Small Craft Advisory 778, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
420 AM AKDT Wed Oct 10 2018

.ANALYSIS AND UPPER LEVELS...
A storm force surface low is in the process of crossing the Alaska
Peninsula early this morning. Ahead of and to the north of the
low, east to northeasterly winds are increasing across much of
Southwest Alaska and coastal Southcentral particularly through
channeled terrain and downwind of gaps and passes. To the south
and west of the low the ASCAT scatterometer indicates storm force
west to northwesterly winds with strongest winds to the south of
the tip of the bent back occlusion. Along the eastern portions of
the Alaska Peninsula and in the greater Bristol Bay area there
have been a couple isolated thunderstorms embedded in the
precipitation along the back edge of the front. To the east of the
low, the ridge aloft has shifted east over the Southeast Alaska
Panhandle and Yukon Territory, while to the west a multi-center
upper level low stretches across the Bering.

&&

.MODEL DISCUSSION...
Models are in good synoptic agreement regarding the current low
and the next two troughs which follow it. By Thursday night and
Friday, some differences start creeping into the model runs
regarding which features become closed triple point surface lows
as opposed to remaining open troughs however the timing of the
waves does remains similar between models.

&&

.AVIATION...
PANC...Wind shear will become an increasing concern this morning
as east to southeasterly gap winds strengthen through Turnagain
Arm. Northerly down inlet surface flow however, should keep these
strong winds from surfacing until after the front moves through
midday. Following that expect strong, gusty southeasterly winds
turning more southerly through the afternoon and early evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The front stretching across the Kenai Peninsula and northern Gulf
will move rapidly northward today, pushing across the Alaska Range
this afternoon. The main surface low associated with this front
will move from near King Salmon this morning to the Yukon Delta
this afternoon. A triple point surface low forming on the front
near Kamishak bay this morning will race up Cook Inlet to near
Denali this afternoon, though this feature is somewhat obscured by
the terrain in the model plots. The result of all of this will be
windy conditions over most of the area. Ahead of and with the
front, the winds will be easterly, and favor gaps in the terrain.
Behind the front and triple point low, the winds will be southerly
and more widespread with the strong pressure rises as surface high
pressure follows the front. Rain will also be more widespread with
and just behind the front, as the flow aloft becomes southwesterly
and downsloping ends. Winds will diminish through tonight into
Thursday as the pressure gradient relaxes. Some showers will
continue as the southwesterly flow aloft remains. Another front
will approach from the southwest Thursday and Thursday night. This
front is not as strong as the Wednesday front. The low level flow
with this front will be more easterly, and thus favor gaps in the
terrain. Some downslope drying will occur, but with plenty of
moisture and fast upper level flow, some showers are still
expected.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
(Today through Friday) The much-talked about remnants of the
former typhoon are working across the AKPEN now, spreading
widespread light to moderate rainfall across almost all of the
region, with even a few lightning strikes from the AKPEN to north
of King Salmon. This general theme of wet weather looks to
continue over the next few days, as this system lifts north before
retrograding towards Saint Matthews Island, with another
developing low moving from the central Aleutians into the Bristol
Bay region for Thursday into Friday. The combination of cyclonic
flow around the first storm and a renewed moisture surge with the
next low will maintain a chance of rainfall across all of
southwest Alaska through the period.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
(Today through Friday) The remnants of the former typhoon are
moving ashore along the peninsula now, with sustained storm force
winds expected to continue through late morning for locations near
Shelikof Strait, before gradually subsiding this afternoon.
Sustained gales will continue for Bristol Bay on the bay side of
the ex-tropical system, with widespread rainfall continuing from
coastal locations of the AKPEN north across the eastern Bering
Sea.

Farther west, sustained low-end gales are expected on the Bering
side of the central Aleutians, as disturbances rotating around the
Bering low help mix down some stronger winds aloft. Otherwise,
precipitation will be more showery compared to locations further
east. Heading into Thursday and Friday, look for winds to be at or
below small craft conditions with no significant seas expected,
and showers continuing.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The mid to long term begins Friday with the models in overall
agreement with a low over the eastern to northern Bering Sea and
a ridge of high pressure extending into southeast Alaska. The
models have also come into good agreement with respect to the next
storm on tap for the western Bering Sea, moving into the western
Aleutians late Friday. This storm is taking a track along the
Aleutian chain to the western Alaska Peninsula through Monday
morning. This is where the models then begin to show more
significant differences in the solutions for it. At that point the
ensemble and WPC solutions will be used. The current forecast have
a slightly faster track for the low along the Aleutians, and we
will nudge toward this solution, primarily resulting in adjusting
the wind direction to better align with the WPC solution.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale 119 120 125 130 131 136 137 139 140 141 150 155 160.
		 Storm 132 138.

&&

SYNOPSIS AND MODEL DISCUSSION...JER
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
LONG TERM...SA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
130 PM AKDT WED OCT 10 2018

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

1027 AM     NON-TSTM WND GST 1 ENE POTTER MARSH      61.06N 149.76W
10/10/2018  M79.00 MPH                          AK   MESONET

1050 AM     NON-TSTM WND GST WNW MCHUGH CREEK RECREA 61.02N 149.74W
10/10/2018  M77.00 MPH                          AK   MESONET

&&

KOBRIEN