Radar — KOKX
Surface Analysis — Eastern U.S. (North)
Satellite
Nearest monitored road: Atlantic Street (Secondary)
A severe thunderstorm watch is in effect through 8PM tonight for NE nj as well as orange and rockland counties. The flood watch has been expanded eastward to include eastern suffolk county and new london county. The rip current statement has been extended through wednesday for today for all ocean beaches.
1) a band of heavy showers and thunderstorms will move through the area tonight into wednesday morning, bringing the potential for flash flooding. Severe thunderstorms with damaging wind gusts will also be possible west of the hudson river this evening.
2) there is a high risk of rip currents through wednesday. (see marine section below for discussion)
3) potential for minor coastal flooding mid to late week with a coastal low.
.key message 1... A broad area of low pressure with a triple point passes through the forecast area tonight with support from a nearby upper low to our north. Upward forcing from both features plus synoptic scale lift from developing upper divergence combine with high moisture content. This alone poses a threat of heavy rainfall with flash flooding, and the threat will be enhanced by a wind profile through the mid levels that supports back-building of and training of storm cells. Given yesterday's rainfall, there is also some concern for river flooding. River forecast points are not expected to go into flood, however a couple are forecast to get pretty close to minor flooding thresholds.
The period when flooding impacts are most likely will be during the overnight. Impacts for the easternmost zones are most likely tonight into wednesday morning. With the surface low nearby and the upper low overhead, the flooding threat continues through the daytime wednesday. The flood watch has remained unchanged regarding its end time of 8PM wednesday as confidence in shortening its duration is not high enough - antecedent rainfall plus slow moving cell potential with lingering sufficient moisture content could lead to additional flash flooding. After collaboration with wfo box, have decided to include new london (and eastern suffolk) counties in the flood watch. Cams suggest a slowing eastern progression of cells with a better chance of cell training tonight into wednesday morning. The WPC maintains a moderate risk (level 3/4) for portions of the area through tonight with a slight risk elsewhere, then a marginal to slight risk for wednesday.
In general, an average of 2 to 4 inches is expected for portions of northeast nj, the lower hudson valley and southwestern ct. Isolated higher amounts are expected, with the latest href pmm showing a max 5-7 in the lower hudson valley into NE nj.
For the rest of the area, an average of 2 to 3 inches is forecast, with isolated higher amounts possible. Peak hourly rainfall rates up to 2 to 3 inches per hour are still anticipated. This is also focused more on NE nj into the lower hudson valley, but can not be ruled out anywhere in the area.
There is potential for some thunderstorms to become severe, mainly for portions of northeast nj into the lower hudson valley and nyc metro. This is shown in spc's latest day 1 convective outlook. SHEAR remains fairly weak, but decent instability could allow for an isolated damaging wind threat with some collapsing storms. The threat appears to end later this evening as the airmass stabilizes some. A severe thunderstorm watch is in effect through 10 PM tonight for NE nj as well as orange and rockland counties.
.key message 2... See marine section for details on rip current risk.
.key message 3... A full moon occurs wednesday morning and an onshore flow will be preceding it. By the time the wednesday evening high tide cycle arrives, winds will be offshore or at least weakening in the process of shifting offshore. This should offset or at least not significantly contribute to tidal piling with astronomical high tides. Therefore, not anticipating a high enough threat of minor coastal flooding for an advisory. Perhaps a statement for isolated minor flooding could be needed for the south shore back bay locations of southern nassau and queens, but confidence in levels touching minor are not high enough at this time for a statement issuance.
A slow moving low pressure system will send a band of showers and thunderstorms across the area tonight into wednesday morning. Thereafter, the coverage will likely become more scattered in nature. The one exception though will be kgon where the coverage and frequency will be higher on wednesday.
MVFR/IFR conditions are forecast to develop and work from west to east across the area overnight, likely coinciding with a band of showers and thunderstorms. Eastern terminals may not go down until 04-08Z. Lower conditions (IFR/LIFR) may be brief and associated with heavy rain and/or tsra. Expect gradual improvement wednesday for all except kgon which could remain IFR through the day.
S/SE winds around 10 KT, with a few gust 15-20 KT at the coastal terminals, will become light and variable for a time late tonight as the band of showers passes through. Most terminals will then veer to a light SW flow toward daybreak and eventually take on a more northerly component at 10 KT or less on wednesday. However, kgon and kbdr are forecast to stay or take on a E/SE flow with low pressure passing just south of those locations. Kgon may even see gusts up to 20 KT with the gradient remaining a bit tighter during the day.
...ny metro (kewr/klga/kjfk/kteb) taf uncertainty...
Timing of showers and thunderstorms tonight into the morning hours have been slower than forecast and the 00Z tafs have continued to follow that pattern.
In addition, winds will become a bit more uncertain late tonight into wednesday as low pressure tracks slowly across the terminals. Frequent amendments are likely during the taf period.
.outlook for 00Z thursday through sunday...
Wednesday: mostly MVFR improving to VFR by the afternoon likely with showers. Thunderstorms and brief MVFR or lower possible.
Thursday: MVFR or lower possible. Showers possible and a slight chance of a thunderstorm. N-NW wind g15-20KT.
Friday: mainly VFR, chance of an afternoon shower or tstm.
Saturday: mainly VFR.
Sunday: mainly VFR, chance of an afternoon shower or tstm.
Detailed information, including hourly taf wind component forecasts, can be found at: https:/www.weather.gov/zny/N90
A S/SE flow continues to increase this evening and a small craft advisory remains in effect for all waters. The flow peaks tonight with 25 to 30 KT gusts. Ocean seas are expected to build to 5 to 6 feet. Sca gusts still anticipated for the eastern waters wednesday morning, although there is a chance that the sca for central and eastern LI sound and the eastern bays could be canceled at some point during the morning. Have extended the sca on the ocean waters east of moriches inlet as seas will be slow to subside with a lingering swell in spite of lowering winds. Sub-sca conditions then follow for the rest of the forecast period.
Rip currents...
The high rip current risk continues through wednesday as well due to lingering swell.