textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key Messages:

- Isolated marine lightning over the Gulf of Alaska is possible Tuesday and Wednesday.

- Clearing skies and cool temperatures could lead to patchy fog, and widespread lows near or below freezing. Breezy north winds through terrain gaps will increase tonight through Wednesday morning.

- The pattern shifts Thursday and Friday with rain along the coast and Kodiak Island. Strong, southeast winds also return to Southcentral. Forecast confidence is medium overall, but the magnitude in rainfall and wind speed is low to medium.

Discussion:

Dual lows across the Gulf of Alaska are bringing showers from east to west this morning. One low is located west of the SE Panhandle while the other, weaker low is situated east of Kodiak Island. High clouds on satellite has obscured the locations that observed patchy fog. Many areas dipped into the 30s this morning. A few lightning strikes were observed from these lows last night and a lightning strike or two over open waters of the Gulf cannot be ruled out through Wednesday.

Otherwise, the weather across Southcentral will be relatively quiet through Thursday afternoon as the lows weaken and slowly meander east. Any lingering showers would be likely along the Alaska Range, Kodiak, and the northern Gulf Coast this morning, trending drier throughout the day today. Clouds will continue to clear out across much of Southcentral through Wednesday. This will result in colder overnight temperatures, with widespread 20s possible for the Copper River Basin and low to mid 30s elsewhere. Some typically colder locations may see colder temperatures Wednesday morning as East Anchorage, Soldotna, Butte, and Willow may drop as low as the upper 20s and some lows in the teens are possible (10 to 20 percent chance) in the Copper River Basin. Offshore winds look to increase later night through north to south terrain gaps through Wednesday morning. Wednesday and Thursday morning will see dry conditions across Southcentral with high temperatures in the low to mid 50s.

A much more potent system from the Bering Sea will send a strong front into the southwestern Gulf and Kodiak Island by Thursday afternoon. Confidence is still medium with the timing of the front as models slightly differ on progression and strength. Chances for precipitation will increase throughout the day Thursday for Prince William Sound, northern Gulf coast, and for Kodiak Island, becoming likely (moderate to heavy rainfall rates at times) by Thursday evening. With strong southeast flow, northern Cook Inlet communities and farther inland, would become downsloped, thus drier. Gale-force winds will also accompany the front as it lifts through the Gulf Thursday and Friday. Winds could be gusty through Turnagain Arm Friday afternoon, affecting South Anchorage and the Hillside, but there is low confidence in the magnitude of these winds at this time. Stay tuned.

LONG TERM FORECAST (Days 4 through 7)

Key messages:

- A very strong low pressure system will develop over the Bering Sea between later this week.

- A separate low pressure develops in the Gulf of Alaska later this week.

A low forming in the Bering Sea later this week could include moisture from the remnants of ex-typhoon Dujuan. Despite varying differences in the low's formation and its track eastward the past 72 hours, a consistent theme has been that most of the moisture from the ex- typhoon will remain south of the Aleutian Chain. The moisture and heat being entrained into this Bering Sea low will bring widespread rain and wind gusts to the Bering Sea. Models continue to show this Bering Low strength ranging from 960 to 970 mb today; despite its more northerly track and most ensemble model guidance placing its formation location from the Pribilof Islands to the Central Aleutians. Another common theme has been the Aleutian Islands, from Attu through Dutch Harbor, will likely see the strongest winds in this storm with gusts exceeding 70 mph at a 40% to 60% chance Thursday to Saturday.

As for Southcentral and the Gulf of Alaska region: A low that tracks south of the Aleutians will make its way to the Gulf of Alaska region by Friday. At this time, it does appear likely that a fairly strong front will move into the Gulf of Alaska by during the day Thursday bringing rain and wind to the Gulf region. Wind speeds exceeding 60 mph along the Eastern Kenai Peninsula and the Gulf of Alaska range from a 40% to 60% chance late this week and into the weekend. The greatest rainfall amounts from this storm currently are along the coast from the Eastern Kenai Peninsula to Cordova Friday afternoon through Sunday evening.

AVIATION

PANC...VFR conditions and light and variable winds less than 10 kt will persist through the TAF period.