979
FXAK68 PAFC 020037
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 PM AKDT Mon Jul 1 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

A vertically stacked, weak low pressure system is currently over
the Alaska Peninsula with a zonal ridge to the north extending
from St. Lawrence Island east into Yukon Territory. The area of
low pressure and very weak easterly waves will continue to
generate some shower activity near the coast, high terrain, and
Kodiak through early tomorrow morning as the low drops south into
the North Pacific. This will lead to some clearing Tuesday and
Wednesday a weak ridge moves over Southcentral. Up-inlet flow and
southerly winds through Copper Basin will keep temperatures on the
cooler side as to what has been observed recently.

A pattern change to cooler and wetter weather will begin Thursday
(July 4th) as a shortwave rides over the ridge and into
Southcentral in the afternoon to evening. There is some
uncertainty as to the timing and extent of precipitation. Given
the northwesterly flow and overall dry conditions of the past few
weeks, this initial wave may struggle to saturate down to valley
locations, resulting in most of the light rain falling on the
western faces of the regions mountain ranges, particularly the
Talkeetnas and Wrangells. This first wave looks most likely to
bring precipitation to the interior portions of the region, with
more widespread rain moving in for the holiday weekend.

CJ

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, BERING SEA/ALEUTIANS
(Days 1 through 3)...

A ridge of high pressure continues to push the persistent Eastern
Aleutian Low east of the Alaska Peninsula this afternoon
resulting in an end of the spotty precipitation tomorrow. The
aforementioned ridge continues to cause periods of fog and low
ceilings to the Central Aleutians and the Pribilofs Islands as
seen on satellite this afternoon. Periods of fog and low ceiling
conditions will push in to the Eastern Aleutians, Southwest
coastline and the Alaska Peninsula this evening and continue
through the day tomorrow. It will slowly erode Wednesday as
northerly winds shift to a more southwesterly direction
throughout the day.

A Kamchatka Low moving into the Northern Bering Sea will cause
the ridge of high pressure to move southeasterly toward Bristol
Bay. This will push the fog toward the AK Peninsula and coastal
Southwest Alaska Wednesday. Also on Wednesday, scattered rain
showers are expected from the Western and Central Aleutians. Also,
rain showers are expected form Bethel to Sleetmute northward late
Wednesday. Though an increase in precipitation spread and amount
from the past few model runs, it is consistent with the synoptic
setup going into mid-week. Cooler temperatures are also expected
mid- week with this pattern change.


-DJ

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

The ridge of high pressure over Southcentral Alaska will start to
gradually weaken through early next week. This, coupled with an
approaching frontal system from the west, will produce a
southeasterly wind flow across the area. Cooler temperatures and
sporadic widespread precipitation over the region is possible over
the long 4th of July weekend. Precipitation should remain in the
mid to upper elevations but we cannot rule out intermittent rain
over much of Southcentral Alaska and the Copper River Basin
through Monday. Several troughs of low pressure extending from a
cutoff low in the North Pacific will bring some heavier periods of
precipitation across Kenai Peninsula, Kodiak Island and the
Northern Alaskan Peninsula through Monday afternoon. Out west, the
Bering/Aleutians and Southwest Alaska can also expect showery
conditions through the weekend as an upper-level trough and
multiple shortwaves rotate across the regions.

-DD

&&

.AVIATION...

PANC...The coastal surface ridge and associated Turnagain Arm jet
will weaken this evening as a surface trough over the Kenai
Peninsula this afternoon continues to lift slowly northward.
Thus, the gusty southeast winds will diminish by late this
evening (06-09Z) and transition to a lighter up Inlet wind with
SW flow. A broad ridge will then build over the Gulf behind the
trough on Tuesday, leading to a more typical sea breeze type day
for PANC, with light WNW winds developing during the morning hours
and slowly backing toward the S through the day.

Meanwhile, VFR conditions will persist. However, ceilings will
slowly lower as the trough approaches, possibly dropping to 5000
feet or lower overnight through early Tuesday, but staying in the
VFR category. Then expect ceilings to slowly lift during the day
Tuesday as the trough dissipates.

&&

$$