Special Weather Statement, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
125 PM MDT Mon Aug 2 2021

.SHORT TERM...Tonight through Wednesday.

An upper level trough and associated surface front/dry line will
pass through central and east Idaho this afternoon. This will be the
focus for additional thunderstorms this afternoon. Precipitable
water values remain extraordinarily high, around 1.25 inches.
Surface dew points remain in the low to mid 60s. So heavy rain is
almost certain with thunderstorms once again this afternoon and
evening. Flash flood watches remain in effect for the high
country. Isolated flooding remains possible in the Snake Plain,
but mainly concerned with street flooding there, higher threat
along the bench areas.Isolated severe storms can't be entirely
ruled out with strong winds possible as well.

Models show convection ending this evening as the dry line/front
passes into Wyoming. Tuesday and Wednesday looks much drier with
lower dew points. Still moist by Idaho standards, but looking at dew
points in the upper 40s to around 50 as opposed to the current low
to mid 60s we are currently enjoying. Isolated heat of the day
variety thunderstorms are possible Tuesday and Wednesday. Wednesday
is a slightly better chance over the central mountains as a weak
upper level trough enters the region.

13

.LONG TERM...Thursday through Monday. A storm will @see across
eastern Idaho Thursday, with a better chance of showers and
thunderstorms. These storms won't be tapping into deep monsoon
moisture, but we can't rule out a few storms producing locally heavy
rain because of recent rainfall and moisture. The storm track shifts
north through the weekend. We could see some showers and storms
closer to the Montana border, but most of the area will be dry and
breezy. Keyes

&&

.AVIATION...Showers and thunderstorms will be potentially impacting
TAF sites this afternoon and evening. Just like the past few days,
we could see MVFR/IFR weather due to heavy rain and low visibility.
We should see things ending west to east overnight. At the moment,
we don't think we will have fog or stratus issues just due to all of
the recent rainfall...but it might be something we need to monitor.
Tomorrow should be VFR with no storms expected. Keyes

&&

.FIRE WEATHER...Showers and thunderstorms and the risk of heavy
rainfall and debris flows will end overnight from west to east. We
could see a few very isolated storms tomorrow across mainly the
central mountains and near the Wyoming border, but the risk is very
low (around 10% at most). There is an increasing chance in the
central mountains later Wednesday, expanding everything heading into
Thursday. These storms will be more of a mix of wet and dry, as
monsoon moisture won't be around. That said, with all of the recent
rainfall...it's possible enough moisture is there to produce a few
locally heavy rainers. The storm track shifts north heading into the
weekend. While showers and storms are possible closer to the Montana
border, the main issue may become gusty winds across most of central
and eastern Idaho with a drier airmass moving in. Keyes

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 9 PM MDT this evening for IDZ056>074.

&&

Special Weather Statement
National Weather Service Pocatello ID
358 PM MDT Mon Aug 2 2021

IDZ059-022245-
Franklin/Eastern Oneida Region ID-
358 PM MDT Mon Aug 2 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL FRANKLIN COUNTY UNTIL 445
PM MDT...

At 357 PM MDT, Doppler radar was tracking a strong thunderstorm near
Preston, moving east at 15 to 20 mph.

Winds in excess of 40 mph and small hail will be possible with this
storm.

Locations impacted include...
Riverdale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Expect low visibilities while driving through storms.

&&

LAT...LON 4213 11195 4218 11195 4221 11181 4212 11179
TIME...MOT...LOC 2157Z 263DEG 8KT 4217 11187

TW

Special Weather Statement
National Weather Service Pocatello ID
404 PM MDT Mon Aug 2 2021

IDZ058-059-022245-
Franklin/Eastern Oneida Region ID-Marsh and Arbon Highlands ID-
404 PM MDT Mon Aug 2 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ONEIDA AND SOUTH
CENTRAL BANNOCK COUNTIES UNTIL 445 PM MDT...

At 402 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Malad, moving east at 15 to 20 mph.

Winds in excess of 40 mph and small hail will be possible with this
storm.

Locations impacted include...
Malad Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Heavy rain will create reduced visibilities while driving.

