Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 241615
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
915 AM PDT SAT SEP 24 2016

.DISCUSSION...Low-level moisture left behind yesterday`s frontal
system is producing plenty of cloud cover and areas of fog this
morning over the West Side valleys and also much of the Klamath
Basin. The 12z Medford sounding is showing much drier air moving
in over the ridges above about 6500 feet as the subsidence
inversion lowers. Expect the low clouds and fog to yield to
sunshine late this morning and early this afternoon as daytime
heating mixes out the inversion. We`ll see at least a 15-20
degree pop in maximum temperatures today compared to
yesterday...some areas even more than that.

Offshore east-northeast flow develops in earnest tonight into
Sunday with enough drying over the upper slopes and ridges of
Curry/western Josephine and western Siskiyou Counties for fire
weather concerns. Recent rainfall may temper these concerns a bit,
but holdover fires are also possible in those area from mid week
lightning. The stronger winds expected combined with poor
overnight humidity recovery may cause any new or existing fires to
spread quickly. A fire weather watch is out and we`ll be making a
decision on whether or not to upgrade/expand it. See fire weather
discussion below for more details. Another stretch of hot weather
is expected Sunday-Tuesday before cooling sets in mid-late next
week. -Spilde

&&

.AVIATION...24/12Z TAF CYCLE...Residual moisture from yesterday`s
front has congealed into stratus in the valleys and produced
widespread LIFR CIGs with LIFR VIS in fog in some locations as well.
This will continue through mid morning, then burn off to VFR in all
areas. The air mass dries out significantly today, and VFR is
expected to continue through tonight at all locations. -Wright

&&

.MARINE...Updated 200 AM PDT Saturday 24 September 2016...Winds and
seas have dropped below small craft advisory criteria this morning
as a front has moved inland. This break will only be brief as a
thermal trough will bring strong north winds and wind driven seas
back to the area this evening and continuing through Sunday night.
Winds have already shifted to north over much of the area, and they
will increase through the day and reach small craft advisory levels
south of Cape Blanco this evening. Conditions will improve
temporarily again on Monday, but north winds return, possibly
reaching gales by mid week. -Wright

&&

.FIRE WEATHER...Updated 205 AM PDT Saturday 24 September 2016...
There is quite a bit of residual moisture around this morning, and
humidities are high across the board. However, a big change will
commence today as an upper ridge and surface thermal trough develop
over the region. The signs are there as winds are starting to become
offshore over the coastal mountains already this morning. Today will
be noticeably warmer and drier than the last couple of days, and
then a heat wave commences Sunday with temperatures soaring to at
least 20 degrees above normal.

Conditions will be close to critical in Oregon zone 619 tonight, but
some question remains as to how dry they might get with the light
rain that fell over the last 24 hours. The fire weather watch will
be continued there until we can see how the models handle the
moisture.

Wind speeds peak tonight and Sunday morning, then humidities really
take a nose-dive Sunday through Monday. Both days will be extremely
dry, and recoveries Sunday night will be moderate to poor in many
locations. Some of the coastal mountain sites may not get out of the
teens Sunday night. As I mentioned yesterday, the strongest winds do
not quite line up with the lowest humidities, so the entire period
of tonight through Tuesday will be near critical conditions in
various places at various times, but nothing really stands out as
obvious red flag conditions at this time. We will continue to
headline much of the area and watch it closely. -Wright

&&

.PREV DISCUSSION... /Issued 416 AM PDT SAT SEP 24 2016/

DISCUSSION...
Plenty of low clouds and areas of fog, as well as a few drips and
drabs of drizzle exist across the forecast area this morning.
These are the lingering effects of the warm front that pushed in
across the area yesterday. We expect skies to clear today and high
temperatures this afternoon to be 15 to 20 degrees warmer than
were observed on Friday.

Minor adjustments were made to temperatures and the forecast in
general through next Thursday. Primary adjustments made were to
lower high temperatures some across the interior west side today
through Monday, as seasonality and recent moisture should curtail
highs from reaching the maximums that the summer sun angle would
yield. That said, we expect a moderate east wind event tonight
through Monday morning across the upper slopes and ridges of
southwestern Oregon and Northwestern California, so retained near
record warmth for the coast and near coastal areas for Sunday
afternoon.

Early to mid next week the warmth appears as if it will hold a bit
longer than was previously advertised, but then the low pressure
trough sinking southeast from the Gulf of Alaska checks us back to
normal to below temperatures Thursday through next weekend. The
numerical models have continued with the idea of another
appreciable trough of low pressure moving into the forecast area.
Currently, the ECMWF indicates more precipitaion than the GFS, but
the general pattern supports another round of rainfall across the
area next weekend, so have entered/increased precipitation
probabilities for that time period. Details to be determined. BTL

CLIMATE...Updated 255 AM PDT, Saturday Sep 24, 2016...
Friday morning was the coldest September 24th on record at Klamath
Falls International Airport, with a low of 26 degrees. The old
record was 28F set in 1961.

With a high of just 60F, Medford had the 6th lowest high on
record for the calendar date on Friday. This was the coldest
September 23rd at Medford since 1986, when it was only 54F. BTL

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from this evening through Sunday morning for
     ORZ619-620.

CA...None.

Pacific Coastal Waters...Small Craft Advisory for hazardous seas from
     5 PM this afternoon to 5 AM PDT Monday for PZZ350-356-370-376.
     Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Monday
     for PZZ376.

$$

MAS/BTL/TRW



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