NWS Medford, OR wrote its last area forecast discussion before the first event at Oct 13, 9:57 AM PST, 3 hours 3 minutes earlier.
Area forecast discussion, Oct 13, 9:57 AM PST, 3 hours 3 minutes before
Area Forecast Discussion
National Weather Service Medford OR
1057 AM PDT THU OCT 13 2016
Updated Aviation Section
.DISCUSSION... Morning update. With the southwest aspect of the
winds in the Illinois valley, and stronger ridge winds have included
more of the west side in the wind advisory. Sven
.AVIATION...13/18Z TAF CYCLE...Moderate to heavy rain will
occur along the coast this afternoon into early this evening as a
front moves onshore. This will bring widespread MVFR CIGS with local
IFR CIGS/VIS in the heaviest rain. As the frontal system moves
onshore, expect these conditions to shift inland with terrain
obscured. The band of moderate to heavy rain associated with the
front will last 3-6 hours as it moves through the west side this
evening, then eventually through the Cascades to the east side
overnight.
In addition, increasing winds and low level wind shear will
be problems for most sites through this evening. Wind gusts to 40
kt are possible at KOTH/KLMT late this afternoon/evening. An
airport weather warning has been issued for the KLMT airport
highlighting the risk. Some south to southeast wind may also surface
at KMFR/KRBG for a few hours prior to the frontal passage
this afternoon and evening. Winds will drop off after frontal
passage, first along the coast later this evening, then east of the
Cascades overnight. -Spilde
Note: The ceilometer at FAA site KOTH is out of service, so there
will be no ceiling observations available generally between the
hours of 04Z and 14Z.
&&
.PREV DISCUSSION... /Issued 400 AM PDT THU OCT 13 2016/
DISCUSSION...The first of two strong storms will arrive today,
bringing strong winds and heavy rains to our area. While this
storm alone would be notable in terms of winds and rain, it will
be overshadowed by the second storm that is set to arrive on
Saturday. While not as prodigious of a rainmaker as the first, the
second storm has the potential to produce extremely damaging and
even deadly winds over a wide swath of the Pacific Northwest.
Confidence is increasing in this particularly hazardous system,
and all model output suggests that the Saturday event could be one
of the strongest to impact the area in quite some time, perhaps
even rivaling the great Columbus Day storm of 1962. It should be
understood that many uncertainties remain, and just a small change
in the timing or track of the storm could produce significant
changes to the forecast. However, if current model trends hold,
extensive damage including tree blow- downs and widespread power
outages are possible for the western half of Oregon, as well as
extensive wind and wave damage along the coastline. Preparations,
if not already underway, should be taken immediately in order to
prevent the loss of life or property, and any outdoor activities
or travel on Saturday should be strongly reconsidered.
The leading edge of today's storm has already begun to make its
way onshore, as light rain has moved in overhead, mainly as a
result of warm advection ahead of the upcoming cold front. The
front itself will arrive at the coats this afternoon and push
through the rest of the forecast area this evening and tonight.
Winds will be strong along and ahead of the front, and High Wind
Warnings remain in effect for the coast, the Shasta Valley, and
the East Side. Wind advisories are also in effect for the Ashland
to Talent area,and for lesser exposed areas of the East Side. For
more detail on these, see the hazardous weather message at
PDXNPWMFR.
Also with this system, models continue to produce moisture
transport values that have not been seen during this part of the
season for at least the last 30 years. Current rainfall amounts
between now and early next week, including both storms, could be
more than the typical rainfall for the entire month of October,
and for the Medford airport, could be the wettest 5 day period in
October since 1962. With this much water, there remain concerns
for urban and small stream flooding along the coast, as well as
debris flows over recent burn scars, but for most of the area, the
lower river levels should allow for plenty of capacity and no
major hydrologic issues are expected.
After a brief and showery break Friday, the second storm is
forecast to arrive on Saturday. This storm, while not the
rainmaker of the first, will be much stronger in terms of wind.
Similar to the moisture values in the first storm, models are
producing very low pressure values and very high wind speeds with
this storm, reaching values that have not been seen during this
part of the season for at least the last 30 years. Much of this is
the result of an explosive cyclogenesis that is expected to occur
just offshore of Oregon, much closer to the coast than surface
lows typically form during this time of year. Another source of
energy will be the remnants of Typhoon Songda, which have been
ingested into the Westerlies and will wrap itself into the storm
as it approaches our coastline. This tropical connection, as well
as the forecasted track of the surface low, are just two of
several eerie similarities between this storm event and the
Columbus Day storm of 1962, which was the most destructive storm
on record to hit the Pacific Northwest. However, much can change
over the next several forecast cycles, and despite the very
consistent model solutions, some uncertainties remain, and only
slight changes to the storm track or timing could easily result in
a very different forecast. Therefore, while confidence is
increasing, and this very dangerous storm appears more and more
likely, have kept the current High Wind Watches in effect but
extended the areas to reflect the higher anticipated wind speeds.
