Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 270114
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
514 PM AKDT Wed Jun 26 2019

.ANALYSIS AND UPPER LEVELS...
The dominant weather feature today and going into the end of the
week will be a strong building ridge over SW AK. While the ridge
builds over Southcentral AK, it will leave the Bering in a broad
longwave trough. This pattern will make for a stark contrast
between cool, cloudy, and wet over the Bering, while it will be
sunny, dry, and near record heat over Southcentral. For most of
the morning, the ridge allowed for widespread stratus and patchy
fog near marine areas. But as the offshore gradient increases and
June sun heats up the surface, these low clouds are quickly
dissipating. The eastern side of the trough (western side of the
ridge) is being supported by an 80 kt finger of the upper-level
(30,000`) jet. This is supporting some potent southerly winds
across the Alaska Peninsula and some light rain stretching from
there up through the YK-Delta.

&&

.MODEL DISCUSSION...Models remain in great agreement through the
short-term (Wed-Fri). There are only a few times in the year
where forecast confidence is this high. By late Fri, there is a
cut-off low over the Alaska Peninsula that is causing problems in
the models. The American models want to push this feature into the
ridge while the Euro and the Canadian track the low into the North
Pacific. The American solution would lead to a marked increase in
clouds, cooler temperatures, and even some showers by Sat.
Meanwhile, the ECMWF and GEM would continue the hot and dry
weather. For now, the latter solution looks more likely based off
climatology with how strong the ridge is progged to be.

&&

.AVIATION...
PANC...VFR conditions and generally light winds will persist.
Afternoon sea breezes will be likely.

&&

.FIRE WEATHER...Swan Lake Fire...Western Kenai Peninsula: All
signs continue to point to hot and dry weather for the next few
days. The ridge is now progged to be even stronger than the past
few days. As it moves in, the synoptic flow will remain out of
the north. However, with increasing stability, there will not be
much to mix these winds down to the surface. Thus, expect mostly
local and diurnally driven winds in the vicinity of the fire. By
late Thu into Fri, the ridge starts to turn into a closed high and
move overhead. This will lead to even calmer conditions/less wind
aloft with increased subsidence. Temperatures will soar into the
mid 80s with Saturday looking to be the hottest day as of now.
Minimum RH values will drop into the low to mid 30s to end the
week.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight
through Saturday)...
The hot and dry forecast is on track. The latest model guidance
actually looks a little stronger with the upper level ridge as it
moves overhead of Southcentral Friday through Saturday. Standardized
anomalies for low level temperatures show values of 5 or greater.
This type of value is often a good signal of potential for record
events. Thus, have trended a few degrees warmer with the
temperature forecast on both Friday and Saturday. Saturday
appears like it will be the hottest day for most of Southcentral,
with widespread temperatures in the 80s, and likely around 90
degrees in portions of the Mat-Su and Cooper River Basin. There
won`t be much relief at night either, with temperatures bottoming
out in the mid 50s to around 60.

Smoke from the Swan Lake Fire continues to be a significant
concern on the Kenai Peninsula. Dense smoke advisories remain in
effect for the Interior Kenai Peninsula through 6pm Thursday for
near zero visibilities at times. The low level flow will remain
nearly constant over the next couple days, with light northwest
winds. This will bring the worst of the smoke southward from the
fire across the Sterling Highway and Skilak lake, eastward to
Cooper Landing, and on down toward Seward. The worst conditions
will generally be late at night through early morning as the
atmosphere stabilizes. However, the amount of smoke will also
depend on how active the fire is. The advisories may need to be
extended further out in time as the flow does not look like it
will shift until Saturday night or Sunday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Saturday night)...

Showers are currently occurring across the Kuskokwim Delta along
a front tracking south to north over the region. These will
gradually taper off overnight as the front shifts slightly
eastward offshore. A strong upper ridge is expected to remain in
place through Saturday, bringing mostly sunny skies and very warm
temperatures.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today
through Saturday night)...

Showers and gusty southerly winds (possibly exceeding 45 mph in
bays and passes) will continue through this evening over the
eastern Aleutians between a surface low to the west and a trough
to the east. Winds will diminish overnight, though showers are
expected to continue trough Thursday under the low`s associated
stalled front. Strong high pressure will then build in from the
south on Friday, bringing light winds and the usual marine
stratus through Saturday. A series of weak fronts over the
western Aleutians will bring widespread showers and occasional
gusty southerly winds through Friday, and will track over the
central Aleutians by Saturday.

&&

.MARINE (Days 3 through 5)...
(Saturday through Monday)

The Bering will see a pattern change this weekend with low
pressure moving in. A front moves in over the western Aleutians
Fri evening spreading in southerly small-craft winds as the parent
low lifts northward. As the front moves eastward, it weakens
quickly and winds diminish by Sat afternoon. A second low enters
the Bering Mon morning bringing another round of southerly flow.
Small craft winds over the central Bering are expected for
Monday, though pockets of gale force winds cannot be ruled out.
Meanwhile, a ridge of high pressure continues to maintain its hold
over the Gulf which will keep winds and seas quiet.

&&

.LONG TERM FORECAST (Days 4 through 7)...
(Sunday through Wednesday)

Forecast uncertainty through early next week continues to remain
high as models struggle to lock onto key features in place behind
the strong ridge currently over the southern Mainland. It does
appear that this strong upper level ridge of high pressure
maintains its hold over most of the state through mid-week next
week, despite the possibility of several upper level shortwaves
attempting to suppress it. Meanwhile, several upper level troughs
of low pressure propagate over the Bering through the weekend.
Once they encounter the blocking ridge, they are steered northward.
Given the high uncertainty in this pattern, overall long-term
forecast confidence is low for next week.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense smoke advisory 121 and 125.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...MO
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...KO


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