Page Links Change Location One Page Printer Page HELP Default setup SAVE setting RECALL saved setting

Marine Weather and Tides Mercer Island, WA Version 3.4

NOTICE 1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17. 1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

---

Sunrise 6:44AM

Sunset 5:57PM

Tuesday March 2, 2021 5:33 PM PST (01:33 UTC)

Moonrise 10:30PM

Moonset 8:42AM

Illumination 81%

NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.

---

---

7 Day Forecast for Marine Location Near Mercer Island, WA

   Hourly   EDIT   Help

---

Area Discussion for - Seattle, WA

      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
FXUS66 KSEW 022333 AFDSEW

Area Forecast Discussion National Weather Service Seattle WA 333 PM PST Tue Mar 2 2021

SYNOPSIS. Mostly dry and warmer conditions across the region through Thursday as quasi-zonal flow gives way to high pressure aloft. A pattern change late Thursday will see a return of wet weather to Western Washington Friday through the first half of next week.

SHORT TERM /TONIGHT THROUGH THURSDAY/. Ongoing showers associated with the remnants of this mornings convergence zone are trending down this afternoon, with only isolated showers remaining across Admiralty Inlet and portions of Snohomish County at this hour. Visible satellite imagery shows some breaks in the clouds beneath the thin, broken upper level cloud layer, allowing for some moments of sun. Less low level cloud cover is being observed at this hour from Tacoma southward and westward, where low level clouds have mostly mixed out this afternoon and influence from convergence are non-existent. Dry conditions will prevail tonight under mostly cloudy skies.

A large upper level low embedded in the southern flank of the polar jet will eject across Southern California tonight and into the Great Basin by Wednesday night/early Thursday. This, coupled with an approaching upper level low ejecting out of the Gulf of Alaska will amplify the NW to SE oriented ridge, with the ridge axis likely oriented east of Western Washington. While we are expecting warming temperatures, this will be a limiting factor in how warm we will get on Wednesday and Thursday. While 60 degrees F is not out of the question on Thursday, timing of the onset of clouds and rain will be a factor. An onset of clouds and rain earlier on Thursday will preclude warming, while clouds and rain moving into the region later in the afternoon will likely allow readings to hit the 60 degree mark for the second time this week in some areas and for the first time this year in others. With a deepening upper level low tapping into a large fetch of Pacific moisture approaching the coast Thursday night, a shift from quiet and mild weather is expected, as increasing winds along the outer coast and rain are expected to impact the region Friday through the weekend.

LONG TERM /FRIDAY THROUGH TUESDAY/. There remains some variance in ensemble guidance regarding exactly where the bulk of the upper level energy will impact the coast. There remains a signal in the upper level ensemble guidance in a secondary upper level shortwave trough ejecting southeastward out of the parent low and into the southern OR/NorCal coast late Friday/Saturday. That said, confidence is increasing in a weak AR event setting up from southwest to northeast along the northwest coast Friday and Saturday. That said, there are several factors that will preclude widespread flooding with this particular AR setup:

1) Snow levels: These will only rise to ~4000-5000 feet at the most across the region, cutting down the rainfall efficiency.

2) Progressive storm pattern: The AR will only remain pointed at the Olympic Peninsula for roughly 24 to 36 hours before the upper low pushes the moisture eastward.

These factors will limit rainfall amounts and snowmelt runoff through this event. There is reasonable confidence in at least 1 to 2 inches of rainfall from Thursday night through Saturday, with slightly higher amounts in the Olympics. As a result, flooding potential will likely be limited to the Skokomish River basin, with lower potential for urban flooding due to less intense rainfall rates. Aside from rain, breezy southerly winds are expected along the coast through Friday evening.

Active weather will persist through the remainder of the period as another system will eject out of the Gulf of Alaska on Sunday, bringing another round of wet and active weather to the region through the end of the period. It is important to note that there is a wide range of solutions regarding the strength and location of this system which will affect the finer details of the resultant weather. The bottom line is, expect unsettled weather to persist from this weekend through at least the first half of next week.

