Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1046 am EDT Thursday Jul 24 2014
a cold front near Cape Cod will continue to track slowly east
today. High pressure builds into the area tonight and Friday and
then offshore on Saturday. A frontal system approaches Saturday
night into Sunday...with an associated area of low pressure
passing to the northwest on Monday. Following the cold front
passage...high pressure builds in towards mid-week.
Near term /until 6 PM this evening/...
have removed the isolated showers in the forecast with drying low-
levels and strong capping inversion around 750 mb.
Slow moving cold front just east of Cape Cod this morning will
continue working slowly east as the upper trough approaches from
Drier air moves in from the northwest...with weak cold air advection noted
behind the front and with the approach of the trough.
Assuming mixing up to about 800 mb...high temperatures in the lower 80s seem
reasonable based on 800 mb temperatures settling around 12c per NAM and GFS.
MOS numbers close and accepted.
Cannot rule out late day sea breezes if winds remain sufficiently
A moderate risk of rip currents exists for eastern Long Island
beaches today with residual southerly swells.
Short term /6 PM this evening through 6 PM Friday/...
upper trough moves across the area and lifts to the north through
this time frame. At the surface...high pressure builds from the west.
Any evening showers give way to dry weather with lower humidity.
A light northerly wind tonight will give way to onshore flow
Friday as the high moves overhead.
MOS temperatures are close...with 50s across the interior...and 60s near
the coast tonight...and upper 70s to lower 80s Friday.
Long term /Friday night through Wednesday/...
as high pressure shifts farther offshore on Saturday...return flow
will help increase moisture across the tri-state.
Additionally...weak 500 mb shortwaves passing near/just north of the
area in zonal flow result in slight/low chance probability of precipitation across the area.
Late Saturday night into Sunday morning...a warm front will lift
across the area as a stronger shortwave progresses to the east
across southern Ontario/Quebec. As a result...chances for showers
and storms will be on the increase...as SW flow aloft increases over
the frontal surface.
As the warm front lifts north and east of the region during the
first half of Sunday...there may be somewhat of a lull in activity
across the area. However...with several shortwaves embedded in the
flow aloft and the increasing moisture present...timing of more
widespread activity is fairly uncertain. 24/00z GFS is more
robust/quicker than 24/00z CMC/European model (ecmwf) with a wave approaching from
the west on Sunday. Believe it is a little too fast...therefore did
not go with likely probability of precipitation everywhere until Sunday night. During this
time...the CMC solution indicates the potential for widespread heavy
rain...as somewhat strung-out cyclogenesis takes place across the
area...and a strong low level jet develops along an axis of higher 500 mb Theta-E.
European model (ecmwf) appears to keep the upper-level jet dynamics a little farther
NW/weaker...resulting in higher quantitative precipitation forecast bypassing the area to the northwest.
Regardless...precipitation appears likely by Sunday night.
Chances for rain gradually diminish Monday into Monday night and
Tuesday...as the associated surface cold front moves through the
area and off to the east. Nonetheless...with the deep upper-level
trough taking hold and cyclonic flow across the region...some
diurnal activity is possible Tuesday.
Following the frontal passage...temperatures look to be a few degrees below
normal Tuesday into Wednesday.
Aviation /15z Thursday through Monday/...
high pressure slowly builds in from the west today.
Mainly VFR...but tempo ceilings 2000-3000ft could occur this morning.
Winds north-north-northwest around 10kt. Sea breeze/onshore flow forecast for
kgon/kbdr this afternoon...as well as kjfk. Least confidence with kjfk.
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: occasional gusts 17-20kt through 16z. Chance that
winds do not back to SW this afternoon or timing of backing winds could
be off by 1-2 hours.
Klga fcster comments: occasional gusts 17-20kt through 16z.
Kewr fcster comments: occasional gusts 17-20kt through 16z.
The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.
Kteb fcster comments: no unscheduled amendments expected.
Khpn fcster comments: no unscheduled amendments expected.
Kisp fcster comments: westerly winds possible after 18z. Low chance of southerly
winds after 20z. Isolated gusts up to 20 knots through 16z.
Outlook for 12z Friday through Monday...
Sat night-Mon...VFR with a chance of rain showers/thunderstorms with MVFR or
a cold front just east of Cape Cod slowly continues to track away
from the waters today. High pressure builds in Friday. Sub Small Craft Advisory
conditions are anticipated today through Friday.
Relatively tranquil conditions look to exist on the ocean waters
through Saturday. With strengthening S/SW winds Saturday night
into Sunday...seas look to reach Small Craft Advisory criteria during the second
half of the weekend into early next week.
areas of low pressure passing near the area Sunday into Monday
have the potential to produce showers and storms capable of heavy
rain. Significant uncertainty still exists with timing/amounts
though...so will not outlook in severe weather potential statement at this time.
short term...precipitable water