Alert archive / Washington / Special Marine Warnings in 2021
Special Marine Warning 21, NWS Seattle, WA
NWS Seattle, WA issued this special marine warning at Oct 25, 2021, 8:29 AM PDT. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Oct 25, 2021, 8:29 AM PDT (15:29 UTC)
- Expired
- Oct 25, 2021, 9:00 AM PDT
- In force
- 31 min
- Issued by
- NWS Seattle, WA
- Area
- Storm-based polygon
- Hail
- 0.0 in
- Wind
- 34.0 mph
The radar
The Langley Hill radar (KLGX), 35 km from the middle of the area, began a volume at 15:31 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Quillayute State, WA (KUIL), launched 12:00Z, 3.5 hours before the alert went out and 64 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 224 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 480 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 355 m²/s²
- 0-3 km storm-relative helicity
- 347 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 2.2
The text
As transmitted.
557
WHUS56 KSEW 251529
SMWSEW
PZZ153-156-251600-
/O.NEW.KSEW.MA.W.0021.211025T1529Z-211025T1600Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Seattle WA
829 AM PDT Mon Oct 25 2021
The National Weather Service in Seattle has issued a
* Special Marine Warning for...
Coastal Waters From James Island To Point Grenville Out 10 Nm...
Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm...
* Until 900 AM PDT
* At 828 AM PDT, a severe thunderstorm capable of producing
waterspouts was located near Point Grenville, moving north at 40
knots.
HAZARD...Waterspouts and wind gusts 34 knots or greater.
SOURCE...Radar.
IMPACT...Waterspouts can easily overturn boats and create
locally hazardous seas. Small craft could be damaged
in briefly higher winds and suddenly higher waves.
* The severe thunderstorm will remain over mainly open waters.
LAT...LON 4722 12452 4757 12446 4758 12436 4750 12434
4740 12434 4739 12432 4736 12432 4735 12430
4734 12430 4721 12437
TIME...MOT...LOC 1528Z 194DEG 39KT 4731 12440
WATERSPOUT...POSSIBLE
HAIL...0.00IN
WIND...>34KTS
$$
MK2 follow-up statements
159
FZUS76 KSEW 251547
MWSSEW
Marine Weather Statement
National Weather Service Seattle WA
847 AM PDT Mon Oct 25 2021
PZZ156-251556-
/O.CAN.KSEW.MA.W.0021.000000T0000Z-211025T1600Z/
847 AM PDT Mon Oct 25 2021
...THE SPECIAL MARINE WARNING IS CANCELLED...
The affected areas were...
Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm...
The thunderstorm has moved out of the warned area and no longer
poses a significant threat to boaters.
LAT...LON 4739 12446 4757 12446 4758 12436 4750 12434
4740 12434 4739 12432 4736 12432 4735 12430
4734 12430 4735 12435
TIME...MOT...LOC 1546Z 194DEG 39KT 4751 12433
$$
PZZ153-251600-
/O.CON.KSEW.MA.W.0021.000000T0000Z-211025T1600Z/
847 AM PDT Mon Oct 25 2021
...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 900 AM PDT...
For the following areas...
Coastal Waters From James Island To Point Grenville Out 10 Nm...
At 846 AM PDT, a severe thunderstorm capable of producing waterspouts
was located 12 nm north of Point Grenville, moving north at 40 knots.
HAZARD...Waterspouts and wind gusts 34 knots or greater.
SOURCE...Radar indicated.
IMPACT...Waterspouts can easily overturn boats and create locally
hazardous seas. Small craft could be damaged in briefly
higher winds and suddenly higher waves.
The severe thunderstorm will remain over mainly open waters.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Thunderstorms can produce sudden waterspouts. Waterspouts can easily
overturn boats and create locally hazardous seas. Seek safe harbor
immediately.
&&
LAT...LON 4739 12446 4757 12446 4758 12436 4750 12434
4740 12434 4739 12432 4736 12432 4735 12430
4734 12430 4735 12435
TIME...MOT...LOC 1546Z 194DEG 39KT 4751 12433
WATERSPOUT...POSSIBLE
HAIL...0.00IN
WIND...>34KTS
$$
MK610
FZUS76 KSEW 251556
MWSSEW
Marine Weather Statement
National Weather Service Seattle WA
856 AM PDT Mon Oct 25 2021
PZZ153-251606-
/O.EXP.KSEW.MA.W.0021.000000T0000Z-211025T1600Z/
856 AM PDT Mon Oct 25 2021
...THE SPECIAL MARINE WARNING WILL EXPIRE AT 900 AM PDT...
The affected areas were...
Coastal Waters From James Island To Point Grenville Out 10 Nm...
The thunderstorm has weakened and no longer poses a significant
threat to boaters.
LAT...LON 4739 12446 4757 12446 4758 12436 4750 12434
4740 12434 4739 12432 4736 12432 4735 12430
4734 12430 4735 12435
TIME...MOT...LOC 1556Z 194DEG 39KT 4761 12429
$$
MKThe office that day
Everything else NWS Seattle, WA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 24, 7:22 PM PDT | Special Marine Warning | SEW | 23 min | |
| Oct 24, 7:39 PM PDT | Special Marine Warning | SEW | 36 min | |
| Oct 24, 8:02 PM PDT | Special Marine Warning | SEW | 28 min | |
| Oct 24, 8:13 PM PDT | Special Marine Warning | SEW | 32 min | |
| Oct 25, 3:08 AM PDT | Coastal Flood Advisory | SEW | San Juan | 10 hr |
| Oct 25, 3:58 AM PDT | River Flood Warning | SEW | Mason | 5 days |
Nearby
Special Marine Warnings in Washington, 2021Every special marine warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.