Area forecast discussion
National Weather Service New York New York
712 am EDT Thursday may 23 2013
Synopsis...
a broad area of low pressure slowly approaches today and
tonight...dragging a cold front through the area Friday morning.
The center of this system will then exit to the east by the end
of the day...and remains just east of the region through
Saturday. It then tracks north along the New England coast on
Sunday. High pressure over the Great Lakes builds southeast across
the area Monday into Tuesday. A warm front will then approach from
the southwest by middle week.
&&
Near term /until 6 PM this evening/...
forecast on track...with main adjustment to probability of precipitation to account for
expected track of area of thunderstorms over east Li and another
over southeast PA through middle morning.
Otherwise...with models showing plenty of moisture at least in the middle
levels...it looks like clouds will outweigh sunshine across the
area. Perhaps it could be just partly cloudy at times across parts
of CT and Long Island. In spite of this...SBCAPE values are
expected to climb into the range of 1000-1500 j/kg for inland
spots. Lift ahead of the cold front is expected to produce showers
and scattered thunderstorms for roughly the western half of the
area...meanwhile...mid level shortwaves will give eastern areas an
enhanced chance of showers and storms during early this morning
and again this afternoon. With this said...showers and storms will
be still possible at any given point at any given time.
With the given cape and bulk shear near 30-35 knots...severe
thunderstorms will be possible. Precipitable water values around 1.75 inches and
potentially training cells will allow for the possibility of at
least localized minor flooding. Confidence at this time regarding
timing/coverage/placement of flash flooding is too low to go with a
watch for flash flooding. Please see the hydrology section below for
more details.
&&
Short term /6 PM this evening through 6 PM Friday/...
cold front eventually moves into the western zones late at night
providing lift. Farther east...lift comes courtesy of additional middle
level shortwaves and a strengthening low level jet. On a larger
scale...lift from the right entrance region of a jet streak aloft
shifts in late at night. So showers will be likely along with
thunderstorms...as well as the continued threat of localized
flooding. The severe thunderstorm threat should linger at least into
the evening hours.
Although the center of the system and cold front will be to our east
by the end of the day on Friday. Still expecting some showers right
along the system...as well as a continued threat in the afternoon as
a trailing shortwave moves in from the west. Thunderstorms will
still be possible...but mainly associated with the exiting cold
front.
&&
Long term /Friday night through Wednesday/...
model consensus continues to depict a slower and deeper solution with
the approaching upper trough over the middle section of the
country...taking a closed upper low from the Middle Atlantic States on
Friday NE to over New England on sun. Preference at this time is to
continue to trend forecast towards the slower GFS/European model (ecmwf) solution
based on model trends and the run to run continuity being exhibited
over the last several model cycles.
As for sensible weather...this results in a breezy...cool and wet
weekend. Potential exists for moderate frontogenetic rain banding on
Saturday...with gradually tapering to shower activity Sat night
through Sunday. It is not out of the question that instability
shower activity could linger into Monday. Northwest winds of 15 to 25 miles per hour with
gusts up to 35 miles per hour are possible through the weekend.
Temperatures this weekend could be a good 8 to 12 degrees below
seasonable...with temperatures likely struggling to get out of the 50s with
cold pool aloft...clouds and rain. Temperatures on Sunday will likely not
be any better based on trends. Overnight lows will be close to
seasonable. A gradual warm-up to near seasonable levels is then
forecast Mon-Wed.
&&
Aviation /11z Thursday through Monday/...
a frontal boundary will remain nearly stationary north of the
terminals through the forecast period. A low pressure system and
cold front approach slowly from the west during the day.
An area of showers has pushed east of NYC...so eastern terminals can
expect some hit or miss showers. Can not rule out a rumble of
thunder early this morning.
Eastern terminals have MVFR ceilings and visibilities in fog. IFR
ceilings and MVFR visibilities in fog are more likely at the
terminals east of New York City...ceilings may become LIFR after 09z.
MVFR conditions are likely during Thursday with showers
developing after 17z. Isolated thunderstorms are also possible.
Wind will be generally from the south 10 knots or less through late
tonight...then south to southwest 10 to 15 knots late tonight into
Thursday.
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: amendments possible this morning for changing
flight categories in low stratus and fog.
Klga fcster comments: amendments possible this morning for changing
flight categories in low stratus and fog.
Kewr fcster comments: amendments possible this morning for changing
flight categories in low stratus and fog.
The afternoon kewr haze potential forecast is yellow...which implies
slant range visibility 4-6sm or greater outside of cloud.
Kteb fcster comments: amendments possible this morning for changing
flight categories in low stratus and fog.
Khpn fcster comments: ceilings and visibility improve around 13z-14z
Kisp fcster comments: changing flight categories may occur in areas
of precipitation. Amendments may be needed this morning.
Outlook for 06z Friday through Monday...
Thursday night-Friday...numerous rain showers...isolated thunderstorms possible.
MVFR to IFR in showers...fog and stratus.
Saturday...rain showers likely with MVFR or Lower. North winds 25-30g35kt.
Sunday...most likely VFR with northwest winds 20-25kt. Potential for gusts
up to 40kt.
Monday...VFR. Northwest winds 15-20g25kt.
&&
Marine...
patchy fog with visibility of a mile or below is possible until
mid-morning. Otherwise...Small Craft Advisory has been extended through Friday as a
lingering swell likely keeps seas up over 5 feet over a good portion
of the ocean waters. Gusts to 25 kts will be possible as well
during parts of this period.
Small Craft Advisory conditions are becoming increasingly likely...with the potential
for gale conditions Sat into sun...as low pressure forms over the
waters on Friday and lifts slowly to the north and east. Winds and
seas begin to subside late sun into Monday with high pressure
building in from the Great Lakes region.
&&
Hydrology...
there is the potential for around inch basin average rainfall today
through tonight. Higher amounts will be possible in thunderstorms.
Not expecting any widespread flood threat today and tonight...but at
least some minor flooding is probable. Flash flooding is not out of
the question...and this will need to be closely monitored as the day
wears on.
The threat for localized heavy rainfall will continue into the first
half of Friday with embedded convection. An additional 1/2 to 1 inch of
rainfall is possible Friday night into sun. This may exacerbate any
ongoing flooding.
For details on specific area rivers and lakes...including observed
and forecast river stages and lake elevations...please visit the
advanced hydrologic prediction service /ahps/ graphs on our website.
&&
Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory until 6 PM EDT Friday for anz350-353-355.
&&
$$
Synopsis...jc/NV
near term...jc
short term...jc
long term...Nevada
aviation...British Columbia
marine...jc/NV
hydrology...jc/NV
