Marine Forecasts

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7 Day Forecast for Marine Location Near Petersburg, AK

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Area Discussion for -

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FXAK67 PAJK 241500 AFDAJK

Southeast Alaska Forecast Discussion National Weather Service Juneau AK 600 AM AKST Fri Jan 24 2020

SHORT TERM. /Through Saturday night/ Deep upper trof will remain over the central gulf through tonight, then begin to drift W toward the western gulf Sat and Sat night. A strong shortwave trof rotating around the base of the trof will lift NE across SE AK today. This shortwave will interact with another shortwave coming N out of the southern stream, with the two shortwaves merging as they move across SE AK. More southern stream shortwave energy will move N into the far eastern gulf and SE AK late tonight through Sat night. Models differ on timing of these shortwaves though. At the sfc, a sharp cold front will move slowly E across SE AK today into this evening, then stall across the far S by late tonight. This front will begin to drift N as a warm front Sat as low pressure develops over the NE PAC and heads N toward the eastern gulf. The track of the main low differs amongst the models though, due to the differences aloft and how much system interacts with the upper trof over the central and western gulf.

Main forecast adjustment for the today period was to increase snowfall across the central and N areas. The cold front will have moderate to locally heavy precip rates along and on the cold side of the front, enhanced by mid-level frontogenesis and strong upper level PV advection. There will be an onshore flow underneath the strong southerly flow above the frontal surface, which will also enhance precip rates due to upslope flow. Finally, there will be some lower level instability that develops shortly after the colder air moves in but ahead of the mid-level trof. All of this will likely mean a 1-3 hour burst of 1-2 inch per hour snowfall rates from PAGS/PAOH to PAJN areas. Further N, better overrunning will mean a more prolonged snowfall, and they will likely also see a period of 1-2 inch per hour snowfall rates later this morning to early afternoon. Given the above scenario, have issued winter weather advisories for zones 20-21-25 for today. Think 3-6 inches of snow will fall in those locations, but there is a risk that heavier snow could fall around the N part of the Juneau area due to the upslope flow. For Haines and Skagway, kept the winter storm warnings going, with another 5-10 inches of snow expected, with the highest amounts near Haines. Elsewhere across the central panhandle and central outer coast, looks like 1-4 inches of snow will fall today. Further S, precip should be mainly rain, although it may end as a period of snow during the afternoon. Do not expect more than 1 inch today in those areas.

Precip will transition to mainly snow showers for much of the area later this afternoon and evening. The most frequent/intense snow showers will be across the northern panhandle and NE gulf coast. There will likely still be some rain across the far SE part of the area tonight as the shot of colder air will not be as cold as further N.

Then, as southern stream systems move N into the eastern gulf for Sat-Sat night, precip will spread N through the area. Due to the model differences, timing of this precip is still questionable. One thing that will happen though is warmer air will move N into the area Sat into Sat night. Precip will likely start as snow for all but the far SE part of the panhandle, but transition to rain across the S Sat. Looking like at least mixed precip will reach the N-central area by late Sat night. The timing of the precip transition has a lower than average confidence though, with a faster changeover more likely than a slower one based on the model consensus right now. Later shifts can adjust this as needed.

Winds should not get above SCA levels through tonight. Potential for gales is there for Sat and Sat night though as low pressure moves in. Exact location of these stronger winds is still in doubt though, so kept winds limited to SCA levels attm.

LONG TERM. /Sunday through Friday/As of 10 PM Thursday/The picture for the long term continues to look muddy due to large variations within the various models, but what is clear is that we will be returning to a stormy pattern in the coming days. Deep troughing over mainland Alaska and into the Gulf will pool some rather cold air, which will mainly impact northern panhandle locations. around this troughing an active jet pattern will send a series of lows around the trough that will continue to keep flow southerly should bring warmer temperatures through much of the panhandle. This southerly flow will also provide ample moisture for these systems to play with. Given the time of year, and potential interactions with the arctic air camped out to the north, p-type issues will likely be the biggest forecast challenge for next week. North central and northern panhandle locations will be the ones to watch for potential heavy snowfall as some of these systems look like they will be pretty good precip makers. For the southern areas, temperatures look to remain warm enough that precip type should mainly remain as rain, however still can't rule out a few snowflakes mixing in if precip is occurring during the colder parts of the day.

As with any complex set-up, the models really begin to diverge wildly on specific timings and intensity of any particular storm, therefore the forecast remains largely unchanged with some blending to WPC guidance for continuity. The overall message is, it looks like it will be wet, but it is yet to be determined what form the precip will take with any real confidence, it just needs to be noted that the potential is there for at least one or two storms to bring heavy precipitation and strong winds in the coming week.

AJK Watches/Warnings/Advisories. PUBLIC . Winter Weather Advisory from 9 AM this morning to 6 PM AKST this evening for AKZ025. Winter Storm Warning until 6 PM AKST this evening for AKZ018-019. Winter Weather Advisory until noon AKST today for AKZ020-021. MARINE . Small Craft Advisory for PKZ012-013-022-036-041>043-051-052.



RWT/JDR

Visit us at http://www.weather.gov/Juneau

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
LCNA2 - Lincoln Rock, AK	42 mi	56 min	SE 28 G 41	44°F			987.9 hPa	42°F
FFIA2 - Five Finger, AK	58 mi	66 min	W 9.9 G 12	37°F			988.5 hPa (-2.7)
CDEA2 - Cape Decision, AK	77 mi	44 min	WNW 12 G 13	35°F			990.4 hPa	33°F

Wind History for Port Alexander, AK

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Petersburg, AK	13 mi	10 min	N 0	10.00 mi	Light Rain	39°F	37°F	93%	989.5 hPa

Link to 5 minute data for PAPG

Wind History from APG (wind in knots)

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Tide / Current Tables for Anchor Point, Alaska

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Tide / Current Tables for Wrangell Narrows (off Petersburg), Alaska Current

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Weather Map

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GEOS Local Image of PacificNorthwest    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

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Wind Forecast for (12,3,4,5)

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Ground Weather Radar Station Biorka Is., AK

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