Pullin

AVIATION. Westerly flow aloft. Light low-level flow will become southerly on Wed. The air mass is stable and fairly moist. The mountains are partly to mostly obscured especially in the central Cascades. Areas of stratus finally broke up this afternoon but will set back up to some degree overnight. Mid and high clouds will cross the area at times as well.

KSEA . Nice to see the PSCZ give up and the filtered sunshine this afternoon. Some clouds will set back up overnight but we should be done with the low cigs and drizzle.

19

MARINE. Weak high pressure builds over the area but a warm front will brush the area later on Wednesday. A stronger front will arrive Thursday or Friday with southerly gales possible across the coastal waters and portions of the inland waters. Coastal swell will ease a bit but then build right back up again for the end of the week.

19

HYDROLOGY. An atmospheric river is expected to affect Western Washington late Thursday night through Saturday. At this time, several limiting factors will keep the flood threat isolated to the Skokomish River basin during this timeframe.

1) Snow levels will only rise to 4000 to 5000 feet across the Olympic Peninsula, limiting rainfall efficiency.

2) Event duration. The AR will remain pointed at the Olympic Peninsula for ~24-36 hours at the most. Rainfall amounts will generally range from 1 to 2 inches across most locations, with higher amounts to 3 inches in the higher elevations of the Olympics.

These factors coupled with a mostly dry week will limit the flooding potential across the region. An additional system will bring additional rainfall to Western Washington Sunday through early next week.

Pullin

SEW WATCHES/WARNINGS/ADVISORIES. WA . None. PZ . Small Craft Advisory until 10 PM PST this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

Small Craft Advisory until 8 AM PST Wednesday for Grays Harbor Bar.



www.weather.gov/seattle

---

Weather Reporting Stations

   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map

Wind History for Seattle, Puget Sound, WA, WA

(wind in knots)    EDIT      (on/off)   Help

Last 24hr

1 day ago

2 days ago

---

Airport Reports

    EDIT      (on/off)   Help   Click EDIT to display multiple airports. Follow links for more data.

Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Boeing Field - King County International Airport, WA	2 mi	40 min	NE 4	10.00 mi	Overcast	47°F	35°F	63%	1015 hPa
Renton Municipal Airport, WA	3 mi	40 min	NNW 4	10.00 mi	Fair	46°F	36°F	68%	1015.5 hPa
Seattle, Seattle-Tacoma International Airport, WA	7 mi	40 min	N 0	10.00 mi	Mostly Cloudy	48°F	33°F	56%	1015.5 hPa

Link to 5 minute data for KBFI

Wind History from BFI (wind in knots)

6 PM

7 PM

8 PM

9 PM

10 PM

11 PM

12 AM

1 AM

2 AM

3 AM

4 AM

5 AM

6 AM

7 AM

8 AM

9 AM

10 AM

11 AM

12 PM

1 PM

2 PM

3 PM

4 PM

5 PM

Last 24hr

S6

W4

Calm

Calm

Calm

Calm

S3

Calm

Calm

4

Calm

Calm

W3

NE4

3

Calm

3

4

3

Calm

3

E3

NE3

NE4

1 day ago

S5

S4

SW4

SE4

SE6

S6

SE3

SE3

S3

SE4

SE6

SE5

S4

Calm

S4

Calm

SE3

SW3

SE7

S8

SW6

S6

S5

S5

2 days ago

S3

SW5

S5

S6

S5

5

S7

SE7

SE7

SE8

SE9

SE7

SE6

S8

S9

SE9

S9

S10

S8

S8

S8

S9

S7

4

---

Tide / Current Tables for Duwamish Waterway, Washington

   EDIT   Weekend mode (on/off)   (on/off)   Help   One Week of Data

---

Tide / Current Tables for Restoration Point, 0.6 miles ESE of, Washington Current

   EDIT      (on/off)   Help   One Week of Data

---

Weather Map

       (on/off)   Help Weather Map

---

GEOS Local Image of PacificNorthwest    EDIT
NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
Link to Loop

Other links: GEOS-West     Contential US     Full GOES-East

---

Ground Weather Radar Station

---

Please read website Cookie, Privacy, and Disclamers by clicking HERE.

---