May 18, 2011: Warm, Stormy Next Week

Due to the storm updates, the other pages were not updated tonight. The 5-Day Forecast page will be updated with tomorrow’s update.

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Short Term Outlook:

10 PM: Over the last hour, showers and thunderstorms began developing over the immediate NYC area and moving northwest, producing additional moderate to heavy rain showers. As this area of rain expands and bring a slightly longer duration moderate/heavy rainfall to Sussex county, more showers are developing southeast of NYC and moving towards the coast while intensifying, resulting in showers and thunderstorms persisting over the next several hours from NYC and further west.

East of NYC, heavy storms in Connecticut are currently weakening, with areas of light rain affecting Long Island and southern Connecticut. There is another area of heavy rain and thunderstorms offshore moving towards central/eastern Long Island and south central/SE Connecticut, though these storms appear to be slightly weakening at this time.

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The area has been stuck under mainly cloudy skies and occasional showers and thunderstorms since Sunday, though yesterday and today brought the most significant rainfall amounts as the cut off low stalled near North Carolina/Virginia, drawing in a lot of moisture into the region. Yesterday failed to produce much rain due to subsidence, though since last night, rain has been able to move into the area without completely dissipating just off the coast.

The heaviest rains are mostly over, though rain will continue through tonight and tomorrow, with scattered thunderstorms lasting through Friday and Saturday. Beyond Saturday, however, a warmer pattern will develop, with parts of the area reaching the lower to mid 80s early next week, the first time this has happened this month, along with a severe weather risk on Tuesday and/or Wednesday.

Late Week: Rain Continues

Thursday and Friday will finally bring warmer temperatures, reaching the upper 60s to mid 70s from NYC and further west, similar to where they were last week, but the rain and thunderstorm risk continues. The early afternoon hours of Thursday should be dry, and some clearing in the cloud cover is expected, but with the upper level low near the area along with decent Lift Index (LI), CAPE, and Lapse Rates, widespread showers and thunderstorms will develop in the late afternoon, with the best risk of storms from NYC and further west. Some storms could be strong or potentially severe, but a widespread severe weather outbreak is not going to take place.

Friday will bring similar conditions, but with slightly warmer temperatures, more clearing in the cloud cover, and another strong thunderstorm risk from NYC and further west in the late afternoon and evening hours.

Nice Weekend, Warm And Stormy Next Week

Other than a risk of isolated showers and thunderstorms on Saturday afternoon and evening, temperatures will continue to warm up, reaching the lower to upper 70s from NYC and further west. By Sunday, however, as a high pressure is expected to be just east of the area, an onshore wind will develop, bringing high temperatures back into the 60s. Monday will be slightly warmer, with lower 70s possible west of NYC.

By Tuesday, a summer like air mass is expected to move into the region, with 850 mb temperatures ranging from 15-20c, which in a typical summer day can bring 90 degrees. High temperatures are slightly uncertain, but at this time, I am expecting lower to mid 80s from NYC and further west for Tuesday and Wednesday, and even upper 80s cannot be ruled out in Newark, NJ in the warmer case scenario. Lower temperatures are expected east of NYC, though a few lower 80s are expected in these areas away from the immediate coast as well.

A cold front is expected to approach the area sometime around the middle of next week. The exact timing is uncertain as well as the smaller details, but when looking at the overall picture, all models are in agreement by showing widespread precipitation across the region, especially in the afternoon and evening hours. With the area expected to be in the warm sector of the storm, thunderstorms are likely with the cold front, and the GFS is consistently showing supportive Lift Index and CAPE values. As should be expected with something at least a week away, nothing is final yet and details may change, though there is a risk of strong to severe thunderstorms affecting the region, including the NYC area, around the middle of next week. More information will be posted as details become clearer.

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