Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/18/18
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
728 PM EST Wed Jan 17 2018
Uncommon warm advection pattern is now setting up over the Northern
and Central Great Lakes region as Pacific moisture plume advects
directly into southeastern Michigan from the northwest. Developing
fast zonal gradient flow is setting the initial stage, with warm
advection getting accentuated Thursday in advance of the vigorous
shortwave that will dig directly down through the U.P. into Lower
Michigan. High cloud now filling in over Lower Michigan is occuring
on the initial warm air advection aloft. The main item in the
forecast period is the overall likelihood of widespread MVFR cloud
development that is forecasted to occur between 1.5 and 4.0 kft agl
Thursday morning. RAP and NAM are extremely bullish on low cloud
development. There remains some uncertainty yet, namely the lack of
cloud development thus far upstream. However, there has been some
activity on Lake Superior and model data points to Lake Michigan
being a major contributor to the cloud development. Relatively
higher westerly gradient flow will persist through the taf period
with winds in the 15 to 25 knot range throughout the taf forecast.
/DTW THRESHOLD PROBABILITIES...
* Moderate for cigs aob 5kft after 14Z Thursday morning.
Issued at 348 PM EST Wed Jan 17 2018
Cloud trends will be the primary subject of the forecast for tonight
with the main question being how active Lake Michigan will be in
producing stratus/stratocu. Observations show the mid and high
clouds overhead associated with the exit region of the upper jet
over northern Ontario and a broad region of mid level isentropic
ascent. These will exit eastward during the evening and allow a
broad short wave ridge to force a subsidence inversion over Lower
Michigan later in the night. Observations also show very dry
conditions in place over the upper Midwest and northern Plains.
Warmer air is moving into this region on increasing southwest flow
but satellite indicates no low clouds anywhere to our west. This
does not mean that Lake Michigan will not activate, only that the
forecast sides with model solutions that offer more limited coverage
of low clouds until observational trends support a more aggressive
approach. Expect temperatures to continue an upward response to the
increasing southwest wind, gusting near 30 mph during the evening,
however wind chill will end up around zero for much of the night as
overnight lows settle in the teens.
The expectation of scattered to broken lake clouds to start Thursday
will be directed farther north under gradually backing low level
flow during the afternoon. Mid and high clouds associated with the
compact upper level circulation will also pass mostly through the
northern Great Lakes. This moisture starved feature will barely be
capable of precipitation and then only on the northeast flank over
northern Lake Huron where dynamic forcing will be maximized. The
passage of the circulation will mark the beginning of broad upper
level height rises associated with continued low level warm
advection to finish the week. The pattern will be dry but steadily
warmer with highs pushing 40 Friday afternoon.
Significant increase in upper mass gradient is anticipated over the
next few days as east Pac jet energy releases into the northern tier
of the US against the southern periphery of the tropospheric polar
vortex Hudson Bay/northern Quebec. Trailing energy will dig into the
southwest United States Saturday through Sunday, prompting a lee
cyclogenesis episode as strong right entrance support steadily
matures through the weekend and becomes increasingly focused over
the Great Lakes region. Light warm advection/overrunning type precip
will be possible as early as Sunday morning as the low-level jet
responds and moves up the developing frontal slope. Surface cyclone
is then progged to lift from the Lower Missouri River Valley to The
Straits by Monday into early Tuesday. Strong model support that SE
Michigan will remain on the warm side of this system, supporting
temps on the milder side for late January. There is potential for
pre-fropa temps on Monday to make a run toward 50 before showers and
possibly t-storms along the front shift through the area. Cold lake
temps/ice on Lake Erie suggest usual caveats with northward
progression of the surface portion of the warm front. Will leave out
t-storms and remain more conservative, low to possibly mid 40s, with
temps for now. Overall extended period characterized by temps on the
warm side of average, high pops early next week, and mainly liquid
precip. Per the norm, a brief snow-fzra-rain transition is possible
as the warm front lifts through Sunday.
A Gale Warning will remain in effect through Wednesday night as
strong, unstable southwest flow peaks this evening. A tight pressure
gradient between Arctic high pressure over the Tennessee Valley and
low pressure near James Bay will continue driving southwest gusts
approaching 40 knots across Saginaw Bay and the nearshore waters
with gusts reaching 40 knots over the open waters of Lake Huron
through late Wednesday night. The pressure gradient will then weaken
slightly early Thursday as the low pressure near James Bay departs
to the east allowing winds to gradually decrease Thursday morning.
