Gale Warning 316, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
506 AM AKDT Fri Apr 3 2020

.ANALYSIS AND UPPER LEVELS...

A weak surface low centered over the northern Gulf and an upper
level trough in western Alaska are producing widespread light snow
in Prince William Sound, Copper River Basin, and much of
southcentral Alaska this morning. A ridge of high pressure in the
north Pacific is carrying pulses of energy over its northern edge
into the eastern Aleutians. With a weak surface low in the Bering
Strait, these two features are bringing some fog, stratus, rain
and snow to southwest Alaska and the Kuskokwim Delta. A storm
force front is entering the western Aleutians with strong
southwest winds and temperatures in the upper 30's and 40's ahead
of it all the way to Cold Bay.

&&

.MODEL DISCUSSION...

Model agreement remains strong that there will be a significant
push of onshore southwest flow in western Alaska in the coming
days. Finer details of precipitation type and duration are still
up for debate. A significant push of colder and drier air comes in
behind this system to start the week.

&&

.AVIATION...
PANC...Light snow will create IFR ceilings and visibility
conditions through the day. VFR conditions will return by
afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Snow will end today from west to east as the responsible upper
level trough rapidly moves eastward. A ridge of high pressure will
then build in behind this trough. This will be a fairly flat
ridge, and although some clearing is possible this afternoon and
evening considerable clouds will begin to "spill" over the top of
the ridge. Some areas, including Anchorage, could even see some
precipitation late tonight into Saturday morning. The ridge will
slowly migrate eastward on Saturday and Saturday night as a large
upper low moves into the northern Bering. This will bring
southwest flow aloft. Mostly this will result in considerable
cloudiness, but not much chance of precipitation. The exception is
the Susitna valley, where there will be more moisture and better
dynamics.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Friday
through Sunday night)...

An active weather pattern across Southwest Alaska can be expected
through the weekend. The two main events include a strong warm
front moving inland this afternoon, followed by a very strong
cold front barreling through on Saturday.

While lingering snow showers weaken over the Kuskokwim Delta
coast this morning, a strong warm front is drawing near, and will
reach the coast this afternoon. In addition to a lot of warm moist
air, this front will also enhance winds across the Southwest
coast with most locations seeing onshore gusty conditions in place
by this evening. Cold air will be in place at the surface prior
to the arrival of the front, allowing for initial precipitation to
fall as snow, however as the warm front quickly progresses
inland, a fast transition to rain is expected for coastal
locations. Farther inland over the Lower Kuskokwim Valley, it's
possible that cold air will remain in place longer, thus allowing
for additional snowfall into early Saturday.

A transition back to colder temperatures will occur Saturday
night as a strong cold front moves onshore. In addition to gusty
westerly winds, snow showers are likely, especially along the
Kuskokwim Delta coast Saturday night into Sunday. This combination
could limit visibility at times. As the front continues
progressing eastward, cold air will remain in place through early
next week.

&&

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

A strong front pushing through the Bering today will bring a
surge of warm air to the area. Storm force winds are expected with
this front, particularly over the waters north of Adak through the
afternoon. By Friday night, a strong cold front follows, with
northerly flow wrapping around the backside of the low as it
lifts northward. Gales and snow showers will persist across the
Bering through early Sunday before winds diminish and
precipitation tapers by Sunday evening. A ridge of high pressure
builds over the western Aleutians by Sunday evening. Meanwhile, an
upper level trough in place over the central Bering may create
enough of a disturbance to generate some snow over the Pribilof
Islands, though confidence in this feature remains low at this
time.

&&

.Marine (Days 3 - 5/Sunday-Tuesday)

Bering Sea/Aleutians:

There is a high forecast confidence that gale force winds will
occur in the eastern Bering Sea on Sunday. Confidence is much
lower with respect to a weak low developing in the western Bering
on Sunday then moving into the central Bering on Monday as
guidance shows different solutions in the placement and intensity
of this low. However, winds associated with this low are expected
to remain below gale force. There is low confidence in the wind
forecast on Tuesday as a front will move northward into the
western Bering/Aleutians. Guidance shows differences in the speed
at which the front is moving and differences in the intensity of
the front. However, winds are expected to remain below gale force.

Gulf of Alaska:

High confidence exists in a weak low developing over the northern
Gulf on Sunday and thus gale force northwesterly gap winds are
expected in the western Gulf. Freezing spray associated with these
strong northwesterly gap winds is likely as strong cold air
advection will be present. There is low confidence in the wind
forecast on Monday as guidance shows different solutions with the
placement of synoptic features. However, the general trend is that
the strong northwesterly gap winds gradually ease as transient
high pressure moves over the Gulf. Very low forecast confidence is
in store for Tuesday as another low moves into the Gulf from the
west. Guidance shows very different solutions in the placement and
intensity of this low, though as of now winds are expected to
remain below gale force.

