Small Craft Advisory 57, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
257 AM PDT MON MAY 16 2016

.Discussion...The forecast is composed of three distinct
patterns. The first is drawing to a close today, as the upper
level low that brought showers and some thunder to our area over
the past several days finally slides off to the East. some light
showers are still possible through this afternoon, mainly along
the Cascade crest and the Hart and Warner mountains, but these
should dissipate by this evening. Temperatures will also warm by
about 5 degrees from yesterday for most areas, although the South
Coast near Brookings will warm by around 10 degrees. This will
result form offshore flow, which is the first sign of...

The second pattern, during which warm and dry will be the rule.
With upper level ridging building overhead, the thermal trough
will strengthen this afternoon and evening, then push north
Tuesday. Offshore, or easterly, winds will be dry, and will push
temperatures up significantly as it flows down the west slopes of
the Cascades and Coastal ranges. The warming, which will begin
late today, will reach a peak along the coast on Tuesday, then
peak inland on Wednesday as the thermal trough slides east.
Brookings and the surrounding areas could reach near 80 degrees
Tuesday, while upper 70s to mid 80s will be common inland on
Tuesday and Wednesday, even up to 85 in the Rogue Valley. But the
heat and the dryness won't last...

As the pattern shifts once again Wednesday night. A very large
closed upper level low will push south from the Gulf of Alaska,
dropping into the Pacific Northwest and almost directly overhead
of the forecast area by Thursday evening. While some cooler
temperatures and a few showers could make their way into the coast
and the Umpqua Basin Wednesday evening, the low will not truly
make its presence known until Thursday. Temperatures then will
drop to around 20 degrees below the highs of the day before, and a
significant chance of showers will overspread the region. Models
are not showing much in the way of instability with this low on
Thursday, so have left out a mention of thunder, but future runs
may change that thinking.

This final pattern looks to last a while, with all the major
model suites keeping the upper level low, or some version of the
same, directly over us through the remainder of the forecast term.
Some instability does develop in the model solutions during the
afternoons through the weekend. Have therefore kept showers and
cooler temperatures in place through the weekend and into early
next week, with a slight chance of afternoon thunderstorms, mainly
along and east of the Cascades, and in Northern California. -BPN

&&

.Aviation...For the 16/06Z TAF cycle...Over the coastal waters,
along the coast, in the Umpqua Basin and in portions of the Rogue
Valley overnight...a mix of VFR/MVFR conditions will develop in
most of that area overnight, but any showers should end. Then,
MVFR ceilings lift to VFR by early Monday afternoon.

Over the remainder of the area...VFR conditions this evening with
some higher terrain obscuration and isolated to scattered showers.
Showers will dissipate tonight with VFR prevailing into Monday.
/FB

&&

.Marine...Updated 800 PM PDT Sun 15 May...Offshore high pressure
will persist into Tuesday...then weaken. A thermal trough will
develop along the coast and gradually strengthen into Tuesday
night before weakening. This will bring increasing north winds and
building seas to the area beginning this afternoon...with winds
possibly reaching gale force south of Gold Beach Monday afternoon
through Tuesday night. A weak front will move onshore Wednesday...
then weak low pressure will remain over the waters through
Thursday. /FB

&&

.MFR Watches/Warnings/Advisories...
OR...None.

CA...None.

Pacific Coastal Waters...Small Craft Advisory from 11 AM this morning to 11 AM PDT
     Wednesday for PZZ350-356-370-376.
     Small Craft Advisory for hazardous seas from 11 AM this morning
     to 11 AM PDT Wednesday for PZZ350-356-370.
     Gale Warning from 11 AM this morning to 11 AM PDT Wednesday for
     PZZ356-376.
     Hazardous Seas Warning from 11 AM this morning to 11 AM PDT
     Wednesday for PZZ350-356-370-376.

BPN/FB