Scientific Forecaster Discussion
fxus61 kokx 230623
Area forecast discussion
National Weather Service New York New York
223 am EDT Fri Jun 23 2017
a warm front approaches tonight and passes Friday. A cold front
moves across Saturday and behind it another cold front will slowly
approach from the north. The second cold front moves in and
weakens early next week. This eventually moves farther northeast
of the region toward the middle of next week with a strong high
pressure area building in from the west thereafter.
Near term /until 6 am this morning/...
minor updates to reflect current trends. Decoupling has
occurred with the loss of solar insolation, allowing earlier
gusts to diminish across the NYC Metro area. Previous discussion
Warm and increasingly humid conditions will prevail tonight.
Will need to keep an eye on any stratus and fog development,
possibly advecting northward from the ocean later tonight. Long
Island and southern CT most likely locales.
Otherwise, weak shortwaves/vorts in west/SW upper flow, along with
an approaching warm front could trigger a few showers/possible
With clouds and southerly flow, warm temps overnight expected with
not much disparity across the region. A MOS/model blend followed.
There is a moderate risk for the development of rip currents at the
eastern Suffolk ocean beaches into this evening.
Short term /6 am this morning through 6 PM Saturday/...
a series of weak upper level shortwaves/vorts could trigger a few
showers/thunderstorms Friday as a sfc warm front passes in the
morning. CAPES build, with highest values where they typically are,
across the interior away from marine layer. As layer precipitable
water values climb to over 2 inches, will mention heavy rainfall
with any thunderstorms. Instability wanes somewhat Friday night, but
thunder remains a possibility and heavy rain is certainly possible
in any convection. In general, expect scattered to numerous
coverage, but it will not rain all the time.
Warm temps in the 80s during the day can be expected, and 60s to 70
at night, along with high humidity. Again, not much disparity in low
temps is expected due to clouds, southerly winds and high humidity
Long term /Saturday night through Thursday/...
overall, looking at the large scale, a trough remains in the
northeast this weekend into next week with a pattern change towards
more ridging evident towards the end of next week. The area will
have the jet stream in the vicinity of the region through early next
week. It will be oriented from SW to NE with a Max speed of roughly
At the surface, a cold front will be approaching the region Saturday
and moving across from northwest to southeast through the day. A weak low develops
along the front with a sharp mid level shortwave aloft. The front
moves farther offshore southeast of Long Island Saturday night. A weak
pressure pattern sets in place thereafter for Sunday and Sunday
night. A cold front approaches and weakens as it moves in early next
week. Eventually, building high pressure well west of the region
starts to build in mid to late next week.
In terms of weather, a wet start to the weekend with showers and a
few thunderstorms Saturday. Instability is lower Saturday so left
thunderstorm coverage as isolated. Showers are likely. Weather
becomes drier from northwest to southeast during the afternoon with more westerly
flow getting established. Mainly dry conditions are expected
thereafter. There will be mainly diurnally driven low chances for
showers and thunderstorms Sunday through early next week, but expect
majority of the region to remain dry. Temperatures a little above
normal Saturday but otherwise right near normal values for the rest
of the long term period.
Aviation /06z Friday through Tuesday/...
a warm front approaches the region overnight, and lifts nwd
thru the area Friday.
Mainly VFR overnight, however there is a chance that some areas
of IFR develop for a few hours, especially east for kgon and
kisp. Pockets of MVFR are possible again on Fri with cigs
around 2500 ft. There is also some potential for eastern
terminals to briefly go to MVFR in the late afternoon due to
low stratus. For now the tafs indicate VFR because coverage is
in question and too uncertain at this time. More widespread sub
VFR conditions are expected late in the taf period after 0z
Saturday (see outlook below).
There will be a chance of isold-sct shwrs thru the day (friday),
with the best potential for thunderstorms aft 20z, particularly
in areas along and W of the Hudson River.
Sea breeze flow will lessen overnight, and veer to the SW as the
flow weakens. The sea breeze may attempt to back winds closer to
the S again aft 16z Fri.
Outlook for 00z Saturday through Tuesday...
Friday night...MVFR or lower in shra/tsra. IFR or lower
conditions possible in stratus/fog for eastern terminals for the
first half of Friday night.
Saturday...MVFR or lower possible in shra/tsra. S/SW winds.
Saturday night-Sunday night...VFR. Northwest winds...becoming W/SW.
Monday...VFR. Slight chance of afternoon shra/tsra. SW winds.
Tuesday...VFR. Chance of afternoon shra/tsra. SW winds.
southerly winds tonight remain well below Small Craft Advisory criteria, but do
expect these southerly winds to increase by Friday afternoon and
into the evening. At this time, will issue a Small Craft Advisory for the ocean
waters for winds 20 to 25 kt, and building seas in the 5 to 6 foot
The remainder of the waters should remain below Small Craft Advisory criteria.
The other hazards for mariners will be showers/thunderstorms, and
reduced visibilities in fog.
In terms of winds, the pressure gradient will be weak enough through
the long term marine forecast period (saturday through tuesday) to
keep winds below Small Craft Advisory criteria. However, the seas on the ocean will
probably still have southerly swell contributing to higher seas of 5-
6 feet on the ocean that are forecast to last through early Sunday.
The 5-6 foot seas will last through the day Sunday for the ocean
east of Fire Island Inlet. Seas are forecast to go below 5 feet for
all ocean waters Sunday night through Tuesday. Non-ocean waters stay
below 5 feet the entire long term marine forecast period.
there is the potential for heavy rain late Friday into Sat as the
remnants of Cindy move through. At this time expect at least flood
advisories to be issued. It is too early to tell if flash flooding
will occur due to the lack of instability. This potential could be
added to the severe weather potential statement in subsequent forecasts.
Otherwise, no other hydrologic concerns.
astronomical tides are running very high, especially during the
evening high tide cycles through Saturday.
Less than 1 ft of surge is needed during these evening high tide
cycles for minor flooding, and in some cases less then 1/2 ft.
The expected S/SW flow is not favorable for surge, but a
background anomaly will likely be enough for minor coastal
flooding of the most vulnerable coastal locales along the South
Shore bays of western Long Island, along Jamaica Bay, and along
western Long Island Sound during this time.
kokx weather radar is scheduled for maintenance starting Friday
June 23rd for a period of 3 days.
Marine...Small Craft Advisory from noon today to 6 am EDT Saturday for
short term...precipitable water