Tornado Warning 1, NWS Portland, OR

171 
WWUS56 KPQR 292251
SVSPQR

Severe Weather Statement
National Weather Service Portland OR
351 PM PDT MON OCT 29 2018

ORC043-047-292300-
/O.EXP.KPQR.TO.W.0001.000000T0000Z-181029T2300Z/
Marion OR-Linn OR-
351 PM PDT MON OCT 29 2018

...THE TORNADO WARNING FOR SOUTHWESTERN MARION AND NORTH CENTRAL LINN
COUNTIES WILL EXPIRE AT 400 PM PDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning will be allowed to expire.

LAT...LON 4467 12293 4480 12296 4484 12276 4465 12273
TIME...MOT...LOC 2250Z 266DEG 15KT 4473 12282 

$$

JBonk

Area Forecast Discussion
National Weather Service Portland OR
213 PM PDT Mon Oct 29 2018

.SYNOPSIS...Showers continue through tonight with accumulating snow
levels near the higher Cascade passes. High pressure will bring dry
weather to many areas on Tuesday before a moist warm front brings
rain Tuesday night and Wednesday. Moist onshore flow will continue
showers, mostly for the higher terrain on Thursday. A progressive
weather pattern will continue rain chances through the weekend.

&&

.SHORT TERM...Tonight through Thursday...The upper level trough from
the last few days will slowly drift eastward tonight. High pressure
will tease us by building offshore, close enough to put us in a
relatively warmer air mass, but far enough offshore to keep us under
the influence of the storm track.

Tonight, low level onshore flow will continue to bring showers,
bordering on steady Cascade precip through tonight. Accumulating
snow levels will hover between 4500-5500 feet as the precip tapers
off tonight. Most of the accumulating snow will occur roadside until
near and after sunset when perhaps an inch or two accumulate on the
higher pass roadways. Tuesday will remain dry for the bulk of the
area as the upper ridge pushes north. Mainly northern areas could
get clipped by showers from the retreating onshore flow.

Late Tuesday night will see the next impulse arrive riding along the
periphery of the ridge. At the same time, the warmer air mass will
lift snow levels back up, reaching 9 kft around daybreak Wednesday.
This should limit any snow accumulations to well above the passes.
However, there is plenty of moisture coming with this short-wave and
there looks to be potential for 0.50-0.75" of rain within 8 hours or
so for the Coast range and Cascades. The I-5 corridor should see
some rain shadowing develop by late morning with 0.25"+ amounts
possible. Additionally, prefrontal winds will get breezy along the
coast but certainly not overly newsworthy by coastal standards.

Orographic westerly flow will again support lingering showers over
the mountains for Wednesday afternoon and night while they taper off
from south to north. Thursday does have the upper ridge starting to
push inland with most areas again drying out, similar to Tuesday.

By and large, this pattern has increased confidence in bringing a
warm and wet set of days ahead. Have generally favored a blend of
models with heavier leaning on to the NAM during periods of
orographic flow owing to it's tendency to better resolve that
effect. Temperatures will largely remain a couple degrees above
normal for the lower elevations and several degrees above for the
higher terrain. /JBonk

.LONG TERM...Thursday night through Sunday. There is general
agreement among the forecast models that the next upper level trough
approaches the region by Thursday night, bringing another round of
more organized rain across the area with a warm front lifting north
late Thursday. This rain will continue into Friday as the associated
cold front sweeps across the Pacific Northwest. Another organized
system pushes into the region late Saturday and into Sunday, though
differences begin to emerge in the guidance both in terms of the
timing and how far north or south the core of the moisture is
focused. Both of these systems will contain a fair amount of
available moisture, but the location of the focus of moisture may be
more impactful especially with this second disturbance, as model
forecast precipitable water values are approaching 1.5 inches
offshore by late Saturday night. Given the spread of ensemble
solutions, though, utilized a blended approach as a compromise for
the mostly likely period of highest PoPs. However, the confidence in
any specific forecast details remains moderate at best for the end
of the week and into next weekend. Cullen

&&

.AVIATION...Upper level trough along the coast, moving eastward,
and will be east of the Cascades later this afternoon. Cool
onshore and unstable air continues, with scattered showers,
though showers will decrease in coverage this afternoon into the
evening. Still minor chance of a tstorm, mainly north of a
Tillamook to Portland to Mt Hood line. Showers rapidly
decreasing after 02Z, through will linger over the Cascades
through 07Z. Will maintain mix of mid and high clouds overnight,
through these will be thinning. But with cool air mass and light
winds, should see widespread low stratus and fog form tonight,
especially interior lowlands.                         Rockey.

KPDX AND APPROACHES...Cool unstable air over ops area, with
decreasing showers into the evening. Mostly VFR, though may see
brief MVFR under heavier showers. Though chance is quite low,
can not rule out small potential of a thunderstorm until 00Z. VFR
overnight, but expect IFR stratus to form after 09Z.    Rockey.

&&

.MARINE...Showers decreasing as main instability shifts inland
this evening. Then will wait for next frontal system, which
arrives later Tue. The main front will push across the coastal
waters later Tue night into early Wed, with gusty southerly
winds. Strongest gusts around 30 kt with this front, just below
gale force. High pres will build over the region Thu, giving
another break in the weather. But, a fast moving cold front is
expected to push across the region on Fri. Unsettled weather
continues into next weekend, with potential for gales later Sat.

Seas, currently 10 to 12 feet,will gradually subside, but remain
above 10 ft through at least late tonight. Thinking is that seas
will bounce around 7 to 9 ft for most of the week, though could
get back around 10 ft late Tue night into Wed am. With return of
stronger winds next weekend, so will building seas, with seas
nearing 15 ft.                                         Rockey.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for hazardous seas on all waters
        tonight through 8 am Tue.

     Small Craft Advisory for Rough Columbia River Bar conditions
        until midnight tonight, and again 8 am to noon Tue.

&&

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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is