Flood Watch 8, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
1000 AM PST Wed Nov 23 2016

UPDATED AVIATION

.DISCUSSION...The shortwave moving through the area this morning
is producing widespread rain/snow showers along and west of the
Cascades with isolated to scattered snow showers over the East
Side. We had a couple of reports this morning of locally lower
snow levels in some of the heavier showers - one from Williams in
Josephine County (around 1650 feet) and another from Humbug Creek
in Jackson County (2000 feet). But the snow level, in general, is
between 2500 and 3500 feet this morning. The lower passes along
I-5 north of Medford (Sexton, Stage, Canyon Creek and Smith Hill)
are all just wet at this time. Web cams are showing some snow over
the major passes south of Meford (Siskiyou Summit and Black
Butte), as well as all the routes over the Cascades to the East
Side, where roads are very slippery. So, please use extra caution
if traveling out there this morning. The winter weather advisory
at WSWMFR is out until 10 am.

The shortwave and trough axis will shift well to our east this
afternoon and showers will diminish...though won't completely go
away along and west of the Cascades, where onshore flow will be
strong enough to keep some going.

We will be shifting our focus though to the next strong front and
trough expected to approach the area tonight and on Thanksgiving
Day. Winds will increase to gales over the marine waters and some
rain ahead of the front is expected to reach the coast by
morning. Low pressure will develop offshore on Thanksgiving Day
and deepen as it heads toward Vancouver Island. This will slow the
front's forward progression Thursday night, so precipitation
during this time frame will be mostly from the Cascades westward.
However, winds will increase along the coast and eventually inland
(Shasta Valley/East Side) as pressure gradients tighten. We have a
high wind warning (NPWMFR) along the coast. Additional wind
headlines for inland areas may be necessary soon. Rainfall will
be substantial Thursday night into Friday morning along the coast,
especially the south coast in the Curry Coast ranges, where
orographic lift will enhance precipitation rates. This will bring
rapid rises to area rivers, creeks and streams and possible
flooding, depending on rain intensity. Another area of low
pressure is expected to develop offshore then move into northwest
California or southwest Oregon late Friday through early Saturday
morning. This will bring another round of moderate to heavy
precipitation, especially to SW portions of the CWA. The upper
trough will dig southward through the area Saturday through
Saturday night, which will lower snow levels down to 2000-2500
feet. Some snow may even occur down to the passes north of Medford
by early Sunday morning. This trough is expected to move south of
the area, so lingering showers Sunday morning should diminish. If
you have travel plans for Sunday, please continue to monitor
forecasts for any updates should conditions change. -Spilde

&&

.AVIATION...23/18Z TAF cycle...A series of shortwave disturbances
will continue to produce scattered light rain showers and snow
showers this morning, with snow levels near 3500 to 4000 feet.
Expect visibility lowered to IFR in heavier showers. Showers should
clear this afternoon, except for the coast and Umpqua basin which
will continue to get rain today and tonight. Expect ceilings to lift
to VFR to MVFR this afternoon, and continue as MVFR/VFR for the
remainder of the TAF period. -MSC

 Note: The ceilometer at FAA site KOTH remains out of service, so
there will be no ceiling observations available generally between
the hours of 04Z and 14Z.

&&

.MARINE...Updated 230 aM PST Wednesday, 22 November 2016...Several
strong frontal systems will pass through the area over the next
week. During this time, conditions are unlikely to decrease below
small craft advisory levels either from wind, wind waves, swell, or
some combination thereof.

Winds and seas will build through today ahead of the strong front
expected to pass through the coastal waters Wednesday night into
Thursday morning. A Gale Warning has been issued for Wednesday
evening through Thursday night. Storm force winds are possible,
especially in the coastal jet near and north of Cape Blanco. Wind
driven seas will combine with heavy west swell to produce very steep
and hazardous seas well in excess of 20 feet.

Conditions will not improve behind the front, as another very strong
front will arrive late Thursday into Friday, with at least Gale
force winds continuing through at least Thursday evening. Again,
Storm force winds are possible along and ahead of the front due to
the formation of another coastal jet, and seas will remain very
steep and hazardous into Friday morning.

The active pattern will continue through the weekend. with another
system passing through the coastal waters on Saturday, followed by
yet another front early next week. -BPN

&&

.PREV DISCUSSION... /Issued 413 AM PST Wed Nov 23 2016/

DISCUSSION...The current winter weather advisory in the
Siskiyous and the Cascades continues on track as showers track in
into the coast with westerly 700 MB winds and a -31C cold pool at
500 MB. The instability with this cold air mass over the
relatively warm water is producing isolated thunderstorms over the
coastal waters and at the coast and with the westerly somewhat
strong steering flow these could carry inland, perhaps past the
coastal ranges a bit. The cold pool moves east of the area this
afternoon, decreasing instability, but with surface warming
showers will continue with tapering off as the upper levels warm
into the afternoon.

