Marine Weather and Tides
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.
|Sunrise 4:29AM||Sunset 11:39PM||Saturday July 4, 2020 3:47 PM AKDT (23:47 UTC)||Moonrise 10:02PM||Moonset 3:23AM||Illumination 100%|
7 Day Forecast for Marine Location Near St. Paul, AKHourly EDIT Help
Area Discussion for -  (on/off)  Help NOTE: mouseover dotted underlined text for definition
FXAK68 PAFC 041357 AFDAFC
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 557 AM AKDT Sat Jul 4 2020
ANALYSIS AND UPPER LEVELS.
The prominent feature dictating weather for our forecast area is an upper level ridge whose axis extends from the North Pacific up through Southwest Alaska. On the upstream side of this ridge low level cloud cover and fog exist along the coast of SW Alaska and throughout the Bering Sea. The Western Bering also transitions to a long wave trough, keeping the weather unsettled there.
On the downstream side of the ridge axis, warm temperatures and mostly clear skies are present. Afternoon sea breezes were present in coastal areas yesterday and fog has moved into Kenai this morning, both associated with being under high pressure. Shortwave troughs are moving down the backside of this ridge, the effects of which will be detailed in the Southcentral section of the AFD.
Models are handling most features well in the short term. One issue significant to today's forecast that models disagree on is the passage of a 500 mb shortwave trough that moves from the Interior through Copper River Basin late today. The GFS is more bullish with this shortwave than other models. This resulted in hand edits in the forecast for thunderstorm activity in the Copper River Basin. As with yesterday, models fall apart past 48 hrs. This is resulting in quickly decreasing confidence in the forecast early next week.
PANC . VFR conditions will persist. A light sea breeze kicks up this afternoon, then the turnagain arm winds develop and will change wind direction and keep wind speeds elevated this evening into tomorrow.
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2. Sat and Sun) .
Expect another warm and mostly sunny day for your Independence Day across Southcentral. However, there is a key feature that will bring potentially very active weather to northern parts of the area this afternoon and tonight. A strong shortwave is currently developing over the Arctic Coast. This feature will come over the top of the North Pacific Ridge axis and move quickly south through the day today. Thanks in part to that ridge, plenty of warm air and instability will be present ahead of the wave. These two components will work in tandem later this afternoon and evening to trigger a fairly impressive round of thunderstorms. Convection should start first ahead of the wave over the Talkeetna Mountains. Steering flow should be out of the west, so expect cells to drift over the Copper River Basin. Late this evening (near midnight), the shortwave will cross the AK Range. This will provide even more lift and increase thunderstorm coverage across the basin. With some dry air in place in the low levels, we have included mention of some gusty winds in the forecast associated with these thunderstorms. As we head into the overnight hours, there is more of signal that the entire mass of thunderstorms may congeal into one very wet system. Anywhere between a quarter to over half an inch of rain can be expected in the heaviest precipitation corridor north of McCarthy.
For the remainder of the area, today should be another warm and sunny day, especially over inland locations. Sea breezes will be a bit more prevalent than Thu and Fri which will lead to cooler (more normal) temperatures. There will also be the possibility of some isolated thunderstorms over the Chugach and Kenai Mountains this afternoon/evening.
Sunday the area will be split into 2 different weather patterns. Another round of thunderstorms will be possible over the Copper River Basin in the afternoon/evening, but they will not be nearly as widespread as we expect today. For the Kenai Peninsula and Kodiak, expect increasing clouds and chances for precipitation as a weak front pushes into the area from SW AK.
SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3).
An upper level ridge of high pressure will dominate Southwest Alaska today with mainly dry conditions and a partly sunny sky. Some weak upper level waves in the flow will move onshore from the Bering especially across the Yukon-Kuskokwim Delta beginning this afternoon. As a result, the risk for showers will spread further southeast across the Bristol Bay region beginning early Sunday morning. Each wave will become slightly stronger than the previous with the upper level wave moving through Sunday afternoon being the strongest of this series of waves. This wave Sunday afternoon will produce more widespread shower/heavy downpour activity across much of Southwest Alaska, especially interior locations. With the wave Sunday afternoon being the strongest, an isolated wet thunderstorm cannot be ruled out. Instability is marginal with MUCAPE values of 100-400 J/Kg and LI's of 1 to 2. Depending on how much sun breaks out Sunday morning into Sunday afternoon will also factor into how much instability develops to produce a thunderstorm.
Another upper level disturbance separate from the aforementioned series of waves is poised to move through the southern Bristol Bay region Sunday night into Monday with 850 mb temperatures falling from between 8 and 10 degrees Celsius to 3 to 5 degrees Celsius. As a result, winds were started to be nudged up some especially out of the gaps and passes of the southern Aleutian Range near Pilot Point and Point Heiden for Monday.
SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3).
A low pressure system will continue its trek northward towards Siberia with its front continuing to move across the Bering. Accompanying the front will be some rain and wind, with winds reaching small craft advisory level for near St. Matthew Island and near the central Aleutians. Widespread patchy fog and low stratus was added through Monday afternoon in the forecast as model output statistics (MOS) showed a good amount of fog from Shemya to Adak over to near Dutch Harbor and the Pribilofs.
As the front continues eastward it is expected to weaken Sunday (frontolysis) as it outruns the upper level support due to the low it is connected with moving towards Siberia.
MARINE (Days 3 through 5: Sunday through Tuesday).
Gulf of Alaska: Easterly winds become Westerly as high pressure slides across the Gulf through Tue. A front enters the Western Gulf Mon. Confidence is good for small craft winds and waves East of the Shumagin Islands with Gale winds and waves developing South of Kodiak Island through Tue.
Aleutians and Bering: A trough extending from a Northwest Bering low sweeps the Western Aleutians. Confidence is good for small craft winds and waves over the Western Aleutians and Bering for Sun. A front pushes through Bristol Bay. Confidence is good for small craft winds and waves over the Eastern Bering and Bristol Bay Mon and Tue.
LONG TERM FORECAST (Days 4 through 7: Monday through Thursday) .
The strong upper ridge over western Alaska Sunday weakens through Wednesday. This allows short waves spinning off of the Bering Sea trough to progress eastward across the Mainland. This pattern change will bring intrusions of moisture from the west resulting in cloudier conditions, increased chances of rain/showers, and a lowering of daytime high temperatures across the southern Mainland. Although the model trends are similar with the weakening of the upper ridge, differences in solutions will pose a problem in timing systems. So confidence is low on exact timing but fair to good on a trend toward more clouds, cooler temperatures, and chances of rain.
With the main upper low center and trough holding over the Bering Sea expect generally mostly cloudy conditions with periods of rain/showers, and gusty winds.
AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . NONE. FIRE WEATHER . NONE.
SYNOPSIS AND MODEL DISCUSSION . BJB SOUTHCENTRAL ALASKA . MV/RC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . MV MARINE/LONG TERM . MK/BC
Weather Reporting StationsEDIT (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|
|46035 - BERING SEA 310 NM North of Adak, AK||41 mi||58 min||49°F||46°F||4 ft||1008.1 hPa (+2.0)|
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