Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
720 PM EDT Wednesday Jul 30 2014
weak high pressure over the middle-Atlantic region moves offshore
tonight. Upper level disturbance passes north and west of the
region on Friday. A frontal boundary will develop along the coast
through the weekend. A cold frontal passage is likely for the
beginning of next week.
Near term /until 6 am Thursday morning/...
00z water vapor imagery indicating shortwave rounding base of
upper level trough...with reflectivity showing associated showers
and thunderstorms over central PA/western New York. 23z laps shows minimal
instability and very little shear over the lower Hudson and NE New Jersey
and with the timing of the shortwave after the loss of any daytime
heating...expecting precipitation will diminish as it enters the area with
nothing to maintain the structure. As such...will maintain dry
probability of precipitation this evening and the early overnight hours.
High pressure over the middle-Atlantic moves offshore tonight...and
resulting return flow will allow for an increase in moisture over
the region. Middle-level clouds will spread into areas west of the
Hudson River towards daybreak Thursday. With the increase in low-level
moisture...some patchy fog is possible...mainly in the outlying
Lows tonight will drop into the middle and upper 60s in/around
NYC...while most other areas will drop into the upper 50s to low
60s. Lows in outlying portions of the lower Hudson Valley...
interior portions of southern CT...and The Pine Barrens of Long
Island will drop into the middle 50s.
Short term /6 am Thursday morning through Thursday night/...
fairly strong 500 mb shortwave pivots around closed low near the
Hudson Bay in Canada and passes just north and west of the local
County Warning Area. Cape values will rise close to 1000 j/kg and 0-6 km bulk
shear will increase to 40-50 knots. The lifted index will be fairly
weak... generally ranging from -1 to -2c. With the bulk of the
energy staying north of the region...will keep probability of precipitation capped at
chance...and will expect scattered showers/thunderstorms starting in the
late morning...tapering off by Thursday evening. Do think storms
will be hard to make it to far southeast CT and eastern Suffolk
County...and will keep probability of precipitation capped at slight chance for those
Maximum temperatures generally running near or a couple of degrees below
normal on Thursday with highs in the low 80s for NYC...Long
Island...NE New Jersey...and in the upper 70s to around 80 elsewhere.
Any showers/thunderstorms will taper off in the evening. Light...onshore
flow remains over the region with surface dew points rising into the
low-middle 60s. Patchy fog possible after midnight Thursday night
away from NYC.
Long term /Friday through Wednesday/...
Friday...instability across mainly the interior areas will set the
stage for scattered convection during the afternoon hours.
Saturday and Sunday...a surface low pressure along the Atlantic
coast...and subtropical moisture associated with a Bermuda ridge
will aid in the development of showers/thunderstorms Saturday and
Sunday. The 12z/GFS continues to have the best forcing for chance of
showers to be on Sunday...while 12z/European model (ecmwf) shows the best forcing to
be on Saturday. Will continue with previous thinking and maintain
40/50 pop for the weekend.
Monday and Tuesday...a low pressure moving through the Great Lakes
region will bring a cold front towards the area. This will keep schc
probability of precipitation on Monday...with drier air moving in on Tuesday.
Temperatures through the extended period will be close to seasonable
Aviation /23z Wednesday through Monday/...
high pressure remains off the middle Atlantic to northeast coast into
VFR through the taf period. There is a chance of showers across the
lower Hudson Valley from around 14z to 19z...with kswf possibly
impacted. A rumble of thunder in also possible. A few sprinkles are
possible from late morning into the early afternoon across
northeastern New Jersey into the NYC terminals...however no impact
to ceilings or visibilities is expected.
Wind becomes light and variable/light SW tonight. A sea breeze is
expected to develop 16z to 19z Thursday.
..NY 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: no unscheduled amendments expected.
Klga fcster comments: no unscheduled amendments expected.
Kewr fcster comments: no unscheduled amendments expected.
Kteb fcster comments: no unscheduled amendments expected.
Khpn fcster comments: no unscheduled amendments expected.
Kisp fcster comments: no unscheduled amendments expected.
Outlook for 00z Friday through Monday...
Thursday night-Monday...VFR...except MVFR or lower
possible in any isolated-scattered rain showers/thunderstorms that are possible mainly in the
afternoon/evening each day.
with high pressure over the waters...can expect sub-Small Craft
Advisory conds through Friday. Winds and seas will remain below
Small Craft Advisory levels through the extended period.
brief...locally heavy downpours possible in scattered thunderstorms on
Thursday...but not expecting more than localized nuisance
flooding. A humid air mass will be conducive to the development of heavy
showers this weekend.