A coastal flood watch is issued by the National Weather Service of the United States when coastal flooding along the coast of the Atlantic Ocean, Pacific Ocean, or the Gulf of Mexico is possible. The flooding must be due to water being forced from the nearby body of water onto land, and not from rainfall. Nor'easters, hurricanes, tropical storms, and thunderstorms can all lead to the issuance of a coastal flood watch.[1]
The following is an example of a coastal flood watch issued by the National Weather Service office in Norton, Massachusetts.[2]
462
WHUS41 KBOX 130725
CFWBOX
URGENT - IMMEDIATE BROADCAST REQUESTED
Coastal Hazard Message
National Weather Service Boston/Norton MA
325 AM EDT Mon Mar 13 2023
MAZ007-015-016-019-022-132030-
/O.NEW.KBOX.CF.A.0001.230315T0700Z-230315T1200Z/
Eastern Essex MA-Suffolk MA-Eastern Norfolk MA-
Eastern Plymouth MA-Barnstable MA-
325 AM EDT Mon Mar 13 2023
...COASTAL FLOOD WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH
WEDNESDAY MORNING...
* WHAT...Up to one foot of inundation above ground level
possible in low-lying areas near shorelines and tidal
waterways (2.1 to 12.9 feet Mean Lower Low Water).
* WHERE...Eastern Massachusetts coast from the Merrimack River
to Cape Cod.
* WHEN...From late Tuesday night through Wednesday morning.
* IMPACTS...Flooding is up to one foot deep and affects more
vulnerable shore roads, including Morrissey Boulevard in Boston.
* ADDITIONAL DETAILS...Large waves may produce pockets of moderate
flooding along the ocean shoreline in places such as Gloucester,
Revere, Hull, and Scituate. Flooding could be 1 to 2 feet deep in
some locations and debris could wash onto coastal roadways.
Significant beach erosion is also possible.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.
&&
&&
Time of high total tides are approximate to the nearest hour.
Gloucester Harbor
MLLW Categories - Minor 11.5 ft, Moderate 13.0 ft, Major 15.0 ft
MHHW Categories - Minor 2.0 ft, Moderate 3.5 ft, Major 5.5 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 10.2/10.7 0.7/ 1.1 0.8/ 1.3 6 None
13/04 PM 8.9/ 9.4 -0.7/-0.2 0.6/ 1.1 5-6 None
14/05 AM 10.4/10.9 0.9/ 1.4 1.1/ 1.6 6-8 None
14/05 PM 10.0/10.5 0.5/ 1.0 2.0/ 2.5 13-17 None
15/06 AM 10.7/11.2 1.2/ 1.7 1.5/ 2.0 12-15 Minor
15/06 PM 8.9/ 9.4 -0.7/-0.2 1.0/ 1.5 8-10 None
Merrimack River near Newburyport MA
MLLW Categories - Minor 11.0 ft, Moderate 12.0 ft, Major 13.5 ft
