Lake Wind Advisory 6, NWS Pocatello, ID

724 
WWUS75 KPIH 171843
NPWPIH

URGENT - WEATHER MESSAGE
National Weather Service Pocatello ID
1243 PM MDT Sat Apr 17 2021

IDZ054-172300-
/O.CON.KPIH.LW.Y.0006.000000T0000Z-210417T2300Z/
Lower Snake River Plain-
Including the cities of Pocatello, Blackfoot, American Falls, 
Shelley, and Fort Hall
1243 PM MDT Sat Apr 17 2021

...LAKE WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM MDT THIS
AFTERNOON...

* WHAT...Northeast winds 10 to 15 mph with gusts to 20 mph.

* WHERE...American Falls Reservoir.

* WHEN...Until 5 PM MDT this afternoon.

* IMPACTS...Moderate to strong northeast winds will create rough 
  waves making hazardous conditions for small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Boaters on the American Falls reservoir should use extra caution
since these northeast winds will create rough waves which can
overturn small craft.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/pocatello

786 
WWUS75 KPIH 172244
NPWPIH

URGENT - WEATHER MESSAGE
National Weather Service Pocatello ID
444 PM MDT Sat Apr 17 2021

IDZ054-172345-
/O.EXP.KPIH.LW.Y.0006.000000T0000Z-210417T2300Z/
Lower Snake River Plain-
Including the cities of Pocatello, Blackfoot, American Falls, 
Shelley, and Fort Hall
444 PM MDT Sat Apr 17 2021

...LAKE WIND ADVISORY WILL EXPIRE AT 5 PM MDT THIS AFTERNOON...

Northeast winds were decreasing below Advisory criteria across
American Falls Reservoir and thus the Advisory will be allowed to
expire at 5 PM this afternoon.

$$

For more information from the National Weather Service visit
https://weather.gov/pocatello

Area Forecast Discussion...UPDATED
National Weather Service Pocatello ID
706 PM MDT Fri Apr 16 2021

.UPDATE...A couple of updates as we begin this Friday evening. One
is to let the LAKE WIND ADVISORY for American Falls Reservoir end
on time. It might remain a bit gusty on the north end, but winds
elsewhere are light and variable. Also, showers continue across
the area, especially from the Snake Plain and the southern and
eastern highlands. Those should hold through 8-10pm although they
already beginning to decrease as we head toward sundown. Looking
ahead, we may need another LAKE WIND ADVISORY for tomorrow...but
will let the overnight shift take one last crack at that.  Keyes

&&

.PREV DISCUSSION... /issued 209 PM MDT Fri Apr 16 2021/

SHORT TERM...Tonight through Sunday night. Upper trough remains
to the south tonight, with a few light showers this afternoon
mainly over the southern and eastern highlands. Northeast
down-valley gradient continues, and winds remain strong enough
for chop concerns on American Falls Reservoir so the Lake Wind
Advisory stands. High pressure begins tilting over the region for
most of the weekend. Expect a warming trend with winds decreasing
and returning to a southwesterly daily up-valley flow for the
Snake Plain. That should limit the threats to boaters on American
Falls Reservoir for the weekend. DMH

&&

.SHORT TERM...

.LONG TERM...

&&

.AVIATION...
LONG TERM...MONDAY THROUGH NEXT FRIDAY...
Rain/snow shower activity will be ongoing Mon AM, and will continue
throughout the day as the responsible shortwave drops across the
region from the north. It continues to look like the brunt of this
system will remain to our east across MT/WY, and thus, potential
impacts continue to look limited (although colder high temps only
reaching the 40s/50s can be expected Mon). 500mb cluster analysis
continues to support this "glancing blow" idea with the majority of
clusters keeping our CWA almost centered between the trough to our
NE and ridging to our W (although one cluster is perhaps coming in
favoring more of an influence from the trough). It does increasingly
look like breezy NNE winds can be expected, especially during the
afternoon/eve and maximized down the Snake Plain from Dubois to
Pocatello. By Wed, models advertise the potential for some sort of
shortwave or even closed low to rotate in from the west, but with
very low confidence at this juncture on eventual track and any
impacts for our CWA. Effects from this trough could linger into
Thurs/Fri. Temps will gradually warm again Tue-Fri. - KSmith

AVIATION...
Forecast confidence is very high in widespread VFR cigs/vsbys for
all SE Idaho terminals from today right through the weekend, with no
significant impacts for aviation through Sun eve. Stepping down from
this concept into the details, high-res guidance (HREF ensemble
members/RAP) are all generating varying degrees of very
light/isolated/"popcorn" shower activity coincident with diurnal
heating this afternoon/early eve, with perhaps a slight maximum to
this development across the terrain south/east of the Snake Plain.
This is accompanied by a cig nudge toward slightly increased SCT to
borderline BKN mid-level cumulus, again especially over terrain
areas. Granted a localized troughing feature on the far back side of
a departing low pressure center ejecting east into the Plains will
still be in our neighborhood, but NAMNest/RAP instability is almost
non-existent, and we think it's going to really hard to pull off
much shower activity near the TAF terminals. NBM PoPs are coming in
at 10% or less as well, highest at KDIJ. Generously added VCSH at
KDIJ, but otherwise will simply expect that slight uptick in clouds.
After sunset tonight, those clouds largely dissipate with FEW to SKC
conditions overnight through midday Sat, with just a few clouds Sat
afternoon. Expect a relatively light NE down-valley flow to continue
today, tonight, and Sat at KPIH/KIDA/KBYI, with a normal diurnal SE
day/NW night pattern at KSUN. The airmass should remain too dry to
support fog/low stratus concerns, and development is not reflected
in any guidance. Enjoy the break! - KSmith

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&