I'm not fully sold, but tomorrow does seem like a day to watch in SNE. There could be some localized flash flood risk. Maybe higher end. Here was BOX and WPC this afternoon:
BOX
Models still indicate favorable ingredients for heavy rainfall.
Broad anticylonic flow will advect high PWATs into the region. In
some instances values will approach 2.5 inches. Values this high are
around +2.5 STD above climatology and are certainly a significant
signal for heavy rain. Unsurprisingly model soundings have also
hinted at favorable conditions for localized flash flooding. The
most notable signals include weak winds through the column, deep
warm cloud depths, and tall skinny CAPE profiles. HREF ensembles
have started highlighting areas in our CWA with 5-15% probabilites
for 6 hour precipitation totals to locally exceeding the 100 year
annual return interval. Not every area will see heavy rainfall
tomorrow, but any storm that forms in this environment will be
capable of producing rainfall rates of 1-2 inches per hour.
Communities most at risk include poor drainage and urban areas with
little in the way of permeable surfaces.
WPC
...Mid-Atlantic and Northeast...
Post-tropical cyclone Chantal will be exiting east of Cape Cod to
start the period as it continues to get caught up in increasing
southwesterlies downstream of a trough approaching from the Great
Lakes. This trough will continue to translate eastward through the
day, but will be slow to advect due to downstream Bermuda-type
ridging. Between these two features, SW flow will remain prevalent
over the area, with 850-500mb winds being nearly unidirectional
from the W/SW at 15-20 kts. This will result in a continued
extremely moist environment with PWs likely eclipsing 2" from
eastern VA through southern New England Tuesday afternoon,
coincident with a plume of SBCAPE exceeding 2000 J/kg.
Into these impressive thermodynamics, a shortwave embedded within
the mean flow will traverse northeast ahead of a cold front and
along a surface trough, providing additional ascent atop the
already impressive convergence on these boundaries. This suggests
showers and thunderstorms will become widespread, which is
additionally supported by high-res CAM simulated reflectivity.
Storms that develop will move very slowly, and Corfidi vectors
collapsed to just around 5 kts will support backbuilding and
training echoes along the surface trough and front. With warm cloud
depths potentially eclipsing 14,000 ft, this will support efficient
warm-rain processes and rain rates above 2"/hr at times. Where
training occurs, this could result in total rainfall in excess of
3", with instances of flash flooding possible across much of the
I-95 corridor from Richmond, VA to Portland, ME, and a slight risk
has been added for this area.