812
ACUS11 KWNS 052010
SWOMCD
SPC MCD 052009
ORZ000-WAZ000-052215-

Mesoscale Discussion 2196
NWS Storm Prediction Center Norman OK
0209 PM CST Wed Nov 05 2025

Areas affected...Coastal Oregon

Concerning...Severe potential...Watch unlikely

Valid 052009Z - 052215Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated to widely-scattered low-topped storms are
expected to move onshore over the next few hours. Very strong shear
profiles will support some storm organization, with damaging gusts
and a brief waterspout/tornado possible. Conditions will be
monitored, but a WW is currently not anticipated.

DISCUSSION...As of 2005 UTC, afternoon water-vapor imagery showed a
strong shortwave trough moving onshore over the Pacific Northwest
within a broader Pacific upper low. Regional VWPs continue to show
strong mid-level flow with ample low-level shear as a jet streak
south of the main trough moves onshore. Beneath the upper low, cold
mid-level temperatures (-22 to -24 C) and filtered diurnal heating
within a moist maritime air mass are steepening low-level lapse
rates and supporting weak buoyancy (MUCAPE around 500 J/kg). Strong
ascent and continued destabilization should allow for several rounds
of thunderstorms to move onshore over western OR this afternoon and
evening.

Already, low-topped cells have gradually intensified, with a notable
increase in lightning near the mouth of the Columbia River and
father offshore. As these storms move inland, downward momentum
transfer of the strong mid-level flow (50+ kt at 4km AGL) should
allow for isolated damaging gusts as downdrafts become established.
Enlarged veering hodographs (ESRH 200-250 m2/s2) may also support
the potential for a waterspout/brief tornado with any transient
rotating storms. However, the weak buoyancy should limit broader
organized severe potential.

..Lyons/Smith.. 11/05/2025

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

ATTN...WFO...MFR...PQR...

LAT...LON   42912311 42572423 43172506 44332503 44652499 45502516
            45972511 46282429 46302372 45762318 42912311

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH