textproduct: Juneau

SYNOPSIS

Key Messages:

- Diminishing trend in winds and precipitation for Monday into Tuesday. Lingering showers primarily across northern panhandle.

- Another system arrives Tuesday night bringing predominantly rain and warming temperatures into midweek.

- Late week into next weekend, long range models are hinting at a weather pattern that has been known to produce heavy snow. High uncertainty at this time but worth watching closely.

LONG TERM.../through this week/

The upcoming week is looking like another cloudy and rainy week. There will be lulls between the frontal passages but the overall trend in the long term forecast is cloudy and rainy this week. But late this week into next weekend, the long range weather models and ensembles are hinting at a weather pattern that has been known to produce heavy snow.

After the midweek frontal passage, continued showery weather with on/off type rain with above normal temps.

Friday into the weekend, the overall weather pattern looks to change. The long term weather models and ensembles are hinting at a low pressure trough to develop to our north with a high pressure ridge to our south at the higher levels of the atmosphere. This kind of pattern usually allows for cold air from Canada to slide southward into SE AK while moisture streams in from the gulf at the mid to higher levels. This type of pattern is called overrunning and has been known to produce heavy snow here.

The forecast challenges will be centered around the the cold air from the north and the flow from the gulf. These two variables will be fighting each other. Too much cold/dry air from the north causes the precip amounts to be limited. Too much wind from the gulf causes the atmosphere to mix and the snow switches to rain. But where that balance sets up just right is where heavy snow is likely.

As of now, there is high uncertainty in the details but overall trend is on the snowy side of the rain/snow spectrum. Stay tuned.

AVIATION

Early Monday morning conditions are generally poor across the Panhandle, with coastal TAF sites reporting IFR to LIFR CIGS and VSBY and interior areas seeing MVFR with CIGS near 1500 to 3000ft, vsby 5SM to 10SM. Expecting these conditions through most of the morning as the remnants of a front move into Canada, with precip trending downward through Monday. Expecting some showers later Monday afternoon as VFR makes a brief appearance; however, CIGS are expected to diminish to near 1000 to 2000ft across the inside tonight, with coastal areas likely IFR from CIGS into Tuesday morning.

LLWS threats continue to diminish through Monday morning, with southwest post-frontal winds impacting the coast and southerly winds across the inner channels. Speeds should generally remain near 10 to 20 knots, highest winds in Icy Strait, Stephens Passage, and Lynn Canal.

MARINE

Outer Waters: W to SW winds of 20 to 25 kt rule the gulf waters today in the wake of yesterday's system. Expect these winds to persist into this evening before diminishing and starting to turn to a southerly direction on Tuesday ahead of the next system. Winds will then start increasing through Tuesday afternoon to around 20 to 25 kt as the next front moves from West to East. Seas are currently hovering around 10 ft (with a S swell around 8 to 9 ft. period of 10 sec) and are expected to persist at that level through Tuesday at least due to persistent SW swell and then the increased winds from the front on Tuesday.

Inside waters: Stephens Passage, Misty Fjords, and Clarence Strait are still seeing some southerly winds to 25 kt early this morning from the departing system. Those winds should diminish through the morning hours before winds in most channels switch to a W and S direction as onshore flow takes over (Clarence Strait will be the exception with flow turning westerly enough that NW winds will likely be observed in Clarence for this afternoon and tonight). Highest winds up to 25 kt in this flow pattern will be in ocean entrances that are exposed to the W and SW (especially Cross Sound, and near Cape Decision) through this evening. Then expect diminishing winds for Tuesday before they increase to 20 kt Tuesday night as a new front moves in. Seas mainly dominated by wind wave up to 5 ft in windier areas. Ocean entrances will see higher seas up to 8 to 9 ft in areas exposed to the SW and W due to 8 to 9 ft SW swell invading from the gulf.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ022-031-053-641>644-651-652-661>664- 671-672.