Wind Advisory 23, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
306 AM MDT Sun Jul 17 2022

.SHORT TERM...Today through Monday Night.
Pre-dawn satellite showing just a few clouds beginning to stream
into the area this morning near Twin Falls. This can be considered
a tracer of higher moisture content beginning to swell northward
ahead of a low pressure system sliding into the PacNW. These
clouds should continue to stream northward into the central
mountains wrapping mostly north of the South Hills and Snake
Plain, at least initially. Clearing to the south should allow for
a quick warmup this morning, exacerbating heat stresses from warm
temperatures yesterday and poor overnight relief, especially
through the South Hills. Will issue a Heat Advisory for these
locations because of this.

The early afternoon will allow for destabilization with rapid
heating, generating convective development first in the central
mountains and through the South Hills. HREF showing pooling PWAT
values in excess of an inch through Cassia Co. so these showers and
thunderstorms should be rather efficient, but the increasing low- to
mid-level flow should allow these showers and thunderstorms to move
rather quickly. Can't rule out gusty winds or small hail with any of
the stronger storms. As the moisture continues to surge northeast
ahead of the low pressure system, shower and thunderstorm activity
will follow. The best chances for running into these are through the
South Hills, Southeast Highlands or Upper Snake Plain into the
Montana divide.

While most shower and thunderstorm activity should wane in the
evening tonight, the approaching system could keep some nocturnal
activity alive as the axis of deeper moisture shifts east. Monday
will see a re-invigoration of this convection, primarily over the
Eastern Highlands, Southeast Highlands and Upper Snake Plain. The
bigger impact and story will be the increase in winds through the
Central Mountains and Snake River Plain. Efficient mixing through
Monday afternoon will allow these locations to bring down the 30-
40kt 700mb jet dropping in from the northwest. Wind Advisories
may be needed in addition to the Fire Weather Watch issued this
morning (see Fire Weather below).
TAX

.LONG TERM...Tuesday through next Sunday.
As a closed low continues to track eastward along the Canadian
border, an upper ridge begins to rebound over the region Tuesday.
Winds will be breezy again but conditions will not be as windy as
Monday.  Many locations could see 20 mph sustained winds and 30 mph
gusts.  The ECMWF Extreme Forecast Index (EFI) is indicating
elevated wind gusts across the eastern highlands and Snake River
Plain for Tuesday evening.  Have continued to increase forecast
winds throughout the extended by blending with NBM 90th Percentile.
Temperatures will climb several degrees Wednesday, with the Eastern
Magic Valley, Snake River Plain and many other locations further
south seeing highs reach into the mid to upper 90s.  The next upper-
level trough reaches the PNW coast early Thursday.  The GFS ensemble
(GEFS) is a bit quicker to bring the trough inland across WA/OR and
ultimately breaks down the upper ridge over our region, while the
ECMWF ensemble (EPS) keeps us under persistent high pressure through
the end of the week.  The National Blend is currently forecasting
predominately dry conditions, with PoPs generally 25% or lower
across the eastern highlands each afternoon over the weekend.
However, there is potential that forecast PoPs will be increased
during this period depending on how models continue to trend, with
monsoonal moisture from the south a consideration as well. Cropp

&&

.AVIATION...Mid- to upper-level SCT clouds will begin to filter in from the
south throughout the early morning, turning BKN to OVC by mid-
afternoon.  Southwest winds of 10-25 kts are expected from early
afternoon through around sunset at KPIH, KIDA, and KDIJ, while
calmer winds of 15 kts or less are expected at KBYI and KSUN.
Isolated showers and thunderstorms could impact all terminals again
throughout this same period and therefore have forecast VCTS at all
sites. Clouds will begin to scatter again overnight and throughout
the day Monday. Cropp

&&

.FIRE WEATHER...Satellite showing moisture beginning to pool ahead
of a system sliding into the region today. This moisture will
continue to surge northward through the afternoon, generating
showers and thunderstorms, first over the high terrain of zones 422,
476, and southern 475. This will be closely followed by showers and
thunderstorms moving into the south hills zone of 427. Scattered
lightning will be hit and miss with these storms and with surging
moisture, rainfall may be rather efficient. At this time, will
continue to hold off on Red Flag Warnings for thunderstorms, but
zone 427 will is borderline.

In addition to the thunderstorm activity, surface winds and gusts
will also increase, which could still lead to challenging conditions
containing any established fires. We're expecting south-
southwesterly winds sustained in the 15-25 mph range with gusts as
high as 30-35 mph in zones 410, 476, and 475.

Monday is still shaping up as the big day where strong winds will
combine with drying to lead to critical fire weather conditions.
Sufficient mixing in the afternoon will bring gusts of 40-50mph
through the central mountain zones 422, 475, and 476 as well as the
Snake Plain zones 425, and 410. A Fire Weather Watch has been issued
for Monday afternoon.
TAX

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Monday morning through Monday evening
for IDZ410-425.

Heat Advisory from 9 AM this morning to 8 PM MDT this evening
for IDZ054>059.

&&