Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kmfr 141836 
afdmfr

Area forecast discussion
National Weather Service Medford or
1030 am PST Thu Nov 14 2019

The aviation and marine sections have been updated...

Aviation...for the 14/18z tafs...LIFR/IFR stratus/fog are impacting
the coast, where the low conditions are expected to persist through
early this afternoon. Conditions there are then expected to lift
some with visibilities improving, but stratus will likely remain all
day due to onshore flow. LIFR to IFR across the Umpqua basin will
persist through into the early afternoon, once again, before
improving to VFR this afternoon. South of there, patchy IFR fog in
portions of the rogue/Illinois/lower Klamath River valleys appears
to have dissipated per web cameras, but observations indicate
there's likely still some out there. Expect this will dissipate by
noon for most areas.

A frontal system moving into the area today through Friday morning
is likely to result in more mixing through the period, scouring out
valley haze along and near the coast and on the east side, and, most
likely, at least partially across the interior west side. This
evening through Friday morning MVFR ceilings will spread inland west
of the Cascades with areas of IFR, terrain obscuration and some
light rain. Precipitation probably won't make it much past the
Cascades though. Btl

&&

Marine...updated 930 am PST Thursday, 14 November 2019...
calm conditions will continue through this morning, then conditions
will deteriorate rapidly this afternoon as a cold front approaches
and a long period west swell builds into the waters. Expect gusty
south winds, strongest north of Cape Blanco, later this morning and
into tonight as the front passes. Steep seas from the long period
west swell will create potentially hazardous bar conditions. Seas
peak early Friday, but will remain elevated through the weekend.

The thermal trough makes a brief return Sunday, but another front
early next week will keep it from strengthening. So a brief period
of gusty north winds south of Cape Blanco is expected Sunday
afternoon before winds turn southerly again Monday. /Br-y

&&

Update...
no updates were needed to the forecast this morning.

For more detailed notes on the forecast, please refer to the
previous discussion. A summary of current weather in the area
follows.

Low stratus is expected to linger at North Bend throughout the day.
The fog in Roseburg should disperse some as the day draws closer to
noon. There is also some stratus on the Highway cameras along US-97
east of Crater Lake and south of Chemult that seems to be lifting
already. There is likely more stratus lingering in the marshy areas
on the east side. Off the coast, the cloud shield can be seen
encroaching, ahead of which are a few diffuse returns appearing on
radar. Soundings indicate a sizable dry layer from about 950 mb
through 600 mb, indicating that any precipitation production should
become virga.

And lastly, a large swell will be building into the inner waters
this morning creating a moderate risk for sneaker waves. Caution
should be taken by anyone going to the coast today and remember to
not turn your back on the ocean.

&&

Previous discussion... /issued 353 am PST Thu Nov 14 2019/

Short term...an upper level shortwave is moving onshore today and
the upper ridge will gradually shift eastward. Current radar
imagery shows some weak returns over the coastal waters with
lower to mid clouds likely. Some areas of light drizzle may
develop over the coastal waters and along the coast today.
Additionally expect low clouds and fog along the coast through
today. Inland, areas of fog and low clouds will persist through
this morning in the Umpqua basin and areas of low clouds or fog
are possible in the Grants Pass area as well. Otherwise, inland
areas are expected to remain dry today but expect an increase in
higher clouds.

Tonight, a front, which is associated with a low in the Gulf of
Alaska, will move towards the coast then inland on Friday. Model
solutions continue to show rain will develop over the coastal
waters and along the coast tonight with areas of rain spreading
inland tonight and Friday morning. Light rain is possible for many
western portions of the County Warning Area with rain likely from the coast, into
the coastal mountains, Umpqua basin, western Josephine and across
the southern Oregon Cascades. For other areas in eastern
Josephine, Jackson and Siskiyou counties, expect a chance for
light rain. East of the Cascades, a slight chance of light rain is
possible, mainly in Klamath and Northern Lake counties. Areas of
showers will linger into Friday afternoon, then taper off Friday
evening.

Saturday, a ridge will build into the area then remain in place
into Sunday. A frontal system will move inland to the north.
However, expect this system to remain north of the area with dry
weather across the County Warning Area. Stable conditions combined with lingering
moisture from earlier rain are expected to allow areas of fog to
develop in western valleys and in coastal areas Friday night and
Saturday morning.

Long term...Monday into Tuesday, a strong shortwave trough and
low pressure system are forecast to approach the area late Monday
into Tuesday. As this system brings a front into the area, expect
additional chances for precipitation over the area Monday night
through Tuesday. Model solutions vary on the strength and timing
of this system. However, models are showing a trend towards having
the system come in slower compared to previous runs. So have
lowered the chance for precipitation on Monday and raised the
chance for precipitation Monday night through Tuesday to reflect
this. Snow levels are forecast to lower as the upper trough moves
inland Tuesday night into Wednesday. With the cold showery airmass
in place, expect a chance for light snow or a mix of light rain
and snow across higher mountains, mainly above 5000 ft elevation.

Conditions dry out Wednesday night and remain dry on Thursday as
a ridge builds into the area. However expect cold temperatures
Wednesday night and Thursday morning with mild daytime
temperatures.

&&

Mfr watches/warnings/advisories...
or...
- beach hazards statement through late tonight for orz021-022.
- Air stagnation advisory until 4 PM PST this afternoon for
orz023-024-026-029-030.

California...none.

Pacific coastal waters...
- Small Craft Advisory from 10 PM this evening to 4 PM PST Saturday
for pzz350-356-370-376.

National Weather Service Glossary of Abbreviations