Storm Warning 15, NWS Juneau, AK

842 
FZAK52 PAJK 261344
CWFAEG

COASTAL WATERS FORECAST FOR SOUTHEAST ALASKA
National Weather Service Juneau AK
444 AM AKST Mon Feb 26 2018

Southeast Alaska Coastal Waters from Dixon Entrance to
Cape Suckling out 100 NM

Wind forecasts reflect the predominant speed and direction
expected. Seas forecasts represent the average of the highest
one-third of the combined windwave and swell height.

PKZ099-270745-
444 AM AKST Mon Feb 26 2018
.SYNOPSIS FOR OUTSIDE WATERS...
A storm force low will track across the northern gulf Mon
morning and lift into the Yukon by the afternoon. On Tue 
another low will enter the northern gulf with a developing low 
moving into the central gulf.  

$$

PKZ041-270745-
Dixon Entrance to Cape Decision-
444 AM AKST Mon Feb 26 2018

...GALE WARNING THROUGH LATE TONIGHT...

.TODAY...W wind 15 kt increasing to 30 kt. Seas 16 ft. Rain and
snow in the morning. 
.TONIGHT...W wind 40 kt. Seas 20 ft. Rain showers. Snow showers
late. 
.TUE...W gale to 35 kt. Seas 23 ft. Snow showers and rain
showers in the morning, then rain and snow showers in the
afternoon. 
.TUE NIGHT...W wind 25 kt. Seas 19 ft. W swell. Rain and snow
showers. 
.WED...NW wind 30 kt. Seas 16 ft. 
.THU...NE wind 30 kt. Seas 14 ft. 
.FRI...NE wind 25 kt. Seas 8 ft. 

$$

PKZ042-270745-
Cape Decision to Cape Edgecumbe-
444 AM AKST Mon Feb 26 2018

...GALE WARNING THROUGH LATE TONIGHT...

.TODAY...W wind 15 kt becoming SW 30 kt. Seas 17 ft. W swell.
Rain and snow in the morning. Rain showers in the afternoon. 
.TONIGHT...W wind 35 kt. Seas 22 ft. Rain and snow showers. 
.TUE...W gale to 35 kt. Seas 23 ft. Rain showers in the
morning. Snow showers. 
.TUE NIGHT...SW wind 20 kt. Seas 19 ft. W swell. Rain and
snow showers. 
.WED...N wind 25 kt becoming NE gale to 35 kt. Seas 16 ft. 
.THU...NE wind 30 kt. Seas 13 ft. 
.FRI...NE wind 20 kt. Seas 8 ft. 

$$

PKZ043-270745-
Cape Edgecumbe to Cape Fairweather-
444 AM AKST Mon Feb 26 2018

...GALE WARNING THROUGH LATE TONIGHT...

.TODAY...SW wind 20 kt becoming W 45 kt with gusts to 65 kt. Seas
12 ft building to 19 ft. Snow early in the morning. Rain and snow
showers in the afternoon. 
.TONIGHT...W wind 35 kt. Seas 22 ft. Rain and snow showers. 
.TUE...W gale to 35 kt. Seas 24 ft. Snow showers. 
.TUE NIGHT...S wind 25 kt. Seas 21 ft. W swell. Rain showers.
.WED...NE gale to 40 kt. Seas 16 ft. 
.THU...E gale to 40 kt. Seas 14 ft. 
.FRI...E wind 25 kt. Seas 9 ft. 

$$

PKZ051-270745-
Cape Fairweather to Icy Cape-
444 AM AKST Mon Feb 26 2018

...STORM WARNING THROUGH THIS MORNING...

