FXUS66 KMFR 250350

Area Forecast Discussion
National Weather Service Medford OR
850 PM PDT Sun Jun 24 2018

.DISCUSSION...As expected, it was a hot day inland across the CWA
with temperatures topping out near or above 100 degrees in the
Rogue/Illinois/Shasta and lower Klamath River Valleys. Officially,
we reached 100 degrees here in Medford, which is the first time
this year. Incidentally, it was even hotter last year as the high
on June 24, 2017, was 107 degrees. But not even that was a record.
The record for the date was 109 degrees set way back in 1925.

The upper ridge responsible for the inland one-day heat wave is
exiting stage right and an upper trough offshore will move in
tonight. Satellite imagery is showing marine stratus pushing
onshore along the coast and into interior Coos County as well as
the lower Umpqua Valley. The marine layer will deepen overnight
into Monday morning such that there could be a little light rain
or drizzle in those areas. This may also be the case closer to
sunrise in just about any location along and north of the Umpqua
Divide, but won't amount to much (only a couple of hundredths here
or there). South of there, including here in the Rogue Valley,
we'll be mostly clear overnight, but some clouds may spill over
the Divide toward or just after sunrise. Even so, we're not
expecting precipitation this far south. Clouds will break up
Monday afternoon and it will be 15-20 degrees cooler for inland
areas west of the Cascades, compared to today. East side areas
won't see quite as large of a 24-hour temperature change, but it
will be cooler in most areas. It will be breezy just about
everywhere Monday afternoon and evening, but gusty north to
northwest winds can be expected in portions of the Shasta Valley
and over the east side with gusts of 20-30 mph.

Please see the previous discussion below for details on the rest of
this upcoming week's weather. -Spilde


.AVIATION...For the 25/00Z TAFs...IFR cigs have moved over the
coastal waters and are barely edging into Coos Bay, including KOTH.
Expect IFR/MVFR cigs to become widespread along the coast this
evening and MVFR cigs with local IFR cigs to spread inland across
the Umpqua Basin late this evening into tonight, including at KRBG.
These IFR/MVFR cigs will persist through late Monday morning.
Elsewhere VFR conditions will continue through the TAF period, with
gusty winds developing Monday afternoon as a weak front moves
through the area. BR-y/CC


.MARINE...Updated 800 PM PDT Sunday 24 June 2018...The thermal
trough has weakened and this has resulted in diminished winds across
the waters. Seas will be relatively calmer tonight as a weak front
moves through, but low end small craft conditions are expected to
continue south of Cape Blanco overnight into Monday. These improved
conditions will be short lived as the thermal trough quickly
redevelops late Monday. Gusty north winds will resume and wind
driven seas will build Monday afternoon into mid-week. Steep to very
steep, hazardous seas may develop south of Nesika Beach by Tuesday
morning. The thermal trough will continue to strengthen on Tuesday
and gales could be possible south of Cape Blanco, with small craft
conditions spreading north of Cape Blanco by late Tuesday afternoon.

Seas look to improve Wednesday night into Thursday as an upper level
trough moves through and disrupts the thermal trough pattern. Winds,
however, may continue to reach small craft advisory levels through
the end of the week. /BR-y


.PREV DISCUSSION... /Issued 257 PM PDT Sun Jun 24 2018/

DISCUSSION...Sunny skies prevail over the entire forecast area.
Much of the west side has reached into the 90s, and east side in
the 80s. Smoke has cleared out of the Cascades and East Side, and
do not expect it to return in the near term. Temperatures will
continue to rise until this evening. Then, a cold front push into
the area. Water vapor satellite shows the trough axis near
135W...consistent with model analysis. A marine push behind the
front will bring low level clouds and possible fog and light rain to
the coast and portions of the Umpqua Basin. Other than any light
precip along the coast and northern Umpqua Valley, this will be a
dry system. It will be cold though; highs tomorrow will be 10 to
15 degrees colder than today. Also expect breezy winds in eastern
Lake and Modoc County.

After Monday, expect a few days of uneventful zonal flow with
gradual warming conditions, then mid to late next week, the area
will transition to a more progressive pattern. A weak cold front
will pass through the area Wednesday into Thursday, bringing
breezy winds over the East Side Wednesday afternoon, and
bringing a dip in temperatures from Wednesday to Thursday. Any
precipitation will likely be directed to northern Oregon and
southern Washington, but northern Douglas and Klamath County could
squeeze a few drops out.

The GFS develops an upper low over the northern Rockies and
drifting southward Saturday, which could bring some showers to
eastern Oregon. Confidence is low as this time frame has been
highly variable over the last few model runs. -McAuley

FIRE WEATHER...Updated 300 PM PDT Sunday 24 June 2018...The thermal
trough will shift east and lie over Lake and Modoc counties by late
this afternoon. This thermal trough location will result in the
peak of warmth and dry conditions inland. By very late this
afternoon and early evening the winds will become a bit gusty west
of the Cascades as marine air spills inland with a dry cold front.

Breezy, cooler and more humid conditions are expected Monday as a
dry cold front, except for some drizzle early on the coast and coast
range, moves through. The strongest winds will occur east of the
Cascades by Monday evening.




Pacific Coastal Waters...Gale Watch from Tuesday afternoon through
Wednesday evening for PZZ356-376.
Small Craft Advisory until 5 PM PDT Tuesday for PZZ356-376.
Hazardous Seas Watch from late Monday night through Tuesday
afternoon for PZZ356-376.

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