Rivers and Streams
With the heavy rain and snowmelt, river and stream flooding look to
be a significant possibility. The MMEFS indicating several locations
for 30% exceedance of minor flooding with a few locations having a
30% chance for moderate flooding. As stated above, the big X factor
will be how much snowfall remains after Sundays event and will
likely be a big impact in the river flood threat.
Strong to Damaging Winds
A powerful LLJ will likely bring strong winds and possibly damaging
winds to the region late Tuesday night into Wednesday morning.
Deterministic guidance is in good agreement with a 80-100 kt 850mb
LLJ which is approaching 4-5 standard deviations above climatology
for this time of year. Even at 925mb, winds could be as high as 70-
90 knots. GFS bufkit soundings at this time don`t show much of any
inversion which means these high winds will likely mix down to the
surface. NBM probabilites for 58mph gusts (High Wind Warning) are
high at 70-90% for Cape Cod and the Islands. Even inland for areas
east of the I-95 corridor, probs for 58+ mph gusts are moderate at
40-70%. NBM probabilities for 46mph gusts (Wind Advisory) already
showing moderate probs at 40-70% for the interior. As for the marine
areas, storm force winds are very likely with hurricane force winds
certainly in the realm of possibility with this system.
Coastal Flooding
Given this system is still more then 3 days out, uncertainty remains
high for level of coastal flooding expected. As of right now, minor
to moderate coastal flooding is possible along the south coast where
2-4 feet of surge is possible if the timing of the maximum winds
aligns with the Wednesday AM high tide. Astro tides are also coming
up for the the south and east coast during this time period and may
lead to minor coastal flooding impacts even for the eastern facing
coasts despite the the unfavorable southerly winds due to rapid
pressure drops.