Small Craft Advisory 584, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
823 AM AKDT Tue Jul 31 2018

.ANALYSIS AND UPPER LEVELS...
The vertically stacked low, currently northwest of the Pribilof
Islands, continues its northward trek. Several disturbances
are rotating around this feature, bringing periods of heavier
rain. A front attached to a low near Kamchatka is approaching the
western Bering Sea, with steadier precipitation associated with
it.

Further east, the upper-level ridge positioned across Southcentral
Alaska which brought yesterday's warm temperatures, is currently
repositioning itself into the north Pacific, as the system to the
west is helping to flatten its northern extent. However, there's
still sufficient subsidence from the ridge to maintain light winds
and with the warm temperatures aloft passing over the cooler
marine waters, some marine fog has developed along portions of the
Cook Inlet and northern Gulf coast.

&&

.MODEL DISCUSSION...
Model continuity has improved over the last 24 hours, although
some appreciable differences still exist for early next week. The
general change in the numerical solutions is to increase
precipitation coverage and amounts over the next few days for
Southwest and Southcentral Alaska.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.
Similar to yesterday, some IFR fog and stratus has developed
south of the terminal, and this looks to remain south of it
through the morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Upper level high pressure will be over the area today. This is a
"dirty" ridge with plenty of mid and high level clouds. Afternoon
high temperatures will remain quite warm, especially over the
Copper River Basin. The high will slide east tonight as a front
associated with the Bering Sea low moves in from the west. This
front will bring chances of precipitation to the area, and
temperatures will cool to near normal. The upper flow will remain
somewhat cyclonic Wednesday through Wednesday night which will
keep conditions fairly cloudy with some isolated to scattered
showers.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A low over the central Bering will slowly track northward into
the northern Bering while weakening by Wednesday. The next wave
ejecting from the low will push into the southwest coast this
afternoon. This will bring another round of wet and mildly gusty
conditions to the area, as the front pushes further inland tonight
through Wednesday. A much more potent shortwave trough moving in
southwest flow will spread widespread rain over Southwest Thursday
through Thursday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A low over the central Bering will slowly track northward into
the northern Bering while weakening through Wednesday morning.
Right behind it, a weak front will travel over the western
Aleutians and Bering this morning and dissipate over the central
Bering Wednesday morning. A stout warm front will move into the
western Bering Sea early Wednesday and will strengthen into a near
gale force low over the Bering Sea as it moves eastward through
Thursday.

&&

.LONG TERM FORECAST (Days 4 through 7...Fri through Mon)...
The pattern is shifting to a much more dynamic westerly flow
regime. If you have plans across much of the southern half of the
state Thu night into Fri, prepare to get wet. A system will plow
through in the west-northwest flow and drag up an impressive
amount of moisture into the area from the Gulf of AK. This steady
(and sometimes heavy) rain looks to last into much of Fri. Models
have fairly good agreement on this for now.

Heading into the weekend, things grow slightly less certain. A
ridge of high pressure from the North Pacific nudges up into SW AK
and eventually over to Southcentral. This should bring a brief
reprieve from the rain on Sat, at least for most areas. But more
energy from the Bering will be ride right over the ridge and bring
more rain to SW AK by Sun.

Going into next week, models are struggling with the energy caught
up in the zonal flow and how it interacts with a vertically
stacked upper-level low over the Arctic. But with no sign of
ridging, pretty much the entire domain can expect clouds and high
chances for rain.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...gale Warning 178.

&&

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