Coastal flood warning

A coastal flood warning is an hazardous weather statement issued by the Weather Forecast Offices of the National Weather Service in the United States which indicates coastal flooding is either imminent or occurring along the coast of the Atlantic Ocean, Pacific Ocean, Arctic Ocean, or the Gulf of Mexico. The flooding must be due to water being forced from the nearby body of water onto the land, and not from rainfall. Nor'easters, hurricanes, tropical storms, and thunderstorms can all lead to the issuance of a coastal flood warning.^[1]

Coastal flood warning in Maryland

An example of a coastal flood warning in Calvert, MD, and St Mary’s, MD on 8 January 2024.

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The following is an example of a coastal flood warning issued by the National Weather Service office in Boston, Massachusetts.^[2]

  000 WHUS41 KBOX 071920 CFWBOX  URGENT - IMMEDIATE BROADCAST REQUESTED COASTAL HAZARD MESSAGE NATIONAL WEATHER SERVICE TAUNTON MA 220 PM EST THU FEB 7 2013  ...COASTAL FLOOD WARNING FOR THE MASSACHUSETTS EAST FACING COASTLINE AROUND THE TIME OF THE FRIDAY EVENING AND SATURDAY MORNING HIGH TIDES...  .A POWERFUL COASTAL STORM WILL PRODUCE MODERATE COASTAL FLOODING FRIDAY EVENING AND MODERATE TO MAJOR COASTAL FLOODING SATURDAY MORNING ALONG WITH POTENTIALLY SEVERE EROSION. LARGE WAVES COMBINED WITH A 2 TO 3 FOOT STORM SURGE MAY CAUSE A NUMBER OF VULNERABLE SHORE ROADS TO BECOME IMPASSABLE FOR A WHILE...AND MAY CAUSE DAMAGE TO HOMES ALONG THE IMMEDIATE SHORELINE DURING THE SATURDAY MORNING HIGH TIDE.  MAZ007-015-016-019-022>024-080330- /O.NEW.KBOX.CF.W.0001.130209T0100Z-130209T1700Z/ /O.EXT.KBOX.CF.A.0001.130209T1700Z-130209T1800Z/ EASTERN ESSEX MA-SUFFOLK MA-EASTERN NORFOLK MA- EASTERN PLYMOUTH MA-BARNSTABLE MA-DUKES MA-NANTUCKET MA- 220 PM EST THU FEB 7 2013  ...COASTAL FLOOD WARNING IN EFFECT FROM 8 PM FRIDAY TO NOON EST SATURDAY...  THE NATIONAL WEATHER SERVICE IN TAUNTON HAS ISSUED A COASTAL FLOOD WARNING...WHICH IS IN EFFECT FROM 8 PM FRIDAY TO NOON EST SATURDAY.  * LOCATION...EAST FACING COASTLINE OF MASSACHUSETTS  * COASTAL FLOODING...MODERATE COASTAL FLOODING IS LIKELY FOR THE   FRIDAY EVENING HIGH TIDE AND MODERATE TO MAJOR COASTAL FLOODING   IS LIKELY FOR THE SATURDAY MORNING HIGH TIDE...WITH THE MOST   SEVERE IMPACT EXPECTED ALONG EAST AND NORTH FACING SHORELINES   SOUTH OF BOSTON.  * TIMING...FRIDAY EVENING AND SATURDAY MORNING HIGH TIDES  * IMPACTS...A NUMBER OF SHORE ROADS WILL LIKELY BECOME IMPASSABLE   FOR A TIME FRIDAY EVENING. COASTAL FLOODING AROUND THE SATURDAY   MORNING HIGH TIDE WILL LIKELY CAUSE NUMEROUS SHORE ROADS TO   BECOME IMPASSABLE AND PUT SOME STRUCTURES AT RISK ALONG THE   IMMEDIATE SHORE...ESPECIALLY THOSE VULNERABLE LOCATIONS SOUTH OF   BOSTON FROM HULL TO SANDWICH. SEVERE BEACH EROSION WILL ALSO   OCCUR...ESPECIALLY DURING THE SATURDAY MORNING HIGH TIDE.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  A COASTAL FLOOD WARNING MEANS THAT MODERATE OR MAJOR COASTAL FLOODING IS LIKELY. MODERATE COASTAL FLOODING PRODUCES WIDESPREAD FLOODING OF VULNERABLE SHORE ROADS AND/OR BASEMENTS DUE TO THE HEIGHT OF STORM TIDE AND/OR WAVE ACTION. NUMEROUS ROAD CLOSURES ARE NEEDED. LIVES MAY BE AT RISK FOR PEOPLE WHO PUT THEMSELVES IN HARMS WAY. ISOLATED STRUCTURAL DAMAGE MAY BE OBSERVED.  