Dry Heat Dominates Jersey Weather Pattern On Thursday And Friday
The heat wave continued across the Garden State on Friday. For some like residents in Newark, it was the ninth consecutive day of 90 plus degree weather. For others such as those in Northwestern Middlesex County, it was the third straight day of 90 plus degree heat in the third heatwave of the young summer. Feeling more like the Desert Southwest though, these past couple days have been noticeably different than most of the other hot days in the Summer of 2012.
On both Thursday and Friday, temperatures were hot. Mid-afternoon highs were in the mid 90s, but the air was quite arid. At peak temperature on Thursday, the humidity ranged from 37 to 41 percent. The dew point in South Plainfield peaked at 64.8 degrees and the heat index was 99. On Friday, it was even drier in Northwestern Middlesex County. While the mercury soared to 95 degrees, the humidity dropped to 24 percent for a dew point of 53 degrees and a heat index not much higher than the actual temperature.
Skies were uncharacteristically blue with very little in the way of haze or cloud cover. Only some sporadic fair weather high cirrus clouds were present. In addition, there was a light breeze out of the North and Northwest to make conditions somewhat comfortable despite the heat. What is the cause for this? The clockwise circulation around the dome of high pressure that has built up in the middle of the United States this week.
The circulation pattern around the high has brought warm, moist air from the Gulf of Mexico far north into places such as North Dakota and Minnesota where temperatures climbed into the upper 90s and heat index values approached 115 degrees on the Fourth of July. Those areas of the Upper Midwest were under the influence of the southerly flow from the high. Meanwhile, back east here in New Jersey, the clockwise flow around the massive high brought a more northwesterly flow following a cold front that passed through late Wednesday into early Thursday.
Consequently, the weather has been less humid and more comfortable even though temperatures are still very hot. Conditions are changing as I write this though. High pressure is migrating eastward and moderating. Winds are beginning to shift to the southwest and west. In the past hour and a half, the temperature has dropped somewhat, but humidity levels and dew points are on the rise. The peak of the heat wave is coming.
On Saturday, the National Weather Service office in Mount Holly has issued an excessive heat warning for much of the Garden State. Only Sussex and Passaic Counties have heat advisories. The warning indicates that temperatures will be over 100 with heat index values between 102 and 108 degrees anywhere in the warned area.
The torrid spell should begin to break on Saturday night with the passage of a cold front. The forecast is calling for showers and thunderstorms to develop in the evening around 7:00 PM. Some could be strong to severe with possible hail and high winds. After the front goes through, temperatures should begin to cool down to the lower 90s on Sunday, and upper 80s at the beginning of next week.