Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 261602
Area Forecast Discussion
National Weather Service Medford OR
902 AM PDT TUE JUL 26 2016
.DISCUSSION...Only a few minor adjustments were made to the sky
cover this morning to reflect the current visible image. Also
removed any mention of patchy drizzle for the coast this morning
given no drizzle is being reported. Rest of the forecast is on
track fore today. We`ll be looking at couple of things today.
First will be max temperatures over the next few days for interior
locations. Second, thunderstorm potential Saturday. Max
temperatures could end up even higher than what`s forecast
Wednesday, Thursday and Friday for interior locations with the
hottest temperatures in the Rogue and Illinois Valley and valley
in Oregon and Scott, Shasta and Klamath River Basin in Siskiyou
County. A preliminary look at some of the data this morning does
not support thunderstorms development and they will likely be
removed from the forecast Saturday afternoon/evening if this
mornings GFS and EC are consistent with last nights run.
AVIATION...26/12Z TAF cycle...
Gusty winds are expected along and west of the coast today, greatest
in strength this afternoon and evening. LIFR to IFR low clouds and
fog along the coast is likely to remain locked in until about noon.
Clearing of IFR clouds in the Umpqua Basin, to include Roseburg,
should be at about 19z. VFR is expected otherwise and elsewhere. IFR
is likely to redevelop along and near the coast between 00Z and 06Z.
MARINE...Updated 330 AM PDT Tuesday, 26 July 2016...
A strong and persistent thermal trough along the coast and high
pressure offshore will continue to produce strong north winds and
steep to very steep wind driven seas through this week and into the
weekend. Gales will continue south of Cape Blanco beyond roughly 5
NM from shore with small craft advisory level conditions elsewhere.
Winds will be strongest and seas will be steepest during the
afternoons and evenings.
Surface pressure gradients tighten today through at least Thursday,
and winds just above the surface increase to as much as 50 kt. As a
result, the area of gales is expected to expand and there may be
occasional storm force gusts over a small area west of Brookings
between approximately 10 and 40 NM from shore. At that time, gales
may also briefly affect the waters north of Cape Blanco, but not
enough to warrant expansion of the Gale Warning north of the Cape.
What is more likely to occur north of the Cape, at times, is 10 foot
seas, primarily in the evening hours. It should be noted that,
unlike many of the north wind events, thus far, this summer, model
guidance indicates elevated and steep seas across all waters during
much of this north wind event. BTL/Wright
FIRE WEATHER...Updated 600 AM PDT Tuesday, 26 July 2016.
Weather conditions will turn hotter and drier through Friday.
High pressure building stronger into the Pacific Northwest will
continue to bring periods of breezy northeast winds and moderate
humidity recoveries through the week in the high terrain of Curry
and Western Siskiyou Counties. Moderate humidity recoveries are also
expected east of the Cascades. Wednesday and Thursday morning look
to be the windiest and poorest recoveries of the week for the high
terrain in Western Siskiyou and Curry counties with east to
northeast wind gusts to 25 mph and RHs in the 35-55% range.
Some weak instability on Saturday will bring a slight chance of
thunderstorms from about the Marble Mountains east-northeastward
into the Warner Mountains. Current data suggests these are more
likely to not occur than to occur, though, due to marginal moisture
and instability, and because the 500mb ridge axis is just about
directly over the forecast area on Saturday. Given the very dry
fuels we`ll have by then, any lightning would be likely to start
fires, and west winds will turn gusty Saturday and Sunday as an
upper trough approaches from the west. It appears that any
thunderstorms that do form won`t bring much rain with them. A cool
down is expected this weekend into early next week. BTL/SK
.PREV DISCUSSION... /Issued 635 AM PDT TUE JUL 26 2016/
SHORT TERM...Zonal westerly flow with a flat upper level ridge
will continue over the region today through Wednesday... with weak
disturbances moving into the area from the west. These
disturbances will have little impact on the overall hot and dry
pattern over the area though. Late Wednesday into Thursday, the
ridge will strengthen over the region. Meanwhile, at the surface,
offshore High pressure and a strengthening surface thermal trough along
the coast will bring an increasing pressure gradient today through
Thursday. This will result in increasing east to northeast flow
over the mountains with gusty winds developing tonight and
continuing through Thursday over the coastal ridges. Along the
coast and across the coastal waters, also expect gusty northerly
winds during the afternoons and evenings today through late this
Temperatures are expected to warm a couple degrees across inland
areas today and on Wednesday then another 2 to 3 degrees on
Thursday. As a result, expect inland high temperatures to warm
into the upper 90s and low 100s for many inland valleys in
Northern California and Southwest Oregon with highs in the low to
mid 90s east of the Cascades in Oregon. The Umpqua Valley will be
slightly cooler than other western valleys but is expected to warm
in to the lower to mid 90s by Wednesday. The warmest conditions
are expected Thursday and Friday. Model guidance continues to
support high temperatures reaching the low to mid 100s for valleys
in Southwest Oregon and Northern California and into the mid to
upper 90s for eastern valleys in Oregon and in the Umpqua Valley.
Offshore easterly flow will bring a Chetco effect with warming
temperatures to the Brookings area as well, especially on
Wednesday and Thursday, when highs are expected to be in the 80s
LONG TERM...Looking towards the weekend, models continue to show
some southerly mid level moisture moving up into southeast
portions of the CWA on Saturday. However, any triggers for
convective activity area weak. So have kept a only slight chance
for thunderstorms in the forecast for portions of Northern
California and east of the Cascades on Saturday. Temperatures are
expected to be slightly cooler on Saturday as a trough moves
inland to the north and brings lowering heights. The cooling trend
continues into Sunday with high temperatures returning to near
seasonal normal values.
Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Monday for
Gale Warning until 5 AM PDT Monday for PZZ356-376.