Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
138 am EDT Sat Jul 12 2014
high pressure will slowly move to the east through the weekend.
A cold front approaching from the northwest will slowly move in
Monday into Monday night...and then stall across the region
through early next week. Small weak lows forming along the front
will pass through and eventually push the front to the east by
Wednesday. High pressure will build across Thursday into Friday.
Near term /until 6 am this morning/...
marine stratus across southern coastal sections of NYC into
western Long Island starting to scatter. Otherwise...expecting
mostly clear conditions and with dewpoints not expected to lower
much...some patchy fog will also form outside of NYC overnight
into daybreak as temperatures cool and surface relative humidity rises. Not expecting
much visibility restriction with this...with 3sm in grids for the
patchy fog. Temperatures and dewpoints were slightly adjusted to
better match observed trends.
Surface high pressure settles overhead overnight. Low temperatures
will range from the middle/upper 50s in the normally cooler
locations...to the Lower/Middle 60s along most coastal locations...to
the upper 60s in NYC.
Short term /6 am this morning through 6 PM Sunday/...
for Saturday...surface high pressure gradually slides east of New
England with return southerly flow developing during the morning.
It should be a dry day with a fairly dry air mass in place across
the region and the southerly flow will not yet transport in higher
humidity. The afternoon sea breeze may increase to near 15 miles per hour
along the South Shore of Long Island. High temperatures will be fairly
similar to today...in the lower to middle 80s. Mav/met MOS were
almost identical in most locations so saw no reason to take
anything other than a model blend. The dry forecast will continue
for Saturday night but there will be an increase in middle and high
clouds from west to east. This...combined with a continuing light
southerly wind will keep low temperatures several degrees warmer than
Long term /Sunday night through Friday/...
high pressure on Sunday...moves further offshore. A warm front lifts
north of the area Sunday night...as a pre-frontal trough ahead of a
cold front across the Great Lakes moves east.
The trough on Monday will help trigger scattered convection and
heavy rainfall across the local area. The cold front moves in on
Monday into Monday night and lingers within the local area through
Tuesday night. As a result...expect rounds of showers and
thunderstorms from Sunday night through early Wednesday...as weak
lows move along the stalled front. Drier air moves in for later on
Wednesday and through the end of the week.
High temperatures will be near to slightly above normal on average
across the region Sunday through Tuesday and then slightly below
normal on average Wednesday through Friday.
Low temperatures at night are forecast to be slightly above normal
Sunday night through Tuesday night and trend to slightly cooler than
normal for the remainder of the week.
Aviation /06z Saturday through Wednesday/...
high pressure will remain just offshore through the forecast period
with VFR conditions.
Light and variable to calm wind overnight will become
southerly...generally 10 knots or less. With sea breeze enhancement
stronger wind will be likely after 17z along the coast...with kjfk
as high as 15 knots.
There is some concern of stratus development across the NYC
terminals overnight as low-level moisture is deeper than previously
forecast. Stratus is patchy...however...IFR ceilings are possible
for a few hours...mainly at kjfk and will indicate this in the
terminal forecast. If the ceilings occur...improvement is expected
11z to 12z.
Outlook for 06z Sunday through Wednesday...
Saturday night-Sunday morning...VFR.
Sunday afternoon-Wednesday...scattered to numerous shra/tstms.
Stronger thunderstorms during this time frame could produce periods of
MVFR or lower conditions...locally heavy rainfall...and gusty
winds should become light and variable overnight with high
pressure overhead. Winds gradually increase out of the south on
Saturday into Saturday night...with seas remaining around 2 feet on
the ocean and 1 feet or less elsewhere.
Quiet conditions will continue on Sunday as high pressure moves
east. A prolonged southerly flow will begin to increase late on
Sunday...and Small Craft Advisory conditions may be possible Sunday night...
continuing through Tuesday night as cold front moves across.
Below Small Craft Advisory conditions should return on Wednesday.
no widespread significant hydrologic issues expected through
There is the potential for significant rainfall from late Sunday
into early Wednesday. At this time there is too much uncertainty to
specify exact amounts or specific threats...other than to note the
potential for minor urban/poor drainage flooding is possible in
areas that experience locally heavy rainfall.