Marine Forecasts

    EDIT      (on/off)   Help

---

7 Day Forecast for Marine Location Near Point Possession, AK

   Hourly   EDIT   Help

---

Area Discussion for -

      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
FXAK68 PAFC 311257 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 457 AM AKDT Sun May 31 2020

ANALYSIS AND UPPER LEVELS.

The pattern remains amplified as a large upper ridge extends along the west coast of North America into the northeastern Alaskan Interior. A broad upper trough currently extends from eastern Siberia and across the Bering/Aleutians. A closed upper level low is currently weakening over the eastern Gulf of Alaska while gradually weakening. A developing low is currently near 49N 167W and is moving northeastward. Water vapor imagery shows the trough-axis associated with this low changing from a positive to a negative tilt which is more conducive to cyclogenesis. An occluded front associated with this low is currently moving northeastward across the eastern Aleutians into the AKPEN. This front will bring rain to the eastern Aleutians northeastward through the APKEN.

At the surface, radar imagery shows showers moving southwestward across the Kuskokwim Valley into the Kuskokwim Delta. Another area of showers is moving southwestward across the AKPEN. Middleton Island radar shows showers moving westward across the northern Gulf. Temperatures continue to remain above normal due to the aforementioned Rossby Wave pattern with upper level ridging extending over the Alaskan mainland.

MODEL DISCUSSION.

The pattern remains amplified across the region with upper level ridging along western North America into mainland Alaska while upper level troughing persists across eastern Siberia through the Bering/Aleutians. Teleconnections (oscillations that effect the long wave pattern) support a change in the orientation of the Rossby Waves (long wave pattern) over the next week. During the next week the Western Pacific Oscillation (WPO) will change from the positive to negative phase while the Eastern Pacific Oscillation will change from the negative to the positive phase. At the same time, Pacific North American Pattern (PNA) will change from the positive phase to the negative phase. The ECMWF, GFS and GEM ensembles reflect these phase changes of the WPO, EPO and PNA and are in good agreement with the 500 mb height forecast as they show upper troughing develop over the eastern portion of the Alaskan mainland while upper ridging develop over the Bering/Aleutians, extending into Southwest Alaska. The result of this pattern change will allow for a warming trend across the Bering/Aleutians into Southwest Alaska over the next week while a cooling trend is to be expected across the eastern portions of the Alaskan mainland (Copper River Basin). This pattern will also allow for low pressure to more likely develop in the eastern Gulf as this location will be under an upper trough.

On the synoptic scale, guidance is in good agreement with respect to the placement and intensity of the aformentioned developing low that is moving northeastward over the next 1-2 days and then in fair agreement on day 3. The ECMWF appears to have a fast bias as the low center is much farther to the northeast on day 3 than the rest of guidance. Due to this forecast confidence remains high through Monday evening and then fair on Tuesday.

On the mesoscale, high resolution models were favored to better resolve local effects such as the Turnagain Arm wind.

AVIATION. PANC . Conditions will remain VFR through the TAF period. There is a chance of southeasterly gusts between 15-20kts through 16z today. As pressure gradients increase this afternoon in Turnagain Arm with the potential for up-inlet flow, there is the chance for southeasterly Turnagain winds after 00z. As the up-inlet flow weakens with down-inlet flow developing, these Turnagain winds are expected to ease after 14z.

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

An upper low which has been over the Gulf of Alaska over the last several days moves slowly north and weakens tonight. A secondary long wave trough moves north into the Gulf on Monday with a new upper low center developing. As a result, broad easterly flow continues across Southcentral through Monday. Embedded Easterly Waves in the upper flow track west bringing periods of showers or rain through tonight. Even though the thermal trough weakens and slips north, there still may be enough instability over the western Copper River Basin/Talkeetna Mountains to kick off a few thunderstorms this afternoon and evening. A weather front, associated with the north moving upper long wave, heads north toward Kodiak and the Gulf on Monday. This system will bring rain to Kodiak Island and perhaps the eastern Kenai Peninsula. Showers are expected elsewhere across Southcentral.

