Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 230545
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1045 PM PDT FRI JUL 22 2016

.UPDATE...See the Aviation ane Marine Updates below.

.AVIATION...23/06Z TAF cycle...IFR/MVFR cigs in low clouds will
return to the coast around midnight and continue through early
morning on Saturday. Inland expect some area of MVFR cigs to develop
in the Umpqua Valley and south into the Grants Pass area late
tonight and early Saturday morning. Low CIGS are expected to
dissipate around 16z. Other areas inland will remain VFR through the
TAF period. Gusty winds are expected along coastal areas Saturday
afternoon. -FB

&&

.MARINE...Updated 900 PM PDT Friday 22 July 2016...High pressure
will strengthen offshore and a thermal trough will develop over
northern California tonight 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. But, beginning on Saturday seas will at least
be hazardous to small craft elsewhere. A gale watch remains in
effect for the southern waters beyond 10 nm from shore for Saturday
afternoon through late Wednesday night. -FB

&&



&&

.PREV DISCUSSION... /Issued 839 PM PDT FRI JUL 22 2016/

DISCUSSION...High temperatures today are about 5 degrees warmer
than yesterday, and we can expect another 5 degrees warming on
Saturday as the ridge will start to build into our forecast area
Saturday. We are still expecting onshore flow into Coos and
Douglas Counties and there is still plenty of low level moisture.
Expect low clouds to develop in the Umpqua Basin again late
tonight and we have updated the sky grid to reflect this trend.
The latest NAM12 is consistent with a strong warming on Monday
and the forecast high of mid to upper 90s for the Rogue Valley
next week is reasonable. /FB

AVIATION...23/00Z TAF cycle...IFR/MVFR cigs in low clouds are
expected to return to the coast this evening and continue through
early morning on Saturday. Inland expect some area of MVFR cigs to
develop in the Umpqua Valley and south into the Grants Pass area late
tonight and early Saturday morning. Low CIGS are expected to
dissipate around 16z. Other areas inland will remain VFR through the
TAF period. Gusty winds are expected along coastal areas Saturday
afternoon. -CC

MARINE...Updated 900 AM PDT Friday 22 July 2016...High pressure
will strengthen offshore and a thermal trough will develop 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. But, beginning on Saturday seas will at least be
hazardous to small craft elsewhere. A gale watch remains in effect
for the southern waters beyond 10 nm from shore for Saturday
afternoon through late Wednesday night. -DW/SK

FIRE WEATHER...Updated 200 PM PDT Friday 22 July 2016.
There is high confidence in a hot and dry forecast through at
least Thursday. Onshore flow is weakening across the area, and the
marine push tonight into Saturday morning west of the Cascades will
not be as substantial as this morning.

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 develop 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
Saturday night 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 the expected Haines Index value of 6 (meaning very
dry and unstable conditions) east of the Cascades and in Modoc
County on Sunday. Lastly, weak instability may develop at the end of
next week...Friday or Saturday...but until then, no thunderstorms
are expected. /SK

PREV DISCUSSION... /Issued 340 PM PDT FRI JUL 22 2016/

Updated fire weather discussion.

DISCUSSION...22/12Z NAM/GFS/EC in.

Lots of marine stratus over the coastal waters...mostly north of
Cape Blanco...along the north coast...and in the Umpqua Basin.
Also quite a bit in the Rogue Basin. Mostly clear skies prevail
over the remainder of the Medford CWA...and the stratus should
clear to the offshore waters later today.

Flow aloft has turned westerly behind a long wave trough that moved
onshore earlier this morning. Precipitation has ended and today
will be the first day of a dry stretch that will last through most
of next week...maybe longer. The upper level pattern will
alternate between weak zonal flow and weak troughing...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 flow. Stronger
winds are returning to the coastal waters as the thermal trough
returns to the coast.

Temperatures will warm Saturday 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. Temperatures will warm a degree or two a day
from Monday through Wednesday.

Upper level ridging will build in more strongly towards the end of
next week...bringing hotter temperatures to the area. Inland highs
will warm to around 10 degrees above normal...possibly even
higher...at that time. The Medford area may see highs over 100
degrees by the end of next week.

The 22/06Z model runs indicated the possibility of afternoon and
evening thunderstorms beginning next Friday. The 22/12Z runs came
in dry for Friday...so will hold off putting thunder in the
forecast for now. Maybe next Saturday.

AVIATION...22/18Z TAF cycle...Daytime heating and weakening onshore
flow is helping ceilings to lift and clear early this afternoon at
the north coast and lower Umpqua Basin. Elsewhere, VFR conditions
will continue with mostly clear skies through the TAF period.
Marine clouds are expected to return to the coast this evening
then into areas of the Umpqua Valley for a few hours early
Saturday morning. The stratus on Saturday morning is expected to
dissipate by 16Z. -DW/SK

MARINE...Updated 200 PM PDT Friday 22 July 2016...High pressure
will strengthen offshore and a thermal trough will develop
along the coast of Northern California and far Southern Oregon today
then will strengthen Saturday. Models show that this thermal trough
will remain strong this weekend and into 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.

Today expect small craft advisory conditions for areas south of Cape
Blanco then for Saturday and Sunday  expect areas of gales south of
Cape Blanco beyond 10 nm from shore with small craft advisory
conditions developing elsewhere. A gale warning is in effect for the
southern waters beyond 10 nm from shore for Saturday afternoon
through Sunday evening with a gale watch Sunday night through
Wednesday. Models do show variability for Monday on how strong winds
will be as a disturbance moves into the area, which may weaken the
thermal trough slightly and decrease the area of gales. However for
Tuesday through Wednesday, models show moderate to high confidence
of gales returning for areas south of Cape Blanco. -CC

FIRE WEATHER...Updated 200 PM PDT Friday 22 July 2016.
There is high confidence in a hot and dry forecast through at least
Thursday. Onshore flow is weakening across the area, and the marine
push tonight into Saturday morning west of the Cascades will not be
as substantial as this morning.

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 develop 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
Saturday night 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 the expected Haines Index value of 6 (meaning very
dry and unstable conditions) east of the Cascades and in Modoc
County on Sunday. Lastly, weak instability may develop at the end of
next week...Friday or Saturday...but until then, no thunderstorms
are expected. DW/SK

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Thursday for PZZ356-376.
     Small Craft Advisory for hazardous seas until 2 PM PDT Saturday
     for PZZ356-376.
     Small Craft Advisory from 2 PM Saturday to 5 AM PDT Thursday for
     PZZ350-370.
     Gale Watch from Sunday evening through late Wednesday night for
     PZZ376.
     Gale Warning from 2 PM Saturday to 11 PM PDT Sunday for PZZ376.

$$

FJB/JRS/FJB


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