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fxus61 kokx 221055 
afdokx

Area forecast discussion
National Weather Service New York New York
555 am EST Wed Nov 22 2017

Synopsis...
rain this morning ends from west to east as a cold front moves
through. High pressure builds in Wednesday through the end of
the week. A cold front crosses Saturday night, with high
pressure building in from the west for the beginning of next
week.

&&

Near term /until 6 PM this evening/...
530 am update. Believe forecast is on track based on radar and
latest hrrr run! Area of moderate rain now moving out of
Maryland and Delaware reaches the New York Metro around 730 am. 4/10"
so far at kisp - so also thinking quantitative precipitation forecast should work out as well.

The jet dynamics have resulted in the very rapid evolution of
the rain event for this morning with cold frontal passage resulting in a
rapid end from mid morning to mid afternoon (west to east). The
right rear jet entrance to the 120+ knots is the forcing. Rather
complex, but interesting pattern.

High resolution cam's and href appear to have good handle on
the pattern/timing - uncertainty though lies in the quantitative precipitation forecast. Have
gone with around 1/4" for the city and 3/4" for the Twin Forks
of Suffolk County. 06z NAM has gone back to 1.5" and is
consistent with the rapx (version 4). While the operational
rap/hrrr time-lagged runs keep with what we've gone with.

Other uncertainty of "will back edge be west or east of the New York
metro" appears very certain now as the jet dynamics have
"widened" and next wave of precip west. Thus, full expect the
categorical rain (100 pop) for the Metro and lower Hudson
Valley as the area of precipitation over Maryland/Delaware moves north.

It's a quick shot for the city with rain ending around 10 am.

Thank goodness it's not February and we were dealing with snow!
A nice case for zero to 12+" of uncertainty in the first few
hours of the forecast.

Otherwise - skies clear and northwest winds gust up to 25 mph by late
afternoon as cold air advection sets in.

&&

Short term /6 PM this evening through 6 PM Thursday/...
clear, with diminishing winds overnight allows for radiational
thermal decoupling in the rural areas. A blend of MOS was used
with near freezing in the New York Metro for lows forecast.

Sunny and chilly, but with a light wind for Thanksgiving. Cooler
NAM/European model (ecmwf) blend seems best for temps (about 8 degrees below
normal).

&&

Long term /Thursday night through Tuesday/...
high pressure at the surface, pushes off the East Coast late
Friday into Friday night as a warm front over the eastern Great
Lakes lifts well north of the area. Warm air advection doesn't
seem to kick in until Friday evening, so dry and continued cool
for Friday, but slightly warmer than Thursday with highs in the
middle to upper 40s.

Another cold front approaches the area late Saturday and passes
through Saturday night. Southwesterly flow ahead of the front will
bring temperatures to normal levels to above normal levels, in the
upper 40s to upper 50s. 00z gefs keeps it dry.

A secondary cold front moves through on Sunday with a
reinforcing shot of cold air. Some instability with the colder
air aloft associated with the upper level trough may produce
some light rain showers.

High pressure then keeps the area dry through the beginning of next
week.

&&

Aviation /12z Wednesday through Sunday/...
a cold front approaches from the west early this morning, then
crosses the area later this morning. A coastal low passes to
the east of Long Island this afternoon. High pressure then
builds in from the west into tonight.

MVFR conditions develop towards daybreak as rain overspreads
the terminals, except IFR conditions at khpn/kisp/kgon. There is
a chance that the city terminals have IFR conditions during the
morning, as well, but confidence in this is too low to put in
the tafs at this time. Rain likely ends by around noon for the
city terminals and points west, and early afternoon farther
east. There is a low chance for isolated thunderstorms at kgon
and kisp through around 15z.

Light and variable winds become northwest and increase by mid morning.
20-25kt gusts become frequent during the afternoon, then taper
of during the evening.

New York 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: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. Low chance of IFR
conditions this morning. Moderate to high confidence in winds to
the right of 300 true/310 magnetic this afternoon.

The afternoon kjfk haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.

Klga taf comments: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. Very low chance of IFR
conditions this morning. Moderate to high confidence in winds to
the right of 300 true/310 magnetic this afternoon.

The afternoon klga haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.

Kewr taf comments: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. Very low chance of IFR
conditions this morning. Moderate to high confidence in winds to
the right of 300 true/310 magnetic this afternoon.

The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.

Kteb taf comments: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. Very low chance of IFR
conditions this morning.

Khpn taf comments: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. There is a low chance
conditions do not fall to IFR and only to MVFR.

Kisp taf comments: timing of changes in wind speed, direction
and gusts could be off +/- 1-2 hours. There is a very low
chance conditions do not fall to IFR and only to MVFR. There is
a low chance that IFR conditions could linger up to a few hours
longer than forecast.

Outlook for 06z Thursday through Sunday...
late tonight-Friday night...VFR. Northwest winds g15-20kt possible
late tonight/Thursday morning. SW winds g15-20kt possible
Friday night, mainly at eastern terminals.
Saturday-Saturday night...MVFR possible. West-northwest winds g15-20kt
possible Saturday night.
Sunday...becoming VFR. Northwest winds g20-30kt possible.

&&

Marine...
Small Craft Advisory continues for the ocean waters as seas will be slower to
subside. A cold front will be moving east of the forecast waters
this afternoon as high pressure builds to the west, with
Small Craft Advisory gusts likely all waters in its wake.

5 to 6 ft waves on the ocean waters on Thursday as a northwest
flow shifts to the west-southwest. Waves will diminish Friday,
generally coming down below 5 ft for most areas on the ocean by
Friday afternoon. Waves increase again on the ocean late Friday
night as a southwesterly flow sets up ahead of an approaching
cold front, diminishing Saturday night.

Winds should generally remain below 25 kt until Sunday afternoon as
a northwest flow strengthens behind the passage of a cold front.
Winds should remain above 25 kt from Sunday evening throughout the
rest of the long term.

&&

Hydrology...
rain this morning 1/4-3/4" with the potential for up to 1.5
inches across Long Island to southeast CT. Some urban ponding possible.
Otherwise, no hydrologic problems are anticipated the next 7
days.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory from 3 PM this afternoon to midnight EST
tonight for anz330-335-338-340-345.
Small Craft Advisory until 6 am EST Thursday for anz350-353-
355.

&&

$$
Synopsis...tongue
near term...tongue

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