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]
462WHUS41 KBOX 130725CFWBOXURGENT - IMMEDIATE BROADCAST REQUESTEDCoastal Hazard MessageNational Weather Service Boston/Norton MA325 AM EDT Mon Mar 13 2023MAZ007-015-016-019-022-132030-/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 THROUGHWEDNESDAY 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 beclosed. Do not drive around barricades or through water ofunknown depth. Take the necessary actions to protect flood-proneproperty.&&&&Time of high total tides are approximate to the nearest hour.Gloucester HarborMLLW Categories - Minor 11.5 ft, Moderate 13.0 ft, Major 15.0 ftMHHW 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 NoneMerrimack River near Newburyport MAMLLW Categories - Minor 11.0 ft, Moderate 12.0 ft, Major 13.5 ftMHHW 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 NoneBoston HarborMLLW Categories - Minor 12.5 ft, Moderate 14.0 ft, Major 15.0 ftMHHW 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 NoneRevereMLLW Categories - Minor 12.5 ft, Moderate 14.5 ft, Major 16.0 ftMHHW 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 NoneScituate MAMLLW Categories - Minor 11.5 ft, Moderate 13.5 ft, Major 15.5 ftMHHW 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 NoneBuzzards Bay at Woods HoleMLLW Categories - Minor 5.5 ft, Moderate 7.0 ft, Major 8.5 ftMHHW 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 NoneChatham MA - East CoastMLLW Categories - Minor 9.0 ft, Moderate 11.5 ft, Major 13.0 ftMHHW 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 NoneChatham - South sideMLLW Categories - Minor 9.0 ft, Moderate 10.5 ft, Major 11.5 ftMHHW 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 NoneProvincetown HarborMLLW Categories - Minor 13.0 ft, Moderate 14.0 ft, Major 15.0 ftMHHW 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 NoneDennis - Sesuit HarborMLLW Categories - Minor 13.0 ft, Moderate 14.5 ft, Major 16.0 ftMHHW 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 NoneSandwich HarborMLLW Categories - Minor 12.0 ft, Moderate 14.0 ft, Major 15.0 ftMHHW 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 NoneWings NeckMLLW Categories - Minor 6.5 ft, Moderate 9.0 ft, Major 11.5 ftMHHW 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&&$$
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