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Area forecast discussion 
National Weather Service New York New York
1011 am EST Sat Jan 31 2015

Synopsis...
deep low pressure slowly moves northeast as high pressure builds
in from the west. A cold front will move through on Sunday. Low
pressure approaches from the Ohio Valley and passes south of Long
Island Monday. The low tracks well to the east Monday night with
high pressure building in its place. The high moves across Tuesday
and offshore Tuesday night. A cold front moves across midweek with
another low passing well offshore late in the week. By that time
frame...high pressure will be centered west of the region.

&&

Near term /until 6 PM this evening/...
clear skies...gusty winds and cold temperatures are expected
today.

Wind and windchill advisories have been cancelled/expired based
on subsiding boundary layer winds and slowly moderating temperatures
through the late morning/early afternoon. Northwest wind gusts of
35 to 40 miles per hour expected into the afternoon. Localized gusts to
around 45 miles per hour possible through around midday. Subzero windchills
this morning rising into the single digits above zero for most of
the region.

Afternoon high temperatures will struggle to rise through the teens
today...approaching 20 degrees near the coast. Followed a mav/met
blend which is supported by hourly GFS lamp numbers.

&&

Short term /6 PM this evening through 6 PM Sunday/...
high pressure passes to the south as a cold front approaches from
the north. Winds turn toward the west ahead of the cold
front...and lighten. Temperatures will not be quite as cold with lows in
the teens and 20s. In fact...readings will not fall much as the
night progresses due to warm air advection.

On Sunday...high clouds increase as temperatures rise through the
20s...into the 30s. Stayed close to a met/mav MOS blend. A few
snow flakes may be observed over New Jersey and western zones very late in
the day as low level moisture increases ahead of low pressure
riding along the frontal boundary.

&&

Long term /Sunday night through Friday/...
do not see a big shift in the models this run...and general
agreement is noted. Low pressure will pass to the south Monday.
Analysis of low level thermal fields suggests snow Sunday
night...with a wintry mix for the southern half of the forecast
area Monday morning. Expect a mix of snow...sleet and freezing rain
for a portion of the area. The east end of Long Island could see a
changeover to plain rain for a time.

Overall...expect 6 to 8 inches near the coast...and 8 to 12
inland. Some light icing is possible near the coast as well. For
Long Island and NYC...these accumulations are a total. The actual
amounts could be lower due to rain/freezing rain changeover.

For the coast...snow to brief period of rain/freezing rain and ice pellets...before
changing back to snow Monday afternoon.

Interior...mainly snow with a period of sleet mixed in Monday morning.

Timing for heaviest precipitation would be midnight through about noon or
so Monday.

After collab with surrounding offices...a Winter Storm Watch has
been posted. Start time 00z Monday through 6 PM Monday. This can
be fine tuned as we get closer to the event.

Of course any shift in track north or south will make a big
difference as our area will be dealing with the rain/snow
line...which is always difficult to forecast.

Temperatures are a NAM 2m blend with gridded MOS. Hand edits were needed
as well. Lows Sunday night will range from the teens inland to the
middle and upper 20s near the coast.

On Monday...middle 30s possible near the coast...eastern Li...and around
20 well inland. Temperatures drop during the afternoon as the storm
passes to the southeast as cold air rushes in.

After this system...Monday night until midweek...we will be in a
quasi-zonal middle level flow. A weak low amplitude shortwave moves
across Tuesday with a larger more amplified shortwave moving
approaching Wednesday night. There will be an associated cold
front at the surface approaching Wednesday night into Thursday.
There will be a chance of snow with this.

For late in the week...a low pressure area moves far offshore...more
offshore with the 12z European model (ecmwf) run today...but did not want to totally
make for a dry forecast. Left in a chance of mainly snow for
Thursday into Friday. However...the models have conveyed more of a
progressive solution and less amplified than before so the low is
not that strong offshore and high pressure could prove to be more
dominant in allowing for a drier forecast.

For high temperatures...below normal overall...mainly in 20s except
for Wednesday and Thursday with low to middle 30s. Lows are forecast to
be teens to lower 20s Sunday night and Wednesday night. For other
periods...low temperatures are forecast as follows...single digits
to a little below zero Monday night...single digits to lower teens
Tuesday night...low to middle teens Thursday and Friday night.

&&

Aviation /15z Saturday through Wednesday/...
VFR conds through the taf period as high pressure builds in from the
west.

Northwest winds just to the right of 310 mag will back to around 310 mag by
mid-afternoon. Winds could favor left of 310 mag as early as late
afternoon. Wind speeds will average 15-25 knots with 25-35 knots gusts this
morning and will diminish to 15-20 knots with 20-30 knots gusts this
afternoon. West winds will gradually diminish to less than 10 knots
tonight.

Outlook for 12z Sunday through Wednesday...
Sunday...VFR. SW winds 5-10 knots.
Sunday night-Monday...potential high impact day. IFR and snow
likely. Chance mixed precipitation. NE-north g 25-35kt possible.
Monday night...becoming VFR as snow comes to an end. North-northwest wind
g20-25kt possible.
Tuesday-Wednesday...VFR.

&&

Marine...
northwest gales of to 45 knots on the ocean waters and up to 40 knots on all
other waters this morning...will gradually subside through the
afternoon. The combination of rough seas...strong winds...and
cold water temperatures will also result in at least moderate freezing
spray today.

Gusty winds diminish this evening...though a few 35 knots gusts are
possible on the eastern ocean waters. Small Craft Advisory wind
gusts likely on the ocean waters through tonight. Seas will also
gradually subside to less than 5 feet during the overnight hours.

Tranquil conds on the waters as high pressure builds overhead and
departs. Another low approaches Sunday night and Monday. Conds ramp
up to at least Small Craft Advisory levels Monday and gales are
likely on all waters for a period Monday night.

These conditions gradually taper down early Tuesday. The relatively
more quiet period looks to be late Tuesday morning through early
Wednesday morning. There could be some marginal Small Craft Advisory seas on the
outer ocean Tuesday of around 5 feet. Small Craft Advisory conditions possible once
again with the approach of the cold front towards midweek.

&&

Hydrology...
generally around 0.8 to 1.2 inches of liquid forecast with the
system Sunday night through Monday. A snow and wintry mix event is
forecast. No hydrologic issues are expected at this time.

&&

Okx watches/warnings/advisories...
CT...Wind Advisory until 10 am EST this morning for ctz009>012.
Winter Storm Watch from Sunday evening through Monday
afternoon for ctz005>012.
New York...Wind Advisory until 10 am EST this morning for nyz069>075-
078>081-176>179.
Winter Storm Watch from Sunday evening through Monday
afternoon for nyz067>075-078>081-176>179.
New Jersey...Wind Advisory until 10 am EST this morning for njz002-004-006-
103>108.
Winter Storm Watch from Sunday evening through Monday
afternoon for njz002-004-006-103>108.
Marine...freezing spray advisory until 6 PM EST this evening for anz330-
335-338-340-345-350-353-355.
Gale Warning until 6 PM EST this evening for anz330-335-338-
340-345-350-353-355.

&&

$$
Synopsis...precipitable water
near term...pw/NV
short term...precipitable water
long term...jm/pw
aviation...mps
marine...mps
hydrology...precipitable water

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