INCREASING RISK OF FLASH FLOODING AND SEVERE WEATHER BEGINNING THURSDAY AND CONTINUING THROUGH THE WEEKEND

The first "official" heat wave of the season for the city is underway, but it'll break by Thursday as cloud cover increases.

Intellicast.com

Through Wednesday, the majority of thunderstorms during the day will be confined to the northern and western suburbs of NYC. However,  a very atypical weather pattern will evolve by late week, setting the stage for a daily barrage of heavy rains, thunderstorms and very muggy temps to linger across the entire region. An uptick in activity will start Thursday, but should really get going by Friday through Monday.

 The evolution of this wet pattern will most likely take several days to clear the east coast, making the threat of flooding almost certain for the usually vulnerable rivers and streams around the region.

Accuweather.com

The bottled up nature of the pattern-- akin to a wintertime "blocking" pattern, will mean that the front will move painfully slow, which will exacerbate the flood risk for the unfortunate areas that receive the most rains.

The maps from NOAA for Thursday, Saturday and Sunday illustrate the problem nicely, as the meandering front only crawls eastward....

Sunday could be a real problem for a widespread flood threat, as the front makes its closest approach.

The 7-day totals forecasted from now through Monday night from NOAA show an average of 2 inches in the red shading:

However, with the very rich availability of moisture in the atmosphere, the potential is there for some places to see much higher totals, particularly if a certain location gets hit multiple times in one day.


So to sum up:

• heavy rain/thunderstorms will increase in coverage and intensity from Thursday onward across the entire region.
• the weather will be most prone to flare-ups of heavy showers and storms during the afternoon and evening hours --- similar to a Florida-type weather pattern. It will not rain the entire period
• Closest approach of frontal system will happen Sunday into Monday, which should give us the best opportunity for widespread heavy rainfall as opposed to scattered showers and storms. 

Another update will be needed by Wednesday