MHHW Categories - Minor 1.5 ft, Moderate 2.5 ft, Major 4.0 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 9.2/ 9.7 -0.3/ 0.2 0.8/ 1.3 5 None
13/05 PM 8.1/ 8.6 -1.5/-1.0 0.7/ 1.1 5 None
14/05 AM 9.5/10.0 0.0/ 0.5 1.1/ 1.6 4-5 None
14/05 PM 9.0/ 9.5 -0.6/-0.1 2.1/ 2.6 8-10 None
15/06 AM 10.0/10.5 0.5/ 1.0 1.6/ 2.0 9-10 Minor
15/07 PM 7.8/ 8.4 -1.7/-1.2 0.9/ 1.4 5-7 None
Boston Harbor
MLLW Categories - Minor 12.5 ft, Moderate 14.0 ft, Major 15.0 ft
MHHW Categories - Minor 2.4 ft, Moderate 3.9 ft, Major 4.9 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 10.6/11.1 0.5/ 1.0 0.8/ 1.3 1 None
13/04 PM 9.4/ 9.9 -0.8/-0.2 0.7/ 1.1 2 None
14/05 AM 11.0/11.5 0.9/ 1.4 1.3/ 1.8 2 None
14/05 PM 10.4/10.9 0.2/ 0.8 2.0/ 2.5 2 None
15/06 AM 12.3/12.8 2.2/ 2.7 2.6/ 3.1 2 Minor
15/06 PM 9.3/ 9.8 -0.9/-0.4 1.1/ 1.6 2 None
Revere
MLLW Categories - Minor 12.5 ft, Moderate 14.5 ft, Major 16.0 ft
MHHW Categories - Minor 2.6 ft, Moderate 4.6 ft, Major 6.1 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 10.6/11.1 0.7/ 1.1 0.8/ 1.3 1 None
13/04 PM 9.3/ 9.8 -0.7/-0.2 0.7/ 1.1 1-2 None
14/04 AM 10.8/11.3 0.9/ 1.4 1.2/ 1.7 2 None
14/05 PM 10.2/10.7 0.2/ 0.8 1.9/ 2.3 2 None
15/05 AM 12.1/12.6 2.2/ 2.7 2.6/ 3.1 2 Minor-Mdt
15/06 PM 9.1/ 9.6 -0.9/-0.4 1.1/ 1.6 2 None
Scituate MA
MLLW Categories - Minor 11.5 ft, Moderate 13.5 ft, Major 15.5 ft
MHHW Categories - Minor 1.8 ft, Moderate 3.8 ft, Major 5.8 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 10.2/10.7 0.5/ 1.0 0.8/ 1.3 5 None
13/04 PM 9.0/ 9.5 -0.8/-0.2 0.7/ 1.1 5 None
14/05 AM 10.6/11.1 0.9/ 1.4 1.2/ 1.7 5-7 None
14/05 PM 10.1/10.6 0.4/ 0.9 2.0/ 2.5 11-14 None
15/06 AM 12.0/12.5 2.2/ 2.7 2.6/ 3.1 11-13 Minor-Mdt
15/06 PM 9.1/ 9.6 -0.7/-0.2 1.2/ 1.7 7-8 None
Buzzards Bay at Woods Hole
MLLW Categories - Minor 5.5 ft, Moderate 7.0 ft, Major 8.5 ft
MHHW Categories - Minor 3.5 ft, Moderate 5.0 ft, Major 6.5 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/01 PM 2.5/ 3.0 0.5/ 1.0 0.7/ 1.1 2-3 None
14/01 AM 3.4/ 3.9 1.4/ 1.9 1.3/ 1.8 4 None
14/01 PM 2.7/ 3.2 0.8/ 1.3 1.3/ 1.8 4 None
15/02 AM 1.9/ 2.3 -0.2/ 0.3 -0.2/ 0.2 6-7 None
15/03 PM 2.3/ 2.8 0.4/ 0.9 0.7/ 1.1 5 None
Chatham MA - East Coast
MLLW Categories - Minor 9.0 ft, Moderate 11.5 ft, Major 13.0 ft
MHHW Categories - Minor 1.3 ft, Moderate 3.8 ft, Major 5.3 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 5.9/ 6.4 -1.9/-1.4 0.8/ 1.3 5-6 None
13/05 PM 4.7/ 5.2 -3.0/-2.5 0.7/ 1.1 5-6 None
14/05 AM 6.2/ 6.7 -1.6/-1.1 1.1/ 1.6 7-9 None
