Frost Advisory 16, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
848 PM PDT Wed Jun 19 2019

.UPDATE...Once again the sky is almost completely clear across
the region this evening, with signs of low clouds about to form
along the coast. Clouds are expected to build into the Umpqua
basin tonight, with some spilling over into the Rogue valley by
morning. Current forecast looks on track and will not update this
evening. Sven

&&

.PREV DISCUSSION... /Issued 249 PM PDT Wed Jun 19 2019/

DISCUSSION...

We'll see clear skies continue into this evening with winds
starting to increase in the valleys and over higher terrain. Then,
we'll see a short wave approach from the northwest during
Wednesday night. By Thursday morning, a dry cold front is expected
to move through the region and bring in relatively cooler
temperatures and drier air to much of the Pacific Northwest. High
temperatures are expected to be roughly 10 degrees cooler than
average for this time of year on Thursday and for Friday as well.
Looking at anomaly tables, the temperatures moving in will be in
the 10th percentile for early June, so it's not going to be an
extremely abnormal airmass Thursday or Friday.

Eventually, this shortwave will depart the region and high
pressure will try to build in it's wake. The ensemble guidance
suggests the ridge will struggle to build inland/eastward and
remain strongest over the Pacific. Because of this, temperatures
will be near normal for this weekend into next week. The next
important talking point is the next approaching long wave around
Tuesday.

We have pretty high confidence that a long wave is expected to
approach the Oregon coastline around Tuesday next week. The exact
time is of course up in the air. This is the type of pattern when
we expect some thunderstorms, but exact location is uncertain. We
kept a slight chance of thunderstorms east of the Cascades Tuesday
evening and Wednesday evening just based off the pattern and the
fact that this area is the most convectively active region in our
warning area.

-Smith

.AVIATION...For the 20/06Z TAFS...VFR will prevail this evening and
with gusty north winds near the TAF sites. a mix of VFR and MVFR
CIGS will make their way back into the Coast and Umpqua valley later
tonight. The air will be more unstable, so we're not expecting MVFR
to prevail all night. Things will scatter out again tomorrow with
more gusty north winds tomorrow afternoon. -Schaaf/Smith

&&

.MARINE...Updated 800 PM PDT Wednesday 19 June 2019...Gale force
winds will continue into this evening mainly south of Port Orford.
The thermal trough pattern will continue into the weekend, but
weaken briefly Thursday as cooler more unstable air moves into the
waters.  Winds will then strengthen and resume gale force strength
south of Gold Beach from Thursday afternoon into Saturday.
Conditions hazardous to smaller crafts will occur north of Port
Orford through Saturday.

FIRE WEATHER...Updated 200 PM PDT Wednesday 19 June 2019...Gusty
north-northwest winds will continue into this evening as an upper
trough and dry cold front approach from the north. Temperatures are
running 5-10 degrees cooler than yesterday at this time, but it is
drier, in some cases much drier, than 24 hours ago. The combination
of gusty winds and very dry air makes for near critical fire weather
conditions through this evening. The upper trough and dry cold front
will cross the region tomorrow and bring another 5-10 degrees of
cooling along with slightly higher humidities. However, gusty north
winds are expected again in the afternoon. Expect warmer and drier
than normal weather to return this weekend.

Guidance shows another upper trough moving into our area next week
which will bring cooler weather and at least some chance of showers
and thunderstorms. Unlike yesterday when models had the upper low
moving right over us, they are now keeping the center of it
offshore. This puts us in a favorable position for thunderstorm
development. However, if and where storms form will depend on many
factors, and it is too far out to nail down those details.

-Wright

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Watch from late Thursday night through Friday morning for
     ORZ029>031.

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Saturday for
     PZZ350-356-370-376.
     Gale Warning until 11 PM PDT Saturday for PZZ356-376.

SBN/SBN/SBN