textproduct: Juneau

AVIATION...06z TAFs

Showers over the southern and central panhandle continue to linger and slowly will diminish through the next 6 hours with the parent low moving towards Haida Gwaii. Ample moisture in the Yukon is expected to stream across the Coast Mountains, bringing more rain showers from north to south, with CIGs AoB 3500 ft. Not expecting any IFR conditions with this moisture, as easterly flow over the mountains will likely dry out low levels enough to keep MVFR CIGs with rain. Airports sheltered from northwesterly flow (Haines, Gustavus, Sitka) will likely only have showers in the immediate vicinity, but may not cross directly over the TAF site.

PREV DISCUSSION

SYNOPSIS...

Key Messages:

- Rain continues across the central and southern panhandle, diminishing later Thursday into Friday.

- A disturbance coming down from Canada brings more precipitation to the northern panhandle and inner channels Thursday PM into Friday. A couple thunderstorms are also possible in northeastern portions of the region late Friday.

SHORT TERM.../Through 12Z Sunday/...A frontal wave is slowly weakening across the southern portions of the panhandle, but scattered showers have reached as far north as Pelican and Gustavus with at least a few sprinkles here in Juneau as well. The heavier showers south of Point Alexander have diminished. But with some breaks in cloudiness there has been a bit of differential heating, which has in turned aided in the development of a few additional showers.

As we lose peak heating and the frontal wave disintegrates with low pressure moving off to the east, precipitation will decrease in the southern peninsula tonight. Meanwhile, farther north, cloudiness will continue to increase, especially from Skagway to Juneau as a shortwave from Canada advects moisture and lift into the region. Rain chances will also increase through the night and persist through much of Friday, along with the return of slightly cooler temperatures. Precipitation rates and overall amounts will not be that high, but a persistent steady light to moderate rainfall can be expected. With sufficient mid level lift and modestly steep lapse rates, a couple of thunderstorms cannot be ruled out across the northeastern areas of the forecast area, where a slight chance of thunderstorms was retained for Friday afternoon and early evening. Although the better thunder chance still looks to remain just to our north and east, any breaks in cloud cover could provide just enough additional instability for convective development and also help any storms advance southwest out of the higher mountain ranges into our area. Showers are also expected to develop across the rest of the region and become widespread before slowly diminishing later Friday night.

Precipitation chances drop region wide on Saturday as we lose the upper level support. Much of the model guidance still wants to give at least a slight chance of showers from Juneau to Klawock and points east. But, widespread activity is certainly not expected as high pressure will briefly push into the region from the west in advance of our next trough by early next week.

LONG TERM.../Sunday through Thursday/... By Sunday, a low pressure system looks to form in the Gulf of Alaska. As the low approaches the area, stronger winds (up to 25kts or 27 mph) and higher seas (up to 9 feet) are expected west of Icy Bay. The low will move east Monday, but weaken as it does so. After Tuesday, models disagree about the exact progression of an additional low pressure system. Overall, a fairly wet weather pattern looks to continue for Southeast Alaska.

Rainfall totals with the active weather pattern are expected to remain below an inch through next Thursday. However, depending on the exact track of the low pressure system Tuesday, higher rainfall totals are possible. After warmer temperatures this weekend, rain chances should keep temperatures cooler than the climatological average.

AVIATION.../Through 00Z Friday/...Winds are calming in southern Clarence Strait and near PAKT, and shower activity is decreasing over the southern Panhandle as the weakening Gulf low continues its southeastward track. Prevailing conditions remain VFR this afternoon, with the exception of PAKW and PAKT, where lingering bands of rain showers from the low continue to push northward. Looking ahead, a mid-level disturbance tracking eastward from western Canada will introduce moisture to the inland northern and central Panhandle. This is expected to trigger localized rain showers beginning late tonight and continuing through Friday, leading to MVFR CIGs for much of the day. Winds will increase across the northern region Friday afternoon, with speeds near PAGY reaching 12 to 15 kts. Across the southern Panhandle, spotty showers will gradually dissipate as they drift southward, with more clearing expected by Friday afternoon, allowing conditions to return to VFR. However, tonight's clearing across the south may support the formation of lower clouds early Friday morning, causing brief reductions in VSBY.

MARINE... Outside (Gulf and Coastal Waters): A weakening area of low pressure is traversing across the eastern Gulf of Alaska with an occluding front extending east into Prince of Wales and the southern Panhandle. Updated guidance and observations show winds decreasing under Small Craft Advisory criteria, and seas less than 8ft, so cancelling the current hazards for the 15nm-80nm offshore zone off Prince of Wales Island through tonight as activity in the Gulf continues to weaken. In the Dixon Entrance to Edgecumbe offshore zones from Prince of Wales to southern Baranof, expecting southerly winds 15 to 20 kts south of the front today before weakening a bit tonight into Friday, and seas 6 to 7 ft. Another low pressure system moving into the eastern Gulf is expected to increase seas to 9ft along the coast between Cape Suckling and Icy Bay late Sunday, though diminishing by early next week.

Inside (Inner Channels): Southeast winds increase diurnally again today in southern Clarence Strait and Taiya Inlet with 15 to 20 kts generally and 5 ft seas along the Dixon Entrance region. Expecting winds to relax slightly Friday as the weakening Gulf low moves southeast. A generally lighter wind pattern is expected for most of the panhandle going into the weekend as weak ridging builds over the southern region. The exception will be Taiya Inlet and Northern Lynn Canal as the pressure gradient greatly increases going through the weekend. Current thinking is southeast winds increasing to 15-20 kts, gusting to 25 kts, and peaking in the afternoon hours.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...None.