Alert archive / Oregon / Mesoscale Discussions in 2021

Mesoscale Discussion 1057

June 21, 20215 counties in Oregon

The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2021, 3:54 PM PDT for 5 counties in Oregon. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jun 21, 2021, 3:54 PM PDT (22:54 UTC)
Expired
Jun 21, 2021, 6:00 PM PDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Crook County, OR, Deschutes County, OR, Jefferson County, OR, Klamath County, OR, Lake County, OR

The nearest sounding before it

Medford/Jackson, OR (KMFR), launched 12:00Z, 10.9 hours before the alert went out and 195 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-pSkew-T log-p diagram, Medford/Jackson, OR at 12:00Z on 2021-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Medford/Jackson, OR at 12:00Z on 2021-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1842 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
54 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

002 
ACUS11 KWNS 212254
SWOMCD
SPC MCD 212254 
ORZ000-220100-

Mesoscale Discussion 1057
NWS Storm Prediction Center Norman OK
0554 PM CDT Mon Jun 21 2021

Areas affected...Southern to central Oregon

Concerning...Severe potential...Watch unlikely 

Valid 212254Z - 220100Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated thunderstorms may pose a risk for hail and
damaging winds this evening ahead of an approaching upper-level
wave. A watch is not expected.

DISCUSSION...A few lightning strikes have been noted in GLM data
within a slowly deepening cluster of cumulus across south-central
OR. Water vapor imagery also hints at deeper convective development
within this cluster ahead of an approaching mid-level vorticity
maximum. Dewpoints in the low to mid 40s and diurnal warming into
the 90s have been sufficient to increase MUCAPE values into the
250-500 J/kg range (with a pocket of 500-1000 J/kg MUCAPE noted in
recent analyses). Although some inhibition remains in place,
increasing lift ahead of the wave combined with orographic ascent
should support isolated thunderstorms during the early evening
hours. Increasing deep-layer flow will augment effective bulk shear
values to near 30-35 knots within the zone of instability, which may
aid in storm organization and support at least a low-end hail
threat. Additionally, high dewpoint depressions are noted and are
indicative of a dry, well-mixed boundary layer that may allow for
damaging wind gusts. Given the isolated nature of this threat, a
watch is not expected.

..Moore/Grams.. 06/21/2021

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

ATTN...WFO...BOI...PDT...MFR...PQR...

LAT...LON   42062134 42292202 43442247 44362242 44832145 44882062
            44601991 44021965 42711909 42101919 42062134

Nearby

Mesoscale Discussions in Oregon, 2021Every 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.