Scientific Forecaster Discussion
fxus61 kokx 191318
Area forecast discussion
National Weather Service New York New York
918 am EDT Thu Oct 19 2017
a weak frontal passage will occur tonight. High pressure will
dominate from Friday night through Monday. A slow moving frontal
system will then move across during the middle of next week.
Near term /through tonight/...
the patchy fog has dissipated across the region and temperatures
were updated to reflect latest conditions. Otherwise, the
forecast remains on track this morning.
A upper level system over northern Ontario will track across
Hudson Bay today and into northern Quebec tonight. This will
drag a boundary through the forecast area late tonight. It is
difficult to call it a cold front because temperatures behind it
on Friday will be virtually the same, but the temperature
structure aloft does indicate that it is indeed a cold front.
Regardless, there is very little moisture to work with so the
frontal passage will be dry.
Winds ahead of the front today will ramp up out of the
southwest. A solid breeze can be expected along the south coasts
by late afternoon, particularly across eastern Long Island.
Temperatures will remain way above normal again with most spots
at least 70 for highs. Slightly milder temperatures are likely
tonight as winds likely stay up, at least a little, in most
areas. A blend of guidance was used.
Short term /Friday/...
northwest winds and continued dry. 850 flow in the 35-40kt
range, and with subsidence and a dry airmass, there is a good
chance mixing over preforms the model data. Because of this,
winds were bumped up significantly from the model blend. The
deep mixing flow is also the reason temperatures will be near 70
or above once again. Temperatures were raised above guidance,
but if mixing to 850 is realized, 80 degrees highs will be
Long term /Friday night through Wednesday/...
ridging at the sfc and aloft will dominate into Monday ahead of an
upper trough in the western states. As this trough reaches the
plains states, its southern extension will likely cut off over the
south and tap into Gulf moisture before phasing with another trough
digging into the northern plains. Wx should be dry and unseasonably
warm until at least Monday, with high temps in the 70s, and possibly
nearing 80 in NE New Jersey on Sat.
Nwp guidance continues to trend toward a later timing of the
approaching frontal system for mid next week. There could be some
sct showers and/or patchy of light rain/drizzle via low level
warm/moisture advection well ahead of the approaching front as early
as Mon night-Tue. More significant rainfall with the front now looks
to hold off until at least Tue night and possibly until Wed, and the
slow moving front, with attendant warm/moist conveyor belt, low
level jet, and multiple tropical connections, one out of the Gulf of
Mexico and another developing out of the subtropical western
Atlantic, could become a heavy rain producer during this time.
Aviation /13z Thursday through Monday/...
high pressure across the region weakens as a weak cold front
approaches from the northwest today. The front begins to cross the
area tonight into early Friday as high pressure returns.
Winds become SW at less than 10kt at all terminals by mid morning.
By early afternoon winds back to the south-southwest and increase to around 10kt
with gusts up to around 20kt at all but kisp, where infrequent gusts
up to around 20kt are possible. Wind gusts should abate during the
evening, with winds veering to the SW-WSW.
New York Metro enhanced aviation weather support...
Detailed information...including hourly taf wind component fcsts
can be found at:
Kjfk taf comments: occasional gusts to around 25kt possible late
The afternoon kjfk haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Klga taf comments: occasional gusts to around 25kt possible late
The afternoon klga haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kewr taf comments: occasional gusts to around 25kt possible late
The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.
Kteb taf comments: no unscheduled amendments expected.
Khpn taf comments: no unscheduled amendments expected.
Kisp taf comments: no unscheduled amendments expected.
Outlook for 12z Friday through Monday...
Friday-Friday night...VFR. Northwest-north winds g15-25kt possible through
Saturday-Monday...VFR. SW winds g15-20kt possible Sunday and
Monday in the afternoon/evening.
a quick round of marginal Small Craft Advisory level winds and
seas are still expected late afternoon and evening on the
eastern ocean. Elsewhere, winds and seas will generally be below
Small Craft Advisory levels through Friday. There could be some
nearshore gusts approaching 25 kt Friday afternoon on northwest
Quiet conditions expected this weekend into early next week as high
pressure dominates. Any Small Craft Advisory conditions with a slow moving frontal
system would occur beyond the end of the fcst period.
a Special Weather Statement remains posted for interior
Connecticut for enhanced fire weather spread today. After a wind
shift tonight, an elevated fire weather risk is again likely on
Friday. In fact, relative humidity is likely to be lower on
rainfall of 1-2 inches with locally higher amounts is possible
during the middle of next week. Timing is a little uncertain as nwp
guidance continues to trend toward a later timing, occurring either
Tue night into Wed night or Wed into Thu Thu morning. The most
likely impact at this early juncture appears to be urban/poor
Marine...Small Craft Advisory from 4 PM this afternoon to 6 am EDT
Friday for anz350-353.