Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1153 PM EST Tuesday Jan 27 2015
high pressure builds in through Wednesday behind the Nor'easter.
He moves off the coast Thursday as a clipper system approaches
from the northwest. This low will affect the area Thursday night
and usher in very cold air on Friday. High pressure builds in
from the west Friday night through Saturday night...then slides to
the east on Sunday. A storm system approaches from the southwest late
Sunday...then passes just south of the area Monday...then exits
to the northeast Monday night. High pressure then builds in on
Near term /until 6 am Wednesday morning/...
very light snow over southern CT and Suffolk County is best
detected by the latest rap. All indications are that this
dissipates before sunrise. The kokx radar showed the most enhanced
area passing right over the office where 2-3 tenths of an inch
Thus...calling this occasional light snow and flurries. Again -
all advisories/warnings have been canceled. Winds gusting to 25
miles per hour will result in some blowing snow.
Temperatures fall 3-5 degrees from current levels.
Short term /6 am Wednesday morning through Wednesday night/...
upper trough departs with ridge building in late Wednesday and
Wednesday night. Dry weather is expected...with gusty northwest winds
persisting. These winds...combined with chilly temperatures will produce
wind chill readings in the single digits to teens.
Morning clouds give way to sunshine from west to east.
High temperatures middle 20s to around 30...with lows from zero to the
teens. Good radiational cooling conditions are anticipated due to
clear skies...lightening winds and snow cover.
Long term /Thursday through Tuesday/...
northern stream ridging exits to the east on Thursday...with a
northern stream shortwave quick on its heels. For now appears
Thursday should be dry...except for a slight chance of light snow
late in the afternoon over far western zones. This shortwave lifts
through Thursday night followed by the approach of a deeper full
latitude trough...whose axis crosses the area on Friday.Have likely
probability of precipitation for light snow as a result Thursday night with the
shortwave...then chance probability of precipitation on Friday with the upper trough. At
this time it appears that the area will experience a sub-advisory
(less than 3 inch) snowfall from Thursday night through Friday.
For highs on Thursday a blend of mav/met/ecs guidance...with NAM
2-meter temperatures and a mix down from 975 hpa per BUFKIT
soundings were used. Highs should be around 5 degrees below normal.
The minimum of mav/met guidance...the previous forecast and NAM
2-meter temperatures was used for lows on Thursday night...then a
degree was subtracted to reflect the influence of snow cover. Lows
should be slightly above normal. For highs on Friday a blend of
mex/men/ekd/ece/ecm/wpc guidance with NAM 2-meter temperatures and a
mix down from 900-875 hpa was used...with values forecast to be a
few degrees below normal.
Deep layered ridging builds in Friday night through Saturday
night...with its ridge axis sliding to the east on Sunday. It should
be dry Friday night-Saturday night due to subsidence underneath the
There are some differences in solutions for a storm system forecast
to impact the area early next week. The European model (ecmwf) is the warmest
solution...the Canadian the coldest and fastest...and the GFS in
between. Noting the gefs ensemble mean supports a solution to the southeast
of the GFS...leaned towards a slightly cooler version of the GFS
solution. So have a rain snow mix near the coast and snow across the
interior from late Sunday into Monday.
Ridging begins to build in Monday night and Tuesday...with a dry
forecast as a result.
For temperatures Friday night-Tuesday a blend of
mex/men/ekd/ece/ecm/wpc guidance was used with temperatures forecast
to be below normal during this time frame.
Aviation /06z Wednesday through Sunday/...
low pressure east of Cape Cod will drift northward through the Gulf of Maine and
into the Maritimes on Wednesday.
Mainly VFR across NYC/New Jersey metropolitan and western terminals through taf
period. Bdr/kisp will see MVFR conds...possibly brief
IFR...through around 08z with snow showers...then mainly VFR. Low
probability of MVFR ceilings today...more likely few-scattered 2500 feet.
MVFR conds at kgon early this morning in -sn...brief IFR conds
possible. Light snow bands diminish towards daybreak...but scattered-broken
MVFR ceilings could linger into Wednesday.
Northwest winds generally around 330-360 magnetic through the taf period.
Gusts may become occasional for western terminals overnight...but
should become frequent once again after 14z Wednesday.
Outlook for 00z Thursday through Saturday...
Wednesday night...VFR. Diminishing winds.
Thursday night...MVFR or lower in snow.
Friday...MVFR possible in the morning with snow. Northwest winds 20-30kt.
Sun...MVFR or lower possible.
deep low pressure east of Cape Cod will depart to the northeast as
high pressure gradually builds in from the west.
Small Craft Advisory gusts continue overnight and through Wednesday for all waters.
Seas gradually subside...but remains rather rough through
Winds diminish further Wednesday night as high pressure builds.
A relatively relaxed pressure gradient will produce sub-small craft
conditions over the waters Thursday and Thursday evening. The
pressure gradient begins to increase Thursday night...with at least
Small Craft Advisory level seas possible on the coastal waters late Thursday night.
A tightening pressure gradient and strong low level cold advection
makes gale conditions probable on all waters from Friday and Friday
Winds diminish Saturday as high pressure builds in...with only Small Craft Advisory
level seas possible on the coastal ocean waters by afternoon. Sub
Small Craft Advisory conditions should develop on all waters by late Saturday
night...and continue on Sunday...with a relaxed pressure gradient
forecast to be over the region.
no significant precipitation through Sunday. Some light snow is
likely Thursday night and Friday...but no hydrologic impact is
There is the potential for at least a half an inch of liquid
equivalent to fall from late Sunday into Monday. Some or most of
this is currently forecast to be in the form of frozen
precipitation...so little or no hydrologic impact is expected at
this time. However...if the warmest solution with this system
verifies...then most of this could be of liquid form...and could
produce hydrologic concerns...especially over areas just receiving
a foot or more of snow.
Marine...Small Craft Advisory until 6 PM EST Wednesday for anz330-335-
short term...precipitable water