textproduct: Juneau

UPDATE

Extended High wind warning for the Skagway area to the morning, as gusts near 60 mph persisting and should continue to Wednesday morning.

06z TAF issuance. Clear conditions over majority of the forecast area, as planned with possibility of LLWS or turbulence near terrain and winds from the outflow. No big changes to the thinking that was used for the 00z package.

PREV DISCUSSION...ISSUED AT 328 pm Dec 23

SHORT TERM...The cold weather continues for the panhandle as some places managed to set record cold temperatures today. The cold weather is expected to continue tonight as similar conditions to last night are expected. One concern will be just how cold locations across the northern panhandle get as temperatures this morning were quite cold. High wind gusts remain possible for the Skagway area through this evening but the concern for high winds in the Downtown Juneau have diminished as the mountain wave is not looking to be as big of a factor now. Headed into Christmas Day, a low moves out of the Interior and move across the northern gulf before working south and east. This will bring some snow to the outer coast from Sitka south to Prince of Wales Island. Most accumulations look to remain under a few inches but will reinforce the cold air across the area. Concern then turns to the long term for the next impactful system to move into the area.

LONG TERM...We continue to watch the upcoming shift in the weather pattern that would give the next round of significant snow to Southeast Alaska.

The next major system will begin to move into the Gulf of Alaska Friday, following behind the weak low clipping the panhandle Thursday. As the weaker low moves southeast, before the larger low approaches from the west Friday night, there will be another brief lull in the winds into Friday along the southern waters, while the northern offshore flow will remain stronger ahead of the next low moving in from the west. Winds begin to pick up across the entire panhandle Friday night into the weekend as the stronger low approaches, and a gale force front begins to move in from the southwest. These southerly winds moving into the panhandle will allow for some warming across the panhandle alongside bringing precipitation through from W to E into the start of the weekend.

As far as temperature relating to snow potential, the EURO and GFS ensembles and deterministic models have come into greater agreement over low tracks and 500mb flow. The Canadian remains the outlier. The 500 mb flow continues to have the deep trough further west, keeping a southwesterly flow into the panhandle and allowing for deep moisture and warmer air to be moved in from lower latitudes with the deep trough position, with the arctic trough and 500 mb cutoff low over the Pacific to the southwest connecting over the Kenai Peninsula down the west Gulf. Some of the deterministic models show the arctic trough separating from this lower latitude troughing as it becomes a cutoff again and moves southward, leaving a southwesterly flow into the southern panhandle but the arctic trough allowing for colder arctic air to move across the northern Gulf into the northern panhandle, bringing the potential for cooling the north much sooner than the southern panhandle into next week. This has not been shown on the ensembles as of yet, and is seen on the EC deterministic run and not the GFS one, so the certainty of the timing of the cold air coming back into the northern panhandle is still a bit uncertain for the period into early to mid next week.

Looking at the EFI tables, as well as looking at AR and IVT tools for this heavier precipitation coming up this weekend, QPF amounts have been adjusted to keep the southern panhandle at between 2.5 and 3.5 inches of liquid precipitation every 24 hours, coming down first as snow Saturday morning before quickly transitioning to rain from the SW coastline inwards as the warm front pushes through, with the switch to rain expected during the morning hours for PoW and Sitka into midday for areas like Ketchikan and Wrangell that are a bit further inland. This is from the extreme and AR tools showing a higher confidence of a shift of tails for QPF for the southern panhandle, particularly near the Ketchikan area, with an increased confidence from yesterday's model runs. Overall the heavy rain will begin for the southern panhandle Saturday, but the next wave of precipitation pushing through will bring another round of heavy rain Sunday that has been primed by the first warm front pushing through the day prior. The warm temperatures in the high 30s to low 40s will continue into the early week as onshore flow continues to bring in southerly warmer flow into the southern half of the panhandle.

