Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 190140
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
940 PM EDT Wed Oct 18 2017

.SYNOPSIS...
High pressure will remain in control through the end of the week
before gradually shifting offshore through the weekend.
Meanwhile, a dry cold front will approach from the north on
Thursday and move through the local area on Friday. Another cold
front will then slowly approach and pass through during the
middle of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Seasonable weather continues as high pressure remains across
the area. Although clear skies and light winds will create
favorable radiational cooling conditions tonight, subtle return
flow has allowed dewpoints to increase into the mid 40s to lower
50s. As such, low temperatures tonight will be closer to normal
climatological values rather than the below normal we have
experienced the past few nights.

Forecast is generally on track. Minor adjustments made to
T/Td/winds based on latest obs and trends. Also added some
patchy fog to the forecast overnight with minimal dewpoint
depressions and light to calm winds.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Southwesterly flow will strengthen into Thursday ahead of a weak
cold front. Temperatures will be 5 to 10 degrees above normal
in warm advection, particularly to the west of NYC where marine
influence will be minimal. Have trended a few degrees above
guidance in these areas, primarily for northern NJ. A few gusts
will be possible by evening ahead of the front and with its
passage late. The mixing associated with the front will keep
temperatures above normal into the overnight. Given the
antecedent dry air mass, no precipitation is expected with the
frontal passage.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Large ridge remains in place Friday and Saturday, ahead of
downstream trough that will makes its way east, deepening as it does
so.

The global models prog a southern stream cutoff low over the
southeast states Monday, and this shortwave energy quickly moves
northeast Tuesday ahead of the main longwave trough that remains to
the west, slowing down as it deepens Tuesday and Wednesday.

Surface high pressure builds behind a weak front during the Friday
through Sunday period.

By Monday, a wave of low pressure likely develops over the southeast
states along a cold front. The front will make slow eastward
progress, approaching Tuesday and passing Tuesday night as low
pressure rides along it. Still, there is much uncertainty though on
all these features and forecast details this far out as the front
could move east or stall nearby.

As for sensible weather, dry conditions are expected until Monday,
or Monday night. Increasing chances for showers Monday night/
Tuesday can be expected ahead of shortwave/trough/front. In fact,
increasing moisture sweeps northward as the Gulf of Mexico is tapped
which could lead to some heavier showers Tuesday or Tuesday night.

These showers could very well linger into Wednesday depending on
speed of front and trough, a conveyor belt of moisture advecting
south to north. Have a feeling the slower solutions will pan out due
to strength of the trough. Either way, showers will be possible as
upper cold pool approaches from the west if the front passes quicker.

Temperatures through the period will remain several degrees above
normal.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR through the TAF period with high pressure remaining southeast of
the region through Thursday evening.

SW winds 10-12 kt will continue for next few hours at city
terminals. Winds will diminish overnight to around 5 kt at city
terminals and light and variable elsewhere. SW flow increases
on Thursday and becomes gusty in the afternoon. Start time of
the gusts could vary a few hours from forecast.

     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: A few gusts in the upper teens possible
through 01-02z.

KLGA TAF Comments: No unscheduled amendments expected through
tonight.

KEWR TAF Comments: No unscheduled amendments expected through
tonight.

KTEB TAF Comments: No unscheduled amendments expected through
tonight.

KHPN TAF Comments: No unscheduled amendments expected through
tonight.

KISP TAF Comments: No unscheduled amendments expected through
tonight.

.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.Thursday night...VFR.
.Friday-Friday night...VFR. NW-N winds G15-20kt possible Friday
afternoon and evening.
.Saturday-Sunday night...VFR.
.Monday...MVFR possible with chances of showers in the
afternoon.

&&

.MARINE...
Minor adjustments made to winds/seas based on latest obs/trends.

Winds and seas will remain tranquil into tonight before
gradually building into tomorrow in strengthening southwesterly
flow. A SCA has been hoisted for the ocean areas east of Fire
Island as gusts near 25 kt and seas briefly building to 5 ft
will be possible by tomorrow evening. Conditions gradually
subside into Friday as the front passes to the east and high
pressure begins to build into the area once again.

The high pressure then builds this weekend, with sub SCA
conditions forecast.

As the high moves east Sunday and Monday, southerly flow will
increase as the waters sit between the high to the east and an
approaching cold front to the west.

&&

.HYDROLOGY...
No hydrologic issues expected through the weekend. Locally heavy
rain is possible during the beginning of next week. Urban/poor
drainage flooding would be the main threat if heavy rain does
indeed occur.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 4 PM Thursday to 6 AM EDT Friday for
     ANZ350-353.

&&

$$



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