Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 231500
Area Forecast Discussion
National Weather Service Medford OR
800 AM PDT SAT JUL 23 2016
.DISCUSSION...23/12Z NAM in.
Lots of marine stratus over the coastal waters...mostly north of
Cape Blanco...along the north coast...and in the Umpqua Basin.
Mostly clear skies prevail over the remainder of the Medford
CWA...and the stratus should clear to the offshore waters later
Flow aloft remains nearly westerly this morning. The upper level
pattern will alternate between weak zonal flow and weak
troughing through Wednesday...with little in the way of short
wave activity over our area. The ridges of the coast range will be
dry and breezy during the overnight hours due to low to
moderate...but persistent...easterly low level flow. Stronger
winds have returned to the coastal waters due to the strengthening
Temperatures will warm through Monday. Highs in the Umpqua Basin
will warm to near normal values by Sunday...and inland highs over
the remainder of the area will warm to 5 to 10 degrees above
normal. High temperatures will warm around 5 degrees or so over
the west side and northern California Monday through
Wednesday...but only a degree or two over the east side during
Upper level ridging will build in more strongly Wednesday into
Thursday...bringing hotter temperatures to the area. Inland highs
Thursday will warm to 5 to 10 degrees above normal over Oregon and
10 to 15 degrees above normal over northern California.
The ridge will begin to weaken Thursday into Friday as short waves
embedded in the westerly flow move through...but inland
temperatures will keep on warming through at least Friday...when
the highs will be 10 to 15 degrees above normal.
The ridge will weaken further Saturday as more short waves move
through. Inland temperatures will cool a few degrees. The 23/06Z
model runs indicate the possibility of afternoon and evening
thunderstorms beginning next Saturday. Yesterday the 22/06z
indicated that possibility for Friday...then backed off in the
22/12z runs. Let`s see if history repeats itself today.
.AVIATION...23/12Z TAF cycle...MVFR cigs in low clouds returned to
the Coquille and Umpqua Valleys overnight. These clouds will
dissipate this morning with clear skies expected by 18Z. Low level
northerly winds at the coast will become strong this afternoon and
evening with local gusts to 35 KT. A similar/slightly less extensive
intrusion of low clouds into Coos and Douglas Counties is expected
late this evening into Sunday morning. Skies will remain clear
elsewhere through Sunday morning. -DW
.MARINE...Updated 300 AM PDT Saturday 23 July 2016...High pressure
offshore will strengthen and a thermal trough will deepen over
northern California today then remain strong much of next week.
This will result in an extended period of strong north winds and
steep, hazardous seas. Winds will be strongest and seas will be
steepest during the afternoons and evenings beyond 10 nm from shore
south of Cape Blanco. Gales are expected in that area with small
craft advisory conditions over the remainder of the waters. With
excellent run to run consistency in the GFS, ECMWF and latter
portion of the NAM, the gale watch that was in effect for next week
has been upgraded to a gale warning.
.FIRE WEATHER...Updated 500 AM PDT Saturday 23 July 2016.
It will be hot with low humidity through the next week. The
breeziest afternoon winds on Saturday will be in north to south-
oriented valleys west of the Cascades and into Siskiyou County. A
surface thermal trough will deepen along the coast and result in
periods of breezy east winds over the coastal ridges and the
ridges in Western Siskiyou County with moderate humidity
recoveries from tonight into Thursday. Tonight may feature a brief
period of poor to moderate recoveries above 5000 feet in Western
Siskiyou County and in the Cascades...and this similar situation
may affect the Coast Range Wednesday night. Another aspect of the
forecast worth noting is higher Haines Index on Sunday (meaning
very dry and unstable conditions) with widespread values of 5.
Readings are forecast to approach but not reach a 6 in Lake and
Modoc Counties. Lastly, weak instability may develop on day
7/Saturday. We will leave a mention out of the forecast at this
early juncture and await a consistent model solution.
Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Thursday
Small Craft Advisory for hazardous seas until 2 PM PDT this
afternoon for PZZ356-376.
Small Craft Advisory from 2 PM this afternoon to 5 AM PDT
Thursday for PZZ350-370.
Gale Warning from 2 PM this afternoon to 5 AM PDT Thursday for