Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kokx 281344 
afdokx

Area forecast discussion
National Weather Service New York New York
944 am EDT Tue Mar 28 2017

Synopsis...
a frontal system will approach today, and pass early Wednesday.
High pressure will build in for Thursday, and drift offshore
Thursday night. A low pressure system will impact the region
Thursday night into Saturday. High pressure builds in Sunday and
Monday.

&&

Near term /through tonight/...
satellite indicates the main upper level system was moving
over eastern Kentucky into West Virginia. Elevated instability
was increasing across the forecast area evidenced by showers and
thunderstorms. These should continue to develop per the NAM
which appears to have a very good handle on the activity thus
far. Fog was widespread, however, visibilities were generally 2
to 4 miles, with areas 1 to 2 miles. As the main system
approaches this afternoon and evening, more showers can be
expected. Some embedded thunderstorms cannot be ruled out until
the instability axis exits, leaving remnant stratiform light
rain. The models were in good agreement so a blend was used for
temperatures through tonight.

&&

Short term /Wednesday/...
dry weather with a northwesterly breeze. Despite a cooler
airmass in place, temperatures will actually be warmer than
Tuesday because of deep mixing. Mostly sunny skies are progged,
although some fair weather convective clouds will be possible if
they are able to overcome the subsidence. A blend of the
guidance was used for temperatures.

&&

Long term /Wednesday night through Monday/...
the extended period will feature a split flow across the Continental
United States with systems moving through active northern and
southern streams. As a result, even through there are similarities
in the longwave and overall solutions, the details of the forecast
have become more uncertain, and inconsistencies from run to run have
increased. Currently there is now little to no phasing of systems
impacting the east, and in particular the region, Thursday night
into Saturday, and yet another system Monday night into Tuesday.
There are now more uncertainties as to the depth of the lows,
timing, and tracks.

For late Thursday night through Saturday night have long period of
probabilities, and even likely probabilities from Friday into
Saturday. This is likely too long a period however, with the
uncertainties wanted to maintain some consistency with prior
forecasts. Both the European model (ecmwf) and GFS have some lingering cold air
across the northern portions of the County Warning Area Thursday night before warm
advection increases. So have kept a mix of snow and rain inland.

Canadian high pressure builds in for late Saturday night into
Monday, and possibly Tuesday if ridging remains as per the GFS.
The European model (ecmwf) is quicker to weaken and shift the ridge off shore
Tuesday. Have introduced a low chance of precipitation for
Tuesday.

&&

Aviation /14z Tuesday through Saturday/...
a front remains just south of the terminals and attempts to
push back north as a warm front today.

Light east-northeast winds this morning with areas of rain and low
ceilings. LIFR conditions at times this morning, otherwise areas
of rain this morning will result in IFR conditions at times,
and then back down to LIFR when the rain lightens or stops.
Some thunder will be possible along the southern terminals
(kewr, kjfk, kisp) this morning between 14z-16z

Another area of rainfall will arrive later in the day and for
the evening. There is a thunderstorm chance with this next area
of rainfall for the city terminals, but not confident enough to
put in tafs at this time. IFR to LIFR conditions are expected
to prevail until about 6z late tonight, with improving
conditions thereafter from west to East.

New York Metro enhanced aviation weather support...

Detailed information, including hourly taf wind component forecasts,
can be found at: http:/www.Weather.Gov/zny/n90

Kjfk taf comments: timing of next area of rain may be off by +/-
2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

Klga taf comments: timing of next area of rain may be off by +/-
2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

Kewr taf comments: timing of next area of rain may be off by
+/- 2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

The afternoon kewr haze potential forecast is yellow...which
implies slant range visibility 4-6sm outside of cloud.

Kteb taf comments: timing of next area of rain may be off by +/-
2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

Khpn taf comments: timing of next area of rain may be off by +/-
2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

Kisp taf comments: timing of next area of rain may be off by +/-
2 hours this afternoon. There is a thunderstorm chance late
today but confidence is low.

Outlook for 12z Wednesday through Saturday...
Wednesday...VFR. North-northwest gusts 15-20kt.
Thursday...VFR.
Friday...a wintry mix possible early north and west with IFR
conditions possible before a change to rain, otherwise sub VFR
conditions with rain elsewhere.
Friday night and Saturday...chance of rain with MVFR or lower
conditions. East winds g20-25kt at coastal terminals for Saturday.

&&

Marine...
winds and seas will remain below Small Craft Advisory levels
through tonight. Patchy fog may limit visibilities to less than
1 nm at times today, but it is no longer expected to be
widespread. The dense fog advisory was therefore cancelled.
Marginal Small Craft Advisory level winds are possible on
Wednesday after the frontal passage.

Small Craft Advisory conditions will be likely across the ocean
forecast waters Wednesday night into Thursday, with strong and
gusty northwest winds, as high pressure builds in behind a cold.
Ocean seas will build Wednesday nigh into early Thursday and may
be around small craft levels. In addition, occasional gusts
across eastern Long Island Sound, and the eastern bays may be
near small craft levels Wednesday night.

Northwesterly winds will develop behind the cold front and then
increase into Wednesday and Wednesday night as high pressure
builds to the north. Minimal Small Craft Advisory conditions are possible across
the ocean waters Wednesday night into early Thursday.

Sub advisory conditions are expected late Thursday into Friday
as high pressure moves across the waters.

The next chance of small craft conditions will be late Friday
through Saturday night as southerly winds increase ahead of a
low pressure system.

&&

Hydrology...
basin average rainfall of a half inch or less can be expected
through tonight. Locally heavier amounts can be expected however
in any thunderstorms that develop.

Additional rainfall of 1/2 inch to 1 inch will be possible
Thursday night through Saturday. No hydrologic concerns are
anticipated.

&&

Tides/coastal flooding...
astronomical tides remain high due to a recent new moon.

Water levels may approach minor flood thresholds during the high
tide cycles Thursday night, with minor flooding possible Friday
night as a low pressure system approaches.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.

&&

$$
Synopsis...12/met
near term...12/met
short term...12

National Weather Service Glossary of Abbreviations