Marine Forecasts

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7 Day Forecast for Marine Location Near Gustavus, AK

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Area Discussion for -

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FXAK67 PAJK 161411 AFDAJK

Southeast Alaska Forecast Discussion National Weather Service Juneau AK 611 AM AKDT Thu Jul 16 2020

SHORT TERM. An upper level low over the Yukon-B.C. border has a trough extending southward over the panhandle and is the driving force for a surface low over the Southern Inner Channels. Seeing both of these lows rotating on satellite is interesting, but helpful to know that these are at different levels of the atmosphere. The surface low caused moderate rain on Wednesday over the south, resulting in record rainfall for the day of 1.61" at the Ketchikan Airport, beating the previous record of 0.81" by almost double (but should note this was the lowest daily rainfall record in the whole month). The upper level low will slowly track ESE through Thursday, causing the upper level winds to change from W to NW and push the surface low off to the east as well. Therefore, expect a drying trend with decreasing clouds. Have gone below guidance for POP today, outside of Hyder, think that they are overspreading afternoon convective showers from the mountains and had +30% POP where there are currently mostly clear skies. Will have to watch for any CU build up in the afternoon in case isolated showers need to be added back into the forecast. Expect high temperatures to easily get into the mid 60s with some sunshine.

A ridge formed over the gulf last night, causing a marine deck of clouds to form. This has also trapped in the moisture from yesterday's rain and caused fog to form as the clouds broke. Hoonah, Kake, and Petersburg were even as low as 1/4 mile VIS for a while and a Dense Fog Advisory is out until 8am.

The ridge will shift eastward early Friday and flatten. The increasing onshore flow will likely cause any marine layer clouds over the gulf to be pushed inland. As that occurs, all models are showing a band of vorticity aligned with the length of the coastline to move over those low clouds. As a result, think that there is good potential for some drizzle to be wringed out and have added that to the forecast for early Friday morning from Yakutat to POW. Otherwise the increasing onshore flow will cause more clouds and moisture to move in from the gulf. Then the next system will be approaching from the SW Friday night. This system will still be developing as the first drops of rain spread inland late overnight, ending our dry break. The NAM moved the rain in the earliest and was an outlier compared to other operational models.

LONG TERM. /Saturday through next Thursday/ Rain, showers, precipitation . whatever word you use to describe liquid falling from the clouds, will most likely happen in the long term. A large ridge of high pressure over the central and northern Pacific will continue to build through the weekend. The ridge axis sets up south and east of the Panhandle, with southwesterly flow pumping ample gulf moisture into the region. A strong baroclinic zone will form on the north side of the ridge with multiple systems riding along it, increasing precipitation coverage and intensity. Persistent clouds and precipitation appear likely this weekend through early next week.

The chance for rain increases Saturday and remains high through Monday. A low in the central gulf will head NE towards the NE gulf coast while swinging a front into the Panhandle Saturday morning/afternoon.

There won't be much of a break in the precipitation as another system moves in from the SW following almost the same path. This second system Sunday into Monday looks to have more upper level support, better dynamics, and more moisture associated with it. As the low on Sunday moves into the NE gulf, a fetch of moisture from the tropics oriented SW to NE will be pointed right at the Panhandle with plenty of mid and upper level support. Abundant moisture streaming into the region combined with persistent onshore flow, a strong mid level jet, and impulses moving into the Panhandle will make for a good heavy rain set up. GFS ensembles IVT values approaching 500 kg/m/s Sunday into Monday. EC standardized anomaly tables also show precipitable water values 2 to 3 standard deviations above normal for this time of year. The potential is there for an atmospheric river to impact much of Southeast Alaska late this weekend and into early next week. Confidence is high that this weekend through early next week will be very wet; however confidence is still lower regarding timing and placements of the systems and the finer details. Towards the middle of next week, confidence remains low as guidance keeps flip flopping between solutions. Latest model runs suggest a ridge starting to form towards mid week; however details as to where the ridge axis sets up are still unclear. Kept with WPC by keeping at least a chance for rain in the forecast for now. Will trend PoPs up or down later this week once guidance has a better handle on the set up.

AJK Watches/Warnings/Advisories. PUBLIC . Dense Fog Advisory until 8 AM AKDT this morning for AKZ021-026. MARINE . Small Craft Advisory for PKZ041-042.



Ferrin/CM

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
BLTA2 - Bartlet Cove AK	1 mi	88 min	Calm G 1	49°F
GUXA2	9 mi	32 min	Calm G 1	49°F			1008.1 hPa	48°F
ELFA2 - 9452634 - Elfin Cove, AK	30 mi	66 min			54°F
GEXA2	31 mi	31 min	W 4.1 G 6	49°F			1008.5 hPa	49°F
CSPA2 - Cape Spencer, AK	44 mi	44 min	SSW 2.9 G 5.1	50°F			1010 hPa	50°F
LIXA2	45 mi	32 min	NNW 2.9 G 5.1	53°F			1008.1 hPa	51°F
RIXA2	48 mi	32 min	W 7 G 9.9	53°F			1007.6 hPa	51°F
PRTA2 - Point Retreat, AK	49 mi	44 min	Calm G 4.1	53°F			1010.2 hPa	53°F

Wind History for Juneau, AK

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Gustavus, Gustavus Airport, AK	8 mi	58 min	N 0	0.25 mi	Fog	46°F	46°F	100%	1011.1 hPa

Link to 5 minute data for PAGS

Wind History from AGS (wind in knots)

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Tide / Current Tables for Bartlett Cove, Glacier Bay, Alaska

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Tide / Current Tables for Lemesurier Island Light, North Passage, Icy Strait, Alaska

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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 (10,2,3,4)

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Ground Weather Radar Station Biorka Is., AK

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