Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 240833

Area Forecast Discussion
National Weather Service Pocatello ID
233 AM MDT Thu Jun 24 2021

.SHORT TERM...Today through Saturday. Occasional showers and
thunderstorms will continue through Friday. As with yesterday, the
latest trends in the forecast may easily change in the next few
hours, as we see where breaks in the clouds can help us reach
higher instability and better thunderstorm potential. Right now,
the looks like it will be across mountains. Today though looks
like a better day for rainfall as moisture increases a bit. It
also looks like a better day for storms across the Snake Plain and
Magic Valley due to outflow boundaries showing up in the higher
resolution models. Wind gusts over 40 mph are still possible with
storms today and this evening. Thunder potential will decrease
overnight, although not to zero, before increasing tomorrow
afternoon. The trend for Friday is for scattered storms closer to
the Wyoming border and southeast corner, with isolated coverage
elsewhere we can get storms to develop. By Saturday, we begin the
rapid dry out and prolonged heatwave coming to the part of the
country. We might an isolated storm across the southeast
highlands, but that risk is low. One thing that is expected as the
high is still to our northwest is gusty north to northeast
winds. If this trend continues we will be definitely looking at a
LAKE WIND ADVISORY for American Falls Reservoir. Keyes

.LONG TERM...Sunday through next Thursday. High pressure will
build into the area starting Saturday and last all next week. Very
hot temperatures are in store through the period, especially
Tuesday, Wednesday, and Thursday, where widespread records are
expected. We could break all-time temperature records for several
locations Tuesday, Wednesday, and, possibly, Thursday. Excessive
heat warnings will likely be needed Monday through Thursday. Models
are slow to move out the high pressure. Extreme heat will likely
continue through Friday, possibly longer. The GFS model is showing
moisture, supporting dry thunderstorms, moving into our southern and
eastern areas by late Wednesday, possibly late Tuesday, and
continuing through Thursday afternoon.


.AVIATION...Moisture and instability will bring isolated
thunderstorms this afternoon. Models are showing the best chance of
thunderstorms for our eastern areas mainly impacting KIDA, KDIJ and
KPIH. However, have vicinity thunderstorms for all TAF locations
tomorrow. Strong thunderstorm outflow winds of around 40 mph will be
the biggest impact. Some outflows in the Snake Plain may be higher.


.FIRE WEATHER...Showers and thunderstorms will continue through
tomorrow before we see that prolonged heatwave begin. Just like
yesterday, we are trying to based today`s forecast on the latest
smaller scale trends. It looks like today, showers and storms will
be possible just about everywhere. The latest lightning
probability puts scattered coverage across 476, 411, 413, and 427.
We also may see scattered coverage across the higher terrain along
the northern border of 422. We will be borderline across 410 as
there seems to be indications of better storm development across
the Snake Plain. We did issue a RED FLAG WARNING for 411, 413 and
427 last night and will continue that. We didn`t for 422 and 410
right now. That may change once the day shift gets a look at
things. The only thing that could really change things is morning
cloud cover. This is what basically nixed storms across the south,
but allowed for more storms up north for yesterday. One thing we
are for sure should see is more storms producing rainfall,
including localized wetting rains. Overnight, we expected a few
storms across portions of 410, 411 and 413. For Friday, the focus
of storms will begin shifting east. Scattered coverage looks to be
confined to portions of 411 and 413, with isolated coverage
elsewhere we get storms to form. We quickly dry out over the
weekend, but the strong high will still be to our northwest. This
will allow for some breezy north to northeast winds areawide.
After that, the ridge builds and we are still looking at several
days of very hot weather. Not only are we still thinking we will
see record highs, but some unusually warm overnight lows and poor
humidity recovery.  Keyes


Red Flag Warning from noon today to 9 PM MDT this evening for


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