&&

LAT...LON 4229 11234 4244 11238 4248 11225 4230 11221
TIME...MOT...LOC 2202Z 263DEG 8KT 4233 11227

TW

Special Weather Statement
National Weather Service Pocatello ID
411 PM MDT Mon Aug 2 2021

IDZ057-059-022300-
Franklin/Eastern Oneida Region ID-Raft River Region ID-
411 PM MDT Mon Aug 2 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN ONEIDA COUNTY UNTIL
500 PM MDT...

At 410 PM MDT, Doppler radar was tracking a strong thunderstorm near
Holbrook Summit, or 14 miles north of Snowville, moving east at 10
to 15 mph.

Winds in excess of 40 mph and small hail will be possible with this
storm.

Locations impacted include...
Holbrook.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Expect low visibilities during heavy rain.

&&

LAT...LON 4213 11284 4221 11285 4224 11259 4211 11257
TIME...MOT...LOC 2210Z 263DEG 8KT 4217 11274

TW

Special Weather Statement
National Weather Service Pocatello ID
421 PM MDT Mon Aug 2 2021

IDZ058>063-022300-
Franklin/Eastern Oneida Region ID-Bear Lake Valley ID-
Bear River Range ID-Marsh and Arbon Highlands ID-Caribou Range ID-
Blackfoot Mountains ID-
421 PM MDT Mon Aug 2 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN CARIBOU...NORTH
CENTRAL FRANKLIN AND NORTHWESTERN BEAR LAKE COUNTIES UNTIL 500 PM
MDT...

At 419 PM MDT, Doppler radar was tracking a strong thunderstorm near
Grace, or 12 miles southwest of Soda Springs, moving east at 10 to
15 mph.

Winds in excess of 40 mph and small hail will be possible with this
storm.

Locations impacted include...
Soda Springs, Grace, Thatcher, Georgetown Summit, Niter and Clear
Creek Ranger Station.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Expect very low visibilities while driving in heavy rain.

&&

LAT...LON 4235 11183 4256 11187 4261 11168 4266 11166
      4267 11111 4257 11109
TIME...MOT...LOC 2219Z 263DEG 8KT 4251 11173

TW

Special Weather Statement
National Weather Service Pocatello ID
435 PM MDT Mon Aug 2 2021

IDZ052-053-067-022315-
Arco/Mud Lake Desert ID-Upper Snake River Plain ID-
Beaverhead/Lemhi Highlands ID-
435 PM MDT Mon Aug 2 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN JEFFERSON AND SOUTH
CENTRAL CLARK COUNTIES UNTIL 515 PM MDT...

At 434 PM MDT, Doppler radar was tracking a strong thunderstorm near
Hamer, or 11 miles south of Dubois, moving east at 35 mph.

Winds in excess of 40 mph and small hail will be possible with this
storm.

Locations impacted include...
Dubois, Terreton, Mud Lake, Hamer, Monteview and Sage Junction.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Expect very low visibilities while driving through heavy
rain.

&&

LAT...LON 4376 11252 4411 11256 4419 11223 4373 11217
TIME...MOT...LOC 2234Z 261DEG 32KT 4401 11226

TW

Special Weather Statement
National Weather Service Pocatello ID
441 PM MDT Mon Aug 2 2021

IDZ066-022330-
Centennial Mountains/Island Park ID-
441 PM MDT Mon Aug 2 2021

...SPECIAL WEATHER STATEMENT...

At 438 PM MDT, Doppler radar was tracking a strong thunderstorm over
Last Chance, or 19 miles north of Ashton, moving east at 35 mph.

Winds in excess of 30 mph and small hail will be possible with this
storm.

Be cautious on area lakes. Storms will produce moderate to heavy
brief rain. Brief bonding of water is likely.

Locations impacted include...
Henrys Lake, Island Park Village, Shotgun Village, Ponds Lodge, Macks
Inn, Last Chance, Island Park Reservoir, Red Rock Pass, Big Springs,
Targhee Pass and Harriman State Park.

LAT...LON 4426 11157 4454 11172 4456 11170 4456 11159
      4454 11147 4459 11152 4464 11152 4467 11147
      4470 11149 4471 11142 4475 11137 4473 11132
      4467 11127 4465 11128 4462 11122 4461 11124
      4458 11123 4457 11118 4449 11109 4434 11109
TIME...MOT...LOC 2238Z 261DEG 32KT 4435 11142

TW