Southwest flow will then continue through the remainder of the week
with diminishing gust potential due to an increasingly warm, stable
Lake Huron...Gale Warning until 4 AM EST Thursday for LHZ363-441-462.
Gale Warning until 10 PM EST this evening for LHZ362-421.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Gray ME
1018 PM EST Wed Jan 17 2018
Low pressure will depart the region this evening bringing the
snow to an end. High pressure builds eastward into the region
for the rest of the week and into the weekend with a return
southwest flow bringing warmer temperatures by the weekend. A
storm system may affect the region early next week with mixed
precipitation and rain.
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
1000 PM Update
Flurries are winding down in midcoast areas of Maine late this
evening and skies are clearing over western New Hampshire.
Expect clearing skies downwind of the mountains through midnight
while clouds and a few flurries continue in the north. Have
adjusted temp/td/sky and pop grids to reflect latest obs and
expected trends. No major changes plan for the current forecast.
700 PM Update... Quick update to drop expired headlines for
Warnings and Advisories. Left over flurries currently exiting
southeast New Hampshire and lingering flurries over southern
Maine will be ending through midnight with no further
accumulation expected. Expect clearing skies downwind of the
mountains by midnight or shortly after. Have updated area pops
based on current radar trends. Aside from a few temp and td
tweaks no other changes planned to current forecast.
530 PM Update...Have adjusted PoPs just a little bit for the
next couple of hours based on latest trends in radar imagery.
The HRRR has been doing a pretty good job with the light
snowfall progressing over our forecast area early this evening.
Have therefore stuck with HRRR forecast for the departure of the
accum snow this evening with the departure of a short wave
trough and weakening of an inverted SFC boundary. Advisories and
warnings remain up until 7 PM and should be able to expire on
time. Up to an additional inch is possible through that time.
Low pressure will gradually move away from the region this
evening bringing an end to the snow early on. Winter weather
advisories are in effect for the southern half of NH until 7 pm
with winter storm warnings and advisories continuing for
portions of ME until that time also. A short wave trough will
swing across northern New England late this afternoon and early
evening allowing much the advisory and warning area to pick up
an additional inch or two of snow. This will make the evening
commute slippery in most areas. Some spotty freezing drizzle may
occur as well for a short period of time early this evening, but
that looks like a low probability at this time. Clearing is
expected to occur in the wake of the short wave trough later
tonight downwind of the mountains.
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday looks to be a fair weather day with seasonable
temperatures. However, the northern Whites and a portion of the
western ME mountains will probably see upslope snow showers
especially in the morning. Another short wave trough will cross
the region Thursday night with an increase in clouds. Some snow
showers may occur as well if the column moistens up
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Zonal flow will replace the trough which has been plaguing the
East Coast by the end of the week. A more southwesterly warm
air advection pattern develops for the weekend and into early
next week as low pressure detaches and forms along the base of
southern stream troughing over the southern and central plains.
Weak upslope snow showers will be possible over the White
mountains and the western Maine mountains Friday through
Sunday with persistent but non-significant short wave energy
passing by. Precipitation then spreads east with time on Monday
into Tuesday. Coastal locations may see rain with the
possibility of mixed wintry p-types as an eastward moving cold
front brings lifting for ascent towards low pressure pivoting
up the eastern seaboard. This will allow cooler air back in with
temperatures dropping back towards normal values by next
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term /through Thursday night/...MVFR to IFR conditions
early this evening in snow and low clouds will give way to VFR
conditions after midnight tonight through Thursday.
Long Term...Mainly VFR conditions across the region Friday
through Sunday. There will be a chance of light mountains snow
showers/MVFR ceilings for mainly HIE and possibly LEB during
this time. Widespread lower ceilings and visibilities in
possibly mixed wintry precipitation late Monday night as low
pressure heads towards New England.
Short Term /through Thursday Night/...Marginal SCA for seas
remains in effect for the ocean waters for tonight into early
Long Term...Waves and winds increase to near SCA conditions
late Friday into Saturday in gusty SW flow before dropping off
River flood warning for the Kennebec has been reissued as jammed
up ice has caused the river to rise just above flood stage
again. It is expected to go below flood stage Thursday
MARINE...Small Craft Advisory for hazardous seas until 7 AM EST
Thursday for ANZ150-152-154.