.TODAY...SW wind 20 kt becoming W 50 kt in the morning, then
becoming W 40 kt in the afternoon. Seas 11 ft building to 19 ft.
Snow early in the morning. Rain in the morning, then rain and
snow showers in the afternoon. 
.TONIGHT...W wind 35 kt. Seas 22 ft. Rain and snow showers. 
.TUE...W gale to 35 kt. Seas 24 ft. 
.TUE NIGHT...W wind 20 kt. Seas 18 ft. W swell. 
.WED...E wind 30 kt. Seas 13 ft. 
.THU...E gale to 35 kt. Seas 11 ft. 
.FRI...SE wind 20 kt. Seas 6 ft. 

$$

PKZ052-270745-
Icy Cape to Cape Suckling-
444 AM AKST Mon Feb 26 2018

...GALE WARNING THROUGH LATE TONIGHT...

.TODAY...S wind 25 kt becoming W 40 kt. Seas 12 ft building to
18 ft. Snow and rain early in the morning, then rain and snow
showers in the afternoon. 
.TONIGHT...W wind 35 kt. Seas 23 ft. Rain and snow showers in the
evening. 
.TUE...W gale to 35 kt. Seas 22 ft. 
.TUE NIGHT...N wind 25 kt. Seas 14 ft. SW swell. 
.WED...NE wind 30 kt. Seas 10 ft. 
.THU...E wind 20 kt. Seas 9 ft. 
.FRI...SE wind 10 kt. Seas 5 ft. 

$$

773 
FZAK52 PAJK 270027
CWFAEG

COASTAL WATERS FORECAST FOR SOUTHEAST ALASKA
National Weather Service Juneau AK
327 PM AKST Mon Feb 26 2018

Southeast Alaska Coastal Waters from Dixon Entrance to
Cape Suckling out 100 NM

Wind forecasts reflect the predominant speed and direction
expected. Seas forecasts represent the average of the highest
one-third of the combined windwave and swell height.

PKZ099-271830-
327 PM AKST Mon Feb 26 2018
.SYNOPSIS FOR OUTSIDE WATERS...
As strong low pressure resides in the Canadian Yukon a new storm 
force low will track E along the northern gulf Monday night into 
Tuesday. 

$$

PKZ041-271830-
Dixon Entrance to Cape Decision-
327 PM AKST Mon Feb 26 2018

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 35 kt. Seas 20 ft. Rain showers. Snow showers
late. 
.TUE...W wind 35 kt. Seas 23 ft. Snow and rain showers. 
.TUE NIGHT...S wind 15 kt becoming W 25 kt late. Seas 18 ft.
W swell. Rain and snow showers. 
.WED...NW wind 30 kt. Seas 16 ft. Rain and snow showers. 
.WED NIGHT...N wind 30 kt. Seas 16 ft. 
.THU...NE wind 30 kt. Seas 14 ft. 
.FRI...NE wind 25 kt. Seas 8 ft. 
.SAT...E wind 15 kt. Seas 6 ft. 

$$

PKZ042-271830-
Cape Decision to Cape Edgecumbe-
327 PM AKST Mon Feb 26 2018

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 35 kt. Seas 22 ft. Rain and snow showers.
.TUE...W wind 35 kt. Seas 23 ft. Rain showers in the morning.
Snow showers. 
.TUE NIGHT...SW wind 20 kt. Seas 19 ft subsiding to 15 ft
late. W swell. Rain and snow showers. 
.WED...N wind 25 kt. Seas 15 ft. W swell. 
.WED NIGHT...NE gale to 35 kt. Seas 15 ft. 
.THU...NE wind 30 kt. Seas 13 ft. 
.FRI...NE wind 20 kt. Seas 8 ft. 
.SAT...E wind 15 kt. Seas 5 ft. 

$$

PKZ043-271830-
Cape Edgecumbe to Cape Fairweather-
327 PM AKST Mon Feb 26 2018

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 35 kt. Seas 22 ft. Rain and snow showers. 
.TUE...W wind 35 kt. Seas 24 ft. Snow showers. 
.TUE NIGHT...W wind 25 kt. Seas 19 ft subsiding to 15 ft
late. Snow and rain showers in the evening. 
.WED...NE gale to 35 kt. Seas 15 ft. 
.WED NIGHT...NE gale to 40 kt. Seas 15 ft. 
.THU...E gale to 40 kt. Seas 14 ft. 
.FRI...E wind 25 kt. Seas 9 ft. 
.SAT...E wind 20 kt. Seas 5 ft. 