MAJOR COASTAL FLOODING IS CONSIDERED SEVERE ENOUGH TO CAUSE AT LEAST SCATTERED STRUCTURAL DAMAGE ALONG WITH WIDESPREAD FLOODING OF VULNERABLE SHORE ROADS AND/OR BASEMENTS.  SOME VULNERABLE HOMES MAY BE SEVERELY DAMAGED OR DESTROYED. EVACUATION OF SOME NEIGHBORHOODS MAY BE NECESSARY.  &&  &&  ALL TIDE HEIGHTS ARE RELATIVE TO MEAN LOWER LOW WATER. TIME OF HIGH TOTAL TIDES ARE APPROXIMATE TO THE NEAREST HOUR.  NEWBURYPORT     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      8.3    07/09 PM     8.3      0.0       1        NONE      9.9    08/09 AM     9.7      0.2      2-3       NONE     11.1    08/10 PM     8.6      2.5      8-13     MINOR     12.1    09/10 AM     9.9      2.2       21     MDT-MAJOR      9.0    09/11 PM     9.0      0.0      8-10      NONE     10.0    10/11 AM    10.0      0.0       5        NONE  GLOUCESTER HARBOR     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.1    07/09 PM     9.1      0.0       1        NONE     11.0    08/09 AM    10.7      0.3      3-4       NONE     12.0    08/10 PM     9.5      2.5     12-18     MINOR     13.1    09/10 AM    10.9      2.2       21     MODERATE      9.8    09/11 PM     9.8      0.0       10       NONE     10.9    10/11 AM    10.9      0.0      6-7       NONE  REVERE     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.6    07/09 PM     9.6      0.0       1        NONE     11.4    08/09 AM    11.2      0.2      2-3       NONE     12.5    08/10 PM    10.0      2.5      8-12     MINOR     14.0    09/10 AM    11.5      2.5       13     MDT-MAJOR     10.3    09/11 PM    10.3      0.0      7-9       NONE     11.5    10/11 AM    11.5      0.0       5        NONE  BOSTON HARBOR     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.6    07/09 PM     9.6      0.0       1        NONE     11.4    08/09 AM    11.2      0.2       2        NONE     12.8    08/10 PM    10.0      2.8      3-4     MODERATE     14.0    09/10 AM    11.5      2.5       3      MODERATE     10.3    09/11 PM    10.3      0.0      2-3       NONE     11.5    10/11 AM    11.5      0.0       1        NONE  SCITUATE     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.4    07/09 PM     9.4      0.0       1        NONE     11.3    08/09 AM    11.0      0.3      3-4      MINOR     12.6    08/10 PM     9.8      2.8      8-17    MODERATE     14.2    09/10 AM    11.2      3.0       26      MAJOR     10.1    09/11 PM    10.1      0.0     10-13      NONE     11.3    10/11 AM    11.3      0.0      6-7      MINOR  SANDWICH HARBOR     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.0    07/09 PM     9.0      0.0      1-2       NONE     11.1    08/09 AM    10.5      0.6      2-3       NONE     12.5    08/10 PM     9.4      3.1      7-11    MODERATE     14.7    09/10 AM    10.7      4.0       20      MAJOR      9.7    09/11 PM     9.7      0.0      6-8       NONE     10.8    10/11 AM    10.8      0.0      3-4       NONE  PROVINCETOWN HARBOR     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      9.6    07/09 PM     9.6      0.0       1        NONE     11.4    08/09 AM    11.1      