High Wind in Oregon, January 8 to 9, 2023

Area Forecast Discussion
National Weather Service Medford OR
832 PM PST Sun Jan 8 2023

.DISCUSSION...Showers have ended across the majority of the area
as the air mass has grown increasingly stable over the last few
hours in the lee of the recent frontal passage. This period of
clear weather will be brief, however, as the next system
approaches the area. Winds have started to pick up ahead of this
next front (gusting to 40+ in Weed and 20-30 mph over exposed
areas on higher terrain and in coastal regions), but will not peak
until later tonight. Our forecast is on track, and no updates were
needed this evening. More details about the forecast as it stands
can be found in the previous discussion below. -Price

&&

.AVIATION...09/00Z TAFs...Areas of gusty south winds will continue
to affect the region with wind shear concerns diminishing this
afternoon through early evening. Another strong front will pass
through the area tonight, and low level wind shear concerns will
return again late tonight and continue into early Monday morning.
Cloud cover will remain mostly VFR. However expect areas of MVFR
cigs and local IFR cigs in any lingering showers this afternoon and
again tonight. Mountain obscurations will persist through TAF
period, with the most widespread mountain obscurations this morning
and again tonight. /BR-y

&&

.MARINE...Updated 800 PM PST Sunday, January 8th 2023...Stubborn low
pressure over the eastern Pacific will continue to provide stormy
weather and dangerous marine conditions across the coastal waters.
Another strong front approaches tonight and moves through Monday
morning with strong gales and gusts that approach storm force. There
will be brief periods of relatively weaker winds, though still
strong, but heavy seas will remain very steep and hazardous well
into Monday.

Conditions improve Monday into Tuesday as the storm track shifts
farther south and focused along the California coast. Winds will
drop below advisory criteria, but seas will remain steep and
relatively lower...11 to 13 ft vs the recently persistent 15 to 20+
ft. South gales should return late Tuesday into Thursday as deep low
pressure remains active offshore. /BR-y

&&

.PREV DISCUSSION... /Issued 255 PM PST Sun Jan 8 2023/

SHORT TERM...Through Tuesday, January 10...Showers have been
slowly tapering off this afternoon and will continue to do so
this afternoon. Showers have a 20 to 40% chance to persist from
Curry County north and east across Southern Coos and Central &
Eastern Douglas Counties over the next few hours. Meanwhile the
next weather system can be seen in satellite spinning offshore,
with the moisture plume advancing northeast from the central
Pacific.

The main impact from this system will be strong gusty winds almost
everywhere from the coast to east of the Cascades. The most
recent guidance didn't vary much from what was already forecasted,
so changes were mostly cosmetic if at all. The high wind warnings
and wind advisories issued last night remain in place, with more
details found in those text products (see NPWMFR).

The reason for wind being the main impact are snow levels that
start around 3500-4000 feet and will rise behind the next front
tonight to 4500-5500 feet. The snow level around 4500-5000 feet
tonight is expected across NorCal south of the Siskiyous and
across the East Side, while the snow level west of the Cascades
in Oregon is forecast to be between 5000-5500 feet. This will
limit the majority of impacts due to snow to areas of Siskiyou
County above 4500 feet.

As we have observed with the previous two fronts during the
heaviest periods of precipitation, the snow level has lowered an
additional few hundred feet. This could bring accumulating snow
down to Black Butte Summit or Snowman, with amounts of 1 to 4
inches possible before 10 AM Monday when the heaviest snow is
expected. Additional details for the snow above 4500 feet can be
found in the Winter Storm Warning text product (WSWMFR).

Rain amounts are expected to be highest in Curry County, southern
Josephine County, and Siskiyou County (plus everywhere south in
California). Amounts should range from 0.4" to 1.5" in Curry and
Josephine County, and < 0.1" in the Shasta Valley to 2.5" plus in
the mountains and southern most part of Siskiyou County. Even with
saturated soils, these rain amounts should not be enough to cause
any flooding concerns more serious than nuisance ponding of
pasture land or poorly draining urban areas.

The remainder of the coast, the Umpqua Divide and the Cascades
have also picked up rain recently, generally less than 1" in the
last 72 hrs per the MRMS radar product estimates. Other areas have
found precipitation hard to come by because of the strong
orographic influences of the coast and NorCal with southerly
oriented systems. this system tonight will also be oriented south
to north by the time it moves onshore in our region, so the chance
for rain/snow is not 100% in most places and rain shadowing is
expected for most west side valleys. Before planning for rain,
check the forecast to see the probability associated with it.

