Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 260300
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
800 PM PDT WED MAY 25 2016

.DISCUSSION...26/00Z NAM in.

No thunderstorms developed Wednesday...but there were isolated to
scattered showers from the Cascades east and Siskiyous south which
were supported by an upper level short wave moving through eastern
Oregon into northern Nevada. Amounts were light and coverage
spotty. Any remaining activity will end soon.

Northwest flow aloft is now in place over the Medford CWA...and
this is usually a dry pattern. Thursday and Friday will be almost
dry.

There will be more sun Thursday south of the Umpqua Divide and
east of the Cascades where stability will be increasing and the
low levels will be drying. Temperatures Thursday will be similar
to Wednesday...which will be a few degrees below normal.

A short wave embedded in the flow will move in Thursday night and
this will support a weak front that will brush the northern
portion of the area. This front won`t be wet...but it may induce
an onshore marine push into the north coast which may bring some
drizzle to the coast and Umpqua Basin. It will increase cloud
cover over some of the remaining west side valleys...but the
southern portions will remain mostly clear under easterly flow.
It will also remain mostly clear over the east side...and this
will allow low temperatures to drop to near freezing. A Freeze
watch is now in effect for the Klamath Basin in Oregon and
California for Thursday night into Friday morning. Friday highs
will be a few degrees colder than the Thursday highs.

Upper level ridging will build in more strongly Friday night into
Saturday...bringing mostly dry conditions with a warming trend.
Saturday morning will be the coldest morning overall...and
freezing conditions may occur over the east side again. Inland
temperatures will warm to around normal values Saturday. The
current forecast does have a marine push bringing a slight chance
of showers to the north coast and Umpqua Basin...but the latest
model runs indicate it will remain dry then.

Extended discussion from the Wednesday afternoon AFD...Sunday
through Tuesday. An upper trough will move through on Sunday and
it will bring a slight chance for showers. Instability is not
significant, mainly due to the deep flow being from the west but
could be enough to generate some showers mainly for Coos, Douglas,
Northern Klamath and Lake Counties. Interestingly, the upper
trough doesn`t cool the air mass per the EC and GFS so
temperatures are forecast to be above normal for Sunday, but
future shifts may want to trim high temperatures a bit if the
upper trough becomes more potent in the models.

Drying and warming is expected for Memorial Day with
temperatures about 5 degrees above normal. The air mass warmth
will likely peak Tuesday and Wednesday but there are some
differences between the EC and GFS in terms of how warm and
whether there will be some southerly flow east of the Cascades to
promote shower or thunderstorm development. The NAEFS ensemble
mean is somewhere between the EC And GFS, and we have favored
this, meaning dry conditions and continued warming are reflected
in the forecast.

&&

.AVIATION...For the 26/00Z TAF cycle...It will be breezy this
evening, diminishing most areas by 06Z. Areas of MVFR ceilings are
expected along the coast from Cape Blanco northward and in the
Umpqua Basin mostly between 06Z and 17Z. There are some indications
that conditions will improve to VFR in the 09-12Z time frame along
the near coastal areas as cooling occurs above the boundary layer.
Otherwise, VFR will prevail. It will be breezy again later tomorrow
afternoon and evening, especially along and near the coast. BTL

&&

.MARINE...Updated 500 PM PDT Wed 25 May 2016...Strengthening high
pressure over the eastern Pacific and low pressure inland will
continue to cause north winds and seas to increase to Small Craft
Advisory levels this evening. Thursday afternoon and evening
warning level conditions are expected over portions of the
southern coastal waters area as north winds and seas peak. This
pressure pattern will then generally remain in place through the
holiday weekend. Since there is currently only low to moderate
confidence in Small Craft Advisory level conditions continuing
south of Cape Blanco each afternoon and evening through the
weekend, advisories currently end Friday evening. The higher
resolution NAM12 numerical model this afternoon indicated the band
of advisory level conditions shifting south of Point Saint George
Saturday while the GFS continues and even increases these winds in
our southern coastal waters area through the weekend. The ecmwf
indicates a decrease in winds Saturday and Sunday, increasing
again on Monday. Thus, we`ll be looking for better model consensus
before extending advisories. It does appear that conditions are
likely to subside below advisory levels for areas north of Cape
Blanco to at least Newport for Saturday and Sunday. BTL

&&

.MFR Watches/Warnings/Advisories...
OR...Freeze Watch from late Thursday night through Friday morning for
        ORZ029.
     Freeze Watch from late Friday night through Saturday morning for
        ORZ029.

CA...Freeze Watch from late Thursday night through Friday morning for
        CAZ084.
     Freeze Watch from late Friday night through Saturday morning for
        CAZ084.

Pacific Coastal Waters...Small Craft Advisory until noon PDT Thursday
        for PZZ350.
     Small Craft Advisory for hazardous seas until 11 PM PDT Friday
        for PZZ350-356-370-376.
     Gale Watch from Thursday afternoon through Thursday evening for
        PZZ356-376.
     Small Craft Advisory until 11 PM PDT Friday for PZZ356-376.
     Hazardous Seas Warning from noon to 11 PM PDT Thursday for
        PZZ356-376.

$$

15/15/15



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