Area Forecast Discussion
Issued by NWS Juneau, AK

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FXAK67 PAJK 242235
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
235 PM AKDT Thu Sep 24 2020

.SHORT TERM...Complex but fairly low impactful weather through
the end of the week. Significant changes for the weekend with
highly impactful storm system moving in.

The broad mid level low which has been situated over the AK Gulf
the past days will finally pull back to the NW through Saturday.
At the surface the complex series of low pressure systems that are
continually rotating around each other will also pull the the NW.
Through that time bands of showers still push over the AK
Panhandle from south to north. Very difficult time tracking these
bands as no one model or model run has fully captured the
situation. Overall the southern areas getting majority of showers
and higher rainfall amounts as many bands have some signs of
shearing apart once they hit the northern areas. Not counting out
breaks in precip and cloud cover, especially later on Saturday,
which could result in some fog formation. Some 20 kt winds over
the southern inner channels and coastal waters through Saturday
but overall winds less than 15 kts. However do anticipate gustier
winds near any shower activity.

Main change to the forecast...storm force low/front moves into
the AK Gulf Saturday night into Sunday. Latest models runs in
better agreement with gulf winds at least 50 kts. Stronger winds
are possible. NE Panhandle coast gets first hit of stronger winds
along the front with wind gusts over land at 40 mph. Secondary
wrap aims next band of high winds at the central panhandle coast.
Rain moves in from the SW late Saturday night into Sunday with
heaviest rain over the southern panhandle. 12 hour rain totals
upwards of 2 inches possible with atmospheric river setting up.

Better agreement between GFS/NAM for the Sunday system. 12z ECMWF
fell more in line with other models but has been showing much
larger run to run inconsistencies. Due to the better model
alignment made the call for such a large change to the forecast.
Will likely see higher QPF amounts added once more model runs
come in as well as possible higher winds.


.LONG TERM...Saturday through Wednesday...As of 10 PM Wed...
Period begins with a deepening upper trough over AK pen with SW
flow into the panhandle. Models continue to show some spread in
strength and position with a low approaching the SE gulf Sun along
with heavy rain for the first half of next week. Given the
continued spread will need to continue monitoring guidance as
this has the potential to push an AR and stronger winds to the
gulf coast and S panhandle. Little change in the overall pattern
through the period with long wave ridge anchored over W NA. This
will maintain the active pattern through the extended with
continued chances from precip but normal to above normal temps.
Overall forecast confidence remains about average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ041>043-051.

&&

$$

PRB/BC

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