June 23, 2012: After Storms, Dry Weekend

Forecast Highlights:


- Seasonable, dry weekend coming up
- Cold front results in rain, storms on Monday
- Cooler temperatures for first half of next week
- TROPICS: Tropical storm about to form in Gulf of Mexico


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Yesterday's Storm Overview:

During the day yesterday and into the evening, the NYC area observed its most widespread strong to severe weather outbreak of the year so far, ahead of a cold front that ended NYC's first official heat wave of the year. Following temperatures surging into the upper 80s to mid 90s in the morning hours with humid conditions, strong to severe thunderstorms rapidly developed over New York City around 1-2 PM, with the storms resulting in very heavy rain, strong winds which resulted in wind damage in parts of the city and western Long Island, and some hail. The first round of thunderstorms focused specifically on New York City, Nassau county, and parts of Suffolk county.

While the first round was ongoing, clearing in the cloud cover took place west of the city as scattered storms approached from Pennsylvania. As these storms ran into an outflow boundary drifting west through New Jersey, rapid storm development took place over interior northern NJ around 4-5 PM, resulting in a line of strong thunderstorms that moved through the rest of SE New York/NE New Jersey and into New York City. The strong thunderstorm event concluded after the line moved into NYC and fell below severe levels, although occasional rain lasted until close to midnight in some areas. Wind and tree damage was reported in parts of northern NJ, NYC and western Long Island, where the worst of the storm activity in the area took place. Storm activity was also notable to the south of the area, where storms frequently moved over parts of southern New Jersey from the afternoon through the overnight hours, resulting in rain locally over 3-4 inches.

Following the cold front, a high pressure will move through for the weekend, resulting in mostly sunny skies and seasonable temperatures, in the lower to mid 80s. By early next week, a cold front will move through with rain and some thunderstorms. Cooler temperatures are expected again for the first half of the week, although a gradual warming trend will take place leading up to next weekend.


Weekend Outlook:


With a weak high pressure moving in, mostly sunny skies are expected for this weekend along with seasonable temperatures. Highs will reach the lower to mid 80s inland, mid to upper 80s in the immediate NYC area, and the lower to mid 80s in Long Island/S CT.


Next Week: Rainy, Then Chilly


The heat wave observed late in the week was only an interruption in the pattern; as ridging returns into Greenland and parts of Canada, a trough will once again lock into the region, with a strong upper level low dropping into the region, resulting in another round of colder than average temperatures that resemble spring more than summer. Areas of rain and thunderstorms, heavy at times, will move through between Sunday night, after at least 1-2 AM, into Monday afternoon. The early timing of the cold front will limit severe thunderstorm potential, although some of the storms could be strong. Temperatures will then reach the mid to upper 70s for highs across most of the area on Monday.

A much cooler air mass will move in behind the front as the upper level low moves into the Northeast region. Temperatures on Monday night will be unusually chilly for this time of the year, dropping into the lower to mid 50s inland and the mid 50s to lower 60s across the rest of the area. Tuesday will be chilly compared to average as well, with partly cloudy skies and highs in the lower to mid 70s inland and the mid to upper 70s for the rest of the area.

Following the departure of the upper level low, a strong ridge accompanied by a very warm air mass will spread further east. While the strongest heat will stay to the south of the region, there will be a gradual moderation in temperatures throughout the rest of next week, with temperatures gradually rising into the 80s in the second half of next week with dry conditions likely. Stay tuned for more information on next week's outlook.


Tropics: 4th Named Storm About To Form


The Gulf of Mexico, mentioned in my June 12th update as being at risk for tropical cyclone development in the June 19-25 time frame, is seeing activity picking up with Invest 96L slowly moving through the central Gulf of Mexico. 96L is expected to soon develop into a tropical depression or storm; should it be named, which is the expectation, it will be named Debby, the 4th named storm of this year's hurricane season. This year's Atlantic hurricane season is already off to an unusual start, with Alberto forming unusually early, Beryl marking the first time in over a century that 2 named storms formed in May, and Chris becoming a hurricane at an unusually northern latitude considering the time of the year and the cool sea surface temperatures. The expected formation of a tropical storm will make this one of the earliest 4th named storms on record in the Atlantic Ocean. There is still some uncertainty with exactly where the invest, soon to be a tropical storm, will end up, although at this time it is likely to take a track further west, with the Gulf coast from western Florida to Texas at risk of a tropical storm or hurricane landfall.