Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
935 PM EST sun Mar 1 2015
weak low pressure south of Long Island tracks towards Nova Scotia
overnight with a cold front moving across the area late. High
pressure will briefly build in Monday into Monday night... then
pass to the east on Tuesday. Low pressure will track well north of
the area Tuesday night and Wednesday...with a warm front lifting
into the area Tuesday night...followed by a cold front Wednesday
and a reinforcing cold front Wednesday night. High pressure will
then build in for the remainder of the week.
Near term /until 6 am Monday morning/...
precipitation winding down across NE New Jersey...lower Hudson Valley and NYC with
just one last band of precipitation to move through. A few more hours to go
east of here...with precipitation ending completely shortly after midnight.
Dual pol cirrocumulus is indicating mixing remaining over South Shore...kfok
just changed over to freezing rain...so have backed off on the extent of
mixing across Long Island and kept it generally confined to the
Will keep advsys/warnings up until the next update with precipitation
continuing although the real accumulating snows over
aforementioned western areas is ending.
Areas experiencing freezing rain should expect less than 1/10 of an inch of
Short term /6 am Monday morning through Monday night/...
high pressure approaches from the west on Monday...then builds
overhead on Tuesday. Highs on Monday will be in the middle and upper
30s...with a brisk northwest winds gusting to 25-35 miles per hour. Much colder air
will follow for Monday night...and undercut MOS guidance by 2-3 degree
given diminishing winds late at night and fresh snow cover...with
lows in the teens for NYC metropolitan and Long Island...and single
digits farther north/west.
Long term /Tuesday through Sunday/...
models are in decent agreement at 500 mb through the week...although
slight differences in heights begin to take shape during the latter
half from a digging trough in the middle of the country.
Ridging at the surface and aloft tracks moves offshore on Tuesday. Precipitation will
overspread the area late Tuesday afternoon as snow...but with increasing S-SW
winds and strong warm air advection temperatures will warm Tuesday evening/night with snow
changing to mixed precipitation then rain from S to north. Warm front lifts
towards the area Tuesday night...but there is some uncertainty if the
low level jet will be strong enough to push it through at the surface. Climatology
says no with the low so far to the northwest and very cold waters/ice...so
have gone below guidance with highs Wednesday...generally lower 40s with
middle 40s possible in NYC metropolitan.
The combination of these temperatures and rainfall will result in melting
snowpack which could lead to minor flooding across the area on Wednesday.
Cold front moves across Wednesday followed by a reinforcing cold front Wednesday
night. The northern edge of the precipitation shield of a southern stream
system riding along this secondary boundary could keep precipitation
lingering Wednesday night into Thursday. Models remain split on this...GFS is
further suppressed than ec so have kept chance probability of precipitation.
Cold air filters in behind the initial cold front on Wednesday. Thermal
profiles support a change back over to snow Wednesday night and Thursday with
any precipitation associated with the southern stream system. Another shot of
Arctic air infiltrates the area Thursday into Friday.
Strong Canadian high pressure then builds towards the area into the
weekend with dry weather. Temperatures will rebound around 5 degrees below
normal next weekend with warm air advection developing.
Aviation /02z Monday through Friday/...
a frontal system will pass through tonight as weak low pressure
develops southeast of Long Island. High pressure builds Monday.
A wintry mix of freezing rain...snow and sleet will lighten and end
by 5-7z...west to east for coastal airports. Across the interior...any
light snow will also end from west to east.
Generally expect low end MVFR or IFR conditions tonight...although
visibilities should improve once the precipitation ends.
A return to VFR can be expected Monday after 11-13z.
Winds will be light and variable...then will turn to the west 5 to
10 kts well after midnight. Winds become west/northwest after
12z...10 to 15 kts. By 15z...frequent gusts 20 to 30 kts are
expected. Winds should remain to the left of 310 mag for the most
part Monday...but will be close to that direction at times.
Additional light snow accums are expected.
Most likely total runway accumulations:
Outlook for 00z Tuesday through Friday...
Monday night-Tuesday morning...VFR.
Tuesday afternoon...chance MVFR or lower in snow.
Tuesday night...IFR or lower likely. Snow...changing to a wintry
mix after midnight...and then rain late at all terminals except kswf
and possibly CT terminals. Low level wind shear likely.
Wednesday...IFR or lower possible in any rain - with a brief period
of freezing rain possible in the morning at kswf. Low level wind shear possible in the morning.
Wednesday night-Thursday...MVFR or lower possible in any
precipitation...otherwise VFR. If there is precipitation...should
change to all snow Wednesday night and possibly continue into
Thursday. Northwest winds g15-20kt possible.
Thursday night-Friday...VFR. Northwest winds g15-20kt possible Thursday
tranquil tonight...then winds increase to Small Craft Advisory
levels Monday and gradually diminish Monday night. Expect sub-advisory conds
on Tuesday as high pressure builds across. Small Craft Advisory conds possible on the ocean
Tuesday night into Thursday behind the passage of two cold fronts...with a
tight pressure gradient. Sub-advisory conds then expected thereafter as
the pressure gradient weakens with another building high.
another 1-2 tenths of liquid equivalent precipitation is expected through
midnight...highest amounts east. With all of this expected to be
either frozen or freezing precipitation...no immediate hydrologic
Between 1/2 to 1 inch of liquid equivalent precipitation is possible late
Tuesday through Wednesday. Some of this will fall as rain...therefore the
combination of this and melting snow pack could cause minor
Ice will continue to develop on local area rivers and streams as
temperatures remain well below average.
CT...Winter Storm Warning until 7 am EST Monday for ctz008-010>012.
Winter Weather Advisory until 7 am EST Monday for ctz005>007-
New York...Winter Storm Warning until 7 am EST Monday for nyz078>081.
Winter Weather Advisory until 7 am EST Monday for nyz067>075-
New Jersey...Winter Weather Advisory until 7 am EST Monday for njz002-004-
Marine...Small Craft Advisory from 6 am Monday to midnight EST Monday
night for anz330-335-338-340-345.
Small Craft Advisory from 6 am Monday to 6 am EST Tuesday for