Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 231302
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
502 AM AKDT Mon Mar 23 2020

.ANALYSIS AND UPPER LEVELS...

An omega block pattern dominated most of the state, as the
associated ridge axis stretched from near Hawaii, through the tip
of the Alaska Peninsula, peaking near Nunivak Island. Flanking
this feature was a shortwave trough over Vancouver Island, and
a pair of troughs further west. The first of which occupies the
Sea of Okhotsk, with a trough axis extending eastward to a mid-
level low that`s centered between Guam and Amchitka.

&&

.MODEL DISCUSSION...

The numerical forecasts show good pattern continuity at the
surface and aloft over the next few days, leading to higher than
average forecast confidence.

&&

.AVIATION...

PANC...VFR conditions and light winds will prevail through the
forecast period.

&&

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

Outflow wind along the north Gulf coast and other areas of
channeled terrain will persist through today as high pressure
remains tow the west and lower pressure well to the east. This
pattern extends from surface through high in the atmosphere so
there is the upper level support to keep winds going. Since the
flow is tilted more to the northwest than northeast it is
mitigating the winds in the Valdez area and keeping them from
developing in the Matanuska Valley.

High clouds can be seen on satellite riding over the northern
part of this ridge and that will increase cloud cover over
Southcentral as the day wears on. A shortwave will move across the
Alaska Range tonight and bring a chance for some snow there, but
it is not expected to bring any precipitation any farther south.
Another short wave (and stronger one) will move into Southcentral
from the northwest on Wednesday and this one has more potential to
bring some precipitation with it.

&&

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

A 1046 mb high over the Bering Sea will keep things quiet for the
next 24 hours for southwest Alaska. An upper level disturbance
will bring precipitation chances back to the Kuskokwim Delta on
Monday night. Temperatures should be cold enough for snow during
this event. A north Pacific low will lift into the Bering by
Tuesday afternoon and things will shift, as the high pressure of
recent days weakens. Warm air advection pushing onshore will
likely deliver some freezing rain chances late Tuesday night
before switching over to rain. An active pattern will keep
precipitation chances in the forecast through Wednesday and beyond
for Southwest Alaska.

&&

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

High pressure will keep much of the Bering and eastern Aleutians
quiet for the next 24 hours. A frontal boundary from a north
Pacific low will lift into the western Aleutians tonight and bring
precipitation and some gusty winds. As this boundary spreads
northeastward the Pribilofs can expect some rain and snow chances
Monday morning. As the parent low lifts across the western
Aleutians precipitation will increase for the eastern Aleutians
and the Pribilofs on Tuesday. As the system weakens into a series
of upper level troughs Tuesday night, precipitation chances in the
Bering will continue for the Pribilofs and eastward through
Wednesday.

&&

.MARINE (Days 3 through 5)...

In the Gulf, winds should not exceed small craft advisory through
Thursday. The Aleutians and the Bering Sea will also remain at or
below small craft criteria during this time.

&&

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

Strong confidence remains that an upper level ridge will remain
over the southern part of Alaska through the middle of the week.
Early Tuesday morning, a North Pacific low will get caught up in
the backside of the ridge, which will bring it northwest across
the western Aleutians and into the Bering Sea. This low will
weaken the ridge, thereby flattening it, and will force the low
southeastward across the eastern Aleutians and right back into the
North Pacific through Thursday. Following this, zonal flow aloft
will be the dominant feature into Friday. Afterwards, an upper
level ridge will build across the Bering Sea until an upper level
trough upstream enters the western Aleutians Friday night. This
will bring precipitation to the western Aleutians/Bering and
across into the eastern Aleutians through Sunday. During this
time, an upper level trough looks to dip down from northern Alaska
and into Southcentral before becoming a closed off low Saturday.
If this solution holds, chances for precipitation will return to
Southcentral through Sunday.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 155
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...CK


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