Area Forecast Discussion
Issued by NWS Medford, OR

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999
FXUS66 KMFR 261151
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
451 AM PDT FRI AUG 26 2016

.Updated Aviation Discussion.

.DISCUSSION...An end to the very hot pattern continues to approach
on the horizon week from now. Above normal temperatures continue
through the weekend. Offshore flow this morning transitions to
gusty up-valley flow this afternoon as the thermal trough moves
over the east side, as the pressure gradient west to east tightens
mid afternoon. This will bring gusty up-valley winds mid
afternoon, especially in the upper valleys in eastern Jackson and
Douglas counties and the Cascades. These winds will fade towards
sunset.

The upper level ridge weakens Saturday and migrates east Sunday.
Models are in good agreement with the deepening of an upper level
trough offshore Monday. Winds also begin to become southerly
Monday, and begin to feed moisture into the region, especially at
mid levels. From Tuesday onward the GFS and ECMWF both have a
shortwave moving through on Tuesday, with slightly different
timing, the GFS being about 6 hours faster. This first front will
be mostly dry, bringing just cooler temperatures. With the broad
spread of ensemble plots have broad brushed the chances from Thursday
onward as the timing will most certainly changing in this pattern
from run to run over the next several days at least in this
pattern. the GFS is currently indicating a closed low wobbling
off the coast from Thursday onward while the ECMWF slowly migrates
an upper through through the region next weekend. With this in
mind, am not inclined to highlight nay period with higher that low
chance pops as confidence is low. Sven


&&

.AVIATION...26/12Z TAF cycle...The latest fog product shows stratus
creeping up the coast bringing IFR/LIFR to areas south of Bandon.
The offshore flow has weaken which could allow local fog with
temporary MVFR to IFR VIS to form around KOTH near sunrise. Not
confident this will happen or it will be a prevailing condition, so
kept a TEMPO in the TAF. If the marine stratus does not make it into
North Bend, then VFR cigs will continue through this afternoon, then
a marine surge will result in IFR/LIFR CIGS early this evening
through tonight. Elsewhere, VFR conditions will continue through the
TAF period. -Petrucelli

&&

.MARINE...Updated 200 AM PDT, Friday 26 August 2016...The strongest
winds early this morning will be over the outer waters. Even then
they will remain below small craft and will diminish over time this
morning. The primary threat to small craft will be from residual
fresh swell over the outer waters, but the coverage area is not as
great and this has been updated in the detailed hazards. Winds will
be light this weekend, possibly into the early part of next week as
weak low pressure resides over the area. Seas are expected to be
quite light early next week, then they may increase later in the
week as fronts move through. -Petrucelli

&&

.FIRE WEATHER...Updated 350 AM PDT, Friday 25 August 2016...Current
surface analysis shows the thermal trough centered along the west
side valleys from the Rogue Valley north to northwest through the
Umpqua Basin. Recoveries will be moderate to poor over the mid
slopes and ridges, but observations have been showing lighter winds
and expect them to remain the case. Hot temperatures and low
relative humidities are expected for one more day. As what typically
occurs this time of the year, the thermal trough will shift east of
the Cascades late this afternoon. As a result, winds shift from
east to northeast to north to northwest late this afternoon into
this evening. Additionally relative humidities could end up low
enough for red flag conditions to be met in portions of fire zones
623 and 622 with conditions in 633. Thus we`ll issue a fire weather
watch for the above mentioned areas. Details on this can be found at
PDXRFWMFR.

The models are in pretty good agreement advertising a gradual cool
down this weekend into most of next week. We could actually have max
temperatures end up below normal with higher humidities by early
next week. We could also get our first chance of precipitation
mainly for the northwest part of the region by next Wednesday.

The other item we`ll have to keep a close eye on this weekend will
be gusty west to northwest winds east of the Cascades with low
relative humidities. Right now the combination of the two should not
be enough to warrant red flag conditions, but this could change, so
watch for updates on this. Cooler than normal conditions with some
precipitation is expected in the the 6-14 day period, especially NW
sections of the area. -Petrucelli


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from 3 PM PDT this afternoon through this
     evening for ORZ622-623.

CA...None.

Pacific Coastal Waters...Small Craft Advisory for hazardous seas until 11 AM PDT this
     morning for PZZ370-376.

$$



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