textproduct: Juneau

SYNOPSIS

Key Messages:

- Light mist with areas of fog are likely to continue across the panhandle with due to weak onshore flow.

- The weekend through next week, models are falling into line behind a weather pattern that has been known to produce heavy snow. Higher confidence in totals for the northern panhandle, but still significant uncertainty elsewhere about timing and amounts, but details are being watched closely.

LONG TERM...//Saturday through Tuesday/

A pattern change going into this weekend is still looking to bring cold temperatures, heavy precipitation, and strong winds to the panhandle into early next week. Confidence has improved for snow potential in Skagway and Haines over the weekend, and even more for the northern highways. A winter storm warning has been issued for these areas over the weekend, and a watch has been issued for Yakutat. The special weather statement was also continued for the NE gulf coast and the Icy Strait Corridor.

A system sending a front into the panhandle overnight Friday is still looking to stall in the northern gulf through the weekend, funneling consistent moisture over the panhandle. This front will bring moderate to heavy rain rates to the area, with around an inch to an inch and a half of rain in 24 hours expected for a majority of locations and persisting at similar rates through the weekend. Though these rain amounts may seem typical for a 24 hour period, the persistence at those rates lasting through the weekend and into next week will be watched closely, especially at higher elevations. A cold air mass aloft shifts into the Yukon and continues to moves southward through the weekend. A tightening pressure gradient over the northern panhandle will increase outflow winds through the weekend, helping to funnel the colder air south into the panhandle. Decreasing temperatures with ample available moisture will increase the potential for heavy snowfall in the northern panhandle, extending south through the weekend and into next week. Highest confidence of snowfall remains in the N Panhandle over the weekend. Forecast becomes more of a challenge moving towards the Icy Strait Corridor, starting as rain and transitioning into a mix by Sunday, limiting potentially accumulations. Expecting a transition over to snow going into Monday, though uncertainty remains as to how much available moisture there will be, limiting appreciable amounts. As snow level drops south following the colder temperatures, snow potential will also move further south towards the corridor, and the rain/snow mix will then follow into the central panhandle. Stay tuned to the forecast moving into the weekend as details come into clearer view regarding potential amounts and refined timing.

As the gale force low moves into the northern Gulf and a high sets up to the north of the panhandle into this weekend, a tight pressure gradient allowing for northerly flow begins to set up over the northern panhandle into Lynn Canal. This cold air mass to the north contributes to the colder temperature trend over the weekend and into early next week, alongside bringing stronger winds down Lynn Canal. These winds will begin to increase Saturday into Sunday with northerly gales in northern Lynn Canal with 35 to 40 kt winds by Sunday afternoon as the gradient tightens over the northern panhandle. These gale force winds will last into the beginning of next week as the gradient remains. Winds will increase in Skagway at this time, with 25 to 35 mph sustained winds possible Sunday and Monday. A decent 850-750 mb inversion setting up over Whitehorse to the northeast will allow for these winds to impact Skagway not only from the strong pressure gradient, but from a decent density difference, allowing for more confidence at Skagway having elevated winds over this timeframe with gusts reaching up to 40 to 50 mph at times. Other land areas will see an increase in SE winds as the front moves through, with diminished winds between the waves of precipitation that push through this weekend into early next week. Overall the outflow pattern over the northern panhandle is expected to last into midweek, with more northerly winds and offshore flow beginning to move southward to around Icy Strait Corridor Monday onwards. This cold dry air will help to lessen the precipitation amounts across the northern panhandle midweek into the end of the week when looking ahead.

AVIATION.../Until 18Z Saturday/

For the northern half of the Panhandle, generally flight conditions in the MVFR/IFR range are anticipated starting this morning as a weather system approaches & begins moving through. For the rest of the Panhandle, expect conditions to lower to a similar range of flight conditions starting in the afternoon/evening timeframe as the system approaches their area. For the northern Panhandle, SFC winds will become rather gusty starting this evening as the SFC pressure gradient tightens up. For the southern Panhandle, winds remain on the lighter side through the TAF period. LLWS magnitudes up to around 35 kt centered aloft at 2 kft out of a generally southerly to southeasterly direction are expected starting this evening across the area.

MARINE

Outside Waters: Calmer conditions last through Friday over the Gulf as a weak high remains over the area, before being pushed out by the oncoming system moving in from the west by Friday night. This next system will bring southwesterly to southerly fresh to strong breezes (17 to 27 kt) across the Gulf, with winds becoming more southerly by Saturday. As the pressure gradient tightens between the low in the Gulf and the high to the north over Canada Saturday night into Sunday, northeasterly near gale to gale force (30 to 40 kt) offshore winds and gap winds will occur along the NE Gulf Coast between Yakutat Bay and Cape Spencer. The southeastern Gulf will also see an increase from near gales to gales (28 to 36 kt) as a front moves through Saturday night into Sunday morning and again Sunday night into Monday. Seas between 5 and 8 ft tonight will quickly increase tomorrow night into Saturday as the system moves in to between 10 and 14 ft. The seas will continue to see an increase into Sunday to 12 to 16 ft. Southwesterly swell continues tonight through the weekend.

Inner Channels: Predominantly calmer winds give way to a sharp increase Friday night into Saturday as the next system moves into the area. This will bring southeasterly winds across the inner channels between a moderate to fresh breeze into Saturday, and up to a strong breeze (22 to 27 kt) for northern Lynn, Frederick Sound, Stephens Passage, and near the ocean entrances. The channels will see a brief increase as the fronts move across the panhandle this weekend into early next week. Northerly outflow begins to set up over northern Lynn Sunday as the pressure gradient begins to tighten, bringing near gales in the morning becoming gales into the day Sunday. Largely expecting between 35 and 43 kt winds down Lynn Canal lasting from Sunday into early next week, with the stronger northerlies moving southward down to Point Couverden Sunday night into Monday. This will allow some lower level convergence right around Point Couverden from the southeasterly winds up Chatham Strait and the northerly outflow coming down out of Lynn Canal, bringing winds around Rocky Island to around 25 to 30 kt. Frederick Sound near Point Fanshaw and up along Stephens Passage will continue to see strong breezes to near gales throughout the weekend, alongside Clarence Strait seeing near gales as the fronts move through and bring stronger southeasterly winds.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Winter Storm Watch from late tonight through late Saturday night for AKZ317. Winter Storm Warning from 10 PM this evening to 3 PM AKST Sunday for AKZ318. Winter Storm Warning from 3 AM Saturday to 3 PM AKST Sunday for AKZ319. MARINE...Small Craft Advisory for PKZ031-053-641>644-651-652-661>664-671- 672.