River Flood Warning 3, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
243 PM PST Fri Feb 15 2019

.DISCUSSION...The latest satellite image clearly shows a piece of
energy moving into southwest Oregon. A few lightning strikes have
been observed just west of Brookings, so it would not be out of the
question we have a few isolated storms with small hail possible into
this evening. Snow levels into early this evening are expected to be
around 2000 feet, but could briefly lower to 1500 feet in heavier
showers resulting in brief roadside snow accumulations. Once the
heavier showers pass by, then any snow on the roads should melt off.

The biggest concern for road snow will be shortly after dark until
Saturday morning and again Saturday night into Sunday morning. The
greatest concern for additional road snow will be tonight into
Saturday morning and mainly above 2000 feet. The exception to this
will be in portions of the Illinois Valley and Douglas county where
we could see snow sticking around and above 1500 feet. Also keep in
mind the showers will be convective in nature, so it's possible
other locations around 1500 feet could see snow if it's heavy
enough.

In the meantime, another shortwave trough will move south Saturday
afternoon into Saturday evening. Ahead if it will be plenty of
energy resulting in scattered to numerous showers moving from
northwest to southeast, especially along and west of the Cascades
and western Siksyou County. There will be showers east of the
Cascades, but not as widespread. Snow levels Saturday will vary and
much will depend on the intensity of the showers. Generally, they
will be around 2000 feet, but could briefly lower to around 1500
feet in heavier showers. In this case, there could be temporary
roadside snow around 1500 feet, then melt off once the heavier
precipitation moves away or eases up.

Showers linger into Saturday night with snow levels possibly
lowering near or at the valley floors. There is concern for
additional road snow Saturday night into early Sunday morning. The
trend is for showers to decrease Saturday night and there may not be
much in the way of additional accumulation, but temperatures will be
below freezing, so any wet roads could ice up Saturday night.
Therefore have extended the winter weather headlines for west of the
Cascades until 8 am pst Sunday. Note: It's possible we may have to
expand the Winter Weather Advisory to include the Rogue Valley
Saturday night into Sunday morning because confidence at is not high
enough to include them at this time. Watch for updates on this.
-Petrucelli

Sunday through Friday...Only one distinct front will impact the
forecast area Sunday through the day Friday. On Sunday, the upper
trough will depart the region and push into Southern California, and
deep northerly flow will ensue. Some increased sunshine is expected
Sunday and Monday with drier conditions through the atmosphere. Some
ripples are likely in the northerly flow, bringing weak disturbances
in from the north, but no significant precipitation is expected
through Tuesday. This is supported by the range of solutions
presented by GEFS data.

The next real front approaches the area from the north on Wednesday.
The operational GFS and EC models are in very good agreement with
the track of the low, especially at 124 hours out. Timing of this
system is important because if the precipitation comes in during the
day, impacts to roadways will be muted because of daytime warming,
but a nighttime precipitation event would yield more impacts. We'll
keep our eye on this system with a particular focus on timing. For
now, both the EC and GFS suggest the best chances for the heaviest
precipitation will be during the day on Wednesday. Precipitation
chances diminish Wednesday night, and mostly dry conditions are
expected Thursday and early Friday before another front potentially
reaches the area from the north late Friday, bringing the potential
for yet another round of low elevation snowfall Friday night.

One note about temperatures in the extended. Given the very cold air
mass, any nights that clear out will feature well below normal
temperatures. Current data suggest that the first chance for mostly
clear skies and light winds will be Sunday night, but winds will
likely be lighter everywhere on Monday night.

&&

.AVIATION...For the 15/18Z TAFs...Showers and snow showers will
continue this afternoon with freezing levels around 2500 feet MSL.
So, expect snow showers across all mountains and east of the
Cascades and across much of Siskiyou and Modoc counties in Northern
California into mid-morning. The decrease in shower activity has
been short-lived as the next band of showers has come in earlier.
Expect some periods of convective low level wind shear, especially
for West-Side airports near showers. -Schaaf

&&

.MARINE...Updated 215 PM PST Friday 15 February 2019...Seas will
become very steep as a very high west swell builds into the waters
this morning. Showers with a few embedded thunderstorms will be
moving through the waters today associated with a front. These
showers will bring gusty and erratic winds today while the front
will bring gusty south winds that may briefly gust to gale force
during the afternoon. Seas will peak early this evening but remain
very high and very steep into Saturday morning. A series of weak
fronts will follow during the remainder of the weekend with high and
steep seas into Monday morning. -Schaaf

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 10 PM this evening to 7 AM PST Saturday for
     ORZ030-031.
     High Surf Advisory until 10 AM PST Saturday for ORZ021-022.
     Winter Weather Advisory until 8 AM PST Sunday above 2500 feet in
     the for ORZ027-028.
     Winter Weather Advisory until 8 AM PST Sunday for ORZ024.
     Winter Storm Warning until 8 AM PST Sunday for ORZ024.
     Winter Weather Advisory until 8 AM PST Sunday below 2500 feet in
     the for ORZ023-025-026.

CA...Winter Weather Advisory until 10 AM PST Saturday for CAZ082.
     Winter Storm Warning until 10 AM PST Saturday for CAZ082.
     Winter Weather Advisory until 10 AM PST Saturday for CAZ080.
     Winter Storm Warning until 10 AM PST Saturday for CAZ080.
     Winter Weather Advisory until 10 AM PST Saturday for CAZ081.
     Winter Weather Advisory until 10 AM PST Saturday for CAZ083.

Pacific Coastal Waters...Small Craft Advisory for hazardous seas from 10 AM Saturday to
     10 AM PST Monday for PZZ350-356-370-376.
     High Surf Advisory until 10 AM PST Saturday for PZZ350-356.
     Hazardous Seas Warning until 10 AM PST Saturday for
     PZZ350-356-370-376.