Area Forecast Discussion
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049
FXAK67 PAJK 182233
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
133 PM AKST Sun Feb 18 2018

.SHORT TERM.../ Sunday night to Tuesday night / The ridge of high
pressure over the Gulf of Alaska has a weak low forcing itself
over the top of of the ridge with a moisture band trailing to the
southwest from the low. The low moves east from near Kodiak Island
towards the panhandle then curves SE to run along the coast on
Monday. Think there will be enough support for clouds and light
snow, which was in the forecast, although have trimmed the eastern
edge back as it should only impact the coastal zones with less
than an inch of snow.

There looks to be some minor clearing early Tuesday across the
panhandle followed by another small short wave spreading clouds to
the northeast gulf and panhandle region Tuesday evening.

Winds across Southeast Alaska will continue on the downward trend
overall for the next 12-18 hours. Locally gusty winds late Sunday
afternoon and evening are expected diminish through the evening
and a light wind situation should exist early Monday morning, and
slightly northerly winds wind increase behind the low as it moves
south along the panhandle coast.

With more clouds across the panhandle, do not think most lows
tonight will be a cool as the Sunday morning lows. Highs warming
back to the upper 20s to lower-mid 30s especially if increasing
solar heating has a chance to impact the daytime highs.
Temperatures are expected to continue to be close to normal for
the season.


.LONG TERM.../Tuesday through Saturday as of 9 PM Saturday/ Model
agreement is showing the ridge in the Gulf to be flattening by
mid-week next week, as shortwaves continue to eject towards the
panhandle. Shortwaves are possible late Tuesday into Wednesday,
Thursday, and Saturday.

Pressure adjustments, while not many, were the result of a GFS/
WPC blend. The GFS was once again the middle ground of model
choices, with the ECMWF also lining up. Tuesday`s low has become
more early Wednesday`s low. This system passes through quickly and
almost missed this feature when going through model analysis.
Thursday`s low looks to be a repeat of Tuesday/Wednesday`s low
with a low passing north to south along the coast. Several models
were already picking up on Saturday`s low tracking through the
Gulf.

Winds remain on the weaker side through early Wednesday, with it
being difficult to find at least 15 kts even across the inner
channels. Wind speeds will peak late Wednesday, as one system
exits and another will soon begin its entrance. Nudging in the
Gulf actually decreased some of the wind speeds over the Gulf,
with at most 30 kts present. Some local edits were also made.

POP was increased beginning Wednesday with the movement of the
low, with some snowfall (< 1 inch possible). At this point, even
the NAM wants to bring precipitation further inland to Canada.
Thursday`s system looks to be a higher QPF event, with minor snow
accumulations confined to certain locations across the panhandle.
POP updates were performed using a NAM/SREF blend early on and
WPC blend throughout the extended. Snow levels were also
increased.

Temperatures have been experiencing a greater diurnal range
recently due to the increased amount of solar radiation. Maximum
temperatures were increased overall past freezing. However, the
amount of snow cover still present will limit how warm most of the
panhandle will get and keep temperatures slightly under what MOS
Guidance suggests. Minimum temperatures were also warmed slightly
based on MOS.

The small scale of these waves coupled with the dominant ridge-
feature leads to greater uncertainty by mid-week, with model
spread becoming larger and still poor run-to-run model continuity.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...None.

&&

$$

Bezenek/SS

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