994
FXUS65 KPIH 140343
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
943 PM MDT Thu Jun 13 2024

.UPDATE...

Radar shows a couple storms north of the American Falls Reservoir
that seem to be holding together. Updated forecast to continue to
mention storms through midnight with slight chance of showers
after midnight across much of the Snake Plain into the eastern
Magic Valley.

13

&&

.PREV DISCUSSION... /issued 138 PM MDT Thu Jun 13 2024/

SHORT TERM...Tonight and Friday
Afternoon satellite imagery once again shows not much in the way
of clouds across the region. Have seen a few mid/high level
clouds streaking across southeastern parts of the area but most of
us area seeing clear blue skies. Temperatures have warmed into
the 80s across the lower valleys with 70s across the higher
terrain. Some valley locations could hit the 90s before all is set
and done today. Hi-res CAMs show some potential for a
thunderstorm or two to develop later today. Probabilities are
quite low however (less than 15%) so the forecast doesn`t have any
mention of any precip for most areas. This will be the warmest
day we see for at least a week as changes are in store for eastern
Idaho.

We begin to see a few of those changes tomorrow as we start to
feel the influence of an trough moving into the Pacific NW. The
pressure gradient will tighten tomorrow and winds will begin to
increase accordingly tomorrow. As is often the case, the Arco
Desert looks to be the windiest spot and they`ll come close to
Wind Advisory levels (30+ mph) but right now it`s too marginal to
issue an advisory. Much of the Snake Plain and Magic Valley will
see winds in the 15-25 mph range for a good portion of the day.
More wind to come (and stronger on Saturday). Friday looks mostly
dry again although some afternoon convection up around Island Park
will be possible. Temperatures will be around 4-6 degrees cooler
than Thursday but a much more drastic cooldown is still ahead.
McKaughan

LONG TERM...Saturday through Friday
As low pressure scoots to our north, a very strong wind pattern
develops Saturday. The strongest winds will be across the central
mountains and over portions of the Magic Valley and Snake Plain.
Probability forecasts show a 30-70% chance of exceeding 30 mph
sustained across most of the Snake Plain and eastern end of the
Magic Valley, and hitting 90-100% across the Arco Desert and along
I-15 north of Idaho Falls. We similar percentages for gusts over
45 mph. That would put us solidly in WIND ADVISORY territory. We
see a 30-60% chance for sustained over 40 mph and gusts over 55
mph across the INL and along 15 north of Idaho Falls, which is
HIGH WIND WARNING thresholds. These trends seem to be holding, so
the likelihood of some kind of wind headlines is increasing. While
we could see a few early day showers, we should be dry in the
afternoon. Saturday will be the WARMEST, until we reach the end of
next week. This is due an area of low pressure developing and
slowly swinging across our area early next week. This storm does
involve some colder air, with Tuesday being the "coldest". We are
talking highs in the valleys in the 50s/low 60s and 30s/40s in the
mountains. Yes, that does mean some wet snow in the higher
elevations. The latest forecast shows a 75%+ chance of measurable
snow across the central mountains and along the Montana border,
and a 20-50% chance farther south. This once again serves as a
reminder that weather doesn`t always follow the calendar. We
should quickly recover (since it is June after all) by the end of
next week. Keyes

AVIATION...
Mid level clouds will continue to stream overhead. The question
is whether we will see any precipitation or thunderstorms with any
of this in the next 24 hours. We did keep VCSH in the TAFs
(outside of SUN), which was put in by previous shifts. The chance
is low but not zero by any stretch. We opted to not include VCTS,
but again the chance is low but not zero. Gusty winds are possible
with anything that develops. Outside of anything from storms, we
are expecting an increase in wind tomorrow. Sustained wind of
15-25kts are possible for BYI, PIH and IDA, with gusts of 25-35kts
possible. Keyes

FIRE WEATHER...
The hottest day of the next seven is today, with BLM land
elevations reaching the 90s in the TFD and southern portions of
the IFD. Afternoon humidity should get below 15 percent in a lot
of low elevations in the central Idaho mountains and the northwest
side of the two main BLM districts. An approaching trough that
arrives on the weekend with a cold front will start affecting
weather on Fri. While today wind will be light, on Fri the wind
will spike upwards again, with the strongest wind occurring on
Sat. Strong cooling brings back temperatures more like early to
middle spring on Mon and Tue. Messick

HYDROLOGY...
A flood warning remains in effect for the Teton River at Driggs
through Saturday and the Snake River at Heise until further
notice. The latter will likely stay above flood stage into early
next week. McKaughan

&&

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

$$