May 23, 2011: Active Week, Weekend Ahead

On Monday, 5/23, the 5-Day Forecast page was updated for the immediate NYC area, and the Long Range Forecasts page was updated , discussing a potential significant warm spell to end the month.
A warm air mass began moving into the region today, but the area has been under cloudy skies throughout the day, with high temperatures slightly colder than expected, reaching the mid to upper 60s from NYC and further west and the upper 50s to mid 60s in Long Island and southern Connecticut. Occasional showers and drizzle were observed throughout the day.
Tonight’s storms are just the start of what will be a relatively active week and weekend. with the cold front to the west of the area tomorrow, slowly moving east, temperatures will pass the 80 degree mark in NYC for the first time this month, with the potential for strong to severe thunderstorms in the evening and overnight hours. Wednesday, Thursday and potentially Friday will be mainly dry, but warmer temperatures will return ahead of the next potential severe weather producer on Saturday.

Short Term Update: As expected, the storms mentioned in the update earlier this evening are weakening, with light to moderate rain and thunderstorms currently moving into the immediate NYC area, with a few locally heavy storms. These storms will continue to weaken as they move east into Long Island and southern Connecticut.
Tomorrow’s Outlook:

With the cold front slowly moving into the region, along with warm 850 mb temperatures and a southwest wind, temperatures will reach the lower to mid 80s from NYC and further west, with the warmest temperatures focusing on the immediate NYC area. A few lower 80s are possible in parts of Long Island/southern Connecticut as well, with lower to upper 70s expected in these areas for the main part. Partly to mostly cloudy skies are expected.

With the set up in place, there is a severe weather risk tomorrow once again, but it is not as widespread as today’s risk was. The afternoon hours will stay mostly dry, though by the evening and early overnight hours, the GFS and GGEM have been showing an area of strong thunderstorms targeting the area. There is some uncertainty with this feature, which the NAM model does not show, but the potential for strong to severe thunderstorm is in place for tomorrow in the late afternoon, evening and early overnight hours, especially from NYC and further north/west. At this time, I would place an enhanced 15% risk of severe weather over the area. An afternoon update may be posted tomorrow about this potential.
Wednesday – Saturday: Warming Up, More Severe Weather Possible

The storm will bring very little change in the air mass, with Wednesday still expected to be mild with high temperatures reaching the upper 70s to lower 80s from NYC and further west. An isolated shower or thunderstorm cannot be ruled out, but Wednesday will be mainly dry, with partly to mostly cloudy skies expected.
By Thursday, as another storm develops in the central US, another warm air mass will move into the region, bringing warm temperatures once again. Warmth will have some difficulty reaching the area on Thursday, with a SSE wind keeping colder temperatures towards the coast, but especially west of NYC, temperatures will be similar to those of Wednesday. As with Wednesday, a few showers and thunderstorms are possible, but most of the day will stay dry.
The warmest temperatures will finally be able to push into the area on Friday. A south wind will keep coastal areas with colder temperatures once again, but NYC and further west will see high temperatures reaching the mid 80s, and upper 80s are a possibility in Newark in the warmer case scenario. On Friday, however, with the storm closer to the area, severe weather becomes a possibility. The best risk of severe weather will stay to the west of the area, however there is the potential for scattered thunderstorms, some of them severe, in the area, especially from NYC and further west.
Saturday will bring similar temperatures compared to Friday, but the high temperatures may be slightly colder than Friday. Looking at the GFS and DGEX models, severe weather is possible once again on Saturday, with the placement of storms east of Friday, potentially bringing a better risk of severe weather into the western and central parts of the area. More information will be posted on Friday and Saturday’s potential thunderstorms over the next several days.
Longer Range: The “Long Range Forecasts” section has been updated, discussing the potential for a significant warm spell starting on Memorial Day and into the rest of the week.

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