A weak coastal ridge and lower pressure inland increase pressure gradients along Turnagain Arm this evening. So expected gusty easterly winds to develop and likely clip south and west Anchorage before diminishing overnight tonight. Winds will likely develop again across Turnagain Arm and bend into town Monday afternoon as the coastal ridge strengthens some. Gusty southerly winds can also be expected along the Copper River.

SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2).

Rainfall continues this morning across the Alaska Peninsula and the Kuskokwim Valley and Delta as seen on radar. Rainfall will continue throughout the day, with gusty winds possible, as upper level shortwaves continue to influence the area. Weak instability will be present this afternoon and tomorrow afternoon for the northern parts of the Kuskokwim Delta and Valley which will provide another chance for thunderstorm development in these areas. Temperatures look to be cooler today than they have been and will continue to cool into Monday.

SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2).

A front associated with a low pressure system south of Dutch Harbor is bringing gusty winds and rain to the eastern and central Aleutians as confirmed by METAR observations. These winds will continue to strengthen throughout the day, with the anticipation being that gale force will be reached later this morning. These winds will weaken to small craft before Monday morning, as the low remains nearly stationary south of Dutch Harbor. After this, the low will propagate eastward towards the Alaska Peninsula bringing continued rainfall to the eastern Aleutians and the AKPEN.

MARINE (Days 3 through 5). Gulf Of Alaska: A weak surface low situated in the northern Gulf on Tuesday will dissipate by Wednesday as it lifts north and west. Easterly small craft advisory winds associated with this system will also diminish by Wednesday. Areas of rain will continue across the northern half of the Gulf through Wednesday, reinforced by a secondary surface trough moving through the Gulf. Weak ridging then develops over the Gulf for Thursday in the wake of the trough.

Bering: A surface low south of the AKPEN Tuesday will bring northerly winds to much of the Bering into Wednesday. As this system tracks east, ridging will build in behind it, helping to further diminish wind speeds and cloud cover over the central and eastern Bering. A second system moving from west of Attu to the northern Bering on Thursday will bring increasing clouds, precipitation, and southerly winds to the western Bering.

LONG TERM FORECAST (Days 3 through 7). On Wednesday, the long wave pattern continues to show an extensive trough across much of the state. Embedded within the long-wave trough are two well defined upper level lows. The first is a vertically stacked low south of the AKPEN that will slowly work its way southeast and out of the Gulf by Friday. The second upper level low will transit from the Russian coast to Norton Sound by the end of the week. Between the two, a ridge will extend from Southwest Alaska to the Arctic ocean. As the first low moves east, the southerly flow aloft will return to a more northeasterly flow, allowing weak shortwaves to periodically move across Southcentral. This will reestablish the pattern of scattered afternoon and evening shower activity. The second upper level low will help spin up a frontal system that will cross the northern Bering through Friday before weakening as it runs into the ridge. A flat ridge will also remain in place across the Aleutian Chain, limiting clouds and precipitation and keeping temperatures on the milder side. Temperatures across the southern Mainland will also trend warmer through the extended forecast, but remain cooler than what we have seen the past couple of days.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . Gale Warning 155 165 170. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . ED SOUTHCENTRAL ALASKA . BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . CK MARINE/LONG TERM . CJ/TM

---

Weather Reporting Stations

   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map

Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
ANTA2 - 9455920 - Anchorage, AK	25 mi	58 min	SSW 4.1 G 6	50°F	51°F		1006.4 hPa
NKTA2 - 9455760 - Nikiski, AK	66 mi	58 min	S 5.1 G 8	47°F	45°F		1006.1 hPa
SWLA2 - 9455090- Seward, AK	72 mi	64 min			47°F		1005.9 hPa

