Radar — PACG
Surface Analysis — Alaska
Satellite
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Key messages:
- the wet and active pattern will continue through the week as multiple fronts push into the south panhandle, bringing periods of moderate to heavy rainfall and strong winds.
- maritime interests should remain aware of multiple gale force fronts with potential for storm force wind gusts across the gulf and along the southeast alaska coast on tuesday, thursday, and into the weekend.
/through tuesday night/... The meso low is currently jumping inland around CAPE decision as of this afternoon, bringing elevated westerly winds near CAPE decision with increased winds across the central inner channels expected as the low pushes in. It will begin to quickly SHEAR apart in the evening hours as it continues moving northeastward, keeping winds generally lower across the area as it weakens into an open wave trough tonight. This will keep another round of precipitation pushing through the area through tonight. Following this will be more showery precipitation across the central and northern panhandle into monday as the parent low lingers in the NW gulf and pushes in more disorganized rounds of precipitation into the area through monday night.
Another low will also be developing and moving into haida gwaii overnight tonight into monday, bringing moderate to heavy rainfall across the SE portion of the panhandle, including ketchikan, hyder and annette island with 0.5 to 1.0 inch of rainfall by monday afternoon, but its main plume of moisture looks to remain to the south moving into british columbia. A break looks to come for parts of the central and southern panhandle around sumner up to frederick sound, before a larger and more widespread system begins to move in tuesday morning.
Snowfall across the higher elevations of the klondike and haines highways will continue to diminish this afternoon through the night. Light snow above 1400 ft on the klondike and a wintry mix along the haines highway is expected to last through the night and into the morning, with up to 1 to 2 inches of new snow accumulation along the haines highway near customs and 2 to 4 inches along the klondike highway by the morning.
/wednesday through saturday/ an active fall pattern continues through the extended forecast. Maritime interests should remain aware of multiple gale force fronts pushing across the gulf and along the seak coast by thursday and into the weekend.
We pick up the extended forecast on wednesday morning with the remnants of the tuesday system pushing out of seak, scattered showers and diminishing winds briefly through the afternoon. However, wednesday will be the last "quiet" day of the extended period as multiple strong low pressure systems that will traverse the north pacific and then into the gulf for the end of the week and into the weekend. Some variance on timing , but still thinking by wednesday night a strong low develops in the northern pacific and deepens to ~970mb by thursday morning as it moves into the southern gulf of alaska. This low will swing a strong occluding front across the gulf through thursday, bringing another round of sustained gale force winds 35 to 45 KTS and storm force gusts up to 55 KTS across the gulf and along the coast from dixon entrance northward to the fairweather grounds by thursday afternoon into thursday night. Strong overland winds up to 45 MPH focused across the southern panhandle by tuesday afternoon, primarily prince of wales, ketchikan, and annette island so will need to keep on potential wind advisory issuance moving into the middle part of the week. This low and its attendant front continue to push into the NE gulf coast through friday afternoon with scattered,off and on showers becoming more prevalent into friday night, so there is a potential brief break in the widespread rainfall friday night, albeit not high confidence.
Total rainfall amounts from the front on thursday into friday total ~0.5 to 1.5 inches across the northern and central panhandle, and ~1.5 to 2.5 inches of rain for the southern panhandle. With the follow up systems from friday night into saturday night, rainfall amounts will once again be around the same, maybe a bit higher given influx of available moisture tap. All in all, the totals from thursday through saturday night, around 72 hours, are around 2 to 4 inches for the northern and central panhandle, 3 to 5 inches across the southern areas. Give persistent warmer southerly winds across the panhandle, any snowfall should remain at the upper elevations of the klondike highway near white pass and haines border crossing. The further we get into the extended the less forecast confidence in placement of developing systems, but general consensus is that the pattern remains active with yet another surface low developing in the gulf of alaska on the periphery of a deep long wave trough situated across the gulf into latter half of the weekend.
/through monday evening/... The mesolow that brought winds and precipitation across the panhandle sunday is pushing eastward into canada. Winds across the panhandle are expected to continue decreasing tonight. With clouds around, showers are possible with a low in the gulf and onshore flow. As has been observed in sitka, some showers may bring brief IFR ceilings and visibilities. After 00Z tuesday, a more organized band of showers is expected to move into the northern panhandle. As showers move into the area, expect MVFR ceilings for gustavus and sitka, and perhaps juneau, haines, and skagway as well. Yakutat, nearest to the low center pressure, appears less likely to see a VFR with showers in their vicinity.
A low pressure system in the north pacific will move northeastward toward the southern panhandle, and will bring more organized rainfall to areas generally south of fredrick sound early monday. With the system, ceilings are generally expected to remain MVFR through monday afternoon for ketchikan and klawock. However, as the low moves into canada, VFR conditions appear more likely toward the end of the taf period for pakt and pakw. As of now, llws does not appear to be a concern during the taf period, but gusty winds are certainly possible.
Outside (gulf and coastal waters): an area of low pressure southeast of kodiak island has been sending a front through the panhandle today. Behind the front, expect winds and seas to decrease through late tonight. A mesolow currently near CAPE decision tuesday, a stronger front will approach the area, and bring gale force winds into the gulf of alaska. There is also potential for storm force winds due to a barrier jet forming between icy CAPE and CAPE suckling.
Inside (inner channels): along a front impacting SE alaska, a mesolow expected to move NE near baranof island is expected to increase wind speeds for chatham strait and southern stephens passage. As it moves into the inner channels, expect the system to dissipate. Early monday morning, a secondary mesolow in the north pacific will bring stronger winds to the southern inner channels. Based on the track of the low, it may bring gale force winds into clarence strait.
Based on current guidance, the strongest winds should stay in dixon entrance. However, the track will be closely monitored. For the northern inner channels, winds are expected to not be as strong, as the low SE of kodiak island will weaken. Another area of low pressure will move in from the west on tuesday, and this is expected to increase winds again tuesday. Late tuesday into wednesday, the strongest gale force winds are again expected in clarence strait.