Small Craft Advisory 432, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
511 AM AKDT Thu Sep 23 2021

.SHORT TERM...A deepening low over the W gulf will move N towards
Prince William Sound today. Storm force winds expected near Cape
Suckling this morning with gales over the E gulf expanding into
the S inner channels early in the morning and SCA winds
developing over the rest of the channels through the morning.
Winds also become gusty over land areas with gusts to 40-50mph
expected for portions of the panhandle today. This storm will also
bring periods of mdt- hvy rain as well. Sat derived rain-rate
products show two areas of .10-.25 in/hr approaching the coast.
The first is just off the NE gulf coast and the other is
approaching Dixon Entrance attm. Precip will transition to
showers early this afternoon for the NE gulf coast and through the
evening for the rest of the panhandle. Widespread rainfall totals
of 1-1.5 inches expected with NE gulf coast and S panhandle in
store for 3-4 inch totals through early Fri. Area rivers and
streams will rise, but no flooding is expected at this time.
Maintained the mention of TS for the NE gulf and coastal areas
tonight as instability parameters continue to show favorable
conditions. Showers and winds will gradually diminish Fri as the
low slowly fills and dissipates. Forecast confidence remains above
average as solutions remain in good agreement on wet and windy
autumn weather into Friday for SE AK.

.LONG TERM.../Saturday through Wednesday night/...The extended
period continues to be an active period for SE Alaska and the
surrounding waters as low pressure systems move through the Gulf
and into the panhandle. However, breaks will occur for some areas
and it is looking increasingly likely that there could be drier
weather, especially through Saturday and Sunday. Rain could return
for some locations by the end of Sunday, guidance continues to
show that a system may impact parts of the area. However,
ensembles have continued to indicate a preference towards a more
southerly track for this low. Should this verify, much of the
northern panhandle could be spared from much of the associated
weather as offshore flow helps filter in drier air from the
interior, cutting off a significant portion of the moisture
transport. The same cannot be said for southern areas however, and
should the current prognostic reasoning continue to hold, it will
be a wet start to the work week for many. After this system,
ensembles are hinting at yet another system arriving on Wednesday,
but growing run to run divergence means that giving details with
any degree of confidence is difficult. Alongside the active
weather, cooler air will continue to filter into the area at
various times, with 850 mb temperatures progged to be below -2C on
more than one occasion across much of the area.

&&

.AVIATION...Ceilings across Southeast Alaska are expected to
deteriorate from visual conditions to marginal as the front
approaches, then deteriorating further to instrument conditions for
both CIGS and VSBY with frontal passage. Still, the biggest impact
to aviation activities will be turbulence and low level wind shear.
Low level winds between 2000 and 3000 ft are at 60 to 70 kts over
the outer coast in advance of the front and running parallel to the
coastline from south to north. Further south, near the triple point,
southwesterly winds flowing over southern Prince of Wales Island are
even stronger at 90 to 100 kts but at a higher altitude. Model winds
are in good agreement with wind speeds measured off of the weather
radar located at Biorka Island. Topography over Southeast Alaska
will disrupt these winds as the front moves inland, but southerly
wind speeds at typical GA altitudes will still be in excess of 50
kts through at least mid morning. The situation improves somewhat by
late afternoon, but low level winds will veer to the southwest
overnight and continue to produce widespread turbulence through
Friday mid-morning.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 1 PM AKDT this afternoon for AKZ026.
     Strong Wind until 10 AM AKDT this morning for AKZ023-027.
     Strong Wind through this afternoon for AKZ025.
     Strong Wind from 10 AM AKDT this morning through this afternoon
     for AKZ017-028.
MARINE...Storm Warning for PKZ052.
     Gale Warning for PKZ033-035-036-041>043-051-310.
     Small Craft Advisory for PKZ011>013-021-022-031-032-034-053.

&&

Fritsch/BC/GFS

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