August 5, 2010 Morning Update

11:40 AM Update:

The area is currently partly cloudy. There were scattered thunderstorms early this morning, which produced rain amounts locally up to an inch, mainly for the immediate NYC area. Afterwards, there were mostly sunny skies, which allowed the atmosphere to become unstable, with temperatures steadily rising, currently in the lower to mid 80s inland and in the upper 80s to mid 90s for the immediate NYC area. NWS Upton has issued a heat advisory for most of the area, as temperatures will rise into the lower to mid 90s for the immediate NYC area, which combined with dew points in the 70s, will lead to a heat index near or slightly over 100 degrees. There are some clouds approaching from our west, which will slow down the temperature increase over the next hour.

The latest radar was posted to the left, which shows heavy thunderstorms for central NY moving east. Most of these storms are not severe, but they are producing heavy rainfall. This will only be the start of what is likely to be an active day for the region.

Today’s Severe Weather Risk: 10-15% Risk

As was mentioned in previous updates over the last few days, today has a 15% risk of severe weather. With the instability in place, there is currently CAPE near 2000 and LI up to -6 for the area. The clouds moving in will probably limit some of the instability, while at the same time, the parameters increase for New England and the Mid Atlantic. The parameters also aren’t as good just to our south, with some models barely showing rain for the area, and the lack of storms in central Pennsylvania may prevent severe weather from reaching its full potential for most of New Jersey and Pennsylvania. Even though I did add a 15% risk for the area, I would not be surprised to see most of the activity today to our north and south. The more likely places out of the area to see severe weather today are the northern parts of the area, including southern Connecticut.

There is at least a 50% to 60% chance of rain today. With precipitable water values over 2 inches, storms today will be capable of producing very heavy rainfall, with the potential for strong wind gusts and small hail with the storms. I added a 30% wind risk for most of the central and southern Mid Atlantic, as the parameters are supportive there with an area of strong storms also currently approaching that area, with a potential 30% wind risk for New England, where there are also supportive parameters. The severe risk for New England is a little uncertain and depends on the cloud cover, though if there is enough clearing with more instability, a 30% wind risk may be needed there.

There is still some uncertainty with today’s risk, and it is possible that the slight risk may be removed for NYC when I update this post around 2 PM.

If needed, storm updates will be posted between 2 and 4 PM today. Otherwise, the next update will be posted tonight, with more details for this weekend and next week.

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