&&

.LONG TERM FORECAST (Days 3 through 7/Monday-Thursday)...

Guidance shows some discrepancies with the placement of synoptic
features on Monday as some solutions show an upper low over the
northeastern Alaskan mainland while others show this low centered
over central interior Alaska. However, one area of consistency is
there will be an upper trough that will encompass the central and
eastern Alaskan mainland and thus colder temperatures are expected
across those areas. Guidance is consistent with the general
pattern on Tuesday with a second upper trough moving into the
Alaskan mainland from the Bering, though there are discrepancies
on the speed of its movement. Due to these speed discrepancies,
the forecast confidence is low as this will influence the speed at
which the surface cold front will move. Generally, it is to be
expected that cold temperatures will continue across mainland
Alaska. Forecast confidence becomes very low Wednesday onward as
guidance shows significant differences in the upper level synoptic
pattern which results in significant differences in the synoptic
pattern at the surface.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm Warning 175 178 413.
         Gale Warning 165 170 173 174 176 177 179 181 185 411 412 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...LTB
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KO
MARINE/LONG TERM...ED

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ANCHORAGE AK
1010 AM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0753 AM     SNOW             SUTTON                  61.71N 148.88W
04/03/2020  E1.0 INCH        MATANUSKA-SUSITNA  AK   TRAINED SPOTTER

            SPOTTER REPORTED 1 INCH OF SNOW.

0600 AM     SNOW             GATEWAY                 61.62N 149.21W
04/03/2020  M3.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW IN THE
            LAST 8 HOURS.

1003 AM     SNOW             NWS ANCHORAGE           61.16N 149.98W
04/03/2020  M4.4 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            NWS EMPLOYEE REPORTED A TOTAL OF 4.4 INCHES
            OF SNOW SINCE YESTERDAY MORNING.

1002 AM     SNOW             72ND AND LAKE OTIS      61.16N 149.83W
04/03/2020  M2.3 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 2.3 INCHES OF SNOW
            OVERNIGHT.

0931 AM     SNOW             LAKE OTIS AND HUFFMAN   61.11N 149.83W
04/03/2020  M3.3 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3.3 INCHES OF SNOW.

0925 AM     SNOW             76TH AND ARCTIC         61.15N 149.89W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW.

0826 AM     SNOW             UPPER HILLSIDE          61.12N 149.72W
04/03/2020  E4.0 INCH        ANCHORAGE          AK   TRAINED SPOTTER

            SPOTTER REPORTED 4 INCHES OF SNOW THIS
            MORNING.

0821 AM     SNOW             POTTER HILL             61.08N 149.81W
04/03/2020  E3.0 INCH        ANCHORAGE          AK   TRAINED SPOTTER

            SPOTTER REPORTED 3 INCHES OF SNOW.

0715 AM     SNOW             EAGLE RIVER             61.32N 149.55W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW.

0700 AM     SNOW             EAGLE RIVER             61.30N 149.53W
04/03/2020  M3.4 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3.4 INCHES OF SNOW.

0640 AM     SNOW             SPENARD                 61.19N 149.95W
04/03/2020  M2.8 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 2.8 INCHES OF SNOW.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1020 AM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1019 AM     SNOW             SOLDOTNA                60.50N 151.10W
04/03/2020  M3.5 INCH        KENAI PENINSULA    AK   TRAINED SPOTTER

            SPOTTER MEASURED A STORM TOTAL OF 3.5 INCHES
            OF SNOW. 2.5 INCHES YESTERDAY AND 1.0 INCHES
            TODAY.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1048 AM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 AM     SNOW             BONIFACE PARKWAY        61.19N 149.78W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW AS OF 9AM.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1104 AM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1035 AM     SNOW             PALMER                  61.60N 149.12W
04/03/2020  M5.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

            SPOTTER MEASURED 5 INCHES OF SNOW.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1108 AM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1108 AM     SNOW             MULDOON                 61.23N 149.73W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW.

&&

ED

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ANCHORAGE AK
1209 PM AKDT FRI APR 3 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1035 AM     SNOW             PALMER                  61.60N 149.12W
04/03/2020  M5.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

            SPOTTER MEASURED 5 INCHES OF SNOW.

1019 AM     SNOW             SOLDOTNA                60.50N 151.10W
04/03/2020  M3.5 INCH        KENAI PENINSULA    AK   TRAINED SPOTTER

            SPOTTER MEASURED A STORM TOTAL OF 3.5 INCHES
            OF SNOW. 2.5 INCHES YESTERDAY AND 1.0 INCHES
            TODAY.

1108 AM     SNOW             MULDOON                 61.23N 149.73W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW.

0900 AM     SNOW             BONIFACE PARKWAY        61.19N 149.78W
04/03/2020  M3.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SPOTTER MEASURED 3 INCHES OF SNOW AS OF 9AM.

&&