Scientific Forecaster Discussion
Southcentral and southwest Alaska forecast discussion
National Weather Service Anchorage Alaska
556 am akdt Sat Aug 30 2014
Analysis and upper levels...
the main weather pattern is driven by an Arctic low centered north
of Barrow. A shortwave is currently moving over the Copper River
basin and moving east. This is enhancing precipitation along the
northeastern Gulf where a surface low is spinning southeast of
Cordova. Scattered rain is also developing across the southern
Bering along two disturbances diving southeast...one entering the
Alaska Peninsula and the other following behind. Colder
temperatures settled across the southern Mainland overnight as a
cold front pushed along the Alaska Range. The frontal boundary
became diffuse as the surface flow slackened overnight.
models are in good agreement with the overnight package so only
minor changes were needed for the updates. The Arctic low sends
multiple waves from the Bering to the southern Gulf with a drier
air mass over the southern Mainland today. A stronger wave moves
from the low Sunday into Monday bringing increased chances for
precipitation at the beginning of the week. The low then begins to
shift east on Tuesday with zonal flow sending a warmer air mass
back into southern Alaska for middle week.
Short term forecast...
cold temperatures rebound this afternoon with clear to partly
cloudy skies...with a slower temperature trend along the northeast
Gulf and Copper River zone as light periods of rain continue
through Sunday before tapering off. The weak flow pattern
increases today out of the north and west as the dense cold
air mass is forced south. Gusty winds through channeled terrain
increase continue through Sunday as the cold air pushes offshore.
a reinforcing wave from the Arctic low will move a cooler air
mass over the southwest by Sunday. Mainly drier conditions through
Sunday morning with increasing chances for rain as the next
stronger shortwave moves through Sunday afternoon. A zonal flow
pattern sets up Monday with a warmer air mass returning across the
southwest into Tuesday.
upper waves from the Arctic low will bring scattered showers and
cooler temperatures through Sunday and then the pattern shifts
with a ridge building into the western Bering Sunday. The ridge
shifts east through middle week bringing a warmer air mass.
Long term forecast...
a drier pattern sets up middle week for southcentral as the Arctic
low shifts east with a zonal flow pattern through middle week. The
upper ridge over the Bering will slowly shift east through next
week returning warmer temperatures across the southern Mainland. A
long wave pattern over the northern Bering deepens late Wednesday
bringing scattered showers back in the forecast for the southwest
and along the Alaska Range as weak waves progress to the south.
Kh Aug 14