For the rest of the panhandle, which includes everywhere north of Wrangell and Sitka, the snow will last into Saturday as that first front moves in, as the warmer temperatures will not bring temperatures up into the mid to high 30s until Sunday. This will allow for a switch to more of a mix potentially becoming rain by Sunday afternoon/evening up to Icy Strait corridor. These areas will see between 8 and 14 inches in 24 hours Saturday into Sunday morning before transitioning to rain/snow mix to potentially rain. Snow will start off lighter and fluffier Saturday as snow liquid ratios remain high, but as the area warms Saturday into Sunday, ratios will decrease to become a heavier and wetter snow. Areas to the north of Icy Strait corridor will likely remain snow the entire time through both fronts moving through, giving a significant amount of snowfall to the Skagway and Haines areas with between 10 and 18 inches in 24 hours both Saturday and Sunday with more expected along the Klondike Highway. However these amounts for all of the panhandle depend largely on how much of the precipitation actually reaches parts of the panhandle, particularly in these northern areas. Overall the northern half of the panhandle will see 1.5 to 3 inches of liquid precipitation during this system, but there remains uncertainty on how much snowfall there will be exactly during this system and the exact timing of a changeover to rain for the central parts of the panhandle. Overall this will remain more of a heavy rain event for the southern panhandle from Sitka and Wrangell southwards Saturday into Sunday, with only about 3 to 7 inches expected for Ketchikan Sitka and PoW Saturday morning before transitioning to rain, and 6 to 12 inches for Wrangell possible before they too transition to rain.

AVIATION.../through Wednesday afternoon/... Mainly VFR flight conditions expected through the period. Across the north, just a few passing high clouds expected. Further south, Generally VFR flight conditions with skies few to sct AOA 3kft. Snow showers could bring brief MVFR VIS/CIGs for PAKT tonight. Low level turbulence and wind shear will also persist with winds 1-2kft aloft 25-35kts. Strong winds 25g50kt continue for PAGY with breezy outflow winds 12-17G22-30kt for PAHN, PAWG and PAKW. Less than 10kt elsewhere.

MARINE... Outside (Gulf and Coastal Waters): Outflow winds continue across the Gulf. The strongest winds continue to be out of gaps in terrain such as Cape Spencer and near Dangerous River. These winds continue to weaken somewhat but some locally stronger winds remain possible as we head into the middle of the week before starting to weaken. Wave heights are expected to diminish for most of the Gulf but the largest waves will persist in the areas where the outflow winds continue to remain high. The N-NE swell is expected to shift to a S- W swell component by the time we get to Wednesday. Waveheights are then expected to increase as a low ejects of the Interior Wednesday which will bring up heights.

Inside (Inner Channels): Outflow winds continue this afternoon as the wind speeds continue to remain elevated with gales to strong gales continuing for Lynn Canal and Stephens Passage. Outflow winds are expected to increase again as we move into the middle and end of the week in response to two lows moving through the area. The freezing spray concern has trended down somewhat with the decreased winds but will start to trend up again as the winds increase. The strongest winds are expected to continue down Lynn Canal as well as Stephens Passage and down towards Five Finger lighthouse. With the first low increasing winds through the Inner Channels. Then the second low will increase the winds again as a system moves into the area for the weekend.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Extreme Cold Warning until 6 AM AKST Wednesday for AKZ318. High Wind Warning until 6 AM AKST Wednesday for AKZ318. Extreme Cold Warning until noon AKST Wednesday for AKZ319. Cold Weather Advisory until 6 PM AKST Wednesday for AKZ320-321- 323-326-327-329. Extreme Cold Warning until 7 PM AKST Wednesday for AKZ325. Cold Weather Advisory until 9 AM AKST Wednesday for AKZ328-330- 332. MARINE...Heavy Freezing Spray Warning for PKZ011. Heavy Freezing Spray Warning for PKZ012-031. Heavy Freezing Spray Warning for PKZ013. Heavy Freezing Spray Warning for PKZ021. Heavy Freezing Spray Warning for PKZ032. Heavy Freezing Spray Warning for PKZ032. Heavy Freezing Spray Warning for PKZ053. Gale Warning for PKZ012-013. Small Craft Advisory for PKZ011-021-031>034-036-641>643-661>663.