NWS Medford, OR wrote its last area forecast discussion before the first event at Jan 2, 9:34 AM PST, 1 hour 3 minutes earlier.
Area forecast discussion, Jan 2, 9:34 AM PST, 1 hour 3 minutes before
Area Forecast Discussion
National Weather Service Medford OR
934 AM PST Sun Jan 2 2022
.DISCUSSION...
No updates are needed this morning.
Southerly winds are beginning to increase across the forecast
area this morning as an expansive and powerful low pressure
system begins to spin into the area from the Gulf of Alaska.
Today's winds are just the beginning of what could be a damaging
wind storm in some areas and what's likely to yield whiteout to
periodic blizzard conditions across mid and higher elevations,
especially along and near the Cascades and Siskiyous eastward
this evening through Monday. A number of wind, snow, and
hydrologic headlines have been issued in the last 24+ hours for
this powerful storm system, so please be sure to check your the
forecast and headlines via the point-and-click feature on our
website.
Just to put this weather system into some perspective, the
European Model's Extreme Forecast Index indicates that winds with
this storm system from 4PM PST today through 4PM PST Monday are
most likely to end up in the windiest 10 to 20% of climatology as
compared to all events from 2001-2021 when looking 2.5 weeks
before and after the date mentioned. Since December tends to yield
some of our most powerful storms in terms of wind gusts, this is
likely to be a high impact event for portions of the forecast
area.
Said another way peak winds gusts of 70 to 90 mph are possible
along and near the coast this evening through Monday morning. 70
to 90 mph gusts will also be possible across the mountains mainly
above 6kft foot elevations, as well across southwest wind catching
portions of the east side. While it will be breezy to windy in
other areas, these are the highlights.
Where precipitation falls in the form of snow, blowing and
drifting will be significant and white conditions are likely, at
times, with the primary period of concern being 4 AM PST Monday
into 4 AM PST Tuesday. ~BTL
&&
.AVIATION...02/12Z TAFs...Valley LIFR/IFR stratus is beginning to
develop in the West Side valleys south of the Umpqua Divide.
Increasing high level clouds and possible increasing breezes are
likely limiting fog and stratus development in Douglas County and
along the coast. The clouds and breezes are also likely to lead to
valley fog elsewhere lifting mid-morning. Otherwise, VFR conditions
will persist through tonight.
The pattern will begin to change later this morning with the
approach of a strong front. The front will bring precipitation,
heavy at times along the coast (leading to periods of IFR
conditions) but lighter inland (mainly MVFR conditions), and gusty
southerly winds to the coast Sunday, spreading inland through the
day. Stronger winds are expected aloft and wind shear will be a
universal concern for all locations. -Miles
&&
.MARINE...Updated 830 AM PST Sunday 2 January 2022...An approaching
cold front will lead to the development of steep seas and gales this
morning. Conditions worsen and very large and very steep seas
develop this afternoon as storm force winds develop while the front
moves onshore Sunday evening through Monday morning. Wind gusts of
up to 80 mph are possible Sunday night into early Monday morning
from the vicinity of Cape Blanco north to Florence. Winds will
diminish through Monday, but a building west swell will keep seas
quite steep at least through Tuesday morning.
A weaker front will follow Tuesday afternoon into Tuesday night,
with gusty south winds and accompanying steep seas. A continued
series of disturbances is likely through the remainder of the week
with episodes of steep to very steep seas. -BPN/Miles
&&
.PREV DISCUSSION... /Issued 437 AM PST Sun Jan 2 2022/
DISCUSSION...A deepening low pressure center will move out of the
Gulf of Alaska late today and become positioned off the coast of
British Columbia. With this low, a very strong and moist front
will move into the area tonight and Monday. High winds along the
coast, in the Shasta Valley, over the mountains and near Summer
Lake, are expected ahead of and with the frontal passage. Winds
may gust to hurricane force for some areas, especially for exposed
areas along the coast, in the mountains and in the Summer Lake
area. Abundant moisture with this front will also result in
moderate to heavy rain and snow impacting the area. Snow levels
will generally rise to 3500 to 4000 feet as the moderate to heavy
precipitation moves into the area but may remain locally lower
until late in the day in the Mount Shasta City area. Widespread
showers will follow Monday night into Tuesday morning. Additional
fronts and disturbances will then continue to move into the area
Tuesday through Friday. Of note, snow levels will rise late
Tuesday into Wednesday.