$$

PKZ051-271830-
Cape Fairweather to Icy Cape-
327 PM AKST Mon Feb 26 2018

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 35 kt. Seas 21 ft. Rain and snow showers. 
.TUE...W wind 35 kt. Seas 24 ft. 
.TUE NIGHT...NW wind 15 kt. Seas 18 ft subsiding to 12 ft
late. 
.WED...NE gale to 35 kt. Seas 12 ft. 
.WED NIGHT...E gale to 35 kt. Seas 13 ft. 
.THU...E gale to 35 kt. Seas 11 ft. 
.FRI...SE wind 20 kt. Seas 6 ft. 
.SAT...E wind 15 kt. Seas 4 ft. 

$$

PKZ052-271830-
Icy Cape to Cape Suckling-
327 PM AKST Mon Feb 26 2018

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 35 kt. Seas 21 ft. Rain and snow showers in the
evening. 
.TUE...W wind 35 kt. Seas 22 ft. 
.TUE NIGHT...W wind 25 kt becoming N late. Seas 14 ft
subsiding to 10 ft late. SW swell in the evening. 
.WED...NE wind 30 kt. Seas 11 ft. 
.WED NIGHT...NE wind 25 kt. Seas 9 ft. 
.THU...E wind 20 kt. Seas 9 ft. 
.FRI...SE wind 10 kt. Seas 5 ft. 
.SAT...E wind 10 kt. Seas 4 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
254 PM AKST Sun Feb 25 2018

.SYNOPSIS...Low pressure in the southern Panhandle will exit into
central BC Sun night as a weak front moves into the northern
Panhandle. A storm force low will track across the northern gulf
Mon morning and reach the northern Panhandle Mon afternoon. On
Tue another strong low will enter the northern gulf.

&&

.SHORT TERM.../Through Tuesday/ Main forecast concerns will be
precip amounts/ptype and winds. Expect some weak overrunning
precip to develop ahead of the main occluded frontal band early
Mon morning. This will be mainly over the N where there is some
cold air in the lower levels. Precip will increase rapidly Mon
morning as occluded front moves in. Strong jet support and onshore
flow in mid-levels will enhance precip somewhat. The big question
will be how fast snow transitions to a mix or rain. The boundary
layer looks like it will be fairly mixed which will mean sfc temps
will warm more quickly, so anticipate a lower critical 1000-850
mb thickness will be transition line. Think a 1285m thickness will
be that line. This will mean snow should mix with rain by midday
over much of the N area. One thing that could delay the transition
some is if heavy precip rates are going on during the frontal
passage. System is fairly dynamic and with onshore flow, heavier
precip will be possible along S and W slopes. Snowmelt cooling
could keep it all snow until the front passes by early afternoon.
Am currently thinking a general 3-6 inches of snow will fall over
the N third of the area before any rain mixes in, so am issuing
WWA for zones 17, 18, 19, 20, 22, and 25 for the Mon morning
hours. Left zone 21 out of the WWA as the WSW flow will have a bit
of a downslope component that limits precip amounts some and
helps warm things up a bit faster. The S will be a bit warmer to
start so think snow there will be shorter in duration before a
change over to rain during Mon morning. Could see up to 3 inches
of snow in zones 24, 26, and 29 with locally higher amounts near
PAPG and Hyder. Zones 23, 27 and 28 will probably see an inch or
less of snow for most of those areas. Think the only areas that
remain all snow after 00z Tue will be higher elevations of the
highways up N, and Hyder.

Precip should become showery within a few hours after frontal
passage. During first 12 hrs of the showery regime, think most
precip will be rain showers but some snow could mix in during
heavier showers. Colder air moving in late Mon night and Tue
morning will cause more of the showers to fall as snow by late Tue
morning, especially over the N half of the area.

