Area Forecast Discussion
Issued by NWS Anchorage, AK

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147
FXAK68 PAFC 241224
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
424 AM AKDT Sat Jun 24 2017

.ANALYSIS AND UPPER LEVELS...
The upper ridge of the last couple days has shifted over the
Canadian Yukon with only an axis extending over the Alaska Range.
The next feature of interest is an upper low center moving into
the Gulf of Alaska. A previous shortwave trough, ahead of the
upper low is moving inland near the northern Panhandle. Out west,
a stronger stacked system is spinning over the western Bering Sea.
South of this system is the only real jet action over the area,
where a 100 kt jet streak over the northwest Pacific enters the
Bering Sea low pressure. The mainland is left under generally weak
flow aloft with no major features to key in on. The weak flow has
led to the development of diurnal convection in areas of steep
lapse rates, as well as persistent stratus in other areas.

&&

.MODEL DISCUSSION...
Guidance has come into much better agreement with the interaction
between the shortwave near the Panhandle and the incoming Gulf
system. The consensus now is a much more consolidated shortwave
moving inland more over Canada, just grazing the Copper River
Basin. Otherwise the synoptics are very well agreed upon, the Gulf
system will move over the Panhandle, while the Bering system will
propagate to the east and anchor the pattern for the short term.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The low moving into the Gulf of Alaska has turned the flow to the
northeast which has cut off the up-Inlet push causing the low
stratus in the Cook Inlet Region the past few days. While surface
winds will increase from the southwest again Sunday afternoon,
the atmosphere should be dry enough by then and well-enough mixed
to keep the stratus from developing the way it has been lately.

Unstable air remains over the Talkeetna Mountains eastward into
the Copper River Basin. The additional heating today will allow
more showers and some thunderstorms to develop this afternoon
through the evening in these areas. One question is whether any
thunderstorms will make it into Palmer as the northerly steering
flow could cause a thunderstorm over Hatcher Pass to drift that
direction.

&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Ridging has pushed in over southwest Alaska and will continue to
track east through the weekend. Stratus and fog have formed
underneath the ridging and flow has shifted to southwest helping
to push the stratus and fog over areas near the coast. The fog and
stratus will diminish late in the morning but come back tonight.
Meanwhile, inland locations will see afternoon showers with
thunderstorms possible along the mountains until Sunday afternoon
when more widespread rain will push in over southwest Alaska as a
front moves in.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The low over the western Bering is bringing rain to the Central
and Eastern Aleutians that will last until its associated front
moves off to the east tonight. There will be a brief period of
gale-force winds in the marine areas around the Eastern Aleutians
as the front moves through tonight. Then it will track across the
Alaska Peninsula and eastern Bering on Sunday. Behind the front
light showers will persist through much of the weekend.

&&

.LONG TERM FORECAST (Days 3 through 7)...
An amplifying longwave pattern looks to bring an end to the
period of nice weather over much of southern Alaska early next
week. By Tuesday, the broad upper level trough over the Bering Sea
will dig southward and begin tapping into some moist subtropical
air, while advecting that air northward into the Gulf of Alaska.
This moist southwest flow regime looks to set up a rather wet
period for much of southern Alaska late Monday through Friday of
next week, as a series of systems move into the Gulf of Alaska and
north toward the gulf coast. There remains pretty remarkable
model agreement with this change in weather pattern so confidence
continues to rise in the change itself and the likelihood of it
persisting through the entire week. However, it is to be expected
that there could be some breaks in the rain and clouds but
overall, wet and cloudy will be the theme for much of next week
and into next weekend.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 170 172.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...MTL
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...TP



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