Severe Thunderstorm Warning 5, NWS Anchorage, AK

366 
WWAK58 PAFC 070211
SVSAFC

Severe Weather Statement
National Weather Service Anchorage AK
610 PM AKDT Wed Jun 6 2018

AKZ161-070230-
/O.CON.PAFC.SV.W.0005.000000T0000Z-180607T0230Z/
Bristol Bay-
610 PM AKDT Wed Jun 6 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM AKDT
FOR NORTHWESTERN BRISTOL BAY...

At 610 PM AKDT, Doppler radar indicated a severe thunderstorm 
capable of producing up to quarter size hail. This storm was located 
26 miles north of Togiak, and is moving south at 15 mph as 
it begins to weaken.

Locations impacted include...
Kashiagamiut.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Severe thunderstorms produce damaging winds, destructive hail, deadly
lightning and very heavy rain. For your protection move to an
interior room on the lowest floor of your home or business. Heavy
rains flood roads quickly so do not drive into areas where water
covers the road.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Anchorage.

&&

LAT...LON 5931 16057 5949 16037 5944 16001 5924 16002
TIME...MOT...LOC 0210Z 010DEG 14KT 5944 16026 

$$

Kochevar

838 
WWAK58 PAFC 070226
SVSAFC

Severe Weather Statement
National Weather Service Anchorage AK
626 PM AKDT Wed Jun 6 2018

AKZ161-070236-
/O.EXP.PAFC.SV.W.0005.000000T0000Z-180607T0230Z/
Bristol Bay-
626 PM AKDT Wed Jun 6 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN BRISTOL BAY WILL
EXPIRE AT 630 PM AKDT...
        
The storm which prompted the warning has weakened below severe limits
and exited the warned area. Therefore the warning will be allowed to
expire.

LAT...LON 5931 16057 5949 16037 5944 16001 5924 16002
TIME...MOT...LOC 0226Z 010DEG 14KT 5943 16026 

$$

Kochevar

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
500 PM AKDT Wed Jun 6 2018

.ANALYSIS AND UPPER LEVELS...

The synoptic scale pattern has a large upper level low over the
southern Gulf of Alaska with a trough trailing to the west, south
of the Alaska Peninsula and eastern Aleutians. An upper level high
is over the Bering Sea and the thermal trough extends from the
upper Yukon Valley southwest to the Kilbuck Mountains. Bringing
this down to the mesoscale we have a easterly wave transiting off
the Alaska Range through the Bristol Bay and middle Kuskokwim
Valley regions that is keeping the convection brewing over
southwest Alaska today. This will be the primary focus for this
evening and tonight as daytime heating fuels continued convection.
Another easterly wave is now moving across Prince William Sound
and the Copper River basin into Southcentral Alaska. Moisture
remaining from last night is over the Talkeetna Mountains and
Susitna Valley, and will be available to support convection this
evening.

The high pressure over the Bering Sea is resulting in stratus and
fog over the eastern Bering Sea and the Pribilofs today. Visible
satellite shows a distinct northern edge to this stratus and fog
just to the north of the Pribilofs heading south, thus expect
rapid clearing of the stratus and fog. Further west is yet another
North Pacific low heading toward south of the Aleutians, likely
only bringing a glancing blow to the central and western Aleutians
over the next day or two.

&&

.MODEL DISCUSSION...

Models continue to be in generally good agreement through the
short term. The main challenge is the timing and track of the
easterly waves over the next several days and the timing and
location of the convection. By day 3 the models begin to diverge
on the location of a developing low south of the Aleutians, although
they are coming into closer agreement. We will maintain the
current forecast trend in the longer range due to the the lack of
run to run consistency in the longer range model forecast.

&&

.AVIATION...
PANC...VFR conditions are expected through the evening along with
showers in the vicinity of the airfield. Gusty southeast winds
will increase late this evening and continue into early Thursday
morning. There is then expected be a lull in the winds for most of
the morning on Thursday before increasing again for the afternoon
and evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Thursday
and Friday)...

Scattered thunderstorms developing along a westward moving line
over the Talkeetna Mountains will continue into the evening,
eventually making their way towards Talkeetna and Broad Pass.
Meanwhile additional thunderstorms are developing along the
Alaska Range in the Copper River Basin. These too are expected to
continue into the evening hours. Further south towards Anchorage
and the Matanuska Valley, morning cloud cover has largely
prevented enough instability to build up to allow for thunderstorm
development, but a stray shower or two cannot be ruled out.

On Thursday, the thermal trough supporting the development of
thunderstorms will move northward away from the area, leading to a
general reduction in the number of storms over the Copper River
Basin and Susitna Valley on Thursday. With that said, isolated
storms are still possible again Thursday and Friday along the
Alaska Range and Talkeetna Mountains. Meanwhile, temperatures
across Southcentral will gradually rise each day, with lower 70s
forecast over much of the Susitna Valley and Copper River Basin by
Saturday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
With strong instability and the thermal trough in place over
Southwest Alaska, expect to see the already very active
convective pattern continue well into the evening. North to
northwesterly flow over the Kuskokwim Delta should keep
thunderstorms pushed further to the east as compared to yesterday
with vast majority of activity occurring from the Kilbuck
Mountains eastward. Portions of the Wood Tikchik Mountains that
have been sunny through the day, are the convergence line between
the northerly flow from the Kuskokwim Delta and the southerly flow
off of Bristol and additionally have the thermal trough located
overhead have elevated potential for strong to severe thunderstorm
development.

With easterly flow persisting into the weekend and the continued
presence of the thermal trough, isolated to scattered thunderstorm
activity will continue each afternoon and evening with the highest
lightning concentration continuing to follow the axis of the
thermal trough.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Weather over the Bering remains generally quiet as upper level
ridging builds in from the north. A North Pacific low well south
of the Aleutians will track to the east through Thursday night to
be south of the central Aleutians by Friday morning. A rapidly
developing triple point low out ahead of it will swing northeast
on Friday to swings a front up to the eastern Aleutians and
western Alaska Peninsula late Friday night and Saturday.

&&

.LONG TERM FORECAST (Days 4 through 7)...
Beginning Saturday evening, the southern half of the state will
be dominated by weak ridging while a low tracks slowly east along
the southern side of the Aleutian chain. This should lead to
pleasant weather, especially out across SW Alaska over the
weekend, with some diurnally driven convection likely in the
afternoon.

A bit more uncertainty has creeped into the long term forecast as
models are struggling to handle a large upper level low dropping
south from the Arctic Ocean and across the northern half of the
state. Models are not in agreement with how far south energy
associated with this system makes it. The EC is the most
aggressive in bringing a potent short wave trough south across
the Alaska Range out ahead out the low Saturday evening through
Sunday morning. This would bring cloudier and wetter weather to
Southcentral with widespread thunderstorm activity likely over the
Susitna and Copper River Valleys. The GFS solution keeps energy
associated with the low over the eastern half of the state and
mostly north of the Alaska Range, keeping the majority of
Southcentral drier and warmer. For now, the long term forecast
will trend towards the ensemble solution which more closely
follows the GFS' solution.

There is overall good agreement regarding a large area of high
pressure over NE Russia building southeast across the Bering and
over the western half of the state, even nudging into
southcentral, by the beginning of next week. This will lead to
drier and much warmer conditions for the southern mainland through
the middle of the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Severe Thunderstorm Warning 161.
MARINE...None.

&&

SYNOPSIS AND MODEL DISCUSSION...SA
SOUTHCENTRAL ALASKA...JW
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...KVP