textproduct: Juneau

SYNOPSIS

Key Messages:

- High pressure out in the Gulf will bring warm, dry and mainly clear weather through the end of the work week.

- Temperatures will drop overnight across the north, with near freezing temps possible early Thursday morning near Yakutat.

- Gusty northerly outflow conditions for Thursday, especially across the northern panhandle.

LONG TERM.../Saturday through Monday/

At least the first half of the long term forecast remains largely uneventful as an area of high pressure persists over the Gulf through Saturday, bringing northwesterly flow, drier conditions, and warmer temperatures. The entire panhandle will see mainly clear skies Friday into midday Saturday, with cloud cover moving in from the north by Saturday evening. After some stronger winds into Thursday night, especially over the northern inner channels, winds will decrease by Friday morning before the flow switches southerly through the afternoon. For the weekend, southerly winds in Lynn Canal will increase to around 20 kts with the help of sea breeze formation from midday into the early evening hours. High temperatures Friday will reach the upper 60s to low 70s in the northern panhandle and potentially well into the 70s in the southern panhandle under ample clearing. Some areas still look like they may reach the upper 70s Friday and Saturday, mainly in the vicinity of Hyder.

Models have come into somewhat better agreement in regarding to the timing of the next frontal trough. The Canadian still wants to break down the ridge soonest, but even it has slowed. We have higher confidence that conditions will remain mainly dry for the majority of the area through Sunday, except perhaps along the northeast Gulf coast. Rain chances will then gradually increase from northwest to southeast across the region on Monday as the pattern turns more active.

AVIATION

Continued VFR conditions through tonight, with clear skies and winds calm with the exception of some 10 kt sea breezes, and downsloping winds in PAHN. These winds will continue to diminish into the evening, before increasing again from 06z into tonight for the far northern panhandle as a N-S gradient tightens over Lynn Canal. This tightened gradient appears to be strongest by around 18z tomorrow for the northern panhandle, with between 10 to 15 kt and gusts to 25 kt possible in the morning for areas along Lynn Canal. There is potential for winds around PAGY increasing to 20 kt from the north in this time period, however confidence is lower due to the wind staying much lower through the day today compared to the expected wind speeds.

The rest of the panhandle will largely stay light and calm through the night after the sea breezes die out, with some areas seeing potential for some fog development overnight. The highest chances remain for the southern panhandle, including PAPG, PAWG, and PAKW, but Icy Strait Corridor and locations along the outer coast may see some fog development and marine layer low stratus in the early morning. Confidence remains low for the VIS restrictions possible if this develops overnight, as well as if any marine layer will actually impact the TAF sites or just remain just offshore of the Gulf coast in the morning. Any fog or low stratus will dissipate by 18z as northerly winds increase across the panhandle through the morning.

MARINE

Outside: West to northwest winds continue to impact the coast as a high begins to dominate. Primary threat to mariners is winds of moderate breezes building along the northern coast, with northwest winds of fresh breezes along the Chichagof to Prince of Wales Coast. Marines planning to navigate the Chatham and Sumner ocean entrances should be aware of northerly winds flowing out of the inner channels, with speeds likely near moderate to fresh breezes.

West to northwest wind waves near 7 to 9 seconds continues to dominate the coast, with underlying southerly swell from the south pacific and hurricane activity in the central Pac being buried. Significant heights of 4 to 7 ft continue, with 4 ft along the northern coat and 7 ft closer to Dixon Entrance. By Sunday/Monday the jet will shift into the Aleutian storm track, serving up a series of lows. Expect building southwesterly seas of 8 to 12 ft by the start of next week.

Inside: Certainly, a complex forecast for the inner channels Wednesday night into Friday. Primary challenge has been diagnosing northerly wind onset, strength, and duration. Mariners planning to navigate the inside Thursday should be aware of northerly 15 to 25 knot winds impacting most north-to-south orientated channels, with Clarence Strait persisting a bit longer into Thursday night. One note on these northerly winds, there is ample opportunity to miss wind strength and/or localized areas like southern Chatham Strait and northern Glacier Bay. Stay tuned to NOAA weather radio and weather.gov/Juneau for updates. If you get pinned down somewhere, just wait. Northerly winds will subside north to south late Thursday afternoon into Friday morning.

Lets get into the details...overnight Wednesday a quick transiting high will slide into the Yukon, bringing a north/south pressure gradient between our Canadian neighbors and the Gulf. Guidance suggests a mean pressure gradient difference between CYXY and PAJN near 5.8mb, with PAGY to PAJN near 3.5 mb. Historically, this suggests small craft conditions from strong breezes to near- gales (22 to 33 knot winds). However, we are missing a few critical ingredients mainly a deep stable winter airmass in Canada. This means guidance is likely overdoing wind speeds but could have drastic consequences if our forecast under performs, especially with the number of small skiffs currently operating in our waters. For now, anticipate building northerly winds in Lynn late Wednesday night, with sustained wind speeds likely reaching strong breezes. Gusts could reach as high as gale force for a few hours in Lynn. Expect northerly winds to continue to build in Chatham and Stephens Thursday morning, filling into Clarence Strait a little later. Overall, winds of moderate to strong breezes (15 to 25 knots) should be expected in major north-south channels, with the current forecast leaning toward 25 knots for Lynn and fresh breezes for southern Clarence Strait. Winds slowly diminish Thursday from north to south. Again, Clarence Strait will hold onto stronger northerlies until Friday morning. For seas, the northerly winds will have ample room to put in some work on the long fetch of Lynn and Chatham, with choppy seas building to near 4 to 5 ft Thursday morning. Watch the flooding tides and the northerly winds, which could bring locally higher seas.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Frost Advisory from 2 AM to 8 AM AKDT Thursday for AKZ317. MARINE...Small Craft Advisory for PKZ012-661.