Marine Weather and Tide Forecast for Kachemak, AK

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)...

Key Messages:

* A Coastal Flood Advisory is in effect for the Kuskokwim Delta (Kipnuk, Toksook Bay, Kwigillingok, and Kongiganak) from 7 PM today (Sunday) to 7 AM Monday for minor-moderate flooding.

* A Wind Advisory is in effect for the Kuskokwim Delta from 4 PM today (Sunday) to 10 AM Monday. Southwesterly winds of 30 to 40 mph with gusts up to 55 mph are expected.

* Active pattern out west continues as more low pressure systems move through the Bering. The first low brings strong winds and rain through the Bering to Southwest Alaska today into Monday.
The second low looks to bring hurricane-force winds to the far western Bering on Monday.

Discussion:

A low pressure system in the Bering is currently spreading over the the Kuskokwim Coast this afternoon and continuing inland overnight. A Wind Advisory has been issued for the Kuskokwim Delta, from the coast, inland through Bethel from 4 PM this afternoon through 10 AM Monday as southwesterly winds of 30 to 40 mph with gusts up to 55 mph are expected this evening as winds push onshore. Additionally, another round of coastal flooding is expected for the Kuskokwim Coast this evening. A Coastal Flood Advisory is in effect for the Kuskokwim Delta coast between 7 PM this evening and 7 Am Monday. Water levels are expected to reach up to 1.5 to 2.5 feet above the normal high tide line for Kipnuk.
Kwigillingok is not expected to see as relatively high of water levels or impacts from flooding, but will still see waters 1 to 2 feet above the normal highest tide line. Winds rapidly decrease Monday morning as the low dissipates to the north, which will also lower coastal flooding risk. This is compounded by the widespread rainfall over the area continuing through tonight. With the fast motion and rapid dissipation of the low, most showers dissipate by late Monday morning, with highest chances for lingering precipitation through Monday afternoon in the Kilbuck Mountains and along the Alaska Range. Though some stronger winds and cloud cover will move through the eastern Aleutians and Alaska Peninsula through tonight, chances for precipitation are low, and most clouds clear by Monday morning.

The next low moves up from the Pacific and crosses the far western Aleutian Chain late tonight into Monday morning. This low will be stronger than the first low, however it tracks much further north and west. The low reaches its strongest point north of the western Aleutians Monday afternoon. There will be the chance for isolated thunderstorms and lightning strikes embedded in this system as it enters the Bering. As the low continues northward, high pressure builds over the northern Pacific into Southwest Alaska, tightening the pressure gradient. Sustained winds likely peak at hurricane-force in the western Bering Monday, with southerly storm-force winds seen through the western to central Aleutians and central Bering as the low sends a front eastward. In addition to winds, rain will be seen both near the low and along the front. The front stalls on a line from Hooper Bay, to the Pribilof Islands, to Atka, bringing continuous rain to the area underneath. Though not as strong as today's system, prolonged southerly to southwesterly winds will continue throughout the Bering to the Kuskokwim Delta. This will potentially limit the ability for flood waters to recede quickly from today/Monday's system. High pressure over Southern Alaska will make for a mostly clear day across Southwest and the Alaska Peninsula Tuesday. Some weak upper-level shortwaves bring cloud cover and chances of precipitation to the eastern Aleutians Tuesday. A larger upper- level trough moves through the Bering Tuesday-Wednesday and will help progress the front eastward Tuesday night into Wednesday as it breaks down higher pressure to the east.

We are monitoring the progression of a strong low pressure system of tropical origin to enter the Bering Sea by late this week, potentially bringing onshore flow and rainfall to Southwest Alaska again by the Friday timeframe. Confidence is low at this point with regards to orientation and strength of the low, but astronomically driven tides will be at a natural high-end of their cycle.

-CL

.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

The long term forecast continues to favor an unsettled weather pattern across much of Alaska as broad upper-level troughing becomes established over the state. Model guidance remains in fairly good agreement with the overall pattern, showing a series of upper-level lows moving across the Bering Sea and into mainland Alaska. However, differences remain regarding the strength, timing, and placement of individual disturbances, particularly toward the end of the period.

Thursday has a strong low, associated with the remnants of Typhoon Champi, move into the Bering. Strong gale to storm force winds impact the Aleutians from Atka west as the low pushes eastward. By Thursday evening, onshore gusty south-southwesterly winds will push into the Kuskokwim Delta Coast, leading to the possibility of elevated water levels. Higher tides at this point means that there is a greater potential for higher water levels.
Though the storm track is uncertain, so exact water levels cannot be determined at this point. Friday is much of the same with the low moving further east, potentially driving continued south to southwest flow into the Kuskokwim Delta. Elsewhere, periods of precipitation and gusty winds are likely across the Aleutians, Bering Sea, and Southwest Alaska. Precipitation type is expected to be mostly rain as southerly flow keeps temperatures warmer.

Saturday sees the low push inland and quickly weaken. Winds will also switch direction by the afternoon, which will end threats of coastal flooding. Rainfall will linger on and become more showery and scattered as colder air moves in on the back end of the low, with a rain/snow mix to snow for higher elevations possible.
Another low moves in on Sunday, which will lead to gusty winds and rain or rain/snow depending on elevation. There is much uncertainty with this low with many possibilities regarding its track and strength.

Meanwhile, Southcentral sees a front move in on Thursday, stalling on a ridge through the weekend. This will bring scattered rainfall and snowfall at higher elevations through Saturday. Gusty winds in the Gulf of Alaska and in gap areas can be expected as well.

-JAR/LM


AVIATION

PANC...Showers continue to diminish in the area after a trough passage earlier today. Winds will shift by this evening from a SE Turnagain Arm wind to broad up-inlet flow, increasing in the evening hours. Winds will gust in excess of 20kts overnight into the first half of Monday before subsiding. Dry air in the backside of the system should allow skies to clear this evening, with generally just upper-level clouds with a passing shortwave to the north.