The moisture plume will plunge south with no blocking high
pressure over SoCal. And Monday afternoon will be much like this
afternoon, with lighter winds in most places and scattered to
isolated showers.

Then, you guessed it, another short wave ejected from the main
area of low pressure in the Gulf of Alaska, moves towards the
coast. This will keep a 30-90% chance for rain/snow in the
forecast across the whole region, with the higher chances in
NorCal, with the bulk of the moisture plume associated with this
energy directed towards the Bay Area.

Snow levels Tuesday morning are expected to be in the 3500-4000
foot range, climbing to 4000-4500 feet by the afternoon. This will
allow for some light snow/sleet accumulations to be possible on
some of the medium height passes, but again, moisture is expected
to be limited in our region meaning amounts should not be
impactful. The one exception could be Snowman summit near Mt.
Shasta and we will monitor the trends to see if an advisory is
needed.

Winds with the short wave Tuesday morning are not forecast to be
as strong as recent events, except across the highest and most
exposed areas. Afternoon temperatures should also be a few degrees
cooler, with a slightly colder airmass filling the region.
-Miles

LONG TERM...Wednesday, January 11 through Sunday, January 15,
2023...Models and ensembles continue to indicate a strong frontal
system approaching the PacNW coast on Wednesday with a weak upper
level ridge centered inland, just east of the area.  Models support
areas of moderate precipitation spreading inland as the warm
front lifts north over the area on Wednesday. Snow levels are
expected around 4000 ft as precipitation moves into the area early
Wednesday, rising to 4500 to 5000 feet (except higher near 6500
ft from the coastal mountains west) during the day Wednesday. A
cold front will then approach the coast Wednesday night into
Thursday. Models and ensembles remain in agreement that the high
pressure ridge, centered to the east, will strengthen during this
period, with the cold front stalling just off the PacNW coast.
This pattern would keep the main area of precipitation across
western and southwestern portions of the area late Wednesday into
Friday, mainly across the coastal waters, coast, southwest
Joesphine County and western and south- central Siskiyou County
with much lighter precipitation across other inland areas. Strong
winds are likely ahead of this front across the coastal waters,
and possibly into the coast. Areas of moderate, gusty winds are
possible across many inland areas.

The pattern becomes more progressive Friday afternoon into Friday
night, as an upper level low and trough arrive and become positioned
off the PacNW coast. This will allow the front to push inland late
Friday into Friday night with mainly light to moderate precipitation
(focused most over N. California). A low pressure center and frontal
system  are then expected to track towards the area from the
northwest.  This system may move into northern California though,
keeping lighter precipitation over southwest Oregon and a potential
for moderate precipitation across N. California zones. -CC

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 1 AM to noon PST Monday for ORZ029.

     Wind Advisory until noon PST Monday for ORZ030-031.

     High Wind Warning from 1 AM to 1 PM PST Monday for ORZ021-022.

     Wind Advisory until 10 AM PST Monday for ORZ023>025.

     Wind Advisory until 10 AM PST Monday for ORZ026.

CA...Winter Storm Warning until 10 AM PST Monday above 4500 feet for
     CAZ080-082-083.

     High Wind Warning until 10 AM PST Monday for CAZ081.

     Wind Advisory from 1 AM to noon PST Monday for CAZ084.

     Wind Advisory until noon PST Monday for CAZ085.

PACIFIC COASTAL WATERS...High Wind Warning from 1 AM to 1 PM PST
     Monday for PZZ350-356.

     Gale Warning until 10 AM PST Monday for PZZ350-356-370-376.

     Hazardous Seas Warning from 10 AM to 10 PM PST Monday for PZZ350-
     356-370-376.

     Gale Watch from Tuesday evening through Thursday evening for
     PZZ350-356-370-376.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
343 PM PST SUN JAN 8 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     HEAVY RAIN       2 WSW OBRIEN            42.06N 123.73W
01/08/2023  M1.52 INCH       JOSEPHINE          OR   TRAINED SPOTTER

            24 HOUR PRECIP TOTAL.

&&

CSP