May 19, 2011: Severe Weather Next Week?

Note: The 5-Day Forecast page was updated for the immediate NYC area only tonight. Each night, the list of pages that have been updated will be listed in the top right corner of the website, above the radar loop.
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After several days of widespread heavy rain affecting the area, bringing rain totals from 1.5 to as much as 5-7 inches of rain across the area, today was an improvement over the last several days, with partly to mostly cloudy skies across the area and high temperatures reaching the lower to mid 70s across most of the area. The only significant rainfall today came from severe thunderstorms in far western New Jersey, mostly limited to Warren County, and strong thunderstorms that popped up in Rockland county in NY late this afternoon.
Tomorrow will bring slightly more widespread storms as the upper level low moves near the area, and even though these storms will not be as widespread as the storms over the last several days, they will still be capable of producing locally heavy rainfall. The weekend will bring much nicer temperatures with dry conditions, but a warm air mass pushing into the region will bring activity back into the region for next week, first the warmth and then the potential for a severe weather outbreak.


Tomorrow’s Outlook:
With the upper level low moving over the area, tomorrow will start out with mainly cloudy skies and fog across the area. The fog will clear by the late morning for most of the area along with clearing cloud cover, with partly to mostly cloudy skies expected by noon. During the late afternoon, widespread showers and thunderstorms will form across the area, and while a severe weather outbreak is not expected as a result of this, some storms could be strong, producing locally heavy rainfall. The storms will persist through tomorrow evening and the early overnight hours before weakening.
High temperatures tomorrow will be slightly colder than today’s temperatures, reaching the upper 60s to lower 70s across the area. With the upper level low over the area, a light variable wind is expected.


Weekend Outlook: Comfortable, Dry
This coming weekend will finally bring a break in the rainfall, making this the first time there is no rain in the area since last Saturday. High temperatures will be in the mid to upper 70s from NYC and further west, with Long Island and southern Connecticut seeing colder temperatures, ranging from the lower 60s near the coast to lower 70s closer to NYC.
As a high pressure off the coast moves south, a southeast wind will bring colder temperatures, especially for places east of NYC. There is slight uncertainty with high temperatures, though at this time I am expecting high temperatures in the mid 50s to mid 60s east of NYC, and in the upper 60s to mid 70s from NYC and further west. These temperatures are subject to slight changes, and it is possible they may have to be raised slightly.


Next Week: Warmth Returns, But Storms Return As Well
As previously mentioned, a much warmer air mass will move into the region next week, bringing the return of warm temperatures and the first time NYC passes the 80 degree mark this month. Monday is expected to bring temperatures in the mid 70s to lower 80s from NYC and further west, and the mid 60s to mid 70s east of NYC. Partly to mostly cloudy skies are expected, with scattered showers and thunderstorms possible from NYC and further west in the late afternoon and evening hours.
The warmest temperatures are likely to be on Tuesday and potentially Wednesday. The low pressure is expected to be well to the north of the area, and with 850 mb temperatures over 15c, high temperatures will be in the lower to mid 80s from NYC and further west as well as parts of Long Island/southern CT away from the coast. Upper 80s are a possibility in Newark, NJ as well. Meanwhile, all models show a cold front approaching the region on Tuesday, and with some models such as the GFS showing high lift index and CAPE values as well as supportive lapse rates, storms on Tuesday afternoon and evening have the potential to be strong or severe.
Beyond Tuesday, there is some more uncertainty. The 12z ECMWF brings colder temperatures back with a high pressure nearby on Wednesday, while the GFS and DGEX bring the cold front closer to the area on Wednesday while keeping warm temperatures in place, even slightly warmer than those of Tuesday. Such a scenario would bring a higher risk of severe weather on Wednesday, with temperatures above average but not as warm lasting through Thursday and Friday. There is uncertainty with which scenario verifies, but the risk of thunderstorms, potentially strong or severe, may continue through Wednesday and Thursday. Stay tuned for more information on the longer range.

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