Sea Breezes: Thunderstorm Makers or Destroyers?
I believe the answer has to do with the temperature
of the water in Florida versus Long Island, and with the amount of moisture in
the air and the stability of the atmosphere over Florida during the summer.
Consider this: as the sea breeze develops during the morning in Florida, the
temperature of the water, either in the Gulf of Mexico or the Atlantic Ocean,
is generally in the upper 70s or 80s. The land heats up quickly and the air
temperatures over the land may rise into the low or even middle 90s. So, there
is maybe a 10-degree difference in the temperature of the air behind and ahead
of the sea breeze. That may not seem like a whole lot of difference, but there
is enough of a density difference between the two air masses to create a
boundary with a wind shift, and that is enough to initiate thunderstorms. In
addition, the dew point temperatures are generally in the low to perhaps middle
70s, and so that is plenty of fuel to aid thunderstorm development. Also, the
atmosphere up to 30,000 and 40,000 feet over Florida is almost always close to
unstable. Given the heating of the day, and the convergence of air masses
provided by the sea breeze, there is good reason for thunderstorms to develop. Now
consider the situation on Long Island, or along the New England coast. In May
or June the air over the land can heat up very quickly and it can certainly get
into the 80s and even the 90s at points that are well away from the shore. The
water temperature is probably in the 60s. That would appear to be plenty of
temperature difference to initiate a pretty strong sea breeze, and indeed it
does. There were many days in the spring and summer that I watched my
thermometer in Hewlett, N. Y., on the south shore of Long Island climb into the
80s by noon and then drop back into the low 70s during the afternoon. As that
sea breeze moves northward and westward, it does cause clouds to form, and if
the moisture content of the air is high enough, showers or thunderstorms can
form. I have seen that happen in July and August when dew points are in the 60s
to near 70, but earlier in the spring there usually just isn't enough moisture
in the air, and the overall weather pattern is just too stable to initiate
thunderstorm development. So, sea breezes in Florida can and do initiate
thunderstorms on a daily basis, but farther north on the coast the phenomena
becomes rarer. In addition, they can quickly weaken and become very
unimpressive when very impressive squall lines from the west hit the cool sea
breezes in the spring and early summer in the Northeast. As a weather weenie
growing up on the south shore of Long Island, I watched many a squall fade, and
don't get me started about how the warm ocean water in the winter frequently
turned a promising snowstorm into rain ... grrrrrrrr. The ocean is great to be
near, as evidenced by the millions of people moving to the shore every year ...
but to a weather weenie, it can be a cruel task master at times!!!!