most area rivers. The Big Wood at
Hailey is expected to remain below action stage through the weekend
but return to bankful perhaps as early as Monday night and flood
stage by Wednesday night. The Portneuf at Pocatello will remain in
minor flood stage while continuing to fall over the coming week as
we gradually deplete the upper level snow pack in this low elevation
reach. The Bear River at the Wyoming Border will remain at minor
flood stage through the weekend and into early next week as water
rolls over the spillway at Woodruff Reservoir in Wyoming. No
problems are anticipated on the Henry`s Fork near Rexburg as levels
remain below bankful through the middle of next week. Huston
&&could push upper 80s for highs in the Snake Plain and Magic
Valley. Looks like the models are trying to bring in some
scattered showers and thunderstorms by end week, but confidence is
very low in those solutions right now.

Valle


&&

.AVIATION...Mid level cloud deck is preventing the formation of any
organized fog and stratus over the region this morning. Models show
this deck breaking up around midday with some isolated to scattered
showers possible this afternoon. A brief period of mvfr conditions
is possible if one happens to get caught underneath one of these
showers.

Valle


&&

.HYDROLOGY...The stage on area rivers is expected to continue to
drop over the next couple of days due to recently cooler
temperatures. As temperatures warm over the weekend and into the
middle of next week, look for a resumption of snowmelt production
which will drive the stage up on most area rivers. The Big Wood at
Hailey is expected to remain below action stage through the weekend
but return to bankful perhaps as early as Monday night and flood
stage by Wednesday night. The Portneuf at Pocatello will remain in
minor flood stage while continuing to fall over the coming week as
we gradually deplete the upper level snow pack in this low elevation
reach. The Bear River at the Wyoming Border will remain at minor
flood stage through the weekend and into early next week as water
rolls over the spillway at Woodruff Reservoir in Wyoming. No
problems are anticipated on the Henry`s Fork near Rexburg as levels
remain below bankful through the middle of next week. Huston
&&


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 9 AM MDT this morning for IDZ020-021.

&&

$$



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