Marine Weather and Tides
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.
|Sunrise 7:43AM||Sunset 8:00PM||Wednesday September 22, 2021 5:58 PM AKDT (01:58 UTC)||Moonrise 7:37PM||Moonset 8:36AM||Illumination 97%|
7 Day Forecast for Marine Location Near St. Paul, AKHourly EDIT Help
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FXAK68 PAFC 220113 AFDAFC
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 513 PM AKDT Tue Sep 21 2021
ANALYSIS AND UPPER LEVELS.
A negatively tilted upper-level trough continues to dig south across the state to the Gulf. Within the trough is an upper-level low situated over the Kenai Peninsula with the support of a 85 kt jet streak which is helping drive cold arctic air to the Southcentral coast this afternoon. A weak trough at 700 mb (~10,000ft), coupled with the cold arctic air in the lower levels being driven south and moisture advecting from the east, all came together to produce an area of light snow this morning across east Anchorage, the Anchorage hillside, and the Matanuska Valley. Snow has since tapered off in these locations due to drier air moving into the area and the mid-level trough exiting to the east. Snow continues to fall across the Copper River Basin due to a moist southeasterly flow aloft overrunning the colder at the surface. Radar is also showing rain over Prince William Sound, enhanced by weak waves lifting north ahead of the main trough. Cold air advection and increasing pressure gradients are causing winds to ramp up throughout Southcentral this afternoon. Some areas are reporting gusts as high as 45 mph.
A ridge continues to build upstream of the negatively tilted trough with breaks in cloud cover over Southwest Alaska. Satellite shows a blanket of low stratus over much of the Bering and Aleutians as the ridge progresses east. Calmer winds are being observed along the eastern Bering and Aleutians as the ridge continues to influence the area. Farther west, easterly winds have developed across the western half of the Chain as front associated with a North Pacific low lifts north.
Models are in good overall synoptic agreement through the short- term. Model spread begins to grow on day 3 as the models struggle with the placement, timing, and strength of a low that spins up in the Gulf late Wednesday into Thursday. The NAM has the low digging farther south and weaker compared to the other solutions (GFS/GEM/EC). The GFS and EC are advertising similar solutions, whereas the Canadian seems to be a hybrid of the GFS and NAM. As a result, forecast challenges will be the placement of winds and precipitation in regards to this system. Another challenge will be timing the erosion of the cold air that has been drawn south from the digging trough currently over the domain on Thursday and the potential for colder air to return by Friday morning. This will effect precipitation type for the short and long-term forecasts. Thus, forecast confidence beyond day 2 is below normal.
PANC . VFR conditions will persist with gusty conditions. Winds will begin to tapper off this evening around 9z.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Friday afternoon) .
Snow will gradually taper off across the Copper River Basin through this evening as a low in the Gulf departs eastward. Gusty northerly outflow winds will likewise gradually diminish through the evening as the pressure gradient weakens. Quiet conditions are expected Wednesday, with partial clearing, though temperatures will remain generally cooler with highs only reaching the mid 40s over Southcentral. A North Pacific low will enter the Gulf early Thursday morning. There is still significant model disagreement on its position and timing. However, potential impacts include similar gusty northerly outflow winds as occurred today, as well as accumulating snow across Southcentral and the Copper River Basin. This would most likely all occur overnight Thursday into Friday morning.
SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3).
An active low NNW of Nunivak Island remains on track, which will bring Southwest's first sequence of snow. Highest amounts of 4 to 7 inches primarily between Aniak and Sleetmute tonight into Wednesday morning. Cold air advection accompanying the low and its frontal system will race across Southwest AK through at least Friday morning, causing overnight temperatures to fall in the lower 20s to lower 30s and day time temperatures in the lower 30s to lower 40s through the short term. Models materializes another trough over the northern Bering that could potentially move closer to Southwest Coast by Thursday night. For now, will monitor this situation closely and see what happens as future models become available.
An extensive area of moisture from a Pacific low will move across the Alaska Peninsula starting Wednesday afternoon and could stick around through Friday morning.
SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3).
Associated gales from a strong North Pacific low will pass through most areas of the Aleutian Chain with much stronger gusts along the gaps and passes through the next few days. A developing trough east of Kamchatka Peninsula will transit through the central Bering bringing very minimal moisture near Pribilof Islands by Friday morning. Meanwhile, a Northwest Pacific low passes well south of the western Aleutians starting Thursday afternoon. This will bring slightly enough moisture across the Aleutians leading to light rain between Thursday and Friday.
MARINE (Days 3 through 5: Friday through Sunday).
Gulf of Alaska . A low over the North Gulf Coast on Friday remains nearly stationary as it weakens, dissipating Saturday. Predominantly westerly high end gales in the Gulf, with areas of storm force winds between Kodiak Island and the Kenai Peninsula, diminishing into Saturday. Seas to 21 ft in the Gulf, subsiding Saturday.
Bering Sea . A weak Bering Sea low on Friday tracks south over the Aleutian Islands through Saturday. This low spreads northerly winds less than gale force across the southern Bering and Aleutians, diminishing into Sunday morning.
LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday).
Models begin in generally good agreement near the start of the period on Saturday, with a longwave trough with several embedded shortwaves initially centered over much of the mainland and eastern Bering. A low will likely be filling in near or just south of Prince William Sound around this time, with any mixed precipitation and upper elevation snow quickly coming to an end on Saturday morning across the western Kenai Peninsula and Chugach Mountains with the weakening circulation pulling away from the Gulf coast. Meanwhile, a shortwave trough and surface low will most likely be dropping south around the western periphery of the longwave over the eastern Bering and Aleutians from Saturday to Sunday, bringing small craft to perhaps locally gale force winds and rain for a brief period as it dives south.
The pattern from Sunday onwards then becomes significantly murkier, with operational models diverging with even most larger scale features through the start of next week. Even with the details for individual synoptic systems less clear, there is a fairly good signal that the Pacific jet and prevailing storm track will stay relatively far south from this weekend through early next week. Global models and their respective ensemble suites have shifted the track of a North Pacific low farther south compared to previous cycles, now taking the center well south of both the Aleutians and Gulf as it tracks east near the base of the longwave trough axis between late Saturday and Monday. This should keep conditions much less active over the southern mainland, albeit still chilly by late September standards, with abnormally cool low level temperatures likely to remain parked over much of the state through nearly the entire extended period. Another low could track across parts of the Bering between Monday and Tuesday, although any details by this point are far from being resolved.
AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . Winter Weather Advisory 141 152. MARINE . Gale 119 120 130 131 150 172 174 176. FIRE WEATHER . NONE.
SYNOPSIS AND MODEL DISCUSSION . TM SOUTHCENTRAL ALASKA . AP SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . CB MARINE/LONG TERM . AS
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|Stations||Dist||Age||Wind||Air Temp||Water Temp||Waves||Pressure||DewPt|
|46035 - BERING SEA 310 NM North of Adak, AK||41 mi||68 min||ENE 12 G 14||47°F||51°F||6 ft||1019.7 hPa (+0.0)|
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