Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXUS61 KOKX 142028

Area Forecast Discussion
National Weather Service New York NY
428 PM EDT Mon Oct 14 2019

A dry cold frontal passage this evening will be followed by
building high pressure through Tuesday. A frontal system will 
approach on Wednesday, with a rapidly intensifying coastal low 
tracking just southeast of the area Wednesday Night, and into 
the Canadian Maritimes Thursday into Thursday Night. High 
pressure builds in for next weekend. Another frontal system 
approaches for early next week.


Shortwave energy rounding the base of an upper low over eastern
Canada will send a cold front through the area dry this evening.
High pressure over the Ohio Valley then builds east through the

Expect few if any clouds with SW winds veering around to the NW
at less than 10 mph.

Overnight lows will be right around normal, generally in the
40s, except around 50 for the NYC metro.


Shortwave ridging between one departing upper low over eastern
Canada and an amplifying trough over the upper Midwest into the
Great Lakes, will result in dry, seasonably cool conditions. Any
clouds will be on the increase late Tuesday night as a frontal
system approaches from the west. 

A light northerly flow in the morning will become onshore in 
the afternoon as surface high pressure works offshore. 

Highs on Tuesday will top out in the lower 60s. Lows Tuesday
night will likely vary considerably due to good radiational 
cooling, from the lower 50s in metro NY, to the mid 30s to 
lower 40s elsewhere. With a light onshore flow and increasing 
low-level moisture, fog may be a possibility as well as frost. 
Guidance still showing dew point depressions significant enough 
to leave mention of fog out at this time.


Main story during this period will be a strong frontal 
system/developing coastal low affecting the region late Wednesday 
into Thursday.

Main features will be a strongly amplifying northern stream 
shortwave digging through the US/Canada border of the Rockies this 
afternoon. This feature will develop a closed upper low that slides 
into the upper Great lakes Tue/Tue Night, then phases with the 
southern stream Wednesday morning. The phasing and deepening closed 
low will approach the region Wednesday, and then pivoting through 
the area Wed Night into Thu morning and up the New England coast 
into the Canadian maritimes Thu afternoon thru Thu Night. At the 
surface, low pressure associated with the northern stream closed low 
will track east through the Great lakes Tue into Wed, with its 
associated strong cold front pushing towards the region late 
Wednesday. At the same time, phasing jet energy will begin to 
intensify a southern wave of low pressure tracking ne ahead of the 
front off the Mid-Atlantic coast; tracking just SE of LI Wed night. 
This will become the primary intense low pressure by Thursday 
morning as it tracks up the New England coast.

There is good general model agreement in the above scenario, but 
still some spread on intensity of the developing coastal low as it 
tracks se of LI and into New England, and to a lesser extent spread 
in how close or over the area the low tracks. The sensitivity of 
this appear to be with evolution of a Central PAC closed low, and 
downstream amplification of west coast ridging and northern stream 
shortwave, and then the eventual phasing with southern stream. The 
main implication for our area would be modest, in terms of 
amount/axis of rain and strength of winds ahead and behind system. 
This should come into better focus over the next 24-48 hrs.

Strong deep layer forcing with this system and a deep subtropical 
PAC and Gulf moisture connection (+1 1/2-2 std PWATS) point towards 
a heavy rain event late Wed through Wed Night. Strong forcing, 
closed low/vort energy moving through aloft, and weak surface 
instability point to potential for some deeper convection and 
embedded thunder. This bring likelihood for 1 to 2 inches of rain, 
with locally 2-3" inches of rain. Rain should quickly taper off late 
Wed night as trough axis pivots east. Deep cyclonic flow on Thursday 
will result in considerable cloud cover with scattered 
showers/sprinkles, particularly interior. Can't even rule out a wet 
snow flake or two across the far NW hills in any heavier showers as 
cold pool moves through aloft and coolest airmass of the season
works in. 

