Alert archive / Idaho / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 33, NWS Boise, ID

May 25, 2018Adams County, Idaho

NWS Boise, ID issued this severe thunderstorm warning at May 25, 2018, 9:48 PM MDT for Adams County, Idaho. It was in force for 27 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 25, 2018, 9:48 PM MDT (03:48 UTC)
Expired: May 25, 2018, 10:15 PM MDT
In force: 27 min
Issued by: NWS Boise, ID
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Adams County, ID

The radar

The Boise radar (KCBX), 157 km from the middle of the area, began a volume at 03:50 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Boise Airport, ID (KBOI), launched 00:00Z, 3.8 hours before the alert went out and 148 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 107 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 3445 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: -3 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Boise, ID wrote its last area forecast discussion before this severe thunderstorm warning went out at May 25, 1:51 PM MDT, 7 hours 57 minutes earlier.

Area forecast discussion, May 25, 1:51 PM MDT, 7 hours 57 minutes before

Area Forecast Discussion
National Weather Service Boise ID
151 PM MDT Fri May 25 2018

.SHORT TERM...Tonight through Sunday...An upper level low will
move slowly from nrn CA into NV today into tomorrow, before slowly
drifting toward the NV/UT line Sunday. Convection initiating on
the northern side of this system is likely to grow into a
significant convective event across much of the area this
afternoon and evening. Thunderstorms are forming in southeast
Oregon at this time, and they are expected to move/develop
northward and expand into southwest Idaho generally west of
Mountain Home. High resolution models indicate that a large and
strong outflow boundary will form ahead of these storms as the
afternoon wears on. Wind gusts could go over 60 mph along and
behind this boundary. Also, multiple boundaries are possible. The
main boundary is forecast to move through northern Harney and
Malheur counties and into Baker County late this afternoon and
early this evening. It will also likely extend east into southwest
Idaho, entering around 6 pm and moving through the Boise and
Mountain Home areas by 8 pm. It is unclear at this point how
strong the boundary might be once it gets east of Mountain Home.

In addition to the wind threat, flash flooding is possible in
eastern Oregon as multiple rounds of storms occur. Recent burn
scars are most prone to problems, but flash flooding may occur
elsewhere as well. Rainfall totals may reach 2 inches in a short
amount of time this afternoon/evening. A flash flood watch has
been posted for our eastern Oregon zones.

After this event ends late tonight, additional showers and storms
are forecast Saturday and Sunday, but they are not expected to be
nearly as strong. The location with the best chance of
precipitation will shift east Saturday and especially Sunday, and
by then there is very little chance of precip in the Oregon zones.
Temps will cool down 10-15 degrees tomorrow compared to today,
then warm up slightly Sunday.

.LONG TERM...Sunday night through Wednesday...Lingering showers in
the central Idaho mountains to start the period as our upper level
low still sits just east of us. By Monday night a short wave ridge
builds over the Pacific Northwest which helps increase temperatures
to above normal again. This is a short lived break as yet another
long wave trough begins to drop down along the coast bringing moist
southwesterly flow aloft to our area. Showers begin to hit SE Oregon
again by early Wednesday increasing in coverage by late afternoon.

Wednesday night through Friday...Models show the trough along the
coast moving inland during this period, but the latest runs differ
on timing and amplitude. They do agree on at least a slight chance
of showers Wednesday night through Friday, and there will be enough
instability for isolated afternoon and evening thunderstorms.
Temperatures will be close to normal.

&&

.AVIATION...VFR. Scattered showers and thunderstorms this afternoon
with much of the coverage staying in SE Oregon. KBNO and KBKE will
see heavy rain and thunderstorms through late afternoon.
Thunderstorms have the potential of producing gusty winds up to
50kts. Outflow winds are of concern this afternoon after 22z and
could travel up into the Treasure Valley. Surface winds outside of
thunderstorms, variable 15-20kts. Winds aloft to 10k feet MSL,
southerly 25-35kts.

Weekend Outlook...Shower and thunderstorms continue through the
weekend with coverage migrating more to SW Idaho for Saturday and
Sunday with the Oregon side starting to dry out. Gusty winds with
thunderstorms of 25-35kts.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...Flash Flood Watch through late tonight ORZ061>063.

&&

www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise

SHORT TERM...SP
LONG TERM....JC/JT
AVIATION.....JC

In the hours before

Special weather statement, May 25, 7:52 PM MDT, 1 hour 56 minutes before

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Local storm report, May 25, 7:59 PM MDT, 1 hour 49 minutes before

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Local storm report, May 25, 8:07 PM MDT, 1 hour 41 minutes before

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Local storm report, May 25, 8:15 PM MDT, 1 hour 33 minutes before

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Special weather statement, May 25, 8:45 PM MDT, 1 hour 3 minutes before

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Special weather statement, May 25, 9:16 PM MDT, 32 minutes before

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The office that day

Everything else NWS Boise, ID issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 25, 6:01 PM MDT	Severe Thunderstorm Warning	BOI	Canyon, Owyhee	59 min
May 25, 6:34 PM MDT	Severe Thunderstorm Warning	BOI	Ada, Canyon, Owyhee	56 min
May 25, 7:00 PM MDT	Special Weather Statement	BOI	Adams	45 min
May 25, 7:00 PM MDT	Severe Thunderstorm Warning	BOI	Canyon, Owyhee	60 min
May 25, 7:29 PM MDT	Severe Thunderstorm Warning	BOI	Ada, Canyon, Owyhee	31 min
May 25, 7:44 PM MDT	Severe Thunderstorm Warning	BOI	Washington	61 min
May 25, 7:52 PM MDT	Special Weather Statement	BOI	Elmore	53 min
May 25, 8:00 PM MDT	Severe Thunderstorm Warning	BOI	Ada, Canyon, Gem, Owyhee, Payette	45 min
May 25, 8:05 PM MDT	Severe Thunderstorm Warning	BOI	Adams	40 min
May 25, 8:13 PM MDT	Severe Thunderstorm Warning	BOI	Boise, Gem, Valley, Washington	62 min
May 25, 8:41 PM MDT	Severe Thunderstorm Warning	BOI	Adams, Valley, Washington	64 min
May 25, 8:45 PM MDT	Special Weather Statement	BOI	Canyon	30 min
May 25, 8:51 PM MDT	Severe Thunderstorm Warning	BOI	Adams, Washington	54 min
May 25, 9:16 PM MDT	Special Weather Statement	BOI	Gem	29 min
May 26, 2:05 PM MDT	Special Weather Statement	BOI	Boise	55 min
May 26, 2:31 PM MDT	Flash Flood Warning	BOI	Boise	3 hr
May 25, 6:38 PM MDT	Severe Thunderstorm Warning	BOI	Baker, Malheur	67 min

Nearby

Severe Thunderstorm Warnings in Idaho, 2018 Every severe thunderstorm warning in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.