Models are in agreement with the front moving in later Thursday,
and with the heavier precip moving in as well, not bringing the
very heavy precip in to the coast until later Thursday evening.
The winds at the coast continue to look strong, and with BL winds
in the 50-60 KT range Thursday afternoon with 850 MB winds of
70-80 KT from the southwest the formation of a barrier jet is
likely and will bring the strong winds inland from the capes.
with 925 MB winds in the 65-75 KT range with the heavier
precipitation Thursday afternoon. occasional gusts could exceed 65
mph.

With the later timing of the precip the possibility of flooding
is also later, with rapid rises of smaller rivers on the coast now
likely Thursday night into friday morning. Will leave any
hydrological products to the day shift to see first if this slower
trend of this system continues. Likewise wit the slower timing
the next round of Mountain snow does not come in until Thursday
night and looks to be only advisory amounts and will not issue
that until the current advisory expires as that is beyond 36 hours
from now. Sven

AVIATION...23/12Z TAF cycle...A series of shortwave disturbances
will continue to produce scattered to numerous light showers and
snow showers through this morning, with snow levels near 3500 to
4000 FT MSL. This will continue a mix of IFR, MVFR, and VFR ceilings
through the morning with the IFR mainly in the early morning in west
side valleys and the VFR mainly east of the Cascades. Also, low
level westerly winds east of the Cascades will be strongest through
around 09Z then gradually diminish. Conditions will improve in the
afternoon into the early evening with diminishing showers and mainly
VFR ceilings. VFR should then continue through the remainder of the
TAF period. -BPN

Note: The ceilometer at FAA site KOTH remains out of service, so
there will be no ceiling observations available generally between
the hours of 04Z and 14Z.

MARINE...Updated 230 aM PST Wednesday, 22 November 2016...Several
strong frontal systems will pass through the area over the next
week. During this time, conditions are unlikely to decrease below
small craft advisory levels either from wind, wind waves, swell, or
some combination thereof.

Winds and seas will build through today ahead of the strong front
expected to pass through the coastal waters Wednesday night into
Thursday morning. A Gale Warning has been issued for Wednesday
evening through Thursday night. Storm force winds are possible,
especially in the coastal jet near and north of Cape Blanco. Wind
driven seas will combine with heavy west swell to produce very steep
and hazardous seas well in excess of 20 feet.

Conditions will not improve behind the front, as another very strong
front will arrive late Thursday into Friday, with at least Gale
force winds continuing through at least Thursday evening. Again,
Storm force winds are possible along and ahead of the front due to
the formation of another coastal jet, and seas will remain very
steep and hazardous into Friday morning.

The active pattern will continue through the weekend. with another
system passing through the coastal waters on Saturday, followed by
yet another front early next week. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 1 AM Thursday to 1 AM PST Friday for
     ORZ021-022.
     Winter Weather Advisory until 10 AM PST this morning ABOVE 4500
     FEET for for ORZ027-028.

CA...Winter Weather Advisory until 10 AM PST this morning ABOVE 4000
     FEET for for CAZ082-083.

Pacific Coastal Waters...Small Craft Advisory from 4 PM this afternoon
     to 10 PM PST this evening for PZZ350-356-370-376.
     Gale Warning from 10 PM this evening to 1 AM PST Friday for
     PZZ350-356-370-376.
     Small Craft Advisory for hazardous seas until 4 PM PST this
     afternoon for PZZ350-356-370-376.

MAS/SBN/BPN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
851 AM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 AM     HEAVY RAIN       6 SE SELMA              42.23N 123.52W
11/23/2016  M2.27 INCH       JOSEPHINE          OR   TRAINED SPOTTER

            .

&&

NWS MEDFORD OR
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
856 AM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0830 AM     HEAVY RAIN       5 NNE SELMA             42.35N 123.57W
11/23/2016  M2.20 INCH       JOSEPHINE          OR   TRAINED SPOTTER

            .

&&

NWS MEDFORD OR
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
858 AM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0858 AM     HEAVY RAIN       6 E GOLD BEACH          42.42N 124.31W
11/23/2016  M1.61 INCH       CURRY              OR   TRAINED SPOTTER

            .

&&

NWS MEDFORD OR
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1235 PM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     HEAVY RAIN       PORT ORFORD             42.75N 124.49W
11/23/2016  M1.51 INCH       CURRY              OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS.

&&

CZS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1238 PM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     HEAVY RAIN       1 NNW LAKESIDE          43.59N 124.18W
11/23/2016  M1.69 INCH       COOS               OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS.

&&

CZS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1240 PM PST WED NOV 23 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     HEAVY RAIN       1 NNW HARBOR            42.05N 124.26W
11/23/2016  M2.38 INCH       CURRY              OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS.

&&

CZS