Weather with Bill Evans
Good Day On This Friday January 15, 2020
Weak high pressure today gives way to low pressure approaching
tonight and passing through on Saturday. The low moves away
from the area Saturday night into Sunday. A cold front moves
through Monday. High pressure builds in Monday night through
Wednesday. Another cold front moves through Wednesday, with high
pressure building in behind it.
Low clouds and reduced visibilities are prominent in the
northern portions of the CWA this morning as a drop in
temperatures has allowed the development of some patchy fog with
the potential for some freezing fog or black ice through early
this morning. An SPS is out for these areas through 9AM for this
potential.
Cloud cover should gradually increase through the day as a vigorous
trough and surface low pressure system approach the area from the
west. Winds will gradually pick up today out of the E/ESE. This flow
off the ocean will allow for the increase of low level moisture
through the day with temperature expected to rise into the middle
and upper 40s along the coast. Warm air advection will increase
ahead of the approaching frontal system through the afternoon
and with a moist boundary layer, some rain showers may develop
as early as the mid to late afternoon for westernmost areas like
the NYC metro, Lower Hudson Valley, and NE NJ.
By evening, the strength of the WAA is rapidly increasing as a mid-
level PVA allows a surface low pressure to develop along the
baroclinic frontal boundary along the East Coast. This will allow
for the rapid blossoming of steady light to moderate precipitation
to overtake much of the area as the surface low pressure deepens and
moves over the CWA from south to north.
Precipitation will gradually increase in intensity through the night
as the entire system moves fairly quickly through the CWA from
southwest to northeast. There is enough moisture in the atmosphere
to potentially produce rainfall rates of up to 0.5 inch per hour in
the heaviest of precipitation bands. This is more likely to occur
for areas toward the east, like Long Island and southern CT, as the
low will have more time to organize and strengthen before the best
dynamics move to the northeast.
By sunrise much of the heaviest of precipitation should be in the
eastern half of the CWA with only residual rain showers elsewhere.
Winds will shift out of the SW and then W through the day but remain
quite brisk as the pressure gradient remains tight over the area.
The chance of any additional showers remains fairly low through the
day but chance and slight chance pops were left in (mostly for the
northern portions of the CWA) as the large parent low pressure moves
by to our north and an upper level low moves overhead. As
temperatures decrease toward the afternoon and evening on Saturday,
any brief showers may be in the form of snow but no accumulation is
expected.
All said and done, the area can see anywhere from 1 - 1.5 inches of
rain with localized areas in CT and eastern LI approaching 2
inches.
Low pressure will continue to move away from the forecast area
Saturday night into northern New England. There may be some
lingering snow or rain/snow showers early Saturday night as the
broad upper level low will remain to our west, over central New York
and central Pennsylvania. However, models suggest that dry air moves
up along the coastal plain, likely part of the dry slot with the
synoptic system, so much of Saturday night should be dry.
Sunday should be dry as well as an upper level low over the mid-West
moves east and weakens into a trough while the surface low pressure
continues to push away from the region into northern New England.
However, the low will intensify, and the pressure gradient between
it and the high pressure to the south will increase. This will lead
to windy conditions on Sunday, with west winds of 15 to 25 mph and
gusts 25 to as high as 40 mph possible (mainly across south fork of
Long Island). Of course this is still a few days away and will be
fine tuned as we get closer to Sunday.
A weak cold front will move through on Monday. This system appears
to be moisture starved, and should move through dry.
Another cold front approaches Wednesday and moves through late. This
too looks moisture starved, though a stray snow shower cannot be
ruled out as it moves through.
High pressure builds in for Wednesday night. Models show a frontal
system over the mid-West approaching the area late next week, but
there is considerable uncertainty with fronts and low pressure
systems at this time.
As far as temperatures, lack of any arctic air throughout the long
term will mean seasonable temperatures will continue.
.MARINE...
With an increasing southeast flow ahead of a warm front there is the
potential for SCA level wind gusts by early this afternoon.
As a result the advisory beginning time is now 18Z across all the
forecast waters. Winds increase into this evening, with the
possibility of occasional gusts near gale force late this evening
into the overnight east of Moriches Inlet. Overnight winds will
begin to diminish as a wave of low pressure develops along a cold
front moving into the western waters. The SCA will continue for all
the waters through tonight. Then with gusts continuing to near SCA
levels on the ocean waters, eastern Long Island Sound, and the
eastern bays, the SCA was extended for these areas through Saturday,
as well as the ocean waters.
After a brief lull in the winds during Saturday, as the low deepens
and tracks to the north of the waters, westerly winds and gusts
increase. Small craft advisories will likely be needed for all the
waters once again Saturday night. Occasional gusts may even reach
near gale force across the ocean waters east of Moriches Inlet
Saturday night. Small conditions continue into Sunday, diminishing
Sunday night, and falling below SCA levels for all the waters late
Sunday night.
Winds may gusts to 25 kt once again on the ocean waters Monday into
Monday night as a cold front moves through, but there is uncertainty
with how strong gusts will actually be at this time.
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