Marine Forecasts

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7 Day Forecast for Marine Location Near Cordova, AK

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Area Discussion for -

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FXAK68 PAFC 170221 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 521 PM AKST Sat Jan 16 2021

ANALYSIS AND UPPER LEVELS. The upper level flow across the North Pacific and Alaska has started to amplify, which will ultimately lead to a change in pattern as we head through the next few days. For the moment, a long-wave trough remains anchored over the Bering Sea and north- central to northeast Pacific. High amplitude ridges are positioned on either side over the northwest Pacific and along the western CONUS northward to British Columbia and bending westward into Interior Alaska.

The primary weather-maker is a vertically stacked low spinning just south of the Alaska Peninsula, with an occluded front extending north from the low center, then eastward across the northern Gulf. With strong ridging sitting to the north, the low and front are progressing very slowly northward. Winds across the Gulf waters have peaked and are weakening as the front approaches the north Gulf coast. The bulk of precipitation is focused along the coast, heaviest over the eastern Kenai Peninsula. Fairly widespread easterly winds ahead of the front have warmed up temperatures, leading to mostly rain at/near sea level, with snow through Turnagain Pass and nearby mountains.

Meanwhile, a deformation band has formed on the north side of the low, as the occluded front pushes westward up against the arctic air in place over the eastern Bering Sea. This is producing strong gusty winds and blowing snow along the southern Alaska Peninsula, where a Winter Weather Advisory is in place for visibilities one half mile or less at times. Gusty winds and showers are also focused ahead of a trough sitting over the central Bering Sea, from the Pribilof Islands to the eastern Aleutians (Dutch Harbor). Southwest Alaska is seeing some light snow from this storm, but with little or no accumulation. Lastly, conditions are quiet out along the western Bering and Aleutians under the influence of high pressure.

MODEL DISCUSSION. Models have a good handle on the current storm and the next one affecting the Aleutians on Sunday. The focus is on the deep low tracking northward toward Southcentral Alaska on Monday. Solutions are grouped together until the low nears the Kenai Peninsula, at which point model spread increases. Most of the operational runs curve the low center northeastward, passing south of Seward and then into western Prince William Sound. The GFS has consistently depicted a farther west track into Cook Inlet over the past few model cycles. Ensemble means take it directly over the Kenai Peninsula. The weather across the Kenai Peninsula and in Anchorage and the Mat-Su is extremely sensitive to small shifts in low track. Therefore, confidence in the details of the forecast for Monday remains low. However, based on greater confidence in the track prior to reaching the Kenai Peninsula, we continue to highlight the most likely weather and impacts through the issuance of a variety of High Wind Watches and Winter Storm Watches.

AVIATION. PANC . With persistent downslope flow off the Kenai and Chugach Mountains, VFR conditions will persist. Low level wind shear is a possibility, though the strongest winds coming across the Kenai and Chugach Mountains will remain above 2000 feet. The next change will occur around 00Z Sunday afternoon, when pressure gradients look favorable to bend Turnagain Arm southeasterlies into the terminal. Ceilings will also drop as the upper trough lifts overhead, but should remain safely in the VFR category.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 3: Tonight through Tuesday . )

A strong front associated with a surface low currently centered just south of Sand Point continues to move northward into the north Gulf Coast of Alaska this afternoon. Winds at Middleton Island gusted as high as 58 knots or 63 mph with the passage of the front and Amatuli gusted as high as 60 kts or 65 mph earlier this afternoon. In association with the winds, rain was being observed on Middleton Island. This will continue moving northward through this evening bringing another round of rain to low elevations such as Cordova and Seward over to Homer. High elevation snow is expected for the mountains of western Prince William Sound including through Turnagain Pass and the Thompson Pass area this evening. Snowfall of generally 6-12 inches is possible in both areas. Most of the rest of Southcentral will remain quiet this evening and through the overnight hours. The Matanuska Valley wind is expected to continue to blow through the evening hours before subsiding during the overnight hours. As a result, temperatures have risen into the upper 30s and low 40s across much of the Matanuska Valley. Once winds subside, temperatures will only have enough time to fall to around to slightly above freezing for early Sunday morning.

