Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS61 KOKX 061517
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1017 AM EST Fri Dec 6 2019

.SYNOPSIS...
A cold front approaches from the Great Lakes this afternoon, 
passing through the area this evening. High pressure will 
follow for Saturday and then build offshore on Sunday. A frontal
system will impact the area for the beginning of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A northern stream shortwave trough will send low pressure over 
the Great Lakes this morning quickly east, passing to the north 
late this afternoon into early this evening and dragging a cold 
front through the region. 

Ahead of the front, a tightening pressure gradient will result 
in a gusty SW flow by afternoon. Gusts of 30 to 35 mph will be 
possible along the immediate coast, especially across LI.

Limited moisture and upper dynamics will limit precip with the 
frontal passage, but a few snow showers/flurries possible across
the interior Tri-State this morning into early afternoon, and 
then potential for scattered showers across LI and SE CT late
this afternoon into early evening ahead of the cold front as 
it interacts with more moisture. No snow accum expected across
Interior, with less than a tenth of an inch of rainfall for
coastal areas.

For the most part, the day will be cloudy with temperatures in
the mid-upper 30s Interior to lower to mid 40s for city/coast, 
which is right around normal.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Cold front passes through early this evening along the coast
with a brief shower possible, otherwise conditions will be dry 
with a gusty NW flow the first half of the night. 

The gusty winds will keep temperatures from dropping too much
below normal, with lows by daybreak Saturday ranging from the 
mid 20s across the interior, to the around 30 at the coast.

High pressure builds in from the west on Saturday with 
diminishing NW winds and cold conditions. Highs will be about 
ten degrees below normal in the 30s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
The center of high pressure will move over the area Saturday night. 
This will mean light winds and mainly clear skies, leading to a 
pretty good radiational cooling night, especially in the outlying 
areas as usual. Went a couple of degrees below guidance for Saturday 
night, and several degrees below for Pine Barrens of Long Island. 
Lows will be in the 10s and 20s.

Thereafter, the forecast area will be on a warming trend as the 
center of high pressure moves offshore Sunday morning. Veering winds 
in forecast soundings as a warm front lifts well north of the area 
will mean warm advection for Sunday and highs warmer than Saturday, 
but still below normal for this time of year, ranging from the 
middle 30s inland, to the middle 40s along the coast.

A complex frontal system will impact the area at the beginning of 
the new work week as an upper level shortwave over the Northern 
Rockies dives south into the mid-West Sunday into Monday, 
which phases with a southern stream system Monday night into 
Tuesday, inducing a surface low that tracks over the Great Lakes and 
then into southeastern Canada into Tuesday. This will allow a cold 
front to approach through Tuesday. That will mean a continued 
southerly flow and progressively warmer temperatures Sunday through 
Tuesday. By Tuesday, highs will be well above normal, in the 50s 
region-wide. There is a slight chance that some precipitation moves 
in early Sunday night for western sections of the forecast area. If 
it does, it may be cold enough for a wintry mix, including some 
freezing rain across the Lower Hudson Valley. However, it is too far 
out at this time for any certainty in precipitation types, and if it 
does occur, it is expected to be brief. From late Sunday night 
through Tuesday, it should be warm enough for plain rain for the 
entire forecast area. 

There is the potential for moderate to heavy rain from Monday 
through Monday night as there looks to be a sub-tropical connection 
south of the high that comes up northward on its west side. From 
Sunday night through Tuesday night, both the ECMWF and the GFS have 
over 2 inches of rainfall across portions of the area, with a 
widespread 1 to 2 inch rainfall for the entire forecast area. PWATs 
of over an inch are also noted in the GFS (as well as NAM coming up 
the east coast Sunday night). There is still a great deal of 
uncertainty with where the heaviest rain would actually set up and 
with the timing. The one good thing is that this will be a long 
duration event. 

The cold front pushes offshore Tuesday night, ushering in a colder 
air mass for Wednesday, with highs in the 30s to around 40.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
VFR as high pressure settles south early this morning. A cold 
front will pass this evening. 

There is a chance for a mix of light snow and light rain across
the interior Lower Hudson Valley terminals and across most of
Connecticut terminals, this afternoon. TEMPO group for KSWF and
KGON to account for this potential but confidence in occurrence
is on the low side.

Fairly high confidence in winds backing SW and increasing to 
10-15G20-25kt this afternoon. Gusts to 30 kt are possible along 
south coastal locations. Timing of fropa roughly 00Z NYC metros 
and 01Z-02Z east, with winds shifting WNW at first and then 
right of 310 mag toward midnight.

     NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component fcsts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: No unscheduled amendments expected. The 
afternoon haze potential forecast is GREEN, which implies slant
range visibility P6SM outside of cloud. 

KLGA TAF Comments: No unscheduled amendments expected. The 
afternoon haze potential forecast is GREEN, which implies slant
range visibility P6SM outside of cloud. 

KEWR TAF Comments: No unscheduled amendments expected. The 
afternoon haze potential forecast is GREEN, which implies slant
range visibility P6SM outside of cloud. 

KTEB TAF Comments: No unscheduled amendments expected. 

KHPN TAF Comments: No unscheduled amendments expected. 

KISP TAF Comments: No unscheduled amendments expected. 

.OUTLOOK FOR 15Z SATURDAY THROUGH TUESDAY...
.Saturday and Sunday...VFR.  
.Sunday night and Monday...Rain showers likely with MVFR or lower 
conditions.
.Tuesday...MVFR or IFR in rain, with conditions improving late
at night.

&&

.MARINE...
A gale warning remains in effect for the ocean waters with SCA 
conditions elsewhere. 

Winds ramp up quickly late this morning into this afternoon 
ahead of an approaching cold front. The cold front passes 
through the waters this evening. Gusts of 30 to 35 kt are 
expected this afternoon into tonight, diminishing to below SCA 
toward daybreak Saturday as high pressure builds in from the 
west. 

Winds may briefly reach 25 kt Sunday night on the ocean waters. An 
approaching frontal system will allow southerly flow to increase 
late Monday morning into the afternoon, with gusts 25-35 kt into 
Monday night for all coastal waters except the western sound and 
harbor. Winds diminish late Monday night, with 25 kt gusts still 
possible over the waters through the day Tuesday.

Waves will remain below 5 ft through Sunday night, but build to 5 ft 
on the ocean waters by late Monday morning/early Monday afternoon. 
Waves continue to build on the ocean to 5 to 12 ft by Tuesday 
afternoon. Waves of 5 to 8 ft are possible across the extreme 
eastern portion of the eastern sound, with 5 ft waves more likely 
across this area Tuesday. Waves diminish Tuesday night.

&&

.HYDROLOGY...
No significant liquid equivalent is forecast through Sunday. 

A significant long duration rainfall event is possible 
beginning late Sunday Night through Tuesday night.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) is still
operating at reduced power.

The KOKX WSR-88D radar will be out of service until 
approximately 12/7 due to the refurbishment of the transmitter. 
This work is part of the NEXRAD Service Life Extension Program.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 1 PM this afternoon to 3 AM EST 
     Saturday for ANZ330-335-338-340-345.
     Gale Warning from 1 PM this afternoon to midnight EST tonight 
     for ANZ350-353-355.

&&

$$
SYNOPSIS...JP/DW
NEAR TERM...DW/NV
SHORT TERM...DW

National Weather Service Glossary of Abbreviations