Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 250305
Area Forecast Discussion
National Weather Service Medford OR
805 PM PDT TUE MAY 24 2016
.DISCUSSION...25/00Z NAM in.
A long wave upper level trough remains over the western U.S. this
evening...but the Medford CWA is on the relatively dry west side
of the axis with northwest to north flow aloft. Still...short
waves moving through the trough are creating unstable conditions.
Isolated thunderstorms developed over Siskiyou county...western
Modoc county...and southern Josephine county this afternoon.
There were light showers over the remainder of the area with the
exception of the coast and Umpqua Basin...which remained dry.
A long wave ridge will build into the area tonight through
Wednesday evening...and this will bring in drier weather and
warmer temperatures. The exception will be the coast and Umpqua
Basin...which will see increased cloud cover and maybe some
drizzle due to an onshore marine push.
Wednesday will likely be the warmest of the next several days
over the west side and Thursday will be the warmest over the
remainder of the area. High temperatures will be near normal
values on the warmest day. A short wave moving through eastern
Oregon will bring a chance of showers and isolated thunderstorms
over the southern Oregon east side and the California zones
A strong short wave will dive down the backside of the trough
Thursday night into Friday. Previous model forecasts brought this
low into Oregon...but the latest runs indicate it will remain over
Washington state. Temperatures will still cool and there will
still be some showers around though...mostly over the northern
portions of the Medford CWA. Easterly flow will develop Thursday
night...and this will make for gusty winds and moderate RH
recoveries over the west side ridges south of Douglas County.
Cold overnight lows and potentially freezing conditions may become
an issue around Klamath Falls Friday and Saturday morning.
Advisories or warnings may be necessary at some point later this
Long Term discussion from the Tuesday afternoon AFD...Saturday
through Tuesday Night. Saturday, the upper level trough shifts
east and out of the region, and a ridge will attempt to build into
the forecast area. However, another wave will try and dig south
along the West Coast at the same time, and essentially, the area
becomes the battleground for the two opposing forces. While the
trough will provide northwest flow, and therefore will bring some
moisture into the region, the ridge to the south will inhibit much
lift. Therefore, expect precipitation to remain confined just to
our north. This push and pull between the upper level features
continues through the weekend and into early next week, but no
discernible winner appears in the current model suites.
Given the current solutions and trends over the past 24 hours, have
adjusted the forecast towards a dry solution throughout the extended
term, removing mention of showers beyond Saturday afternoon. The
models do agree on a steady warming trend through the period, with
the thermal trough finally beginning to make a push northwards by
Tuesday. With this in mind, have trended temperatures warmer through
the weekend and into early next week, resulting in highs of about 5
to 10 degrees above seasonal normals by Tuesday. -BPN
.AVIATION...For The 25/00Z TAF Cycle...Conditions will remain
generally VFR through this evening. Showers over are in place inland
with isolated thunderstorms mostly in Siskiyou county and the
Kalmiopsis and will taper off late in the evening. Areas of mvfr/ifr
are expected to return to the coast and Umpqua basin tonight, and
some lower cigs are possible in the Rogue Valley as clouds bank up
against the Siskiyous and Cascades. Expect mountain obscurations in
these areas as well. All other locations will remain VFR through the
.MARINE...Updated 500 PM PDT Tue 24 May...With low pressure inland
today and high pressure to the northwest strengthening, north winds
will increase tomorrow and persist at least into early next week.
Winds will reach small craft advisory levels over the waters south
of Cape Blanco late Wednesday and remain at least that strong
through the remainder of the forecast period. Winds will peak
Thursday with low pressure deepest on the coast. the low pressure
moves inland Friday with winds decreasing into the weekend.
Pacific Coastal Waters...None.