Attention is now turning to the next significant winter storm that is expected to impact Southcentral for late Sunday night through Monday evening with impacts ranging from high winds to heavy snow with the threat for avalanches in the mountainous terrain. Refer to the local avalanche forecast center for more details. There still remains some slight uncertainty in the track of this storm, therefore, the High Wind Watches were left as is. The best chance for the high winds will be through the Portage Valley where really any track this storm takes will be a favorable setup for high winds. The more uncertain areas are for the Upper Hillside of Anchorage and the Cordova area. Nevertheless, gusty winds are expected in all these areas mentioned but question still remains as to how strong they will get. A Winter Storm Watch has been issued for Thompson Pass, Turnagain Pass, and for the Copper River Basin for areas mainly west and south of Glennallen. This storm will have a tropical moisture connection with it bringing plenty of moisture northward. Snow will overspread the Prince William Sound area and Thompson Pass area from south to north late Sunday night/early Monday, peaking Monday morning through Monday evening before subsiding. Snowfall rates may reach up to 2 inches per hour during the peak through the passes.

Lastly, due to the amount of moisture with this system, some snow is expected on the front end of this system early Monday for Anchorage with upwards of an inch possible as any downsloping will be mitigated as a result of just so much moisture with it. There may also be the potential for some blowing snow early Monday with especially along the Upper Hillside of Anchorage but this remains uncertain. As the low approaches Monday, the downsloping will have more of an effect Monday afternoon and early evening to keep Anchorage dry. On the backside of the low as the upper level trough lifts through, another round of snow is possible for Anchorage with a general 1-2 inches at this time.

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Saturday Afternoon through Tuesday)..

A low pressure system south of the AKPEN will continue to slowly move east into Bristol Bay tonight. Two surface lows are expected to develop one on Pacific side and another low near Port Heiden this low will continue to bring strong winds and moderate to heavy snow bands across the AKPEN with blizzard conditions across Cold Bay up to the Nelson Lagoon area, a blizzard warning is in effect through noon on Sunday. Otherwise light snow across portions of Southwest Alaska associated with this low with a couple of inches of snowfall expected in some areas especially near Dillingham and the Kuskokwim Delta. Also fairly gusty winds across the Southwest from the north and northeasterly direction as the pressure gradient remains tight across the region. On Sunday this low will slowly track across Bristol Bay and weaken this will continue to bring light snow across the region with another inch or two of snowfall. The blizzard conditions around the Cold Bay area will improve by Sunday afternoon as the low moves north and east. However, snow showers will continue across the AKPEN. On Monday the remnants of this low will move east and become a weak trough as it moves over the northern Bering Sea. Another low moves near Kodiak Island this will bring more snow to the area especially from the AKPEN to the Dillingham area and into the Kilbuck Mountains as a deformation zone moves across the area, up to 5 inches of snow is expected with this system, but still some uncertainty on the details and there is a chance of gusty winds with blowing snow. However confidence is low that an advisory for blowing snow or snow will be needed on Monday. Finally, Tuesday conditions improve as a ridge of high pressure moves across Southwest Alaska, but this is expected to be short lived as another front brings snow by late on Tuesday.

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Saturday Afternoon through Tuesday)..

Broad troughing continues across much of the Bering and Aleutians with low level northerly flow producing widespread snow showers across the region. Otherwise the low near Sand Point is bringing gusty northwest winds to the eastern Aleutians and snow. Sunday a ridge moves across the central Bering and Aleutians as a gale force front moves west to east across the Bering and Aleutians through Monday. This front will bring gusty winds with periods of blowing snow and snow to the Aleutians, but no significant impacts and no advisories expected. This front will weaken as it moves towards the Pribilofs and into the eastern Bering on Tuesday. Some models indicate small lows forming along the front on Tuesday with GFS being the strongest, if this occurs there could be small areas of Gales along the front near these lows and enhanced precipitation. Finally, a north Pacific low is expected to move towards the eastern Aleutians and AKPEN on Tuesday, however uncertainty on track of this low. Some solutions keep it farther south with minimal impacts while others bring stronger winds and precipitation, so forecast confidence is low with this low.

