textproduct: Juneau

UPDATE

Updated aviation discussion for 18Z TAF issuance.

AVIATION.../through 18Z Monday/

A front is passing across the panhandle this morning, bringing conditions from VFR to IFR. Conditions across the northern panhandle have already begun improving as the the low in the gulf moves south. This southern movement of the front has already caused some southern TAF sites to drop to CIGs broken below 1,000ft. Visibilities in the southern panhandle have also dropped due to rain and mist moving into area. Through the day, northern TAF sites are expected to remain VFR with high overcast CIGs, but the southern panhandle is expected to see more of the same reduction of CIGs and VIS. These conditions are expected to be prominent through the time period.

-AGP

PREV DISCUSSION......ISSUED AT

SYNOPSIS...

Key Messages:

- Moderate to heavy rain for Ketchikan, Metlakatla, and Hyder likely for Sunday evening and overnight into Monday. No flooding is expected a this time.

- Strongest winds, Sunday into Monday, will be located over the southern panhandle with winds around 25 to 30 kts over Clarence Strait.

- Rain rates and winds diminish late Monday into Tuesday.

SHORT TERM.../Through Monday/...Moderate to heavy rain returns to the southern panhandle today as a low pressure system moves southeastward across the gulf. This low pressure system is currently located over the west/central gulf bringing it's first front, of many, into the panhandle. As of early this morning light rain has begun for both a few northern and southern areas. As this low continues to move to the southeast, rain rates will begin to increase, especially for southern portions of the panhandle. Specifically the Ketchikan, Annette Island, and Hyder areas are likely to see around 2.5 to 3.5 inches of rain in 24 hours, with isolated areas seeing up to or more than 4 inches. There is even a slight chance for the aforementioned areas to see those higher rates to around 4 inches in 24 hours. Heaviest rain is most likely to fall late this evening into early Monday morning. Rain rates during that time are most likely to be around 0.15 to 0.2 inches per hour with a chance of 0.3 inches per hour falling for some locations. Heaviest rain rates for the south will diminish Monday morning. Rain will then continue with periods of moderate rain through Monday afternoon. Overall rain rates will diminish Monday evening into Tuesday.

During this time overall winds will remain on the lighter side. An exception to this includes areas of the southern panhandle near Clarence Strait. Late Sunday, as the main front pushes into the southern panhandle, winds will increase with gusts around 30 to 35 mph for Annette Island and Ketchikan. Most other portions of the panhandle will see winds around 10 to 15 mph or less. Similarly to rain rates, overall winds will diminish Monday morning.

LONG TERM...Tuesday a longwave trough will continue shifting southeast toward the west coast of Canada, carrying a weakening surface low with it. Widespread moderate to heavy rain will also break apart from north to south, leaving a short and welcome break Tuesday. Upstream, zonal flow becomes briefly established over the Gulf, with a signal for a shortwave trough digging down from the south- central coast. These features will carry west-northwest onshore flow and some moisture into our area; however, deep moisture will likely shear apart before reaching the Panhandle, limiting heavy rainfall potential into mid week. Anticipate low clouds and more typical rainfall, with the farthest reaches of the northern Panhandle likely enjoying drier conditions. Near the end of next week ensembles show agreement on a larger system moving into the Gulf, bringing increased chances for heavier rain and elevated southeasterly winds along our coast into the weekend.

AVIATION...A gradual deterioration in conditions is expected across much of the central and southern panhandle this morning as low pressure and a frontal system advance eastward across the Gulf. The heaviest rainfall will likely occur after about 22Z and through tonight with IFR to low MVFR conditions becoming predominant. We will also see some increase in wind speeds for the southern TAF sites. Farther north, ceilings at PAYA have already dropped to IFR at times in rain showers. However, mainly VFR to MVFR is expected to prevail for the majority of the northeast Gulf coast and northern panhandle as the lower cloudiness and organized rainfall remain farther south.

MARINE... Outer Waters: Low pressure will move across the eastern portions of the Gulf through tonight. In advance of it, winds will become mainly southeasterly and gradually increase. We still expect a weak barrier jet to form along the northeast Gulf coast early today and then slowly weaken. By late afternoon and early evening, winds will generally turn more northeasterly. Around Dixon Entrance, we also expect a rather significant increase in wind speeds to around 25-30 kts, with higher gusts. Seas will also build in that area to around 8 feet before subsiding after 15Z Monday as winds decrease.

Inner Channels: Although there continue to be a few differences in the model solutions, especially in regard to the timing of the incoming system and frontal passage, it still appears that the most significant increase in winds will affect mainly Sumner Strait southward. Wind gusts to 35 kt are possible in Clarence Strait tonight with seas forecast to build to 8 feet. As the low pressure and front pass later Monday, winds and seas will gradually diminish. Elsewhere across the inner channels, winds are expected to remain generally 10 knots or less into Monday, except for parts of Lynn Canal where winds around 15 knots are possible at times.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ036.