Alert archive / Idaho / Mesoscale Discussions in 2021

Mesoscale Discussion 980

June 15, 20215 counties in Idaho; Umatilla County, Union County, Wallowa County, Oregon; Asotin County, Columbia County, Garfield County, Washington

The Storm Prediction Center issued this mesoscale discussion at Jun 15, 2021, 12:40 PM PDT for 5 counties in Idaho; Umatilla County, Union County, Wallowa County, Oregon; Asotin County, Columbia County, Garfield County, Washington. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 15, 2021, 12:40 PM PDT (19:40 UTC)
Expired: Jun 15, 2021, 2:45 PM PDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Clearwater County, ID, Idaho County, ID, Latah County, ID, Lewis County, ID, Nez Perce County, ID, Umatilla County, OR, Union County, OR, Wallowa County, OR, Asotin County, WA, Columbia County, WA, Garfield County, WA

The nearest sounding before it

Spokane, WA (KOTX), launched 12:00Z, 7.7 hours before the alert went out and 229 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 813 m above ground
0-6 km bulk shear: 66 kt
0-1 km storm-relative helicity: -59 m²/s²
0-3 km storm-relative helicity: -154 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

697 
ACUS11 KWNS 151940
SWOMCD
SPC MCD 151940 
IDZ000-ORZ000-WAZ000-152145-

Mesoscale Discussion 0980
NWS Storm Prediction Center Norman OK
0240 PM CDT Tue Jun 15 2021

Areas affected...portions of far northeast Oregon into northern
Idaho and far southwest Montana

Concerning...Severe potential...Watch unlikely 

Valid 151940Z - 152145Z

Probability of Watch Issuance...5 percent

SUMMARY...A few strong gusts and perhaps some large hail may
accompany the stronger updrafts that can develop over the next few
hours. A WW issuance is not expected given the overall isolated
nature of the severe threat.

DISCUSSION...A 700 mb impulse, embedded in the larger scale
mid-level cyclonic flow, is traversing the Pacific Northwest, with
convective updrafts attempting to become established across portions
of northeast OR. At the moment, buoyancy is rather scant. However,
diurnal heating is underway across the Northern Rockies, with at
least some clearing noted across northern ID, with low-level lapse
rates increasing to 7.5+ C/km. The latest RAP forecast soundings
show 50-60 kt flow down to 700-600 mb. Continued heating is expected
to support 250-500 J/kg MLCAPE, with the boundary-layer/steeper
low-level lapse rates mixing up to 700-600 mb. As such, efficient
downward momentum transport of the stronger flow aloft may result in
strong wind gusts with the more robust storms. A couple large
hailstones also cannot be ruled out. 

Nonetheless, buoyancy is expected to remain weak overall, with storm
coverage remaining isolated. With severe winds/hail expected to
remain sparse, a WW issuance is not expected.

..Squitieri/Grams.. 06/15/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MSO...BOI...OTX...PDT...

LAT...LON   45511959 46601771 46901694 46871629 46661545 46511499
            46261473 45971470 45791485 45681497 45401572 45131637
            44841738 44681812 44461880 44491898 44771942 45511959

Nearby

Mesoscale Discussions in Idaho, 2021 Mesoscale Discussions in Oregon, 2021 Mesoscale Discussions in Washington, 2021 Every mesoscale discussion in 2021

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.