Area Forecast Discussion
National Weather Service Wilmington NC
1017 PM EST Wed Jan 17 2018
A cold front will bring a mix of rain and snow, and will clear
the coast late tonight. Cold and dry Arctic air, will spread
into the region through Thursday. Temperatures will warm into
the weekend as high pressure moves offshore. Another cold front
will bring rain chances by Monday evening, but little cooling,
and temperatures are expected to remain above normal into next
.NEAR TERM /THROUGH THURSDAY/...
As of 900 PM Wednesday...Much of the moisture has scoured out
across the ILM CWA, well ahead of the upper closed low. This
potent closed low will move across the FA late this evening and
overnight with continued limited moisture across the FA. Some
Atlantic moisture will be drawn in, however areas north of the
ILM CWA, from Cape Lookout northward, will be the beneficiary`s.
Basically, will have to rely on the dynamics of the upper
closed low and it`s accompanying moisture, which is not much.
Due to the moisture dilemma, we have downgraded the Winter
Storm Warning to a Winter Weather Advisory for those 2 counties.
Have continued the Winter Wx Adv for the 4 inland counties.
Due to the limited moisture, have lowered the total snow
accumulations to 1 to 2 inches across the northern periphery
and that`s being very generous, elsewhere, looking at 1 inch or
less for the those 4 counties within the initial Winter WX Adv.
Wind chills by morning will be in the upper single digits well
inland. Any further decrease in temps and/or higher windgusts
would produce wind chill advisory numbers which is 5 degrees or
As of 3 PM Wednesday...A Winter Storm Warning continues for
Marlboro and Robeson counties, and a Winter Weather Advisory
remains in effect for Darlington, Marlboro, Bladen, and Pender
GOES-East water vapor is showing the mid-level trough moving
into the western Carolina`s. At the surface the cold frontal
boundary is entering into the western portions of the forecast
area. The 2 pm observations is showing rain over most of the
forecast area. The latest HRRR is showing the best chances of
snow in the western half of the area after 3 PM and will slowly
make it to the coast. Timing for the coast appears to be after 8
PM. With the dry air it appears after the initial shot of
precipiation that we will see light snow or flurries well after
Also, with delay in the system making eastward have extended the
warnings and advisories to 1 AM. Also, for areas south of the
warning and advisory area will have to watch for black ice as
any liquid precipiation that does fall will likely freeze.
As the storm pushes off the coast, winds will increase and
combined with the low temperatures will see wind chills in the
the 8 to 13 degree range around sunrise Thursday. This is just
above the Wind Chill Advisory criteria.
On Thursday skies will clear but temperatures will struggle to
get to 40 degrees with brisk winds.
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 3 PM Wednesday...The mid level pattern will have evolved
into a split flow regime initially and translate into a
southwest flow ahead of a mid level low by Saturday morning.
Although seemingly busy at the mid levels, surface high pressure
will be the dominant feature. This high will move across the
Gulf of Mexico then out into the Atlantic by the end of the
period. Once again a temperature forecast throughout and expect
lows Friday in the lower to middle 20s. Highs Friday will
rebound into the 50s.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Tuesday...The chief caption this period ? "Warming
Trend". Even in wake of a cold front early next week, minimal
cold air advection is seen, as the upper pattern sees a SE ATLC
upper ridge gradually expand NW into the area. A weak cold pool
aloft meanders eastward along the Gulf Coast this weekend and
offshore by Monday, will little sensible weather impacts here.
As a result, much of next week may feature sunshine and 60s in
the afternoons, likely feeling like an early spring compared to
the recent weather pattern. Aside from late Monday and early
Tuesday, this entire period will maintain a dry column and low
PWAT values. The coldest period, will be Saturday morning, near
freezing, the mildest, perhaps just ahead of the cold front
Monday into the upper 60s by afternoon. Tuesday looks to be the
breeziest day in wake of the cold front, with W-NW breezes.
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
As of 00Z...Confidence is high that cigs will improve to VFR
this evening and overnight at all terminals. Until then however,
confidence in TAFs is moderate. IFR cigs at KLBT will improve
to MVFR 01-02Z. MVFR cigs at both KFLO/KLBT expected until VFR
develops around 04Z. Expect tempo MVFR vsbys in -SN at KFLO and
IFR vsbys in -SN KLBT until 04Z however.
