Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
950 am EDT sun Aug 2 2015
the local area will be under the influence of weak high pressure
into Monday. A weak cold front will move into the region Monday
night and stall in the vicinity of New York City through Tuesday
before pushing east Tuesday night. Several areas of low pressure
may impact the area during the second half of the week.
Near term /until 6 PM this evening/...
forecast on track.
A broad upper trough will remain across the northeast for the
next several days and will be reinforced from time to time as
shortwaves move around a vortex over Ontario and Quebec.
Heights rise slightly aloft today ahead of upstream shortwave that
dives toward the Great Lakes region. At the surface...weak high pressure
will prevail with light west/northwest flow becoming south/southwest over
the area today. Seabreezes are expected to develop.
Highs will be similar to yesterday...generally middle to upper 80s
and around 90 in the metropolitan under sunny skies.
There is a moderate risk for the development of rip currents at
the ocean beaches today.
Short term /6 PM this evening through Tuesday night/...
500 mb flow amplifies across noam tonight and Monday in response to
cutoff low moving onshore in western Canada and the 500 mb Canadian
vortex drifting southward.
Warm and muggy tonight with weak warm air advection in place. Increasing
dewpoints and clear skies could result in patchy radiation fog.
NAM is also indicating stratus...and there may be some patches
floating around late...but climatology is against it being
widespread. So thinking more fog than stratus would occur.
Model guidance has slowed up a bit with the middle-level energy
approaching for Monday aft/eve...and it now appears that most of the
area won't see any rain showers/thunderstorms until Monday eve/night. Have adjusted
probability of precipitation as such but kept them at chance with a weakening trend noted
overnight. Portions of the lower Hudson Valley and NE New Jersey could see
strong to severe thunderstorms late Monday afternoon into the early evening with
moderate instability in place and 30-40 kts bulk shear moving
into the region. Coverage of the stronger storms will ultimately
depend on the timing. If things speed up again...the storms would
make it here earlier and impact more of the area. Otherwise...hot
and humid for Monday with temperatures again in the middle to upper 80s most
locations...lower 90s NYC/NE New Jersey.
Front stalls over the area...somewhere in vicinity of NYC/western CT...Monday
night and lingers there through Tuesday. Highs on Tuesday are tricky as a
result. Highest temperatures and humidity will be east of the front with the
threat for additional rain showers/thunderstorm development as well. Higher
chances for this east of NYC so have increase probability of precipitation to chance on Li and
CT. Moderate instability and shear will exist again...leading to
the potential for additional strong to severe thunderstorms Tuesday aftn/eve.
Front finally pushes east Tuesday night with drier and seasonable weather
Long term /Wednesday through Saturday/...
a deep upper trough builds east and will remain along the
northeast for the end of the week and into the weekend. Several
shortwaves will rotate around the base of the trough and through
the region during this time. Meanwhile...surface low pressure will form at
the base of the trough. Latest models have the low staying south
of the County Warning Area...resulting in a mainly dry forecast...and then another
low will pass either over or south of the area over the weekend.
For now...will carry chance probability of precipitation on Thursday...and then again on
Saturday with each passing low. Temperatures during this time look to fall
below normal levels with highs topping off in the upper 70s to low
Aviation /14z Sunday through Thursday/...
high pressure builds into the region today.
Light northwest winds back to the SW this morning. Expected afternoon
seabreeze development at coastal terminals...with late day southeast
seabreezes possible at kewr/kteb. A few occasional gusts will be
possible near the coast.
There is a chance of fog and/or stratus after 06z at coastal
terminals east of NYC.
Outlook for 12z Monday through Thursday...
Sun night...VFR. Light S/SW flow.
Monday...gusty S flow. A chance of thunderstorms late.
Monday night-Tue...chance thunderstorms. Cold front passage with S
wind...shifting to west. Patchy fog across outlying terminals Monday
Wednesday...VFR. West flow.
Thursday...sub VFR possible in shra/tstms.
conditions will remain below small craft levels through at least
Monday morning. An increasing SW flow could result in Small Craft Advisory conditions
on the ocean and the bays of Long Island late Monday afternoon into
Monday night as a cold front approaches from the west. Winds and
seas will gradually subside through the day Tuesday...with sub-Small Craft Advisory
conditions expected for Wednesday and Thursday.
locally heavy rainfall is possible in thunderstorms late Monday/Monday
night and again Tuesday afternoon/evening east of NYC...which could lead to minor
poor drainage flooding.