Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 301758
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1057 AM PDT Thu Mar 30 2017

.Updated Aviation Discussion.

.DISCUSSION...No updates planned this morning. The bulk of the
precipitation associated with last night`s frontal system has
moved off to the east. Moist, onshore flow in the wake of the
system will continue to produce some showers today, especially
over the upslope areas west of the Cascade crest. We will also see
gusty northwest winds across the east side, and a wind advisory
remains in effect for portions of Lake and Modoc counties through
this evening. -Wright

&&

.AVIATION...30/18Z TAF CYCLE...The main concern will be moderate to
strong winds east of the Cascades, including Klamath Falls into
early this evening.

VFR conditions are expected to be the predominate condition through
this evening. However cannot rule out MVFR CIGS in showers this
morning in the Umpqua Basin, including Roseburg and kept them as the
prevailing condition in the TAF until 21z. Also partial mountain
obscuration is possible into this afternoon.

VFR conditions will continue tonight into Saturday morning.  There
is a chance for MVFR cigs to develop in the Umpqua Basin, including
Roseburg around 8z, but confidence on the timing and these
conditions developing are low to medium so watch for updates on
this. -Petrucelli

&&

.PREV DISCUSSION... /Issued 319 AM PDT Thu Mar 30 2017/

DISCUSSION...Showers are continuing this morning behind the
departing cold front. Snow levels have dropped to around 3500
feet, but as precipitation is on the lighter side, no significant
accumulations are expected. Showers should taper off through the
day and come to an end by this evening as high pressure builds
into the region.

The front itself was not a major wind producer, but high pressure
to our north and west and low pressure to the south and east will
produce a tightened gradient, and cold air will spill into the
region. As a result, breezy northwest winds are expected over
much of the region, especially for higher terrain, gaps and
passes, and any northwest to southeast oriented valleys, but the
strongest winds are likely to develop over the East Side. A Wind
Advisory continues for portions of Lake and Modoc Counties today,
and details can be found in the Weather Message PDXNPWMFR.

Clearer skies and a cooler air mass are expected to produce cold
morning lows Friday, and frost is possible in the West Side
valleys.

Ridging and high pressure will keep the area dry through Friday
and into Saturday, until the trailing edge of a dissipating front
to our north glances Southern Oregon on Saturday afternoon. Models
are in agreement that an upper level trough will pass in the
vicinity, but vary in the strength and track. Models are also
producing some form of frontal development directly over the area
late Saturday or Sunday, but there is no agreement on timing or
exact location. With such low confidence, have kept at least a
chance of showers in the forecast during this time, but some
changes are likely forthcoming as models attempt to come to some
consensus during the next several forecast cycles.

One note of concern for Saturday and perhaps Sunday will be the
increased risk for sneaker waves along the Southern Oregon coast.
A large and very energetic wave train will make its way into the
coastal waters, and this type of pattern has been known to produce
sudden higher waves with significant sweep across the beaches.
Given the more pleasant weather Saturday, and area Spring Break
travel and recreation ongoing, have issued a Beach Hazard
Statement to illustrate the increased risk. Those on area beaches
Saturday should be aware of this risk, and be extra vigilant for
sudden changes in wave conditions, even if the ocean appears
unthreatening.

The on-again, off-again pattern is expected to continue for the
remainder of the forecast term, with high pressure and dry
conditions returning Monday and Tuesday, then another wet front
arriving by midweek. Due to the wide range of solutions during the
long term, there is little confidence in the details, so will wait
to refine these as focus sharpens in the coming days. -BPN

MARINE...Updated 300 AM PDT Thursday 30 March 2017...Seas will
remain steep this morning due to west swell around 10 feet at 14
seconds. Westerly swell will diminish early this afternoon. High
pressure will build west of the waters today and persist on
Friday. This will bring increasing north winds today into tonight.
An area of small craft advisory level winds and seas is expected
to develop late this afternoon and this evening for locations
south of Brookings within 25 nm of shore. North winds are expected
to lower below small craft levels tonight and Friday. A
disturbance will move across the area late Saturday and Sunday.
High and very long period west swell is expected to arrive late
Saturday into Sunday. This may bring dangerous bar crossings and
possible high surf to the coast.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from Saturday afternoon through Sunday
     morning for ORZ021-022.
     Wind Advisory until 11 PM PDT this evening for ORZ031.

CA...Wind Advisory until 11 PM PDT this evening for CAZ085.

Pacific Coastal Waters...Small Craft Advisory from 5 PM this
afternoon      to 11 PM PDT this evening for PZZ356-376.      Small
Craft Advisory for hazardous seas until 11 AM PDT this      morning
for PZZ350-356-370-376.

$$


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