-RA/BR is moving across the coastal terminals attm with IFR at
KCRE/KMYR developing NE towards KILM. KILM should drop to IFR
01-02Z. There is a chance of MVFR/-SN coastal terminals until
after midnight but expect even lighter intensities than
Thursday expect SKC with NW winds 10-18kt.
NEAR TERM /THROUGH THURSDAY/...
As of 930 PM Wednesday...Continued the SCA timeline for all
waters. The NW offshore winds have begun increasing across the
local waters and should breach SCA thresholds after midnight.
The CFP followed by a tightening sfc pg combined with Arctic
Air Advection, will result in NW winds 20-25 kt with gusts up
to 30 kt possible overnight thru midday Thu. At the moment,
significant seas are responding and have increased 1 to 2 ft
during the past hour. The dominant 3 foot ESE ground swell at
10-12 second periods for the past few days will give way to
building wind driven waves that will overtake the dominance
held by the ground swell.
As of 3 PM Wednesday...Currently winds are from the east with
seas running 3 to 4 feet. This will change quickly as the
front and a developing low shifts to the northeast off the
coast. Winds are expected to reach 20 to 25 knots late this
evening and seas will increase to 5 to 7 feet. The winds will
weaken and with an offshore flow the seas should settle back out
to 3 to 5 feet by Thursday afternoon.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 3 PM Wednesday...Surface high pressure will move from the
northern Gulf of Mexico to well offshore during the period.
Between this feature and the general cyclonic flow to the north
a west to southwestern flow will prevail across the waters. Wind
speeds will be fairly uniform in a 10-15 knot range leaning
moreso toward the higher end early then the lower end late.
Significant seas will generally fall into a 2-3 foot range.
LONG TERM /SATURDAY THROUGH MONDAY/...
As of 3 PM Wednesday...Welcoming and friendly marine conditions
this period, particularly in wake of recent weather. As high
pressure slips offshore by the weekend, a milder return SW flow
will prevail, with seas 3 feet or less, and even 1-2 feet at
times, with winds less than 15 kt. Seas will begin to build
Monday as sustained SE fetch offshore, starts pushing wave
energy toward our coast. By Monday night seas of 4-5 ft in 7
second intervals, may be rolling in. No TSTMS this period, but a
few rain showers can be expected Monday night, as a cold front
crosses the coast. Inshore water temperatures were in the upper
40s to lower 50s.
SC...Winter Weather Advisory until 1 AM EST Thursday for SCZ017-023-
NC...Winter Weather Advisory until 1 AM EST Thursday for NCZ087-096-
MARINE...Small Craft Advisory until 7 AM EST Thursday for AMZ254-256.
Small Craft Advisory until 1 PM EST Thursday for AMZ250-252.
Area Forecast Discussion
National Weather Service Indianapolis IN
943 PM EST Wed Jan 17 2018
The Aviation Section has been updated below.
Issued at 230 PM EST Wed Jan 17 2018
Dry and slowly warming winter weather can be expected the for the
rest of the work week across Central Indiana. High pressure in
place over the southern Mississippi River Valley will continue to
slowly slide southeast...keeping a warmer and drier westerly flow
of air to Central Indiana.
The next best chance for rain will be late this weekend and early
next work week as a low pressure system approaches from the west.
.NEAR TERM /Rest of Tonight/...
Issued at 730 PM EST Wed Jan 17 2018
High pressure was centered over Arkansas at 7 pm, with satellite
loop showing some cirrus spilling down into northern and
northeastern parts of the forecast area. Temperatures plummeted
quickly over the snowpack after sunset, with mid single digits in
the southwest to teens in the northeast. As a result, cut low
temperatures by several degrees and adjusted hourly temperatures
based on the most recent HRRR output, which was a much better match
to current conditions that the hi res consensus. With southwesterly
flow expect temperatures to settle in over the next hour or so and
stay fairly steady then through the overnight, with the
southwesterly flow bringing warm advection and combating the extra
radiational cooling over the snowpack.
.SHORT TERM /Thursday through Saturday/...