0.3      2-3       NONE     11.3    08/10 PM     9.9      1.4      7-12     MINOR     12.6    09/10 AM    11.3      1.3       15     MODERATE     10.2    09/11 PM    10.2      0.0      8-10      NONE     11.4    10/11 AM    11.4      0.0       5        NONE  CHATHAM - EAST COAST     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      4.2    07/09 PM     4.2      0.0      2-3       NONE      6.0    08/10 AM     5.3      0.7      4-6       NONE      7.4    08/10 PM     4.4      3.0     12-16      NONE      8.3    09/11 AM     5.3      3.0       32     MDT-MAJOR      4.6    09/11 PM     4.6      0.0     12-15      NONE  CHATHAM - SOUTH COAST     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      4.0    07/10 PM     4.0      0.0      1-2       NONE      5.6    08/10 AM     5.2      0.4      3-5       NONE      5.4    08/11 PM     4.2      1.2      8-9       NONE      5.7    09/11 AM     5.2      0.5       10       NONE      4.3    09/11 PM     4.3      0.0      6-7       NONE  BUZZARDS BAY - WOODS HOLE     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      2.1    07/06 PM     2.1      0.0       1        NONE      3.1    08/06 AM     2.9      0.2       2        NONE      2.9    08/06 PM     2.2      0.7      4-6       NONE      3.0    09/07 AM     2.9      0.1      7-8       NONE      2.4    10/07 PM     2.4      0.0      3-4       NONE      2.8    10/08 AM     2.8      0.0       2        NONE  VINEYARD HAVEN     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      2.2    07/09 PM     2.2      0.0       1        NONE      3.5    08/09 AM     3.0      0.5       3        NONE      5.1    08/10 PM     2.3      2.8      6-8      MINOR      3.2    09/10 AM     3.0      0.2       8        NONE      2.4    09/11 PM     2.4      0.0      3-4       NONE      2.9    10/11 AM     2.9      0.0      1-2       NONE  NANTUCKET HARBOR     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      3.2    07/10 PM     3.2      0.0       2        NONE      4.8    08/10 AM     4.2      0.6      3-5      MINOR      6.3    08/11 PM     3.3      3.0      8-10    MODERATE      6.1    09/11 AM     4.2      1.9       10     MODERATE      3.5    10/12 AM     3.4      0.1      5-6       NONE  NANTUCKET EAST COAST     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      3.3    07/09 PM     3.3      0.0      2-3       NONE      4.8    08/10 AM     4.4      0.4      4-6       NONE      6.4    08/10 PM     3.4      3.0     12-14    MODERATE      7.6    09/11 AM     4.4      3.2       29      MAJOR      3.6    09/11 PM     3.6      0.0     10-12      NONE  NANTUCKET SOUTH COAST     TOTAL                ASTRO     TIDE    DAY/TIME     TIDE    SURGE    WAVES      FLOOD     /FT/                 /FT/     /FT/     /FT/    CATEGORY   -------  ----------  -------  -------  -------  ----------      3.1    07/10 PM     3.1      0.0      2-3       NONE      4.6    08/10 AM     4.2      0.4      4-6       NONE      4.3    08/10 PM     3.2      1.1     12-14      NONE      4.6    09/11 AM     4.2      0.4       17       NONE      3.4    10/12 AM     3.4      0.0      7-8       NONE  $$  THOMPSON 

• Severe weather terminology (United States)

• National Weather Service