Sea Breeze - from a pilot's perspective

Unless you live or fly within 50 miles or so from the ocean, you may never experience a sea breeze.

A good plain language explanation of a sea breeze, and how it develops, can be found at
http://en.wikipedia.org/wiki/Sea_breeze

A sea breeze can for if there is a large difference between the ocean temperatures and the ambient temperature inland, along with inland winds not strong enough and in a direction to counter the ocean breeze.  The strength (speed) of this breeze is dependent on a few factors:
  • Difference between a higher ambient inland and colder ocean water temperatures - a lager gap can increase its strength
  • How does the direction of the inland wind compare to the base sea breeze direction.
    • Is the wind in a complementary direction - flowing somewhat in the same direction (90 degrees on either side) from that which a sea breeze originates?  Inland breezes with little difference to the sea breeze direction could be susceptible to a stronger sea breeze.
    • Example:  If the sea breeze starts from 160, then inland winds 90 degrees or less on either side (250-050) would be complementary.  An inland breeze from 160 would be a major complement.
  • Inland wind speed
    • Light winds, even from an uncomplementary direction can have little impact on the speed and direction of the sea breeze.
    • Moderate winds from a complementary direction can increase during a sea breeze.
    • Moderate winds from an uncomplementary direction can slow the advance and strength of a sea breeze.
Why should you, as a pilot, be concerned if a sea breeze forms?
  • It could alter the direction and speed of the winds from the surface up to 1500 feet or more
    • Note: an unadulterated sea breeze can range from 6-10kts with some over 20kts
  • If you are closer to the ocean (0-5 miles), the sea breeze may completely prevail over the land winds.
  • You need to be aware of landing areas in the new direction and speed.
  • You may want to cancel or delay a flight if a sea breeze could negatively affect a safe and enjoyable experience.
  • in some cases, a sea breeze could make a normally non-flyable situation flyable (i.e.: slowing the inland wind, etc.).
Here are three hypothetical cases showing how a sea breeze can infuence your decision to fly or not.

Let us start with a couple of constants for these cases:
  • The unadulterated sea breeze direction is from 160.
  • There is a 30F gap between the ocean water and inland temperatures (large gap)
  • The launch site is 20 miles from the ocean.
Case 1 - Inland winds are from 270 at 2kts (light winds from an uncomplementary direction)
Result 1 - A sea breeze could easily form with a wind speed of 12kts, moving 20-50 miles inland, overriding the inland winds with an almost unchanged sea breeze direction and speed.

Case 2 - Inland winds are from 270 at 12kts (strong winds from an uncomplementary direction)
Result 2 - While a sea breeze could form, its impact on the inland winds would be to slow and moderately shift their direction.  The resultant winds could become 220 at 4kts.  The inland distance of travel for the sea breezed might only be 10-30 miles before dissipating.

Case 3 - Inland winds are from 140 at 7kts (moderate winds from a complementary direction)
Result 3 - A sea breeze could form, and the resultant winds inland could become 150 at 12kts, again moving inland 20-50 miles.

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How can you tell if a sea breeze will form or has formed?
The weather service is getting better at predicting whether there is a chance of a sea breeze forming.  Additionally there are tools available on the internet that let you see, if in fact a sea breeze is starting, and track its progress.
  • One of these is Intellicast Base Reflectivity view which updates approx. every 10-15 minutes.  CAUTION: always look at the date and time stamp (given as GMT) on the screen images to ensure they are relatively current.
Below, is an explanation and images of an actual sea breeze captured over a 4-5 hour time period, along the New Jersey coastline using the Intellicast tool.

First a marked up image showing what to look for:

Generally, a sea breeze coming inland to Central New Jersey, as shown here, will flow from the southeast.  This can alter the direction and speed of the pre-existing ambient winds.

On this day, all the elements necessary for a strong sea breeze were present:
  • High ambient temperature
  • Cold ocean temperature
  • Winds inland being out of the sought at around 5mph
The following animated images show the movement of the sea breeze from formation to breakdown.

Note: as the afternoon wore on, a storm system moved in, causing the ambient winds to become stronger and originate from the west.  This was enough to halt and neutralize the sea breeze before it marched 50 miles inland.

Click on any of the pictures below for an action view, in a new window

Watch the ragged line showing a sea breeze starting to form along the central to southern coast of New Jersey.


This image shows the sea breeze line taking shape and moving inland away from the coast.


Now the sea breeze is very visible and moving further away from the coast.


Weather system moving in changed direction of the inland wind from the south to coming from the west, with increased wind speed.  This resulted in a stopped and neutralized sea breeze.