Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 242137
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
237 PM PDT TUE MAY 24 2016

.Short term...Clouds this afternoon are fixed to the terrain,
especially north and west facing slopes. Showers are being
observed in similar locations, and some of these could develop
into thunderstorms. We are featuring the best chance of
thunderstorms in Northern California where HRRR output and
instability suggests lightning will have the best chance of
developing.

Showers and any thunderstorms will wane tonight as drier conditions
aloft move in from the northwest. At the surface, onshore flow will
usher in clouds that are currently situated over the Northeast
Pacific waters. Latest NAM output is showing marine clouds and the
chance for drizzle affecting the coast north of Cape Blanco and in
the Umpqua Basin.  WRF NMM and ARW precipitation fields suggest
drizzle or light rain in these areas as well. The marine push may
make it into the Rogue Valley by Wednesday morning but confidence is
lower in this aspect of the forecast.

Temperatures and conditions will be similar Wednesday and Thursday
under deep northerly to northwesterly flow. Afternoon high
temperatures will be near to just below normal and morning marine
clouds are expected to push into the coastal valleys and Umpqua
basin. The coast south of Cape Blanco should feature less clouds
due to some nighttime offshore flow.

On Friday the air mass cools slightly as an upper trough digs
southeastward from British Columbia. Continued northwest flow will
bring another round of low clouds to the coast and Umpqua Basin.
Morning drizzle will again be possible in areas where the marine
layer penetrates with the rest of the forecast area remaining dry.

Of note are the expected cold overnight lows and potentially
freezing conditions around Klamath Falls Friday and Saturday
morning, particularly Saturday morning. We will be focusing on this
in the next few shifts to determine whether any freeze products are
necessary.

.Long Term...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 24/18Z TAF Cycle...Conditions will remain
generally VFR through this evening. Showers and isolated
thunderstorms will develop this afternoon, especially from the
Cascades and Siskiyous eastward. these should diminish 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 TAF period. -BPN

&&

.Marine...Updated 840 AM PDT Tue 24 May...As low pressure moves
inland today and high pressure to the northwest strengthens, north
winds will increase today 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,
possibly reaching gales, late this week into the weekend. Seas will
be wind driven with little contribution from swell, thus sea state
will closely follow wind conditions. Lighter north winds and sea
state will occur north of Cape Blanco. -BPN/Wright


&&

.MFR Watches/Warnings/Advisories...
OR...None.

CA...None.

Pacific Coastal Waters...None.

$$

NSK/BPN/BPN


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