14/06 PM 5.0/ 5.5 -2.7/-2.2 1.0/ 1.5 13-14 None
15/06 AM 6.4/ 6.9 -1.4/-0.9 1.3/ 1.8 12 None
15/07 PM 5.1/ 5.6 -2.7/-2.2 1.2/ 1.7 9-10 None
Chatham - South side
MLLW Categories - Minor 9.0 ft, Moderate 10.5 ft, Major 11.5 ft
MHHW Categories - Minor 4.5 ft, Moderate 6.0 ft, Major 7.0 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 4.7/ 5.2 0.2/ 0.8 0.8/ 1.3 4-5 None
13/05 PM 4.0/ 4.5 -0.6/-0.1 0.8/ 1.3 4-5 None
14/06 AM 5.2/ 5.7 0.8/ 1.3 1.2/ 1.7 6-8 None
14/06 PM 4.2/ 4.7 -0.3/ 0.2 1.1/ 1.6 10-13 None
15/06 AM 5.2/ 5.7 0.8/ 1.3 1.1/ 1.6 10-11 None
15/07 PM 4.2/ 4.7 -0.3/ 0.2 1.1/ 1.6 7-9 None
Provincetown Harbor
MLLW Categories - Minor 13.0 ft, Moderate 14.0 ft, Major 15.0 ft
MHHW Categories - Minor 2.9 ft, Moderate 3.9 ft, Major 4.9 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 10.7/11.2 0.6/ 1.1 0.8/ 1.3 4 None
13/04 PM 9.4/ 9.9 -0.8/-0.2 0.6/ 1.1 4 None
14/05 AM 10.8/11.3 0.7/ 1.1 0.9/ 1.4 6-8 None
14/05 PM 10.8/11.3 0.7/ 1.1 2.2/ 2.7 12-19 None
15/06 AM 12.5/13.0 2.3/ 2.8 2.6/ 3.1 13-15 None
15/06 PM 9.6/10.1 -0.6/-0.1 1.3/ 1.8 9-11 None
Dennis - Sesuit Harbor
MLLW Categories - Minor 13.0 ft, Moderate 14.5 ft, Major 16.0 ft
MHHW Categories - Minor 2.5 ft, Moderate 4.0 ft, Major 5.5 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 11.1/11.6 0.6/ 1.1 0.9/ 1.4 3 None
13/04 PM 9.6/10.1 -1.0/-0.5 0.6/ 1.1 3-4 None
14/05 AM 11.0/11.5 0.5/ 1.0 0.9/ 1.4 4-6 None
14/05 PM 11.2/11.7 0.7/ 1.1 2.3/ 2.8 7-10 None
15/06 AM 12.7/13.2 2.2/ 2.7 2.6/ 3.1 8-9 Minor-Mdt
15/06 PM 10.1/10.6 -0.5/ 0.0 1.5/ 2.0 6-7 None
Sandwich Harbor
MLLW Categories - Minor 12.0 ft, Moderate 14.0 ft, Major 15.0 ft
MHHW Categories - Minor 1.7 ft, Moderate 3.7 ft, Major 4.7 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/04 AM 9.5/10.0 -0.9/-0.4 0.8/ 1.3 4 None
13/04 PM 8.3/ 8.8 -2.0/-1.6 0.7/ 1.1 3-4 None
14/05 AM 9.8/10.3 -0.6/-0.1 1.2/ 1.7 3-5 None
14/05 PM 9.5/10.0 -0.9/-0.4 2.1/ 2.6 6-10 None
15/06 AM 11.2/11.7 0.9/ 1.4 2.6/ 3.1 8-9 Minor
15/06 PM 8.7/ 9.2 -1.7/-1.2 1.4/ 1.9 6-7 None
Wings Neck
MLLW Categories - Minor 6.5 ft, Moderate 9.0 ft, Major 11.5 ft
MHHW Categories - Minor 2.1 ft, Moderate 4.6 ft, Major 7.1 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
13/01 PM 4.0/ 4.5 -0.5/ 0.0 0.8/ 1.3 3 None
14/02 AM 5.0/ 5.5 0.6/ 1.1 1.2/ 1.7 3 None
14/01 PM 4.2/ 4.7 -0.2/ 0.2 1.4/ 1.9 3 None
15/02 AM 4.0/ 4.5 -0.3/ 0.2 0.2/ 0.8 4 None
15/03 PM 3.7/ 4.2 -0.7/-0.2 0.7/ 1.1 5 None
&&
$$