July 6, 2000
Weather Synopsis...
A stationary front was located well offshore. A coastal wave of low pressure was developing over the NC Outer Banks. This low produced a light NE flow across coastal NJ during the morning hours. This onshore wind prior to seabreeze formation allowed it to move quite far inland during the afternoon and early evening hours.
Seabreeze Analysis...
The seabreeze formed around 1730Z along the NJ coast from Cape May up through Toms River. Additionally a Delaware Baybreeze formed about the same time. It can be seen in the below base reflectivity images by the dark red line extending from Cape May west through Cumberland County. By the last image at 2000Z, the seabreeze had moved all the way to the western borders of Atlantic and Ocean Counties.
The two base reflectivity loops below show the seabreeze's movement after 2000Z.
The image below is a VAD wind profile produced by the WSR-88 doppler radar in Fort Dix. It shows the vertical wind profile directly over the radar site as time goes on. The profiles give an indication as to the general vertical extent of the seabreeze circulation cell. Near the surface, the wind barbs denote a light northeast wind. At about 4000 feet in elevation, the wind barbs denote a light northwesterly wind, which is the highest extent of the seabreeze circulation.
Analysis of Surface Observations Along the NJ Shore
The graph below shows air temperatures during the day of June 6, 2000. Temperatures in all three locations fluctuate wildly until the early afternoon. This is due to the developing coastal low near Cape Hatteras, NC. By 1200 local time (1600Z), the seabreeze has formed and has passed by all three locations, as evidenced by the decline in temperatures after 1200 loacl time.
The wind direction at Avalon, Atlantic City, and LBI was for the most part onshore all day. It began as a north to northeast wind due to the influence of the low to the south. This onshore wind helped the seabreeze to become very well defined on the base reflectivity, move inland more rapidly, as well as helping the front to move farther inland. As the seabreeze passed by the wind direction remained out of an easterly direction until around midnight.
The graph below shows relative humidity at Atlantic City. With the onshore wind during the morning, relative humidities along the coast remained quite high. As the seabreeze moved onshore, the relative humidity dropped from 80% to 67%, and then the humidity slowly increased after the seabreeze front had pushed onshore.
SST Discussion...
The water temperature graph below gives the SST for the Atlantic City Marina. It shows a nearly two degree temperature drop from 0300Z to 1200Z, followed by a rapid increase in SST. The decrease in temperature early in the day is due to a SW wind producing minor upwelling along the coast. The radip increase in temperature is from the northeast wind across the coastal water in the wake of the seabreeze.
The below SST image shows some minor to perhaps moderate upwelling occuring from LBI south along the NJ coast.
CODAR Information...
The four images below are of the ocean currents detected by CODAR at 9, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, and 0Z on July 7. They show the subtle changes that occurred throughout the afternoon as the seabreeze circulation organized. The seabreeze was not recognized onshore until around 1730Z. Through the use of CODAR, however, there was an indication that a seabreeze was forming as early as 15 or 16Z. The full effect of the onshore wind on the currents is not completely seen until 22 or 23Z.
