Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 261147
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
347 AM AKDT Sun Mar 26 2017
.ANALYSIS AND UPPER LEVELS...
Ridging continues to dominate the Bering stretching from the
northern Bering through the eastern Bering and across the Alaska
Peninsula. To the east, a trough extends through Southcentral
Alaska and into the Gulf. This trough is bringing showers to
areas around the north Gulf coast. In between the two features,
dry northerly flow continues for areas from Cook Inlet west. These
areas are also seeing mostly clear skies. West of the ridging a
front has stalled over the Central and Western Aleutians and is
bringing rain to the area.
The models are in good agreement through Sunday, but then struggle
with a low approaching the Eastern Aleutians on Monday. Some stall
it, while others move it to the west, and still others try to
elongate it out. However, by Wednesday there is consensus that
they move it into the Gulf. The discrepancies should not result
in large impact differences with the strongest winds happening
before the varying tracks.
PANC...VFR conditions and light winds will persist.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The broad upper trough over Southcentral and a surface low moving
northwest across the northern Gulf will be the key weather makers
through Monday night. Snow showers will continue over the North
Gulf Coast, eastern Kenai Peninsula, Copper River Basin, and
Kodiak Island. Snow showers may even become mixed over the
northern Gulf this afternoon with warming temperatures. The main
surface low center then moves northwest across the northern Gulf
Monday. This feature will spread snow and rain showers to the
coasts along with increasing chances of snow making it across the
Chugach mountains into the Anchorage Bowl and Matanuska Valley.
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
An upper level ridge over the eastern Bering and an upper trough
over Interior and Southcentral Alaska will keep Southwest Alaska
under cool northerly flow aloft through Monday. At the surface,
locally breezy winds out of the east to northeast will persist
with continued sunny skies. The pattern will begin changing
gradually Monday as the upper level ridge shifts further offshore
and the upper trough in Southcentral cuts off to an upper low
over the western Gulf and drifts north-northwest over the Alaska
and Aleutian Ranges. Isolated to scattered snow showers will
creep west across the Alaska Range Monday night and Tuesday.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
While the upper level ridge over the eastern Bering will shift
east, it will remain a strong blocking feature over the north and
central Bering keeping frontal systems confined to areas from the
Aleutians south. Surface lows rotating around a complex upper
level low centered south of the western and central Aleutians will
track east to be south of the eastern Aleutians tonight and
Monday. The surface lows will weaken and stretch to a trough
extending from south of the eastern Aleutians into the western
Gulf Monday night and Tuesday.
.LONG TERM FORECAST (Days 3 through 7)...
Little change to the longer range forecast for most of the region.
By the day three timeframe, guidance is still in agreement that a
surface low will spin into the Gulf as an upper level wave rides
south from the interior. Coastal locations will see precipitation,
but the question remains on the Anchorage area and how good of a
chance there will be for snow in the area. As each day passes
confidence increases and there is a decent chance that the
Anchorage area will see some snowfall into Tuesday.
At this time, confidence remains too low to go any higher than a
chance of snow or to think about totals. The bottom line is that
the pattern is changing. The longwave pattern undergoes a bit of a
shift following this early week system and will set us up to be
in a little bit of a favorable pattern to see systems beyond the
forecast timeframe reaching all of Southcentral.
MARINE...Gales...155 172 174.
SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR