Below, storm updates will be posted on the heavy rain and thunderstorms affecting the area this evening. Updates are being posted both on the blog and on Twitter. The next forecast discussion will be posted on Tuesday, August 27. Radar images are from the National Weather Service.
9:50 PM: Weakening Storms Affecting Area
Over the last 2 hours, the heavy thunderstorms in northeast PA entered the area and continue to track southeast, currently covering most locations with rain and thunder. The storms are generally weakening, with light to moderate rain and thunder, locally heavy over SE NY, NW NJ and southern CT. At least up to 1/4 inch of rain is expected for most, with near to over 1/2 inch for northern and western areas. These storms will continue for the next few hours before ending towards 12-4 PM from NW to SE, with drier conditions for Tuesday.
This is the last storm update for tonight. The next forecast discussion will be posted on Tuesday morning, 8/27/13.
7:55 PM: Heavy Storms Entering Area
Since the last update, the MCS weakened with some of the storms collapsing as widespread light to moderate rain developed to its east over the Hudson Valley, although the portion of the heavy thunderstorms heading towards the area remains intact and is about to enter northwestern parts of the area. The storms are expected to reach the immediate NYC area towards 9 to 9:30 PM, and Long Island and southern CT between 9:30 and 11 PM. With low instability, these storms will not be severe, but are capable of heavy rainfall and frequent lightning especially north and NW of NYC, with the storms likely to weaken as they reach and pass east of NYC.
4:35 PM: Strong Storms Entering Western NY State
Earlier this morning, scattered showers left over from a decaying MCS (Mesoscale Convective System) entered New York state and produced isolated showers across parts of the area, with conditions otherwise mostly cloudy with temperatures currently in the upper 70s to low 80s. The regional radar image to the left shows another MCS entering western NY state ahead of a mid level vorticity maximum, which is tracking to the ESE along the mid level flow. Extrapolating its current track would take the MCS into the area by the evening and early night hours, entering SE NY and NW NJ by 7-8 PM, the immediate NYC area and north/west suburbs by 8-9 PM, and Long Island/CT by 9-11 PM, with storms lasting for a few hours before ending towards 11 PM-4 AM from NW to SE. While severe weather parameters are marginal, these storms will be capable of producing heavy rainfall with up to 1/2 to 1 inch possible north and NW of NYC, potentially locally higher inland, with frequent lightning and gusty winds a risk as well especially inland, with the storms likely to weaken once reaching and passing east of NYC.