Fire Weather Watch 5, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
421 AM AKDT SAT JUL 16 2016

.ANALYSIS AND UPPER LEVELS...

The ridge aloft over the Southcentral region has moved eastward,
and located over the Yukon Territory extending through the
Southeast Panhandle. While, the satellite imagery is showing the
remnants of the convective showers over the AOR this morning.
This will inhibit instability today with the increased cloud
cover, but there is still a slight chance for isolated
thunderstorms over the Alaska Range, and the Mat-su valleys this
afternoon. Meanwhile, upstream there is a front tracking eastward
through the Kuskokwim Delta extending northward into the Brooks
Range. The surface temperatures are in the mid to upper 60's, and
in the lower 50's behind this front. Over the Eastern Aleutians,
a North Pacific low continues to track towards Unalaska with
support from a 100 knot southwesterly jet. This synoptic feature
is bringing a swath of moisture with small craft easterly winds
accompanied by stratus/rain, and spilling over into the Bering
side. Otherwise, an upper level closed high remains over the
Kamchatka Peninsula with the associated ridge extending into the
northern Bering. This is resulting in abundant marine layer
stratus/fog this morning.

&&

.MODEL DISCUSSION...

Models remain in good synoptic agreement with the different
synoptic features through the short term. The Nam was slightly
slower with the system tracking toward the Eastern Aleutians, but
very little disagreement with the other models. The forecast
confidence remains above average as we head into the weekend.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

The upper level ridge will remain over Southcentral Alaska today.
The air mass over the the Copper River and upper Susitna river
basins continues to be unstable, with more showers and
thunderstorms today. Elsewhere, conditions will be dry with
varying amounts of cloud cover. The upper level ridge flattens out
beginning tonight as the jet stream sags south. This will usher in
dryer air and low level offshore flow. Daytime temperatures will
also climb as this new weather regime settles in. Sunday and
Sunday night look much quieter for the Copper River and upper
Susitna areas with thunderstorms no longer in the forecast and
showers generally confined to areas near the Alaska Range.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

With the main low off to the west weak flow resides over Southwest
Alaska. With this setup there is just enough instability and
moisture for light showers over the mountains today but rain will
be limited with drier air being ushered in by a ridge that is
building in from the south. Ridging will then dominate the area
through Monday giving way to warm temperatures across Southwest
Alaska.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

An upper level wave is moving across the Aleutians from the east
to west bringing rain to the area. The wave is over the Central
Aleutians and is moving quickly. Meanwhile a new system is
approaching the Eastern Aleutians from the North Pacific. The low
will make it over the islands this evening and then track towards
the Central Bering as it weakens. This low will bring more
consistent rain as it passes. Sunday will see diminished rainfall
as ridging builds in to the east, but on Monday another system
will move towards the Central Aleutians from the south.

&&

.LONG TERM FORECAST (Days 3 through 7)...

By Sunday afternoon the axis of the amplifying upper level
Pacific ridge will extend north across Southwest Alaska with an
upper level low centered south of the western Aleutians.
Additionally a second closed upper level low centered just
offshore of Washington and Oregon will anchor this general pattern
in place through early next week.

Some forecast uncertainty is introduced due to shortwaves dropping
down out of the Northwest in the Monday and Tuesday time period.
The bulk of the energy with these will stay along and north of
the Alaska range but they will act increase the westerly flow
across the area and enhance gap winds. With Monday looking the
hottest day for south central Alaska and the potential for dry,
breezy west to northwest winds will need to keep a close eye on
this time period from a fire weather perspective.

Depending on the timing and track of the northern shortwaves there
is also the potential for them to drag some clouds across the area
and perhaps some spotty light precipitation in northern areas
over Southwest and Southcentral Alaska in the Tuesday time
period. Confidence is higher in the potential for the clouds than
precipitation but either way it will help to moderate temperatures
somewhat although the breezy conditions are expected to continue.

A low and associated frontal system tracking through the West/Central
Aleutians Tuesday and Wednesday will cross the Bering Thursday, and
then swing through mainland Alaska Friday. While individual model
solutions vary on the precise timing of the system, they are in
good agreement with its existence, general strength, and track.
Therefore, feeling confident with the trend of increasing
precipitation and cooler temperatures for the end of the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KLONG TERM...JR