Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service New York New York
355 PM EDT Friday Apr 18 2014

Synopsis...
a weak trough pushes north of the region late tonight with another
area of high pressure then building down from southern Canada
through the weekend. A frontal system will impact the area from
Tuesday into Wednesday. High pressure then builds down from south
central Canada into Thursday.

&&

Near term /until 6 am Saturday morning/...
overall...a split flow across the country with northern branch of
upper level jet staying north of the region. Clouds will continue
to move through much of tonight ahead of an approaching trough in
the middle to upper levels. The axis of the upper level trough moves
near by Saturday morning. Clouds are expected to thin and further
scatter with just cirrus by late tonight.

An overall weak pressure gradient will lead to light winds and
they will become more northerly towards daybreak Saturday. The
combination of northerly winds and extra clouds will limit the
lower potential of temperatures tonight. Think enough radiational
cooling will occur across parts of the interior for areas of frost
where winds will be lighter but will be very localized and
restricted to best cooling spots farther south.

Minimum temperatures were a blend of 3/4 met and 1/4 mav...which
is preferring the colder side of guidance. Values overall will be
at least a few degrees below normal.

&&

Short term /6 am Saturday morning through Sunday/...
for Saturday...ridging trend in the middle to upper level behind the
trough will promote subsidence and keep a mostly sunny Sky. High
pressure will be building into Quebec with winds being out of the
north. The setup is there for a much warmer day across the region.
The northerly flow will keep marine influence to a minimum and
downslope will lead to warmer temperatures even at the coast. Maximum
temperatures were a blend of 1/2 mav and 1/2 gmos and increased by
two...preferring the warmer side of guidance. Forecast maximum
temperatures are around 5-6 degrees above normal.

The high pressure area will then build into northern New England
through the rest of the weekend. In the middle to upper levels...a
quasi-zonal flow will result with a cutoff low moving off the
southeast U.S. Coast. While the subsidence will still be strong
Saturday night with the ridge axis moving across...an increasing
northeasterly flow will promote lower dewpoints. While the lows
Saturday night will be similar to those of the previous
night...the relative humidity levels will be lower...limiting frost potential.

Sunday with this return flow developing and more onshore component
as high pressure moves off the northern New England
coast...temperatures will be cooler at the coast. There will be
more marine influence. Highs were a blend of ece and gmos and will
be pretty close to normal values. Still keeping clouds lower with
high pressure not too far away...thereby allowing for another
mostly sunny day.



&&

Long term /Sunday night through Friday/...
high pressure will remain anchored across the area Sunday night into
Monday. On Sunday night...good radiational cooling will aid in low
temperatures dropping into the middle to upper 30s. Monday's high
temperature will mainly be in the low to middle 60s...which is near
normal for this time of year.

A surface low is expected to move into the Great Lakes Monday
night...with its associated cold front tracking through the Ohio
Valley. 12z GFS keeps the cold front to our west on Tuesday
therefore kept conditions dry during the day on Tuesday.
Precipitation associated with this system is expected to spread
across the area from west to east Tuesday evening/night into
Wednesday morning. High pressure builds across the area Wednesday
night and remains through the end of the week.

Temperatures will be above normal on Tuesday...near normal Wednesday
and Thursday and above normal on Friday.

&&

Aviation /19z Friday through Wednesday/...
high pressure will slowly move east while weakening tonight.

Middle and high level clouds for the remainder of the evening.
Southeast-south flow less than 8 knots expected over the next few
hours...then winds diminish to 5 knots or less.

Winds will shift to the west then northwest after midnight as a weak
trough moves through the region. Winds tomorrow will remain from the
northwest around 8-15kt. Expect gusts into the lower 20 knots range.

Low confidence as to whether or not stratus will redevelop after
00z Saturday...so will leave out of the tafs for now. VFR expected
during the day on Saturday.

New York metropolitan enhanced aviation weather support...

Detailed information...including hourly taf wind component forecasts can
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)

Kjfk fcster comments: low chance of MVFR ceilings returning this evening.

Klga fcster comments: winds may become light and variable this evening. Low
chance of MVFR ceilings returning this evening.

Kewr fcster comments: winds may become light and variable this
evening. Low chance of MVFR ceilings returning this evening.

Kteb fcster comments: winds may become light and variable this
evening. Low chance of MVFR ceilings returning this evening.

Khpn fcster comments: winds may become light and variable this
evening. Low chance of MVFR ceilings returning this evening.

Kisp fcster comments: winds may become light and variable this
evening. Low chance of MVFR ceilings returning this evening.

Outlook for 18z Saturday through Wednesday...
Saturday-Tuesday morning...VFR.
Tuesday late afternoon-Wednesday...MVFR possible with showers...cold
frontal passage.

&&

Marine...
Small Craft Advisory for hazardous seas until 10z Saturday as lingering easterly
swell keeps higher seas within the forecast coastal ocean zones.
This afternoon...for buoy 44017 seas were running about 1 feet
higher than wavewatch.

Elsewhere...sub-sca conditions expected through Saturday night with
high pressure gaining control. Once the seas on the ocean subside
early Saturday...sub-sca conditions expected there as well through
Saturday night. Winds will be marginal during the day
Saturday...with gusts up to mostly 20 knots. Will have to watch for
another potential Small Craft Advisory event for ocean seas on Sunday with the more
easterly flow.

Sub-Small Craft Advisory conditions expected across the area waters Sunday night into
Tuesday. Seas across ocean waters are forecast to increase to Small Craft Advisory
conditions on Wednesday as a low pressure system moves across the
waters. Seas are expected to drop back to below Small Craft Advisory conditions on
Thursday and remain below Small Craft Advisory levels through the end of the week.



&&

Fire weather...
a dry day Saturday with gusty north-northwest flow will lead to lower
dewpoints and therefore lower relative humidity values. Min relative humidity values will range
between 18 and 30 percent mostly. Wind gusts will be up to 20-25
miles per hour at times through the day. This will enhance any fire spread
potential.

&&

Hydrology...
no significant precipitation is expected through the weekend.

There is the potential for a rainfall event Tuesday night into
Wednesday morning. At this time...there is too much uncertainty to
specify exact amounts or any potential impacts - if any.

Note...minor flooding continues along the Connecticut River. For
additional information...please refer to the latest flood warnings
from National Weather Service Taunton Massachusetts.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory for hazardous seas until 6 am EDT
Saturday for anz350-353-355.

&&

$$
Synopsis...fig/jm
near term...jm
short term...jm
long term...figure
aviation...British Columbia
marine...fig/jm
fire weather...jm
hydrology...fig/jm