July 9, 2000
Weather Synopsis...
A frontal system and associated low pressure area was located over the Central Plains. A 1023mb high pressure area was located off of the coast of the Carolinas. The synoptic wind flow for this day was from the SSW.
Seabreeze Analysis...
Analysis of Observations...
The air temperature at Tuckerton shows very little, if any evidence of a sea breeze fronal passage. If anything, it appears that after a slow start the temp increased greatly throughout the afternoon hours.
Contrary to the temperature graph, the graph of relative humidity shows a distinct drop in realtive humidity, followed by a increase in the early afternoon hours.
The wind direction graph below shows that throughout the morning, the wind was coming from the west and southwest, and then in the early to late afternoon it became a south wind. While this is not onshore, for the Central NJ shore, it is for the Southern NJ shore, where the effects of this sea breeze were mainly located.
The wind speed data below shows that following the sea breeze frontal passage, wind speeds increased dramatically, reaching approximately 25 mph by late afternoon.
Mesoscale Model Analysis...
All three mesoscale models show a weak onshore wind developing along the coast around 18z.
-RAMS
The RAMS 20Z forecast shows areas of lower pressure over interior Southern NJ and higher pressures offshore, with winds from the SSW to due S. There is a bit of a temperature gradient along the shore, from 28 C onshore to 25 C just offshore. The relative humidity image shows the most evidence of the sea breeze. There is a distinct gradient in the relative humidity field right along the shore. Humidities of 85% right along the immediate shore, and humidities between 70 and 75% just 10 miles away from the coastline
-COAMPS
Below are the COAMPS forecasts of air temperature along the NJ coast. The image on the left is from 12Z and the image on the right is for 18Z. The 18Z image shows a weak temperature gradient along the coast, with the most marine cooled air making it into southern Cape May County.
Below are the 12Z and 18Z pressure and wind forecasts. The 12Z image shows light WSW to SW winds across coastal sections of NJ. The 18Z forecast shows that winds had shifted to SSW to due South right along the shore.
The relative humidity forecast for 18Z is pictured below. There is a substantial gradient in relative humidity right along the shore, especially prevailent along the coast in Cape May, Atlantic, and southern Ocean Counties.
-MM5
The 12 km resolution MM5 forecast for 21Z is shown below. It shows a south wind of strength 10-15 knots right along the immediate NJ shore, and light SW winds across interior Southern NJ. There is also a bit of a temperature gradient along coastal sections, with the 18 C isotherm located just offshore, and the 20 C isotherm located about 15 miles inland.
SST Discussion...
The SST image for 1314Z is shown below. There is a small pool of cooler water located just off the Southern NJ coast from LBI to Cape May.
CODAR Information...
The detided CODAR plots for 16Z and 19Z are shown below. The nearshore currents at 16Z were entirely offshore. By 19Z the current had switched to a NNE bound direction, which along the southern coast of NJ is slightly onshore. This current shift shows some evidence of a wind shift from an offshore wind to a slightly onshore wind component.
