Notices
General Caution: For the most part, tide
PORTS: NOS, in partnership with other
predictions for U.S. reference stations are
agencies and institutions, has established a se-
based upon analysis of tide observations for
ries of Physical Oceanographic Real Time Sys-
periods of at least one year. Since the extremes
tems (PORTS) in selected areas. These PORTS
of meteorological conditions have been ex-
sites provide constantly updated information
cluded from the analysis and predictions, the
on tide and tidal current conditions, water
predicted tidal heights should be considered
temperature, and weather conditions. This
as those expected under average weather
information is updated every six minutes. The
conditions. During times when weather con-
PORTS sites currently in operation on the
ditions differ from what is considered average
East Coast include: Tampa Bay, FL; New York/
for the area, the mariner must take note of the
New Jersey; Houston Ship Channel/Galveston
corresponding differences between predicted
Bay, TX; Chesapeake Bay; Narragansett Bay,
levels and those actually observed. Generally,
RI; Delaware Rive and Bay; and New Haven,
prolonged onshore winds or a low barometric
CT. The information is accessible online or by
pressure can produce higher levels than pre-
a voice response system.
dicted, while the opposite can result in lower
levels than those predicted.
http://www.co-ops.nos.noaa.gov
Exclusive of weather conditions, the astro-
nomical tide is subject to range variations that
East Coast PORTS Sites:
should be noted. Decreased ranges may be
NARRAGANSETT BAY expected near the times when the moon is in
Phone: 1-866-757-6787 (1-866-75-PORTS) apogee (apogean tides) or in quadrature (neap
NEW HAVEN tides); and increased ranges may be expected
(No phone service at press time.) when the moon is in perigee (perigean tides) T
ides
NEW YORK/NEW JERSEY or in a new or full position (spring tides). A
Phone: 1-866-217-6787 (1-866-21-PORTS) larger diurnal range may also result when the
DELAWARE BAY moon is in its maximum declination (tropic
1-866-307-6787 (1-866-30-PORTS) tides). The actual range will depend upon the
CHESAPEAKE BAY LIGHT extent to which combinations of these posi-
Phone: 1-866-247-6787 (1-866-CHPORTS) tions reinforce or detract one from the other.
o
n
s
TAMPA BAY The effect of these astronomical lineups is
a
ti
Phone: 1-866-827-6787 (1-866-TBPORTS) included in the predictions and may be appar-
HOUSTON/GALVESTON ent upon inspection.
Phone: 1-866-447-6787 (1-866-HGPORTS) Mariners may be kept aware of the times of
a
l
c
ul
these astronomical events by referring to the
Saint John, NB, Reversing Falls: To predict astronomical data listed in this book. They
slack water at the reversing falls, apply the fol- should realize, however, that there is generally
e
i
g
h
t C
lowing corrections to the Saint John tide table a time lag from a few hours to several days
on page T 20. For the slack at the end of the from the time of the astronomical event to
inward run, add 2h 30m to Saint John high the time of the resultant tide. During times of
water. For the slack at the end of the outward storm surges or when extreme weather condi-
T
i
d
e H
run, add 3h 50m to Saint John low water. tions are imminent, mariners should closely
CHINCOTEAGUE CHANNEL, VA: follow local weather forecasts as they relate to
United States Coast Guard (USCG) Personnel the effects upon the tide levels.
at the Chincoteague Coast Guard Station, VA,
report that the times of high and low water
computed from differences in Table 2 of the
East Coast Tide Tables are frequently off by
as much as an hour. The channel is subject to
shoaling and is frequently dredged. Exercise
caution in using Table 2 tide differences for
this area (Issued May 17, 1991).
353