Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 250452

Area Forecast Discussion
National Weather Service Medford OR
952 PM PDT Sat Mar 24 2018

.DISCUSSION...It is another night of wintry weather with scattered
to numerous light to locally moderate showers and snow showers.
A cold low now over the coastal waters will works its way east
across the area through around sunrise on Sunday.

The Winter Weather Message /PDXWSWMFR/ has been updated to
downgrade the Curry and Josephine County mountains to a Winter
Weather Advisory, and adjust amounts lower to reflect the portion
of the event that has already transpired. The advisory area
reflects that snow showers will be mainly above 1500 feet and
mainly in Curry, Josephine, and Siskiyou Counties. Additional
amounts will be up to an inch, except up to 3 inches in the
mountains. Even in areas that do not receive snow, wet roads may
freeze overnight and create hazardous driving conditions. Low
temperatures will be a few to several degrees below normal on
Sunday and Monday mornings.

The probability of precipitation Sunday through early Tuesday was
also adjusted slightly to reflect slight weakening in the 00Z GFS of
a series of weak disturbances that will be focused north of our
area. Please see the previous discussion below for further
details of the 7-day forecast.


.AVIATION...25/06Z TAF CYCLE...A mix of VFR/MVFR cigs in showers
will persist through the night with areas of higher terrain
obscured. There will be local IFR vsbys near snow showers as well.
Freezing levels will be 1000-2000 feet MSL. Showers will gradually
diminish Sunday and freezing levels will rise to around 2500 feet
MSL. As a result most areas will see VFR conditions, but there will
still be some obscuration of higher terrain. Showers will end Sunday


.MARINE...Updated 800 PM PDT Saturday 24 Mar 2018....Low pressure
will remain over the waters tonight, bringing numerous showers to
the area. Seas will remain steep to very steep through this
evening, then steep thereafter. Showers will end but seas will
remain steep through Sunday as high pressure builds over the area.
A very weak front will move through Monday, and high pressure will
rebuild Monday night. A thermal trough will develop late Tuesday
and north winds will return, likely bring small craft advisory
winds and seas to areas south of Cape Blanco Tuesday night into


.PREV DISCUSSION... /Issued 251 PM PDT Sat Mar 24 2018/

SHORT TERM...Overnight snow in the surrounding hills of Josephine
County is expected again tonight as well as areas in the Illinois
Valley and the Sexton Pass. However, snow amounts tonight will not
be as heavy as last night and snow is not expected at the pass
until after 8 PM when temperatures have decreased to near or below
freezing. Most of Siskiyou County to the south will also see snow
but heavier snow will be above the major roadways.

The broad low pressure off the Oregon coast is sending another
front inland this evening. So far southerly wind ahead of this
trough is keeping low level temperatures above freezing but
moderate showers along the coastal range is pulling the snow
levels down to near 2000 feet. South to Southeast winds ahead of
this low are also quite breezy in the Shasta Valley and the
Klamath Basin.

More precipitation is expected to spread into the Mount Shasta
area this evening with precipitation band spread north toward the
state line. Snow level this evening will hover around 2500 feet
then lower to around 1500-2000 feet tonight. Temperatures in the
Illinois Valley and over the Sexton Pass are forecast to drop
into the lower 30s as precipitation moves into the area tonight.
As a result snow is possible down to the valley floor in those
areas tonight although snow amounts will be less than last night
as the main energy is further south. Nonetheless if you plan to
travel tonight, be prepared for some snow at both the Sexton and
the Siskiyou Pass tonight primarily from around midnight forward.

The low pressure is expected to move inland Sunday and weaken to a
trough. There will be enough moisture and instability for
scattered showers to continue with snow levels during the day
hovering around 2500 feet for the west side and near the valley
floor for the east side.

On Monday a warm front is forecast to move inland over northern
half of Oregon. Cloudy sky and light rain can be expected north of
the Umpqua Divide with snow levels rising to around 4000 feet west
and 4500-5000 feet east of the Cascades. The atmosphere trends
toward warmer and drier on Tuesday as a ridge builds into the
eastern Pacific. /FB

LONG TERM...Wednesday through Saturday night...With high pressure
offshore and thermal troughing to our south, the forecast area will
remain under a warm and dry pattern for the duration of the extended
term. East offshore winds will keep the region dry, and temperatures
will jump to 10 to 15 degrees above seasonal normal by late week.
Areas along the south coast near Brookings could even reach into the
mid 70s due to the Chetco effect. Overnight, ridges west of the
Cascades will likely stay relatively warm, and inversions should
develop in the valleys underneath. Some valley and coastal fog is
possible due to this, but considering the time of year, exactly
where and for how long fog persists, or even if it develops at all,
is too uncertain to say with any confidence. Inversions should break
and any fog should dissipate quickly in the mornings. Overall, late
week into the weekend, conditions should be more reminiscent of late
May than late March, and should wrap up to be what most would
consider pleasant spring weather. -BPN


OR...Winter Weather Advisory until 5 AM PDT Sunday for ORZ024.

CA...Winter Weather Advisory until 5 AM PDT Sunday for CAZ080>083.

Pacific Coastal Waters...Small Craft Advisory for hazardous seas until
     5 PM PDT Sunday for PZZ350-356-370.
     Hazardous Seas Warning until 5 AM PDT Sunday for PZZ356-376.
     Hazardous Seas Warning until 11 PM PDT this evening for
     Small Craft Advisory for hazardous seas until 5 PM PDT Sunday
     for PZZ376.


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