Issued at 230 PM EST Wed Jan 17 2018
Models continue to suggest a quiet weather pattern during this
time. The GFS and NAM suggest that the broad ridge aloft over the
plains and upper midwest will slowly push eastward through
Saturday and very gradually flatten out. This should keep Indiana
protected from any passing short waves within the flow
aloft...deflecting them to the north. Through Saturday...warm air
advection continues within the lower levels with 850MB temps
reaching near 4c by 12Z Friday and 7C by 12Z Saturday. The surface
high to the south is also expected to drift east of Florida by
Saturday...which will allow warmer and more moist gulf air return
to Central Indiana. Forecast soundings and Time heights remain
quite dry during this period...failing to show much in the way of
saturation. An exception to this is the GFS forecast soundings on
Saturday which suggest some low level saturation mainly due to
warm air advection. At this time...confidence in that is low given
our very dry air mass. Thus will take a wait and see approach for
now. Overall, will aim for partly cloudy days and mostly clear
nights during this period...with temperatures at or above the
forecast builder blend given the warm air advection.
.LONG TERM /Saturday Night through Wednesday/...
Issued at 116 PM EST Wed Jan 17 2018
The long term portion of the forecast will be significantly warmer
as the west coast ridge breaks down and shifts eastward across the
country. This will allow a trailing trough axis to push into the
Rockies Saturday and induce cyclogenesis in the lee of the Rockies.
Warm advection and isentropic lift out ahead of this developing low
will necessitate low pops for rain showers early in the weekend,
with chances increasing into early next week as a well developed
low pressure system pushes northeast through the Great Lakes and
drags a cold front through the area. The vast majority of
precipitation with this system will fall as rain, although it may
turn cold enough with the wrap around precipitation behind the
cold front for a few light snow showers.
Blended initialization handled things well and few significant
changes were required.
.AVIATION /Discussion for 180300z TAF issuance/...
Issued at 943 PM EST Wed Jan 17 2018
Updated current conditions only. Previous discussion follows...
VFR through the period. High pressure will continue to slide
southeast with an upper ridge holding sway over central Indiana
through the TAF period. The pressure gradient will increase a little
Thursday resulting in slightly stronger winds (8 to 12 kts) out of
around 210 to 240, with gusts of 18 to 22 kts during the afternoon.
Visibilities should be unrestricted, and any clouds should be cirrus.
Area Forecast Discussion
National Weather Service Portland OR
250 PM PST Wed Jan 17 2018
.SYNOPSIS...A cold front will move inland this evening, crossing
the Cascades overnight. An upper level trough of low pres off the
coast will then send a series of disturbances inland through the end
of the week, keeping the region in a cooler showery pattern. Another
front will move inland Sunday, bringing a round of heavier rainfall
and some mountain snow.
.SHORT TERM...Tonight through Saturday...Cold front was moving onto
the coast early this afternoon, ushering in a solid looking band of
rain along with some gusty winds. Models indicate the front itself
pushing into the Cascades this evening, with a baroclinic zone
lingering into early Sat morning. The initial shortwave that pushed
the front up to the coast was seen in water vapor pictures lifting
ne into Vancouver Island, but another shortwave lifting up from the
vicinity of 4N 132W will move across early Thu. Cross sections of
moisture indicate deep enough moisture to continue with near 100
pops as the front moves through overnight, and will retain
categorical pops through the night into Thu morning with the next
shortwave moving through. Moist onshore flow continues through Fri
and Fri night as a few more shortwaves move through. keeping pops in
the likely to categorical range for showers. Model soundings
continue to indicate marginal instability, centered along and off
the coast Thu afternoon as the cold upper trough moves closer, so
will keep a slight chance for thunderstorms over the coastal areas
Large seas associated with the deep surface low that is running up
towards the central BC coast tonight will arrive tonight and
continue through Thu before decreasing again Thu night. The system
bears a resemblance to a storm back on 10 Dec 2015, where seas
topped out in the range of 31 to 32 ft with periods around 17
seconds, that wound up producing some property damage around Depoe
Bay and Cannon Beach. GWW deep water wave heights over the coastal
waters expected to top 30 ft early Thu coupled with long periods
will pose a threat for coastal flooding late tonight and Thu, with
the peak threat occurring through the daytime high tide early Thu
On Sat weak ridging aloft initiates weak warm air advection. will
keep likely pops in for what should transition to be more stratiform
precipitation. For the next few days with snow levels coming down
behind the front tonight, will see snow adding up in the Cascades
again. At this time however, no system appears overly strong or
heavy, so accumulations through Sat should occur at rates under
.LONG TERM...Saturday night through Wednesday...Active weather
continues through the weekend, with coast/valley rain and mountain
snow. Will likely see a decent amount of snow in the Cascades on
Sunday, with snow levels down around 3000 feet (below the passes).