In terms of winds, ahead of the low a period of E/SE winds 20 to 25 
mph gusts 30-35 mph (peak winds 25-30 gusts to 40 mph possible 
across eastern LI) likely along the coastal plain Wed 
afternoon/evening. Then in the wake of low pressure W/NW winds of 20 
to 30 mph and gusts to 40 to 45 mph likely late Wed Night into 
Thursday. There is potential for wind advisory 30-35 mph and gusts 
to 50 mph if stronger low development verifies. Windy 
conditions will continue into Thursday Night, although gust 
potential likely decreases with decreased instability. 

Cyclonic flow will be slow to relent through the day Friday. NW 
winds will be weakening, but still a a breezy day. Another below 
seasonable day with sct-bkn afternoon strato-cu. 

Then a gradual moderation to seasonable and then above seasonable 
temps and fair weather this weekend as upper ridging build in and 
high pressure builds to the south of the region.

Next chance of rain looks to be some time early next week, as 
another deep trough develops over the central US, with an 
increasingly moist and active flow deep SW flow developing into the 
Eastern US. indication are a slow moving frontal system or systems 
approaching for Monday/Tuesday.


High pressure builds in today, then a cold front passes through this 

VFR. W-SW winds 5-10 kt into this evening.

     ...NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts, 
can be found at: http:/

KJFK TAF Comments: No unscheduled amendments expected.

KLGA TAF Comments: No unscheduled amendments expected.

KEWR TAF Comments: No unscheduled amendments expected.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.Wednesday...Lowering to IFR in the aftn with rain. Chc SE 
gusts around 25kt.
.Thursday...VFR. NW gusts 25-35kt.
.Friday...VFR. NW gusts 20-25kt mainly AM.


The pressure gradient remains relatively weak during the short 
term through Tuesday night. Conditions are expected to remain 
below SCA across all local waters.

SE winds increase across the waters Wednesday ahead of approaching 
cold front and developing low pressure. SCA conditions expected
on all the water by early Wed afternoon into evening ahead of 
low pressure. A brief period of gales likely on the ocean waters
east of Moriches inlet as low pressure approaches, and possible
for the rest of the ocean waters and E LI Sound/E bays as SE 
llj moves through.

Winds expected to shift to the NW Wed evening, with W/NW gales 
likely developing on the ocean waters late Wed night, and then 
likely all waters for Thursday. Gale conditions should fall to SCA 
Thu Eve/night, with SCA wind gusts likely subsiding Friday morning 
into afternoon. Ocean seas will rapidly build Wed aft/eve, but 
should fall below SCA Fri afternoon as winds weaken as they will be 
wind wave dominant.


A significant rainfall of 1 to 2 inches is likely Wednesday 
afternoon into Wednesday night, with localized swaths of 2 to 3 
inches. The bulk of the rainfall is expected in a 6 to 9 hr period 
late Wednesday afternoon through Wednesday evening. 

Urban, poor drainage, and low lying flooding is expected. There is a 
low probability of flash flooding along a few of the fast 
responding small rivers and streams in NE NJ and Lower Hud
Valley. Additionally, localized flash flooding will also be an 
issue for coastal areas if heaviest rain coincides with the Wed 
Night high tides.


Tidal departures of generally 2 to 2 1/2 ft above astronomical 
are needed for minor flooding during the times of high tide late
Wed Eve into Wed night. There is quite a bit of spread in the 
ensemble guidance, partly due to some differences in the 
potential strength of low pressure wind fields, and equally so 
due to timing of windshift from E/SE SCA winds to NW SCA winds.
At this point, model consensus would indicate potential for 
minor coastal flooding along much of the coastal plain, with a 
low probability for localized moderate impacts where wave 
action combines with elevated water levels.

If heaviest rain coincides with the Wed Night high tide, more 
widespread flooding would be experienced than normally expected 
by minor water levels. 


NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off the





National Weather Service Glossary of Abbreviations