Wind History for Anchorage, AK

(wind in knots)    EDIT      (on/off)   Help

10 AM

11 AM

12 PM

1 PM

2 PM

3 PM

4 PM

5 PM

6 PM

7 PM

8 PM

9 PM

10 PM

11 PM

12 AM

1 AM

2 AM

3 AM

4 AM

5 AM

6 AM

7 AM

8 AM

9 AM

Last 24hr

SW1

NW1

NW2

SW1

NE1 G4

S3

NW2

NE1

N1

S4

S9

S7 G14

S5 G10

S4 G7

SE1

--

NE2

E2

SE2

S2 G5

S4

S6

SW5

SW3

1 day ago

--

--

N2

W2

W1

W1

S2

W2

S12 G17

S10 G18

S4 G9

SW5 G8

NW4

S5

--

W1

--

SE1

E1

NE1

--

SE3

SE1

--

2 days ago

N3

N3

NE3

N3

N4 G7

SW2

SW5

SW1 G4

NE1 G4

N3

N4

NE8 G14

NW5 G10

NW1

N4 G7

N2

N1 G4

SE2

E1

SE4

SE1

NW2

--

--

---

Airport Reports

    EDIT      (on/off)   Help   Click EDIT to display multiple airports. Follow links for more data.

Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Anchorage, Ted Stevens Anchorage International Airport, AK	18 mi	35 min	WSW 5	10.00 mi	Mostly Cloudy	51°F	44°F	77%	1005.8 hPa
Anchorage, Lake Hood Seaplane Base, AK	20 mi	35 min	W 4	10.00 mi	Overcast	52°F	45°F	77%	1006.1 hPa

Link to 5 minute data for PANC

Wind History from ANC (wind in knots)

10 AM

11 AM

12 PM

1 PM

2 PM

3 PM

4 PM

5 PM

6 PM

7 PM

8 PM

9 PM

10 PM

11 PM

12 AM

1 AM

2 AM

3 AM

4 AM

5 AM

6 AM

7 AM

8 AM

9 AM

Last 24hr

S6

S4

S4

NW5

NW7

4

SE8

SE10 G21

SE12 G20

SE16 G25

SE15 G21

SE15 G25

SE12 G17

SE14 G19

SE13 G20

S9

SE10 G18

SE9

Calm

S6

S5

S4

Calm

SW5

1 day ago

SE4

NW5

NW4

NW4

4

S5

W7

S13 G18

S14 G21

S9 G19

S13 G19

S8

W9

W10

5 G14

Calm

N3

SW4

Calm

Calm

SE3

S4

SE5

4

2 days ago

N4

NE4

N5

NW4

4

W4

SW6

SW8

W8

SW8

N11

NE15

NE15

NE11

NE11

Calm

NW3

Calm

S3

SE3

SE4

S4

SE5

S4

---

Tide / Current Tables for Fire Island, Alaska

   EDIT   Weekend mode (on/off)   (on/off)   Help   One Week of Data

---

Tide / Current Tables for Anchorage (Knik Arm), Alaska

   EDIT      (on/off)   Help   One Week of Data

---

Weather Map

       (on/off)   Help Weather Map

---

GEOS Local Image of Alaska    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East

---

Ground Weather Radar Station Kenai, AK

   (on/off)   Help

---

Cookie Policy: This website uses cookies to save your settings. No personal information is saved. I do not collect statistics on your visit. You can disable cookies in your browser if you like but it is not recommended for this site. I do not sell cookies. Go to a bakery for that. In fact I do not sell anything. To disable cookies from L-36.com, please refer to the Help button in your browser. Privacy Policy: I do not sell or share any user data or anything else for that matter. The only personal information I save is in the site log which has a line for each page view which includes the IP address your browser sends in the header as well as which page you requested. I use this to block hackers and other bad actors. I do not use this raw data to create profiles on users. I periodically delete the log files. If you are subject to CCPA, Google ads on this site will not be based on your past behavior so you will likely not see an ad for a lawn mower just because you looked for one at a big box website. I do not believe this site is subject to CCPA but I am doing what I can to follow the guidelines anyway. Disclaimer: The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.