Rain for everyone else means rivers will continue to rise through
Sunday. Transient ridge builds over the Pacific Northwest late
Monday into Tuesday likely means a break in the rain, but energy
riding over the top of the ridge means I kept a slight chance of
rain and clouds in the forecast for Monday night into Tuesday.
Another trough will bring more rain and another stretch of active
weather starting late Tuesday through the end of next week. -McCoy
.AVIATION...Leading edge of a cold front just offshore at 21Z.
Coastal areas were VFR at 21Z, but conditions expected to lower
into MVFR by late afternoon. Vis may slip into high-end IFR as
the cold front moves onshore. The coast will be mainly MVFR
00Z Thu through 04Z or so, followed by a mix of VFR and MVFR
thereafter. Latest model guidance suggests another surface trough
will impact the coast around 12Z for a higher threat of MVFR.
Inland areas to remain VFR through about 02Z Thu. The cold front
reaches the Willamette Valley and SW Washington interior lowlands
between 02Z and 04Z, with the potential for MVFR with the front
and a few hours after passage. Post-frontal pre-dominant VFR
develops in the interior valleys between 07Z and 10Z, but
increasing chance of MVFR between 12Z and 15Z Thu. Higher
terrain becomes frequently obscured after 00Z Thu.
PDX AND APPROACHES...VFR to be the dominant flight category at
the terminal through at least early evening. Cold front moves
across the terminal around 04Z Thu, which will result in MVFR
conditions. Expect more VFR after 08Z in the post-frontal air
mass. Another surface trough is expected to move across the
terminal between 12Z and 15Z for an increasing threat of MVFR.
.MARINE...General forecast trending as expected. A 960 mb to 964
mb low pres center was located near 48N 136W at 21Z. Storm force
gusts to 58 kt have been noted at buoy 46005, with a 51 kt gusts
at 46050 at 21Z. The forecast 80m wind field from the 19Z HRRR
seems to be meshing well with buoy observations. Peak wind will
occur through about 01Z Thu, with the strongest gusts over
PZZ275. The coastal jet signature shown earlier by the NAM has
since disappeared on recent runs with the bulk of the higher
winds associated with the cold front itself.
Post frontal gales to then continue for the outer waters later
this evening through Thu. 12Z model runs are in better agreement
regarding the Sun system. Looks like gale force wind returns to
PZZ255 and PZZ275 in the 06Z-12Z Sun time frame and then move
into the north zones after 12Z. Indicated gusts around 45 kt over
PZZ275 Sun morning. Wind speeds settle down early next week.
Seas starting to build this afternoon, near 30 ft at buoy 46005
at 21Z. Latest ENP guidance indicates seas near 40 ft at 46005
valid 00Z Thu. The highest seas are expected to move inside 60
nm by 12Z Thu. Little change in modeled wave guidance with seas
29-33 feet. The 12Z spectral guidance for buoy 46029 shows 32-33
ft peak wave heights from 12Z-18Z Thu. This is slightly higher
than the Tue runs. The ECMWF continues to be 2-4 ft lower.
Areas of the shoreline will be highly impacted by the expected
large waves beginning late tonight. The expected 30-33 ft west
swell with 15-18 second periods will contain an enormous amount
of energy. Waves will generally break within a mile or so
offshore, with the potential for 40 ft or greater wave heights.
These waves will contain enough momentum to run water much
further up the beaches. It appears this event will be more
significant than the December 2014 impacts but less so than
February 2006 where significant damage occurred across low lying
beach and harbor areas. Seas diminish Fri, but will remain above
20 ft through Fri evening. Seas will continue to subside Fri
night and Sat, easing to the lower teens by 12Z Sun. However,
forecast gale force wind Sun will likely boost seas to near 20
OR...Coastal Flood Warning from midnight tonight to midnight PST
Thursday night for Central Oregon Coast-North Oregon Coast.
WA...Coastal Flood Warning from midnight tonight to midnight PST
Thursday night for South Washington Coast.
PZ...Storm Warning until 7 PM PST this evening for Coastal Waters
from Cape Shoalwater WA to Florence OR out 60 NM.
Small Craft Advisory for Rough Columbia River Bar until 4 AM
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA or forecast area.