textproduct: Juneau

SYNOPSIS

Key Messages:

- Rain showers and lighter winds Friday

- Potential for thunderstorms Saturday.

LONG TERM

/Sunday through Wednesday/ Overall upper level pattern will be in a state of transition across the state and the Gulf of Alaska for Sunday as we switch out of a broad cool upper trough that dominated the weather over the area this week. The pattern will be switching to a closed upper low over the NW Pacific with weak upper ridging over the southern part of Alaska and the Yukon.

At the surface, this translates to a somewhat strong area of low pressure over the NW Pacific with a ridge of higher pressure building over the panhandle for the first half of next week. With this pattern the trend is toward warmer, drier, and sunnier weather especially for Monday into Wednesday. Sunday will have the beginnings of the warm up, but onshore flow will keep at least a chance of showers around. Tuesday is still looking to be the warmest day of the forecast with widespread highs in the 60s and 70s likely (isolated areas of near 80 in the southern panhandle are possible) as offshore flow becomes the strongest at that point likely canceling out afternoon sea breezes in some areas. Not expecting any areas to exceed record highs on Tuesday, but some areas could get close (Record highs for Tuesday for many areas are in the upper 70s to mid 80s). Marine layer low clouds in the gulf and along the outer coast may not be much of a factor for this period as low level flow is generally out of the NE to E direction which will likely keep those low clouds well offshore.

At the moment, the nicer weather is not expected to last much beyond mid week. An easterly wave from BC is looking likely to move into the panhandle from SE to NW possibly starting as early as Wednesday morning (though it could be as late as Wednesday evening) bringing another round of rain and clouds to the panhandle especially from Cape Fairweather south and eastward. Temperatures by Thursday may be down to more seasonal readings with the clouds and rain moving in (normal highs for this time of year are mid 50s to 60).

AVIATION

VFR to MVFR conditions continue this morning as rain showers continue to move across the panhandle. The most organized band of showers this morning at the time of writing is over the Icy Strait corridor and moving to the north. While some areas have been reporting reduced visibilities, the bigger issue continues to be the lowered ceilings. These ceilings are expected to improve later today as the shower activity decreases and VFR conditions become more prevalent.

MARINE

Outside: As of 0400 Friday, ASCAT wind passes showed a weak low center near 56.69N 144.22W, with coastal buoys showing ESE winds of gentle to moderate breezes. Sea state was primarily decaying SW swell; 6 to 8 ft at 11 to 13 seconds with southerly wind chop. For today, southerly winds continue along the coast, with rain showers and swell continuing to lay down. Saturday the gust factor will increase, with gusts likely reaching fresh to strong breezes. Furthermore, there exists potential to see some thunderstorms along the coast; keep a watchful eye to your south. Dominant wave system will switch from SW swell to southerly wind waves, with underlying, but almost negligible, southerly swell from the far south Pacific. Significant heights near 4 to 6 ft and period of 7 to 10 seconds.

Inside: Essentially a cut and copy wind forecast through the inside Friday, with a little less wind and rain showers than we saw Thursday. Highest winds of fresh breezes will continue to be in northern Lynn Canal. Saturday southerly winds increase a bit across the region with the gust factor increasing. Wind gusts Saturday will likely reach fresh to strong breezes by and large. Small hail could also fall under the darkest clouds, foreshadowing the potential to see some lightning, especially south of Icy Strait. For folks on the water, keep a weather eye on the horizon, NOAA WX radio tuned in, and have safe harbor in reach. Late Sunday rain showers end, with much warmer and drier conditions expected into Wednesday.

One note on thunderstorms Saturday. Per NWS definition, a Severe Thunderstorm means wind gusts greater than 58mph and/or hail greater than 1 inch. For now, we are not forecasting Severe Thunderstorm development. Semantics aside, the strongest of storms Saturday could produce some lightning and erratic wind gusts near 25 to 35 knots. So for folks in smaller recreational vessels and sea kayaks, these conditions can be pretty intense. Check weather.gov/Juneau before heading out on the water.

AJK WATCHES/WARNINGS/ADVISORIES

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