Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 232355

Area Forecast Discussion
National Weather Service Pocatello ID
555 PM MDT Sat Jun 23 2018

.DISCUSSION...Today Through Next Saturday. A quick update early this
evening to allow the Lake Wind Advisory across American Falls
Reservoir to expire. Thunderstorm outflow winds drifted over the
lake and dissipated late this afternoon bringing the marginal
southwest wind criteria to halt. Additional lines of convection have
been visible on radar but nothing too terribly strong. See the
previous discussion below. Huston

Scattered showers and t-storms are currently pushing ESE across
northern and central portions of the forecast area. The strongest
cell of the day thus far that pushed across the southern side of
Idaho Falls produced torrential rainfall and pea to nickel size hail
that covered the ground. Have thus added mention of small hail and
heavy rainfall to the weather grids through 6 PM. Severe weather
threat is not zero, but is very low. Best chance of precip through
this eve will be north and east of a line from Minidoka to Malad,
with portions of Cassia County possibly squeaking out dry. Breezy
conditions will continue out of the WSW, especially across the lower
Snake Plain, eastern Magic Valley, and southern Highlands. A Lake
Wind Advisory remains in effect until 6 PM for rough chop on
American Falls Reservoir. Boaters should note that outflows from
nearby t-storms could result in shifting wind directions.

For those looking to enjoy some beautiful summer weather or recreate
outdoors, there is fantastic news! Models are displaying strong
agreement in a ridge of high pressure building across SE Idaho for
Sun and Mon, with a high-confidence forecast in mostly sunny and dry
conditions. A trough tries to brush the Central Mntns early Tues
morning, and while we can`t completely rule out a stray shower or
two and some increased clouds, widespread dry and mostly sunny
conditions look like a better bet Tues and Wed as well. Our next,
more significant storm system looks to approach the region Thurs and
Fri, with increasing chances of showers and t-storms starting in the
Central Mntns and Island Park region Thurs eve and expanding south
across the entire area by Fri night. The GFS continues to carry a
closed low pressure center right across the area. The ECMWF
continues to be a bit weaker, but now does close off a low just
north of our region instead of maintaining an open trough, so it
appears it may be trending a bit toward the stronger and wetter GFS
solution. Still quite a ways out, but have nudged PoPs and cloud
cover up a bit especially for Sat and Sat night. -KSmith/Valle

One thing to watch tonight is a convergence zone setting up this
afternoon over the Arco Desert and driving south to southeastward.
This will potentially impact KPIH, KIDA and KDIJ this afternoon
and evening with showers/thunderstorms. Have kept VCTS for KSUN as
well as an upper trough axis swings southward this afternoon.
Rainfall could potentially be heavy, and briefly lower visibility
below VFR. A north/northeasterly wind should prevail after the
convergence band passes through, then become variable overnight.
- Hinsberger

Surface convergence zone setting up under an upper trough,
providing ample lift for thunderstorms this afternoon. Models show
this driving south/southeastward tonight. Storms could produce
brief heavy rainfall and strong outflow winds. Drier weather is in
store for the region tomorrow and Monday. A dry cold front will
push through Idaho Monday night into Tuesday. Winds will be
strong, particularly on Tuesday afternoon. The next chance of
precip will come as an upper trough moves into the area on
Thursday. This will trigger showers and isolated afternoon
thunderstorms. Models are hinting at a cooler and wetter pattern
next weekend as an upper low drops into the Pacific Northwest.
- Hinsberger


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