Small Craft Advisory 73, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
532 AM AKST Thu Feb 2 2017

.SHORT TERM...Strong northerly outflow event will unfold across
Southeast Alaska through the next 24 hours. The dominant synoptic
feature will remain high pressure over the Alaska Interior and
Yukon. Expect small craft to gale force winds through the central
and northern inner channels by the end of the short term period.
Main change to the previous forecast was to speed up the
increasing northerly winds. Aside from local effect edits to
temperatures in windy/wind sheltered areas, changes were minimal.

Much consideration was given to how to proceed with the high wind
watch for downtown Juneau and Douglas. The potent upper level
shortwave progged to move over the panhandle later today which
will be key in aiding the development of a critical level is
likely tracking farther south and east than previous anticipated.
This would lead to favorable critical level conditions ending up
south of the Juneau. However, based upon the strength of the
cross barrier flow, significant cold air advection, and inversion
think there will still be gusts to 60 mph developing this morning
and continuing into early this weekend. Therefore, we decided to
upgrade the high wind watch to a warning. However, at this point
we would put this on the lower confidence end of warnings.

Used hi-res guidance for minor updates to the previous forecast.

.LONG TERM...Dry and cold weather pattern lasts until the end of
the long range period when blocking pattern finally breaks down
and surface waves begin to track into the eastern gulf. Potential
of an overrunning snow event with these system next week. Until
that time however the main weather impacts will be the strong
northerly and outflow winds. At mid levels high pressure remains
in place over the AK interior with short wave extending from
British Columbia into the SE gulf through early Sunday creating strong
outflow wind patter. By late Sunday into Monday a wave dropping
from the arctic southwestward over the AK interior will disrupt
this pattern. Flow shifts back to onshore as this low moves
toward the Aleutians and begins the return to a wet pattern for
the region.

At the surface, gradient between high pressure over Yukon/N
British Columbia and inverted trough extending from the eastern
Pacific keeping significant northernly winds over the inner
channels. Far northern inner channels getting highest winds with
sustained storm force. As the high shifts late Sunday to the
southeast gradient weakens and winds will begin to diminish. Cross
barrier flow remains high through Saturday and with good
inversion keeping the Taku high wind warning in place. Still
uncertainty with this event as the cross barrier winds remain at
a uniform speed and direction from 850 mb to almost 300 mb, thus
if a critical level is not induced early on the winds may be
limited to only outflow areas.

Used a blend of some NAM/High Res NAM early on then transitioned
to a GFS/ECMWF blend to day 3. Left rest of long range period as
is. Other than some minor changes to winds and some tweaks to
raise temperatures where stronger winds are expected left the
forecast as is. Forecast confidence is average even with stable
pattern due to uncertainty in mountain wave strength.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning from 9 AM this morning to 3 PM AKST Saturday
     for AKZ025.
     Strong Wind through this afternoon for AKZ018.
MARINE...Storm Warning for PKZ043.
     Gale Warning for PKZ011>013-021-022-031-042-051.
     Small Craft Advisory for PKZ032>035-041-053.
&&

TPS/PRB

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
228 PM AKST THU FEB 02 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0846 AM     NON-TSTM WND GST JUNEAU                  58.30N 134.41W
02/02/2017  M64.00 MPH                          AK   OFFICIAL NWS OBS

            PEAK WIND AT SOUTH DOUGLAS ISLAND PROFILER SURFACE WIND.

&&

JBYRD

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE JUNEAU AK
230 PM AKST THU FEB 02 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0846 AM     NON-TSTM WND GST JUNEAU                  58.30N 134.41W
02/02/2017  M63.00 MPH                          AK   OFFICIAL NWS OBS

            PEAK WIND AT SOUTH DOUGLAS ISLAND PROFILER SURFACE WIND.

&&

JBYRD