149
FXAK02 KWNH 292349
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
748 PM EDT Wed May 29 2024

Valid 12Z Sun Jun 02 2024 - 12Z Thu Jun 06 2024

...Overview...

A closed upper low advances across the Aleutians over the weekend,
reaching the northeast Pacific early next week. This pattern will
support a mean low across the Aleutians, the Gulf of Alaska and
southern portions of the state; which will be supportive for
precipitation to spreading along the Southern Coast of Alaska with
cooler than normal temperatures. Upper ridging to the northeast of
this storm track should promote mild to warm temperatures over the
Interior with some convective showers, at least into the weekend,
but with more uncertainty early next week as Arctic energy may
approach. Another round of precipitation for southern/eastern
Mainland and moderate/locally heavy rain possible for the
Panhandle latter in the week.

...Guidance Evaluation and Preferences...

The latest guidance has shown an increase in the clustering of the
pinwheeling energies over the Gulf of Alaska/North Pacific during
the initial and middle part of the forecast period-- an
improvement of an additional 1-2 days from prior forecast before
the spread increases beyond Tuesday. With that said, there
continues to be a degree of variability with the energy/low that
drops south from the Arctic whether is will remain offshore over
the Bering or move over portions of West/Southwest Mainland the
later half of the extended period. To the north and east of the
storm track, a generally ridgy pattern aloft should be in place
across much of the Mainland into late week. Model guidance does
show some possibility of Arctic energy diving southwest toward or
into the northwestern Mainland by the weekend or early next week.
This could increase the potential for convective showers across
the Mainland however this feature remains an uncertain aspect of
the forecast with low confidence.

A combo of the ECWMF/GFS/CMC/UKMET was utilized through hour 144
before introducing a small weighting of the EC ensemble and GEFS
means by hour 156. As the UKMET was dropped off the inclusion of
the means were slowly increased by the end of the period.

...Weather/Hazards Highlights...

During this period no significant weather hazards are forecast.
There may be instances were the convective showers over portions
of the Interior during the afternoons and evenings produce heavy
rain which may lead to very local impacts, however the exact
location and timing is uncertain. In addition, lightning
associated with the convection may increase the risk for wildfires
if strikes hit drier locations. Depending on the eventual flow
pattern over the Mainland next week, precipitation may become more
widespread and heavier, but this remains uncertain. River flooding
is a possibility in a spot or two with the seasonal ice breakup;
see the Alaska-Pacific River Forecast Center for details. For the
Southern Coast of the state--across the Alaska Peninsula (and
Kodiak Island) to the Kenai Peninsula and Prince William Sound to
the Panhandle--can expect some precipitation chances given the
favorable troughing and expected low tracks. Some localized
heavier totals in typically favored areas of terrain are possible,
but heavy amounts should not be widespread.

With weak riding in place over central/northern portions of the
Mainland daily temperatures will be near or above average.
Interior Alaska is likely to see the mildest temperatures across
the state, with highs in the 60s to low 70s late this week into
early next week, around 5-10 degrees above average. The North
Slope is likely to be closer to or below average, with highs just
above the freezing mark in the Arctic Coast communities. For the
southern coast, temperatures at least for highs are forecast to
stay below normal given the troughing and active pattern in place,
with 40s and 50s for the most part. However, 60s look to sneak
into Anchorage to Talkeetna.

Campbell


Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html

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