Further east, GOES-E Visible imagery shows increasing convective
vigor with a few additional stronger cells over the lower Hudson
Valley starting to move into CT. Persistent southwesterly low to
mid-level WAA has been providing moisture flux through this area
into Southern New England with total PWat values increasing from
1.75 toward 2" in the next few hours. Additionally, fairly clear
skies has allowed for increasing instability up to 1500-2000 J/kg
across CT int RI. As such, convection will likely strengthen and
broaden in coverage (both cells and downdraft area). Forward
speeds are slow, but will start to slacken after 00z as a new
850mb pivot/low shifts toward the Hudson Valley, backing steering
flow increasing duration across southern New England for potential
for spots of 1.5-2.5" though 03z. There is some uncertainty, but
initial band/round of cells and upstream advection of
moisture/low-level heating may allow for additional scattered
cells to form upstream and repeat through areas hit by the first
round. As such and in combination with 1-3" that fell last
evening (across S New England)130, grounds may be prone to
scattered incidents of flash flooding tonight.