Area Forecast Discussion

SYNOPSIS

Key Messages:

- A front passing through northern panhandle has brought cooler and cloudier conditions for the north with a few showers. Warm and dry weather will continue for the southern panhandle. - Periods of elevated winds and seas continue for much of the outer coastal waters and inner channels, especially Clarence Straight, Cross Sound, Icy Straight and Lynn Canal. Small Craft Advisories are in effect.

- Trending cooler and wetter from north to south mid to late week.

SHORT TERM.../through Thursday/

The front that brought rain to the north and central panhandle has continued to move eastward this afternoon. Some lower clouds remain, but heaviest rain has moved east of the area. As onshore flow continues allowing for there to be a few light showers that continue for northern areas. The southern panhandle has stayed dry with clear skies. Because of these clear conditions places near Ketchikan, Annette Island, and Hyder reached 80 degrees. As we head into Wednesday, similar conditions will prevail with light showers over the north and drier conditions for the south. As the sharp ridge begins to flatten, more onshore flow will begin Wednesday. Although remaining dry, the southern panhandle may see a few more clouds developing with slightly cooler temperatures.

A full change in pattern arrives late Wednesday into Thursday. At this time an area of low pressure pushes into the northern gulf. As this system arrives, rain showers will begin as early as Wednesday evening for northern areas. Widespread rain then begins Thursday as a low moves more into the central gulf. Mainly light rain rates will occur Thursday morning before slightly heavier rates begin Thursday evening for the north and central panhandle. 24 hour rain rates will still remain on the lower side, but rain will continue into Friday giving an overall longer rain event.

LONG TERM.../Friday through Monday/

A front moving eastward into the panhandle will continue to spread inland into the southern panhandle through Friday morning. Rain will start to taper off from north to south through Friday and into Saturday, though continued onshore flow will keep the potential for showers elevated through the weekend. Rainfall rates may be heavier with the initial onset of the front, with the indication for a plume of moisture being directed into the central and southern panhandle. Behind the initial front, light rainfall rates should take hold for the rest of the period, though more developed showers may bring periods of heavier rainfall and gusty winds as they blow over.

Winds will increase for parts of the N/S facing inner channels with the front, though expecting speeds to remain around 15 to 20 mph and decrease into the weekend. The strongest speeds are expected through Northern Lynn Canal and into Taiya Inlet, which may be accentuated by any light sea breezing through the afternoon. These winds have been increased to 30 to 35 mph through Thursday, but should decrease down to 20 to 25 mph and continue to drop through the weekend. As the low dips south through the weekend, winds in the northern panhandle may turn offshore Sunday night.

As this low dips southward through the weekend, easterly flow indicates potential for Thunderstorms in BC to attempt to make it over the Coastal Range and into the panhandle. While it is still too far out to decide if this will be a strong enough pattern, this will continue to be looked at through the week. High temperatures will be capped around the low to mid 60s with the increased cloud cover and active weather in the forecast.

AVIATION.../through Wednesday afternoon/

An elevated trough brought light showers and lowered CIGs to the panhandle from Petersburg northward and continues to move inland into BC this afternoon. While rain has largely come to an end, lowered CIGs will remain in its wake along with to fairly benign surface winds for much of the inner channels. Further south along the outer coast, increasing parallel and onshore flow will continue to bring intermittent MVFR conditions due to lowered CIGs, with southwest coastal PoW likely to see a marine layer push back in for Wednesday morning before clearing out similar to today. Mid to low level clouds will continue for the outer coast, particularly north of Sitka, through the period as well. While there remains no LLWS concerns, localized sea breezes could still provide some bumps on approach. For the northern coast, another system will push into the region bringing further deteriorating conditions by Wednesday afternoon.

MARINE

Outer Waters: Building surface high pressure near the eastern gulf coast will strengthen northwesterly winds along the coast, with surface observations at Cape Spencer already reporting surface winds around 25 kt as of 4pm Tuesday. Given the longer fetch and stronger winds, wind waves are expected to exceed 8 ft from Cape Spencer and south towards Dixon Entrance, with little swell influence. These conditions are expected to persist through Wednesday ahead of an approaching system in the northern gulf, before gradually weakening and subsiding into Thursday.

Inner Waters: Somewhat persistent, predominantly westerly flow for the inside waters, with strong breezes for Cross Sound, Icy Strait and the backside of Douglas Island are on tap for the rest of Tuesday. The exception is the current brief reprieve in the northern inner channels due to the upper level trough quickly lifting inland, causing some erratic shifts in wind direction and overall slackening of the gradient. Maximum winds should develop around the evening timeframe, enhanced by low pressure developing in northern British Columbia and strengthening high pressure in the gulf waters. A surge of energy is then expected to move over the NE gulf coast and into the northern inner channels Thursday, bringing strong breezes to near gales for Lynn Canal.

AJK WATCHES / WARNINGS / ADVISORIES

PUBLIC...Heat Advisory until 7 PM AKDT this evening for AKZ330>332. MARINE...Small Craft Advisory for PKZ021-022-036-641>644-661>664-671-672.