Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 260032
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
432 PM AKDT TUE OCT 25 2016
.ANALYSIS AND UPPER LEVELS...
Satellite imagery this afternoon shows an impressive front that
stretches from the Alaska Peninsula, across western Mainland
Alaska, and curls to the west towards the upper level low in
eastern Russia. Currently this low is bringing gusty winds along
the Alaska Peninsula along with light steady rain. Strong
subsidence is occurring behind this front and resulting in
relatively clear skies with scattered cumulus across much of the
Bering. Meanwhile...an upper level ridge over the Alaska mainland
is finally being pushed eastward and upper level clouds are
beginning to push into western portions of Southcentral. Offshore
gap winds are also beginning to diminish across the northern Gulf
Coast as the surface high pressure system across the mainland has
begun to weaken.
Models are in generally good agreement for the short term as the
front across the Alaska Peninsula continues to push eastward
inland and dissipates tonight. There is still however some
discrepancy in how the triple point develops south of the Alaska
Peninsula late tonight. The GFS model indicates a more concentric
low with a more well-developed low level jet along the south side
of the low and across Kodiak Island and was the model of choice.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The high pressure that has been over Southcentral is shifting
eastward with high clouds from the front in southwest Alaska
moving into the Cook Inlet region. This front will stall overnight
with some periods of high clouds persisting through Wednesday. A
low moving into the southwest Gulf of Alaska Wednesday night.
Blowing dust persists out of the Copper River Delta and covers a
fairly large part of the northern Gulf of Alaska. Diminishing
winds tonight should improve conditions tomorrow.
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A front will move to the Alaska and Aleutian ranges tonight, with
rain along the southwest coast changing to areas of light snow
inland. On Wed a low forms at a triple point south of the Akpen
and brings another round of rain and snow to the region through
Wed night which slowly decreases on Thu.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Rain showers will affect much of the Bering on westerly flow
through Wed. Some precipitation enhancement over the western
Aleutians is expected Wed and Wed night as a low moves over the
area and then dissipates. Another low west of the Dateline will
deepen Wed night through Thu over the western Bering. An
associated front will move to the central Bering and Aleutians on
Thu, bringing rain along with Small Craft and Gale-force winds as
it progresses east.
.LONG TERM FORECAST (Days 3 through 7)...
Most of the active weather in the AOR will remain confined to the
Bering through Friday as yet another gale-storm force low moves
through the region. There however remains high confidence that persistent
ridging over the Mainland will begin to weaken, allowing the front
associated with this low to move into the Gulf and Southcentral
for this weekend. This will bring an end to the sunny and benign
weather that much of Southcentral has experienced since last week
with increasing clouds and a chance of rain. The north Gulf Coast
will have the best chance of rain from this system, however the
front will have weakened significantly so heavy rain is not
expected. More importantly, the ridge is expected to remain east
of area into early next week, allowing for a much more active
pattern for the Gulf and south Mainland as a broad upper level
trough sets up over most of the AOR. This will bring increasing
chances for widespread rain and Gale-force winds for the Gulf
through early next week as the low track shifts to the east.
MARINE...gale 130 131 138 150 155 176 177 178.
SYNOPSIS AND MODEL DISCUSSION...EN
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DS