Alert archive / Oregon / Mesoscale Discussions in 2021

Mesoscale Discussion 1725

September 10, 20214 counties in Oregon

The Storm Prediction Center issued this mesoscale discussion at Sep 10, 2021, 12:34 PM PDT for 4 counties in Oregon. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Sep 10, 2021, 12:34 PM PDT (19:34 UTC)
Expired: Sep 10, 2021, 2:30 PM PDT
In force: 116 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

Counties Crook County, OR, Harney County, OR, Klamath County, OR, Lake County, OR

The radar

The Medford radar (KMAX), 211 km from the middle of the area, began a volume at 19:33 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

Medford/Jackson, OR (KMFR), launched 12:00Z, 7.6 hours before the alert went out and 206 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: 5 J/kg
Mixed-layer CIN: -235 J/kg
Mixed-layer LCL: 820 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 125 m²/s²
0-3 km storm-relative helicity: 130 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

284 
ACUS11 KWNS 101934
SWOMCD
SPC MCD 101934 
ORZ000-NVZ000-CAZ000-102130-

Mesoscale Discussion 1725
NWS Storm Prediction Center Norman OK
0234 PM CDT Fri Sep 10 2021

Areas affected...South-central and southeastern Oregon

Concerning...Severe potential...Watch unlikely 

Valid 101934Z - 102130Z

Probability of Watch Issuance...20 percent

SUMMARY...A few storms are expected to develop in the higher terrain
of northern California into central Oregon. Cold temperatures aloft
will support isolated large hail. A damaging wind gust is also
possible with the most intense storms. A watch is not likely this
afternoon.

DISCUSSION...Towering cumulus are continuing to deepen within the
Klamath Mountains underneath the upper trough. Though surface
temperatures are relatively cool in the wake of this morning's
stratiform precipitation, mid-level lapse rates near 8 C/km are
supporting around 1000 J/kg MLCAPE. Continued surface heating in
south-central Oregon may support some increase in buoyancy this
afternoon. Greater deep-layer shear lies to the southeast of these
storms within the mid-level jet. However, 25-35 kts of shear may
promote a marginal supercell or two. Isolated hail will likely be
the main threat. Lack of steeper low-level lapse rates should keep
the wind gusts threat lower. Due to remaining cloud cover to the
north and east, the spatial extent of the severe threat will be
limited to where sufficient destabilization can occur. A watch is
not likely this afternoon.

..Wendt/Thompson.. 09/10/2021

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

ATTN...WFO...BOI...PDT...REV...MFR...

LAT...LON   41862106 41852186 42232191 43322141 43922093 44002085
            44222041 43911942 43241881 42631858 42101874 41991972
            41862106

Nearby

Mesoscale Discussions in Oregon, 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; radar from the NEXRAD Level II archive.