N winds will rapidly decrease this evening over the N then start
to flip around to southerly late tonight and rapidly increase Mon
morning. Think gales will occur over much of the inner channels
Mon ahead of the approaching front. After FROPA, winds will become
more westerly in many areas, and there could be storm force winds
in Cross sound Mon afternoon. Over the gulf, strong W-SW winds
will occur to S of the low track, with gale to storm force winds
expected during Mon into Mon evening, with a slow decrease for
later Mon night and Tue but still in the 30-35 KT range by Tue
afternoon.

We made sure to apply strong gusts to 45 mph across
many areas including Juneau, Skagway, Sitka, and Elfin Cove.
Other areas will be very breezy and may indeed reach threshold
gusts of 40 mph but we will keep them around 30 to 35 mph for now.
Given temperatures and moisture content of the snow, we elected
to remove the blowing snow in the lowlands, as impacts and
visibility degradation will be negligible.

.LONG TERM.../Tuesday night through Sunday/ As of 11 pm Saturday:
At mid levels 500 mb trough extending from a low over the arctic
digs into the central AK gulf with amplified ridging building over
the western gulf Tuesday. The trough will dig towards Haida Gwaii
as the sharpening ridge axis builds toward the Chukchi Sea
setting up an omega block for the rest of the week. At the surface
the remnants of the Monday system in the NE gulf will push some
remaining shower activity over the panhandle then transition to a
dry period. As the energy from this system drops south under the
digging mid level trough a low will reform over Haida Gwaii,
resulting in increasing pressure gradient between it and high
pressure over the Yukon. Main impact from this developing pattern,
besides dry and clear, will be an increase in outflow and
northerly winds, at least gale force over the inner channels and
out of interior passes with gusts of 40 to 50 mph. Also expect
much colder air to stream in from western Canada with temps
dropping into the teens to possible single digits over night.

Models were in fair agreement initially with the timing of the
building ridge. Used a blend of 00z NAM/GFS which over all still
in line with previous forecast. Used more NBM/WPC for Thursday to
increase outflow winds over the panhandle and lower temps. could
still drop temps a few more degrees. Typical with any blocking
pattern models are showing large spread in determining how/when
the ridge will break down with a transition to more zonal flow.
GFS breaks the ridge down the fastest, so held off on using it in
later grids keeping with WPC. Forecast confidence is average
initially then drops by the weekend.

&&

.MARINE...Strong northerlies through Lynn Canal will finally
diminish late this afternoon and this evening as low pressure in
the south pulls away into central BC. Then a weak front slides
into the northern Panhandle that will wrestle northerly winds back
to southerly. This will set up for the main event when a storm
force low ushers 30 to 50 kt winds from the gulf into the Inner
Channels for Monday. As there will be cold air advection behind
the system, we fully expect the instability to transfer some of
these super-impressive 925 mb jets down to the surface. We do
emphasize that there will be a period of very strong westerlies
throughout Icy Strait even into Auke Bay, especially Monday
afternoon. Likewise, Lynn Canal winds will not stay shy after a
period of relative calm tonight. Seas of 20 to 30 feet will
present more hazards across the Gulf of Alaska. Winds will be
lighter across the southern Inner Channels, but still very breezy.

While still there is much disagreement with the parent low
sneaking in to the northern gulf on Tuesday. However, models are
coalescing on another southwesterly wind episode for the Inner
Channels. Therefore, we raised wind speeds and seas across the
channels at this time. However, we do not view it as such a strong
episode as Monday.
&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Weather Advisory from 6 AM to noon AKST Monday for AKZ018-
     019-025.
     Winter Weather Advisory from 3 AM to noon AKST Monday for AKZ020-
     022.
     Strong Wind Monday afternoon for AKZ023.
     Winter Weather Advisory from midnight tonight to noon AKST
     Monday for AKZ017.
MARINE...Storm Warning for PKZ022-051.
     Gale Warning for PKZ011>013-021-031-032-041>043-052.
     Small Craft Advisory for PKZ033>036-053.

&&

RWT/JWA/PRB

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