Scientific Forecaster Discussion
fxus61 kokx 221134
Area forecast discussion
National Weather Service New York New York
734 am EDT Thu Jun 22 2017
weak high pressure will slide across today, followed by a warm
front passing through tonight. An upper level disturbance will
approach on Friday. A series of fronts will then move across
the area through the middle of next week.
Near term /until 6 PM this evening/...
forecast is on track. Only minor adjustments needed to T/TD and
sky this morning.
Weak high pressure will slide across, providing a mostly sunny
day today, though there could be an increase in high and mid
level clouds late as a mid level vort Max spills over the upper
ridge to the west. Deep mixing under mostly sunny skies with 800 mb
temps 13-14c should result in another warm day, with temps in
the lower/mid 80s.
There is a moderate risk for the development of rip currents at
the eastern Suffolk ocean beaches.
Short term /6 PM this evening through 6 PM Friday/...
a warm front passing through tonight could produce an isolated
shower late tonight, with the better chances across southeast CT as
isentropic lift with the front strengthens a little. Some hi-res
guidance indicates potential for some low stratus and/or patchy
fog late as well. Low temps should range from the mid 60s
across easternmost Long Island/CT, to the lower 70s in NYC
A lead mid level trough well in advance of any remnants of
Tropical Storm Cindy will be approaching on Friday, accompanied
by a substantial increase in low level moisture in the morning,
with dewpoints in the lower 70s. Best forcing for any convection
should arrive late morning or early afternoon, and while
instability appears meager, with cape 500 j/kg or less, winds
aloft may make up for this and lead to a few strong tstms,
especially from NYC Metro north/west. Had been concerned
initially about a potential tropical predecessor rainfall event
with the area on the poleward side of an upper jet streak
approaching from the west, but think this potential will be
greater to the west at least through daytime Friday.
Temps will only be a tad less warm than those fcst for today,
with upper 70s to mid 80s expected.
Long term /Friday night through Wednesday/...
nwp is in agreement that a broad upper level trough will remain
east of The Rockies through much of the forecast period. The
trough begins to sharpen early next week, but there are
differences as to when the trough axis pushes east.
Could see some heavy rainfall Fri night into Sat if the stronger
NAM 50-60 kt low level jet verifies. GFS is much weaker, around 30 kt,
and ec is around 40 kt. Increasing Theta-E advection and an
approaching short wave/pre-frontal trough should support rain
moving in during the evening, generally west of the city,
although may be too aggressive with likely pop and it may hold
off until after midnight. Precipitable water should increase to 2+ inches Fri
night into Sat as deep tropical moisture advects into the
area. There appears to be enough elevated instability for some
non-severe tstms, which could also aid in heavy rainfall
Rain continues Sat morning as the remnants of ts Cindy are
forecast to ride along an approaching cold front. The front will
be slow to move through, but the heavy rain threat should push
east during the aftn.
Weak ridging then builds in into Monday providing dry and
The 00z ec has started to waver from other guidance on the
progression of the upper trough over the eastern US early next
week. After a dry cold frontal passage Sun night, another will
approach on Mon with the potential for aftn/eve convection. Will
need to monitor trends for the rest of the forecast period as a
slower trough progression could keep unsettled weather into the
middle of the week. Current forecast reflects trof axis moving
through on Tue with a chc for showers. Have kept thunder out due
to limited instability.
Aviation /12z Thursday through Monday/...
weak high pressure builds over the area today. A warm front crosses
VFR through the evening push. Potential for MVFR br/hz development
late tonight for NYC Metro and interior terminals. Low prob of IFR
conditions in stratus/fog for eastern terminals towards daybreak.
Scattered shower/tsra development possible for morning push.
Light and variable flow this morning likely gives way to late
morning/afternoon sea breeze development at coastal terminals. A
NE wind likely at klga this morning giving way to afternoon S
sea breeze. Kewr may waver between southeast seabreeze and SW winds
this afternoon. Winds becoming light S/SW tonight.
..NY Metro enhanced aviation weather support...
Detailed information, including hourly taf wind component forecasts,
can be found at: http://www.Weather.Gov/zny/n90
Kjfk taf comments: timing of shift from NE winds to S winds could be
off by 1 to 2 hours.
Klga taf comments: timing of shift from NE winds to S could be off
by 1 to 2 hours.
Kewr taf comments: winds may waver between a southeast seabreeze and SW
winds this afternoon.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kteb taf comments: winds may waver between a southeast seabreeze and SW
winds this afternoon.
Khpn taf comments: no unscheduled amendments expected.
Kisp taf comments: no unscheduled amendments expected.
Outlook for 12z Friday through Monday...
Friday-Friday night...MVFR or lower in shra/tsra. S/SW winds g20-
25kt possible Friday afternoon. IFR of lower conditions possible in
stratus/fog for eastern terminals 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. Chance of afternoon shra/tsra. S/SW winds.
quiet conditions expected into Friday morning. S-SW flow
increasing to 15-20 kt should push ocean seas to 5-6 ft Fri
afternoon/night. An inversion over the waters should keep winds
below 25 kt, though there could be a brief period Fri eve where
gusts reach this level, again only on the ocean waters.
These hazardous ocean seas could linger into Sunday.
there is the potential for heavy rain Fri night 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.
astronomical tides will be 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.