With this strong front tonight and Monday, models are indicating
a strong upper level (300 mb) jet of 120 to 160 kt will move into
the area. Additionally, a mid/lower level southerly jet of 75 to
90 kt is expected to move over the area. This combined with strong
surface pressure gradients (-11 to -14 mb North Bend to Arcata
and Medford to Redding) will result in strong surface winds for
many areas with strongest winds along the coast, in the Shasta
Valley and from the Cascades east. Winds are expected to gust to
65 mph and locally winds may gust to hurricane force 75 mph,
especially for areas along the coast, in the higher mountains and
Summer Lake area. High wind warnings (NPWMFR) are in effect for
the coast and Shasta Valley with wind advisories for many areas
west of the Cascades. Strong winds along with moderate to heavy
snow will impact the mountains and areas east of the Cascades and
also expect a combination of gusty winds and heavy snow in the
Mount Shasta City area. Winter storm warnings (WSWMFR) are in
effect for Monday morning through Tuesday morning. Heavy snow
rates of 1 to 2 inches per hour are possible across the Cascades
at times Monday afternoon and evening. This combined with strong,
gusty winds will lead to white out conditions at times in the
Cascades and the potential for blizzard conditions in areas of the
Cascades exposed to the strong winds. In the Mount Shasta City
area, heavy snow rates of up to 1 inch per hour are possible
Monday afternoon, which along with gusty winds may lead to
whiteout conditions at times.
Finally, moderate to heavy rain on snow Monday followed by rising
snow levels and additional rain Tuesday into Wednesday will lead
to rapid rises on area waterways, especially across Coos, Curry,
Douglas, and Josephine Counties, during that time period. A
flood potential outlook (ESFMFR) is out covering hydrologic
concerns.
PREV LONG TERM DISCUSSION... /Issued 410 PM PST Sat Jan 1 2022/
..Tuesday Jan 4 through Saturday Jan 8... The deep upper level
trough off the coast of British Columbia will weaken, with much of
its energy retrograding to the Gulf of Alaska as a ridge attempts
to build into the northeastern Pacific. The result will be swift
northwest flow over the Pacific Northwest on Tuesday, squeezed
between the ridge and the departing trough. This moist onshore
flow, a continuation of the atmospheric river of the previous day,
should continue to produce showers and upslope precipitation
through Tuesday, with enhanced precipitation expected Tuesday
evening as a weak surface low pushes onshore. Snow levels through
this time are expected to remain between 2000 and 3000 feet.
Despite the passage of the low, onshore flow will continue into
Tuesday night, with the main moisture plume moving north of our area
as the preferred storm track is pushed north by the building ridge.
This should shove the heaviest of the precipitation out of the area
by Wednesday, although showers are expected to continue all the way
into Thursday morning, especially along western facing slopes. Snow
levels will also rise during this time, reaching around 5000 feet as
a warmer air mass builds in under the ridge.
The ridge axis is expected to pass over the region Thursday, then
build into the Rockies Thursday evening, allowing the next trough in
the Westerlies to approach the area Thursday night. This system,
while much weaker than the early week event, could be another wind
rain, and mountain snow producer for our Friday. There are some
indications in the models of a developing surface low offshore,
which would make this system more impactful, but confidence is too
low at this time to nail down any of those details. The trough then
moves quickly to the east Friday night, with upper level ridging
with drier and slightly warmer weather returning Saturday. -BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 4 PM this afternoon to 4 AM PST
Tuesday for ORZ029-030.
Winter Weather Advisory from 4 PM this afternoon to 4 AM PST
Tuesday for ORZ029-031.
Winter Storm Warning from 4 PM this afternoon to 4 AM PST
Tuesday for ORZ031.
High Wind Warning until 1 PM PST Monday for ORZ021-022.
High Surf Advisory from 4 PM this afternoon to 10 AM PST Tuesday
for ORZ021-022.
Wind Advisory from 4 PM this afternoon to 4 PM PST Monday for
ORZ023-024-026.
Winter Storm Warning from 4 AM Monday to 4 AM PST Tuesday for
ORZ027-028.
Coastal Flood Watch from Monday morning through Monday afternoon
for ORZ021.
CA...Winter Weather Advisory from 4 PM this afternoon to 4 AM PST
Tuesday for CAZ084-085.
Winter Storm Warning from 4 PM this afternoon to 4 AM PST
Tuesday for CAZ085.
Winter Storm Warning from 4 AM Monday to 4 AM PST Tuesday above
3000 feet in the for CAZ080.
Winter Storm Warning from 4 AM Monday to 4 AM PST Tuesday for
CAZ082-083.
High Wind Warning from 1 PM this afternoon to 4 PM PST Monday
for CAZ081.
Winter Weather Advisory from 4 AM Monday to 4 AM PST Tuesday for
CAZ081.
Pacific Coastal Waters...
Storm Warning from 4 PM this afternoon to 10 AM PST Monday for
PZZ350-356-370-376.
Gale Warning until 4 PM PST this afternoon for
PZZ350-356-370-376.
Hazardous Seas Warning from 10 AM Monday to 4 AM PST Tuesday for
PZZ350-356-370-376.
High Wind Warning until 1 PM PST Monday for PZZ350.
BTL/CC/MB