Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 301240
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
440 AM AKDT Thu Mar 30 2017
.ANALYSIS AND UPPER LEVELS...
The upper level shortwave that brought all the snowfall for the
Anchorage Bowl yesterday has exited northward into the central
Alaska interior. While upstream an amplified ridge extends
through the Gulf across the Aleutian Range into the Bristol Bay
interior. Meanwhile, a large complex low is positioned south of
the Central Aleutians. The associated occluded front is
approaching the Eastern Aleutians stretching just south of the
lower southwestern Gulf region this morning. This coincides with
the satellite imagery reflecting a large plume of moisture
entering the aforementioned region, and spreading along the
Eastern to Central Aleutians. The radar imagery is showing a few
lingering snow showers along the northern Gulf coastal communities.
Looking at the Southwest Alaska region, they remain under
offshore flow with continued dry conditions. While the Bering Sea
has predominantly easterly flow with marine layer stratus.
The models remain in good agreement with the next low pressure
system located over the North Pacific. The NAM was the preferred
model through the short-term forecast. The jet stream has
transitioned to a southwesterly flow as it enters the Western
Gulf, before transitioning to northwesterly flow along the
Southeast Panhandle. This pattern will bring warmer temperatures
to the Southcentral Region. The forecast confidence is above
average as we head toward the weekend.
PANC...Conditions will transition to VFR this morning. Look for
the northerly winds to increase this afternoon as the pressure
gradient strengthens with a weather front entering the Gulf.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
A strong front moving in from the southwest will surge across the
gulf and into south central Alaska today. This front will be
accompanied by fairly heavy precipitation along and near the
coast. Inland locations will remain mostly dry through Friday
night due to strong southeast flow across the coastal mountain
ranges. The front will also bring much warmer air, allowing snow
to change over to rain fairly quickly across coastal locations.
This warmer air will move inland on Friday, with temperatures
climbing into the 40s at many locations on Friday.
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The front currently stretched across the eastern Aleutians and
Alaska Peninsula pushes north later today spreading snow and gusty
winds across the Southwest mainland. Gusty east to northeasterly
winds are expected to be strong along the boundary which brings
blowing snow impacts to the Alaska Peninsula into Friday morning.
Winds increase across Bristol Bay late morning with snow
developing in the afternoon. An east to west oriented low level
jet associated with the front limits snow through today as strong
winds along the range keeps most of the area downsloped. However,
the flow weakens tonight as the surface low approaches Sand Point
which brings increased chances for snow. By Friday morning, the
front orients along a north to south position from the Alaska
Peninsula to western Bristol Bay and the Kuskokwim. The boundary
stalls through Saturday, therefore snow amounts were increased
especially along and west of Dillingham. Snow amounts may need
adjusting with the next package as there is still a bit of
uncertainty with the track of the surface low.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Winds increase this morning across the eastern half of the Bering
as a North Pacific low moves a front north toward the southern
mainland. Gale to storm force winds are expected to impact marine
waters through Friday night with the strongest winds along and
south of the eastern Aleutians and Alaska Peninsula. Snow develops
along the frontal boundary mixed with rain along the eastern
Aleutians. Cold air advecting in behind the low is expected to
change precipitation to all snow by this afternoon. Across the
western waters...ridging along Kamchatka moves slowly toward the
western Aleutians with a lighter northerly flow and low clouds the
dominant pattern through the end of the week.
.LONG TERM FORECAST (Days 3 through 7)...
(From yesterdays Forecast Discussion)
Following the chinook on Friday, the possibility of another
chinook on Saturday is growing. Regardless if the chinook happens,
temperatures overnight on Friday will likely remain above
freezing for much of Southcentral Alaska with Saturday high
temperatures in the 40s once again. Southwest Alaska will not see
the extremes that Southcentral will because the storm track
favors the warmer air pushing eastward into the gulf of Alaska. As
the active weather pattern remains entrenched across the region,
a series of low pressure systems will move into the gulf of Alaska
through the upcoming week. This will allow continued pushes of
warm and moist air back toward Southcentral Alaska which could
quite possibly keep high temperatures above freezing for the next
week. The gulf coast should continue to get slammed with rainfall
at lower levels and snowfall toward higher elevations much much of
inland Alaska will remain on the dry side as most locations
should remain downsloped. This pattern really shows no signs of
breaking so until something changes, this warm and spring-like
pattern will continue.
MARINE...Storm Warning 119 130 131 138 139 150 155 172.
Gale Warning 120 125 132 136 137 140 160 165 170 171 173>176 180.
Heavy Frz Spray 179 185.
SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH