Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 260049
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
449 PM AKDT Sat May 25 2019

.ANALYSIS AND UPPER LEVELS...
The pattern aloft is comprised of a vertically stacked low
positioned over the central Aleutians with broad cyclonic flow
over the Bering and western Gulf of Alaska. The jet stream is
highly amplified with the strongest portion of the jet vertically
aligned over the western Gulf and AK-Pen. Here, winds are
approaching 130 kts at 30,000 ft. Southern mainland Alaska is
predominately under southerly flow aloft which is ushering in
warm, moist air from the Pacific into Southcentral, Southwest and
the AK-Pen. Satellite imagery detects more than 200% of the
normal precipitable water in this airmass as it moves through the
Gulf.

At the surface, a warm front that was draped from southwest
Alaska into the central Gulf this morning has pushed northward
into Interior Southcentral and southwest Alaska this afternoon.
The Bethel and Middleton Island radars are all showing widespread
stratiform precipitation, and some convective style showers right
along the frontal boundary. Easterly flow at the surface, combined
with a shortwave present over Southcentral, is creating gusty
conditions over the Barren Islands and through Turnagain Arm this
afternoon.

&&

.MODEL DISCUSSION...
Models are in great agreement as the low over the central Aleutians
remains nearly stationary through Monday. In addition to the low
position and strength, models have a good handle on the location
and quantity of precipitation expected throughout most of southern
Alaska.

&&

.AVIATION...
PANC...Turnagain winds will come to an end late this
afternoon/early evening as pressure gradients force the wind to
bend southward down Cook Inlet. A couple of significant upper
waves will bring rounds of rain tonight and again on Sunday.
While there is some uncertainty in exact timing, ceiling/vis is
expected to remain in the VFR category thanks to persistent low
level southeast flow across the Kenai and Chugach Mountains.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Saturday
night through Monday)...
The weather system anticipated the last few days has arrived
about as expected. The first band of precipitation arrived a few
hours early, but overall the forecast is on track. The main low
pressure system producing this weather is to our west over the
Aleutians Islands. This weather system is a double barrel low,
meaning there are two separate low pressure centers. The second
low is farther south in the North Pacific, which will send a
second frontal system through our region tomorrow night. These
systems combined will produce two more main periods of rain for
Southcentral AK, which are tonight and tomorrow night. Otherwise
clouds with light rain showers are expected for most areas. The
exception is coastal areas, which will still see heavier amounts
of rain. Windy conditions in gaps and hillsides are still expected
over the next couple of days as well.

The earlier arrival of this weather also means a slightly quicker
exit. It is now looking like Memorial Day itself will be nicer
than initially expected, with rain clearing out in the morning.
Just some showers will remain by the afternoon, mainly over areas
of elevated terrain.


&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2: Today
through Memorial Day)...
A North Pacific low has crossed into the Bering and is currently
bringing moderate rain and gusty easterly winds to interior
Southwest and the Kuskokwim Delta. The strongest winds in the
Kamishak Gap will diminish this evening, however widespread
showers and breezy conditions will continue across the entire
region through the weekend as the low stalls. Models are generally
indicating two main waves of heavier precipitation, the first of
which will occur early Sunday morning over the Lower Kuskokwim
Valley. The second will occur late Sunday night into Memorial Day
morning and looks to remain closer to the coast. Although there
may be brief breaks in the rain, overcast skies will persist and
temperatures will remain in the mid-to-upper 50s.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2: Today
through Memorial Day)...
Two successive lows will quickly track southward over the far
western Aleutians today and Memorial Day, however their impacts
will be minimal. A stalled low north of Unalaska will bring
widespread rain and breezy conditions (particularly in bays and
passes) across the central and eastern Aleutians through the
holiday weekend. Temperatures will remain on the cooler side in
persistent cloud cover, generally in the upper 40s.

&&

.MARINE (Days 3 through 5)...
In general gale force winds are not expected. However, there
remains a chance that winds could reach gale force from the
western Gulf westward to about the Pribilofs on Tuesday night
and Wednesday as a low moves toward the Alaska Peninsula.

&&

.LONG TERM FORECAST (Days 4 through 7)...
On Wednesday the upper level pattern will consist of a low
centered south of the Alaska Peninsula and eastern Aleutians,
with an upper level high over central and northern mainland
Alaska. Through Friday the location of the upper low will change
very little, just drifting slightly northeast. However, the high
will retreat a little northward, allowing progressively more
cyclonic flow over southern Alaska as troughiness nudges northward.
Although there are model differences in the timing of individual
short-waves moving around the low and trough, the forecast
confidence is above normal due to the stability of the pattern.
This will generally mean chances of rain and showers across the
area through next week with temperatures near normal.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 120 130 131.
FIRE WEATHER...NONE.

&&

$$

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


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