Alert archive / Oregon / Mesoscale Discussions in 2017
Mesoscale Discussion 650
The Storm Prediction Center issued this mesoscale discussion at May 4, 2017, 7:48 PM PDT for 13 counties in Oregon; 10 counties in Washington. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- May 4, 2017, 7:48 PM PDT (02:48 UTC)
- Expired
- May 4, 2017, 9:15 PM PDT
- In force
- 87 min
- Issued by
- the Storm Prediction Center
All 23 counties
Clackamas County, OR, Columbia County, OR, Gilliam County, OR, Hood River County, OR, Jefferson County, OR, Lane County, OR, Linn County, OR, Marion County, OR, Morrow County, OR, Multnomah County, OR, Sherman County, OR, Wasco County, OR, Washington County, OR, Benton County, WA, Clark County, WA, Cowlitz County, WA, Kittitas County, WA, Klickitat County, WA, Lewis County, WA, Pierce County, WA, Skamania County, WA, Thurston County, WA, Yakima County, WA
The nearest sounding before it
Salem/Mcnary, OR (KSLE), launched 00:00Z, 2.8 hours before the alert went out and 110 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.
- Mixed-layer CAPE
- 25 J/kg
- Mixed-layer CIN
- -264 J/kg
- Mixed-layer LCL
- 1796 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 36 m²/s²
- 0-3 km storm-relative helicity
- 83 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
The text
As transmitted.
161
ACUS11 KWNS 050249
SWOMCD
SPC MCD 050248
ORZ000-WAZ000-050415-
Mesoscale Discussion 0650
NWS Storm Prediction Center Norman OK
0948 PM CDT Thu May 04 2017
Areas affected...Portions of western/northern OR and
southern/central WA
Concerning...Severe Thunderstorm Watch 193...
Valid 050248Z - 050415Z
The severe weather threat for Severe Thunderstorm Watch 193
continues.
SUMMARY...Isolated instances of large hail and gusty winds will
continue in and near Severe Thunderstorm Watch 193 in the short
term. The overall severe risk should slowly diminish over the next
few hours.
DISCUSSION...Isolated to scattered convection that formed this
afternoon along/west of the Cascades has produced some large hail
and damaging wind reports across western OR/WA. East of the Cascade
crest, thunderstorms have struggled to intensify this evening,
although gusty winds may still occur with ongoing convection there
given a well-mixed boundary layer and large surface
temperature/dewpoint spreads. As of 0245Z, the strongest cells
remain along and west of the Cascades in southern OR in closer
proximity to large-scale ascent associated with an approaching
upper-level trough/low. The kinematic environment remains favorable
for organized updrafts, with effective shear of 40-50 kt per 00Z
soundings from SLE/MFR and 02Z RAP Mesoanalysis. Isolated large hail
and strong to locally damaging winds will remain possible in the
short term, primarily in and near southern portions of Severe
Thunderstorm Watch 193. However, the loss of daytime heating will
result in further lessening of already weak instability (MLCAPE
generally 500-1000 J/kg), and the overall severe risk should slowly
diminish over the next few hours.
..Gleason.. 05/05/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OTX...PDT...MFR...SEW...PQR...
LAT...LON 42812204 42492231 42472292 46092332 46742337 47092290
47572119 47552007 46481929 45111930 44802063 43892171
42812204SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 5, 2:16 PM PDT | Mesoscale Discussion | SPC | Baker, Malheur, Union, Wallowa | 119 min |
Nearby
Mesoscale Discussions in Oregon, 2017Mesoscale Discussions in Washington, 2017Every mesoscale discussion in 2017
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.