Wildfire in Alaska, July 16 to 31, 2016

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
401 PM AKDT FRI JUL 15 2016

.ANALYSIS AND UPPER LEVELS...
An upper level low is currently centered over Unalaska Island
and stretches southwestward into the North Pacific. This low is
bringing widespread rain showers to the Alaska Peninsula and
eastern Aleutian Islands today. Meanwhile an upper level ridge is
lingering near the Kamchatka Peninsula and supporting a widespread
blanket of stratus across the western and central Bering. Over
Southcentral, generally clear skies and warm temperatures dominate
this morning. With high pressure established aloft, diurnal
heating should enhance the thermal trough across the Copper River
Basin this afternoon. Instability remains impressive across the
Copper River Basin, and thunderstorms are already beginning to
form along the Alaskan Range and Talkeetna Mountains.

&&

.MODEL DISCUSSION...
Models are in generally good synoptic agreement as the upper
level ridge south of the Gulf of Alaska pushes to the north
and west toward Bristol Bay in the short term. The greatest
uncertainty in the short term remains the intensity and location
of thunderstorms across the Copper River Basin. Models currently
indicate the strongest thunderstorms will occur in the western
Copper River Basin this evening, but widespread clear skies may
support widespread intense convection.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Thunderstorm activity has steadily increased across the Copper
River Basin throughout the afternoon and should continue well
into the evening hours with a few weak thunderstorms possible
through the overnight period near the Alaska Range. Cloud cover
over the eastern half of the Copper River Basin and clear skies
over the western half helped to create a baroclinic zone which
helped provide lift to the increasing instability as temperatures
quickly warmed into the mid to upper 70s. A similar set-up is
expected again on Saturday with thunderstorms encompassing much of
the Copper River Basin throughout the day. Isolated thunderstorms
will be possible near the Talkeetna Mountains as well but
conditions look much less favorable.

On Saturday, the overall paradigm change from sea breezes along
coastal locations to offshore flow will commence. This will help
to bring some of the warmest temperatures of the year to
Southcentral Alaska as sea breezes will be unable to move inland.
Some of the locations that will feel the brunt of this the most
will likely be Seward and Whittier but Anchorage and many interior
locations will be in the upper 70s to possibly lower 80s. Winds
will also pick up through some of the gaps with this offshore flow
developing with Seward seeing north winds 10 to 20 mph with stronger
gusts on Saturday and Whittier gusting upwards to 35 mph from the
west.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA...
A weakening low over the Central Aleutians will keep moving
westward tonight, leaving weak upper level flow over the region.
With a rather stable air mass in place, showers will be rather
limited and will favor mountains ranges. Tomorrow, a few more
showers will be possible mainly north of Bristol Bay, but
instability will once again be rather low with no thunderstorms
anticipated. On Sunday, a rather strong Pacific ridge will begin
building into the region, with warming temperatures and drying
conditions.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS...
A quickly weakening low centered over Dutch Harbor will move west
and fizzle out, leaving showers over the Eastern and Central
Aleutians before another North Pacific low moves north and spreads
more light rain over the same area. As usual, fog and sea stratus
will remain dominant over the western and central Bering Sea where
weak high pressure remains.

&&

.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 Southcentral 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 and
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 so feel 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...EN
SOUTHCENTRAL ALASKA...MC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA
LONG TERM...JR