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FXAK67 PAJK 252231
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
231 PM AKDT Thu May 25 2017

.SYNOPSIS...A ridge of high pressure persists over the eastern
gulf through Saturday. A weak weather front is slowly moving
eastward and will dissipate across the northwestern panhandle
through Thursday night.

&&

.SHORT TERM.../Tonight through Friday/ As of 1 pm Thursday. The
ridge that is extending from the eastern gulf into the central
Panhandle is keeping the main energy from a weak front north of
Frederick Sound. The ridge axis will pivot to the west pushing the
rain to the west overnight, although the clouds will take some
time to decrease. Areas of low clouds and fog are possible along
the outer coastal areas from Baranof Island to Cape Yakataga
overnight and into early Friday morning. Fog is expected to
develop overnight in the southern half of the Panhandle as some
clearing in the clouds should occur. By mid morning on Friday sky
conditions around the panhandle will be much improved as periods
of rain will have diminished overnight tonight.

Winds are generally northwesterly at 15 mph or less, except for
the Skagway/Haines area where southerly winds of 15 to 25 mph will
diminish overnight. For marine winds, small craft advisories are
in effect for Cross Sounds and Northern Lynn Canal this evening.
Cape Decision is also stronger with winds to 20 kt this evening.

Models are in good agreement. For POP, the preference was to the
AKSREF and AKNAMDNG for the increased chances today and the
Canadian for the precipitation across the gulf with the weak
front. Still had to increase the chances to categorical for most
of the northern panhandle today and tonight for the periods of
light rain. Kept the QPF low, as the precipitation as
precipitation rates are minimal with only a few hundredths of an
inch expected, with Yakutat being the wettest with around a tenth
of an inch for the entire day today.

Made only minor changes in the wind, pressure and snow level areas
as the grids looked in good agreement with the new models.

Forecast confidence is generally high, with lower confidence in
the extent of the fog and how much it may restrict visibility
during the overnight and early morning time.

.LONG TERM.../Friday night through Wednesday/ As of 10 pm
Wednesday. A short wave digging south out of the eastern Bering
Sea deepens the upper trough near 160W Friday night through
Saturday night, while an upper ridge builds along the western US
coast and over British Columbia. The corresponding surface ridge
is positioned over the eastern half of the gulf with a complex
pattern of low pressure south of the Alaska Peninsula and the
Aleutians.

The ridge position should be west enough to keep the panhandle
region on the dry side into the start of the next week. For the
early part of next week (Mon-Wed) there are model differences that
are positioning the ridge axis more to to the east which will
allow a better chance of rain to try and ride over the western
side of the ridge.

With persistence of the ridge over the eastern gulf for several
days will need to watch for the development/continuation of the
widespread low marine stratus deck out over the gulf and how far
it will try and penetrate into the southeast panhandle. Have kept
the mostly cloudy skies in the forecast, though if the low clouds
and fog develop then that will be under forecast.

For Friday night to Saturday, used the GFS and then tried to
blend back to the WPC solution where possible. Forecast confidence
is average through the extended part of the forecast.

&&

.AVIATION...Low clouds and very light rain over the northern
panhandle and Yakutat through Thursday night with improving
conditions on Friday. Patchy fog is expected tonight over the
central and southern inner channels where cloud cover will be
thinnest and radiational cooling will be the greatest.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022.

&&

$$

KV/Bezenek

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