MARINE (Days 3 through 5): Tuesday through Thursday.

Gulf of Alaska: Gales over the northern Gulf will be short-lived Tuesday morning, but not so for the central and southern Gulf. Models introduce a 988 mb North Pacific low over southwestern Gulf on Tuesday night, which will reinforce gales to linger over the surrounding waters of Kodiak Island through the central Gulf for another day. As the low weakens while drifting through the northern Gulf, gales will begin to taper off east of Kodiak and central Gulf by Wednesday morning. A strong ridge of high pressure from the North Pacific will extend over the eastern Gulf through Wednesday night, and this feature may be the game-changer should it bend more westward causing winds to dissipate much earlier to small craft conditions for the central Gulf. Hazardous seas between 20 to 25 ft are expected to subside to below 20 ft over much of the Gulf by Tuesday afternoon.

Aleutians/Bering: A strong Kamchatka low will either continue to weaken or merge with a deepening Northwest Pacific storm entering the western Aleutians and Bering Sea between Tuesday night and Wednesday morning. Hazardous seas up to 25 ft will extend across the western Bering where the Kamchatka low will be until it shifts toward the western Aleutians Tuesday night. Meanwhile, life-threatening swells and very hazardous seas will approach the Aleutians Tuesday night with seas reaching up to near 40 ft along the south coastal area of central Aleutians. A broad area of monstrous seas up to 35 ft will spread to the west of Pribilof Islands between Wednesday morning and Wednesday night. All and all, will monitor this situation closely especially its impacts to open-waters and threat to vulnerable parts of the Aleutians. Stay tuned!

.LONG TERM FORECAST (Days 3 through 7): Tuesday through Saturday .

A few North Pacific lows and numerous shortwaves aloft are expected to move across the Aleutians/Bering and Gulf of Alaska in the new week. The potential for increasing snow seems favorable for both Southwest and Southcentral as cold air advection and colder environmental temperatures surround the region throughout the week, except near coastal areas around the northern Gulf and Kodiak Island that may likely receive mix rain/snow around midweek. A strong frontal system wrapped around a deep storm over the Bering will extend across the eastern Bering through the southwestern Gulf through at least Thursday afternoon. Models show another developing Northwest Pacific low entering the Aleutians/Bering by Friday morning which could potentially generate hazardous seas and winds for much of the Aleutians east of Shemya and across the central and eastern Bering through Saturday. Over the Gulf and Southcentral, a relatively quiet pattern will begin to take place after the upper low over the northern Gulf and shortwaves aloft over Southcentral exits the area Wednesday night. Essentially, a very favorable progressive pattern will continue through the long-term.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NPW 101 125 135. WSW 125 131 141 181. MARINE . Storm 352 NONE. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . SEB SOUTHCENTRAL ALASKA . MV SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . RC MARINE/LONG TERM . CB

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
CRVA2 - 9454050- Cordova, AK	22 mi	53 min	ESE 8 G 20	44°F	42°F		992.5 hPa
VDZA2 - 9454240 - Valdez, AK	72 mi	53 min	Calm G 1	36°F	43°F		993.8 hPa
46061 - Seal Rocks 55NM South of Valdez, AK	77 mi	33 min	SE 29 G 37	41°F	42°F	16 ft	991.6 hPa (+0.3)

Wind History for Cordova, AK

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Cordova, Merle K (Mudhole) Smith Airport, AK	10 mi	30 min	ESE 9 G 17	10.00 mi	Light Rain	43°F	35°F	74%	993.8 hPa

Link to 5 minute data for PACV

Wind History from ACV (wind in knots)

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Tide / Current Tables for Pete Dahl Slough, Alaska

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Tide / Current Tables for Eyak River entrance, Alaska

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Weather Map

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