Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
000
FXAK67 PAJK 241427
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
627 AM AKDT Wed May 24 2017

.SYNOPSIS...A ridge of high pressure is located over the gulf. A
weak weather front passes through the Yakutat area Wednesday
before dissipating across the northern panhandle through Thursday.

&&

.SHORT TERM.../Wednesday through Thursday/ Two different features
are in the short term forecast. A ridge of high pressure over the
gulf and a weak weather front that will pass through the Yakutat
area later today. The ridge of high pressure produced significant
marine winds between yesterday and this morning with gusts in
excess of 60 kts reported at Cape Spencer and in excess of 50 kts
at Cape Decision. Marine winds are expected to diminish through
the day however, many small craft advisories remain in the
forecast today.

The other element of the forecast today is a weak front that will
move through the Yakutat area. Rain is expected to begin late in
the afternoon or early this evening. This front dissipates as it
moves eastward through tomorrow with a slight chance of rain in
the forecast for the northern panhandle. Overall think that any
rain that does fall will be on the light side.

High temperatures range from mid 50s to mid 60s across the
panhandle with cooler temperatures along the outer coast today and
tomorrow. Marine layer clouds keep the outer coast cloudy today
while the inner panhandle follows a decreasing cloud trend.

Used a blend of the NAM and GFS to handle the short term with
additional guidance NAMNest with winds.

.LONG TERM.../Friday through Tuesday/ As of 10 pm Tuesday.
Generally a quiet weather pattern over the area for the weekend
into next week. Upper level pattern consists of a ridge parked
over BC and a trough over the Bering Sea. This overall pattern
remains largely unchanged through the period with some
fluctuations as short wave troughs move through (particularly for
the Bering Sea trough). These short waves mainly serve to
strengthen both large scale features by early next week.

Meanwhile lower in the atmosphere, the surface ridge is setting up
further to the west then where the 500 mb ridge axis will be.
Stretching N to S across the eastern gulf, the ridge will be
another rather persistent feature for the long range even though
it will fluctuate in strength. Its persistence will mean NW flow
for the extreme eastern gulf and lighter winds for the inner
channels. Also expect generally dry conditions as gulf storms
stay in the western gulf and mostly warmer weather.

One question mark remains, and that is how widespread marine
layer clouds will be. High-res boundary layer RH model guidance at
the start of the long range reveals that there will be
substantial low level moisture in the gulf. So low clouds are
likely to be widespread over the gulf at least, with the outer
coast and maybe areas farther inland seeing more low clouds during
the nights and mornings. Kept sky cover as mostly cloudy for many
areas of the gulf and outer coast for the extended period to
account for this and temperatures along the outer coast may need
to be lowered due to the persistent cloud cover.

Long range models in good agreement on the overall pattern but did
start to struggle with individual short waves that were rounding
the upstream trough into early next week. Model trends still
favoring a mostly dry and warmer long range period. Used mostly
WPC for updates where needed.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Gale Warning for PKZ022.
     Small Craft Advisory for PKZ012-041>043.
     Small Craft Advisory due to Seas for PKZ052.

&&

$$

Byrd/EAL

Visit us at http://www.weather.gov/Juneau



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.