Sunday, August 15, 2010

August 15: Storms Tomorrow, Heavy Rain Thursday

Today has been another chilly day, but this time there are also cloudy skies, along with light to moderate rain that is still affecting the area. This rain is generally light and has no thunder, however tomorrow will be the complete opposite of tomorrow, with hot and humid conditions as well as the potential for strong to severe thunderstorms.

Tomorrow's Outlook:

Tomorrow is likely to start out mainly cloudy with an isolated shower or two possible at first. By the early or late morning hours, though, the cloud cover is likely to start clearing, with partly cloudy skies expected for the afternoon. This, combined with a warm air mass, will allow temperatures to quickly warm up, reaching the upper 80s to lower 90s for the immediate NYC area, and mid to potentially upper 80s for Long Island and S CT. Humid conditions are also expected tomorrow with dew points in the 70s, which will lead to the heat index reaching the mid 90s for the immediate NYC area.

A cold front will also approach the area, and is expected to move through tomorrow night before stalling just to our east. The models remained rather consistent since yesterday, with a severe thunderstorm outbreak likely for tomorrow afternoon and evening.

Tomorrow's Severe Weather Risk: 15% Risk

As the cold front approaches the area, instability is expected, with supportive parameters, including CAPE up to 2000, Lapse Rates up to 6.0, and bulk shear up to 40 knots. At this time, there is a 15% risk of severe weather in place, however an upgrade to a 30% wind risk is possible with tomorrow's morning update, which will include severe weather risk maps. Storms are expected to start affecting the area during the afternoon hours and last through the early overnight hours, with the main threat being heavy rainfall and strong wind gusts. Small hail an an isolated tornado are also possible.

As we have seen with the last severe weather outbreak, the exact impact area as well as places that get shafted from the storms usually cannot be determined until the day itself, when most short range models and the observations are more useful. It is still possible that the risk could change with tomorrow's morning update.

Tuesday - Friday: Dry Start, Wet End

Tuesday and Wednesday are expected to be dry, but warm temperatures are expected. High temperatures will reach the upper 80s to lower 90s for the immediate NYC area for Tuesday, and the mid to upper 80s on Wednesday. As the cold front will have stalled nearby, however, a low pressure is expected to form to our west and approach the area, bringing a potentially wet Wednesday night and Thursday.

Precipitable water values will again approach 2 inches, and with the low pressure likely to stay nearby, a chilly and wet Thursday morning is likely at this time. There is still uncertainty, however, as the models are not consistent on a solution yet, and the heavy rain area, which is currently over our area, may still change its place several times before the models reach a solution. Stay tuned for more details on this potential.

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