Scientific Forecaster Discussion
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Southcentral and southwest Alaska forecast discussion
National Weather Service Anchorage Alaska
532 am akdt Sat Apr 19 2014
Analysis and upper levels...
the low that has resided over the eastern Bering during the last
several days can be seen on water vapor imagery spinning just
north of the Alaska Peninsula this morning. Another closed low is
moving toward the southern Gulf and is currently southeast of the
Dixon Entrance. A shortwave is following this low near 45n 155w
and becoming more organized. Upper level ridging is building
across the southeastern Mainland. At the surface...gusty east
winds are developing over the Gulf waters as the pressure gradient
tightens in advance of the northeastern Pacific low. The
southwestern areas of the state have a few rain and snow showers
that are developing across a weak boundary in relatively weak
flow. Snow showers are also noted across the central Bering as
northerly winds filter in cooler temperatures.
no significant changes were made in the short term forecast
through Monday night as models are in decent agreement with the
overall shift in synoptic pattern. The European model (ecmwf) was the favored model
solution for the current forecast updates with additional use of
the GFS across the Bering added on Monday. The southern Mainland
will stay relatively dry and warmer into the beginning of next
week as ridging builds into central Alaska. Low pressure moves
into the southeastern Gulf today and and slowly meanders west as
the building ridge over the Mainland blocks this system. The
weather pattern becomes progressive this weekend across the
Aleutians and Bering. A ridge will build over the western
aleutains today and shift east tonight as a North Pacific low
pushes a front into the western Aleutians tonight. The current low
in the eastern Bering will shear apart as it is squeezed by high
pressure over the Mainland and central Bering.
Short term forecast...
dry conditions will prevail across much of the southern Mainland
with temperatures at or above normal into the beginning of next
week. Winds will increase this morning along the Gulf Coast and
Cook Inlet as the pressure gradient increases in advance of the
low moving into the southern Gulf. Gale strength winds are
expected across the western Gulf today and across the northern
half of the Gulf on Sunday. Rain will over spread the Gulf this
morning and continue through Sunday. The heaviest rainfall is
expected today along the western Gulf including Kodiak Island. On
Sunday low pressure weakens as it moves south of Kodiak Island.
Scattered rain showers stay in the forecast Sunday across the Gulf
and then isolated chances on Monday as the low diminishes.
early morning satellite imagery indicates the weakening low has
crossed the akpenn and is entering the eastern Bering Sea. This
is helping for redevelopment of rain and snow along coastal
Bristol Bay. Periods of rain and snow will continue until early
this evening when the system will sheer apart and conditions will
begin to improve. Skies throughout southwest will begin to clear
on Sunday morning as middle level ridging over the eastern Mainland
pinwheels westward. This ridging will then continue into early
next week...providing mostly clear skies with seasonable
temperatures and light winds.
snow and rain showers will continue today for the eastern
Aleutians and akpenn as the eastern Bering low dissipates in
place. Most of these showers will be found on the Bering faces of
the islands...where the showers will be short lived and intense at
times this morning. After the upper trough dissipates this
evening...most of the area will experience a brief respite of
better weather as a transient ridge pushes through ahead of the
next Aleutian low. This low will begin to impact the western
Aleutians on Sunday afternoon.
Long term forecast...
the general long term forecast through next weekend remains
mostly unchanged. The Aleutian low that will move into the area
on Sunday will very slowly move through the Bering over the
course of next week as ridging builds over the Mainland. There
remains good consensus that a weakening front from this low will
reach the southwest Mainland and western Gulf on Wednesday...but
ridging should keep interior locations (including southcentral)
dry and mostly clear through the work week. The one exception to
this will be with a slight chance of diurnal convective
showers...mainly along higher elevations...starting middle week and
possibly continuing into the weekend.
Marine...gales 119 120 131 132 138 155 175 176 177 178.
Kh/dek Apr 14