Small Craft Advisory 574, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
646 AM AKDT Fri Aug 9 2019

.ANALYSIS AND UPPER LEVELS...

High pressure extends from the north Pacific, across the Alaska
Peninsula and through the eastern Bering. This setup has helped
to dry out Southcentral Alaska and bring northerly, outflow winds
to the area. Additionally, the high pressure has helped in
developing stratus and fog over the eastern Bering and surrounding
areas. Farther out west a front is approaching the western
Aleutians with another round of rain.

&&

.MODEL DISCUSSION...

The models are in good agreement with the majority of the synoptic
features through the midterm. The main area of disagreement is
with a weak shortwave tracking southeast through the mainland on
Sunday. The EC and Canadian models have it moving through
Southcentral Alaska Sunday night while the much slower GFS and NAM
have it pushing through Monday afternoon. These differences will
impact the timing of stronger outflow winds for Southcentral
Alaska. A middle ground solution was preferred.

&&

.AVIATION...

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

&&

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

The weather pattern will change little through Saturday night with
the upper level ridge centered to the southwest of the area and
upper level troughing to the northeast. Warm and dry weather will
thus continue. Afternoon high temperatures will continue to be
around 10 degrees above normal for most areas. Winds will be
fairly light as the surface gradient is weak. There is a slight
chance of diurnal thunderstorms over the Talkeetna Mountains today
and Saturday due to some weak instability over the area.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3; Today
through Monday evening)...

High pressure centered east of the Kuskokwim Delta will continue
to bring mostly cloudy skies and cooler temperatures to that
region. Patchy coastal fog will remain possible in weak onshore
flow through Saturday. Meanwhile, northerly offshore flow farther
south will lead to mostly sunny conditions and highs in the low
70s across the middle Kuskokwim Valley and Bristol Bay coasts. A
more dynamic pattern will move into the mainland by Sunday as a
shortwave trough and associated surface front approach from the
west. Though there is still minor disagreement regarding the exact
position and interaction of upper level features, widespread
moderate rain appears likely into Monday as the front moves
inland.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3;
Today through Monday evening)...

Scattered showers are presently occurring across the western
Aleutians under a weak pre-frontal trough and will continue
through today. The main front will track west to east over the
Bering on Saturday and likely bring a small area of southerly
gales in the Atka area. The parent low will gradually begin to
weaken on Sunday as it becomes vertically stacked, thus winds will
diminish as the front tracks farther east. However, moist
southerly flow will continue into early next week between the
aforementioned low and a high to the southeast. As such, rain is
expected to continue.

&&

.MARINE (Days 3 through 5)...

The front progressing eastward across the central Aleutians and
Bering will be the main weather feature moving into Saturday.
Models are in better agreement with this feature that there will
be small craft winds and even the potential for low end gale force
winds. There is only a small disagreement in the speed of how
fast the front makes it to the eastern Bering by Sunday but all
models are trending to a faster solution than yesterday's model
runs.

&&

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

Models are in better agreement today for the period starting on
Saturday. A ridge is still positioned over the eastern Bering and
southwest Alaska with a low entering the western Bering. There is
also consensus of a secondary low extending down from an Arctic
low that could possibly track across Southwest and Southcentral
through Sunday, which could bring precipitation back to the area.
The pattern change continues through Tuesday as models suggest the
Arctic low merging with the Bering low, flattening the ridge
across southern Alaska. Cloudier and moister conditions will
spread across the region in this sort of pattern. By Wednesday, a
new low should enter the Bering Sea, which will help to re-amplify
the ridge across Southwest and Southcentral, leading to a warming
and drying trend late next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...AH