Also, should the current model solutions verify, additional Wind
Advisories or even High Wind Warnings may be necessary for nearly
the entire West Side.
Both events will also produce very heavy seas, and High Surf
Warnings are in effect for the coastline. Adding to the hazard,
spring tides are approaching, and higher than normal tides will
combine with a 1 to 2 foot storm surge and the heavy seas to
produce damaging waves and very hazardous beach conditions.
Jetties and exposed areas of the coast will be particularly
hazardous, and venturing out in these areas could be deadly
throughout the next several days.
By Sunday morning, the worst of the event should be over, and
showers will continue into Monday. A much weaker system is
expected to arrive Monday afternoon into Tuesday, then the
forecast trends drier and slightly warmer for the remainder of the
term.
With the expected hazardous and life-threatening conditions
across the region late this week and through this weekend, it
would be wise to prepare for power outages and possible damage,
and stay up to date with the latest forecasts and warnings. -BPN
MARINE...Updated 245 AM PDT Thursday, October 13, 2016...Winds
are approaching gale force this morning and will continue ramp up
through the morning. Widespread storm force winds with local
hurricane force gusts will occur over our waters this afternoon as
an already strong wind field is compressed between a strong
incoming front and the coastal terrain (known as a coastal jet). A
storm warning remains up for much of our waters through this
evening.
The front moves inland tonight, and winds relax. Winds will be gusty
but not particularly strong from tonight through Friday night as we
are in between systems. Nevertheless, a very high and steep fresh
west swell will keep high seas going through this period, thus
conditions will remain hazardous to most craft. A hazardous seas
warning has been issued to fill in this gap.
Another very strong storm system will affect the Pacific Northwest
on Saturday. The remnants of typhoon Songda are currently chugging
along through the westerlies near 40N and the international date
line. It will deepen explosively as it recurves to the north off the
Pacific Northwest coast on Saturday. It no longer matters which
model one chooses, the result will be a significant windstorm over
our coastal waters. The more disturbing 13/00Z models (European/NAM)
show a 970-975 mb low skirting our waters just to the west, whereas
the GFS shows a much deeper low (956 mb) passing further north and
west of us. The Canadian solution lies somewhere between them all.
The solutions basically range from widespread hurricane force
sustained winds (European/NAM) to frequent hurricane force gusts
(GFS). For this reason, the Storm Watch we have in effect for
Saturday has been increased to a Hurricane Force Wind Watch for
portions of our waters - mainly in the typical coastal jet formation
area from near shore to around 30 NM offshore. -Wright
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 2 PM this afternoon to 8 AM PDT Friday
for ORZ029>031.
High Wind Watch from Saturday morning through Sunday morning for
ORZ029>031.
High Surf Advisory from noon today to 5 PM PDT this afternoon
for ORZ021-022.
High Surf Warning from 5 PM this afternoon to 5 AM PDT Friday
for ORZ021-022.
High Wind Warning from 11 AM this morning to 11 PM PDT this
evening for ORZ021-022.
Flood Watch from 11 AM PDT this morning through late tonight for
ORZ022.
High Wind Watch from late Friday night through Saturday evening
for ORZ021-022.
High Wind Watch from Saturday morning through Saturday evening
for ORZ027-028.
Wind Advisory from 2 PM this afternoon to 11 PM PDT this evening
for ORZ026.
CA...High Wind Warning from 2 PM this afternoon to 8 AM PDT Friday
for CAZ085.
High Wind Watch from Saturday morning through Sunday morning for
CAZ084-085.
Wind Advisory from 2 PM this afternoon to 8 AM PDT Friday for
CAZ084.
Flash Flood Watch from 2 PM PDT this afternoon through late
tonight for CAZ080.
High Wind Warning from 2 PM this afternoon to 11 PM PDT this
evening for CAZ081.
High Wind Watch from late Friday night through Saturday evening
for CAZ081.
Pacific Coastal Waters...Storm Watch from late Friday night through
Saturday evening for PZZ350-356-370-376.
Hurricane force wind Watch from late Friday night through
Saturday evening for PZZ350-356-370-376.
Storm Warning from 11 AM this morning to 11 PM PDT this evening
for PZZ350-356-370-376.
High Surf Advisory from noon today to 5 PM PDT this afternoon
for PZZ350-356.
Hazardous Seas Warning from 11 PM this evening to 5 AM PDT
Saturday for PZZ350-356-370-376.
Small Craft Advisory until 11 AM PDT this morning for
PZZ350-356-376.
Gale Warning until 11 PM PDT this evening for PZZ356-376.
High Surf Warning from 5 PM this afternoon to 5 AM PDT Friday
for PZZ350-356.
Gale Warning until 11 AM PDT this morning for PZZ350-370.