textproduct: New York

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

1) Breezy conditions today ahead of approaching frontal system. Unsettled weather tonight through Friday, with slow moving frontal system/low pressure moving through. Potential for diurnally driven locally heavy downpours and embedded tstms Thursday and Friday.

2) Dry and unseasonably warm conditions developing this weekend through early next week. Cold water safety concerns for this weekend with good boating weather, and water temps still in the lower 50s.

DISCUSSION

KEY MESSAGE 1...

Good agreement in a vigorous shortwave and upper level jet, digging a trough thru the Great Lakes and Ohio Valley today and closing off over the region Thu into Friday. At the surface, resultant low pressure moves thru the Great Lakes and SE Ontario today, with its cold front approaching tonight. Weak secondary low pressure likely develops along the front over the region Thursday under the developing closed low, slow sliding east and then northeast of the region through Friday.

Ahead of the front today, tightening pressure gradient will have S/SW winds increasing to 15 to 25 mph with gusts 30 to 40 mph across much of the region this afternoon and early evening. Isolated gusts to 45 mph possible for NYC/NJ metro and western LI with strong coastal jet development. Winds gradually subside tonight into Thursday morning as pressure gradient weakens.

Isolated rain showers possible for northern portions of the area this morning as a warm front moves north. This will be followed by increasing likelihood for showers from W to E this evening and tonight ahead of a slow moving cold front that stalls over the area tonight. Southern shortwave and developing offshore low pressure will push the axis of greatest moisture advection east and limit deep moisture feed into this system, but potential is still there for a moderate to locally heavy rainfall for portions of the area early Thursday AM into evening. Model guidance and synoptic set-up indicating potential for rainfall intensities to increase along/ahead of the cold front before it washes out Thu AM and then as continue in a more banded and convective fashion Thursday afternoon/early eve.There remains potential for brief 1/2" to 1" hourly rates later Thursday morning into afternoon as diurnal/cold pool instability develops. Generally expecting basin average of 0.50- 1" of rainfall through Thursday night, mostly falling early morning into the evening, but could see some localized spots of 1.5-2" if/where downpours/embedded tstms activity is most persistent. Low predictability on exact location at this point, but should have more detail as the event is resolved by high-res CAMs over the next 24 hrs.

Weak surface low pressure slowly slides northeast Thu night into Friday. Precip will likely dissipating Thu Night with stabilizing low-levels and then potentially re-developing Friday AM into afternoon depending on closed low positions, with potential for additional diurnally driven locally heavy downpours, embedded thunderstorms.

Pea-size hail possible with any stronger thunderstorms activity.

KEY MESSAGE 2...

Transition from persistent upper troughing to zonal upper flow this weekend with strong WAA pattern under deep w/sw flow aloft, and then build-in of southern upper ridging by early next week.

At the surface, high pressure briefly build in from the west on Saturday into Sunday. A weak cold front/backdoor cold front approaches Sun aft and crosses Sun eve. Highs well into the 70s on Saturday (lower 80s NE NJ and adjacent NYC metro). Warmest day of the weekend appear to be Sunday, with widespread highs in the 80s (even for the coast) with deep mixing and offshore flow.

Cold water safety concerns this weekend as water temperatures remain in the lower 50s. The cold water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water. Anyone going out on small boats, canoes or kayaks should plan accordingly and use extreme caution to avoid this threat.

Signal for backdoor cold front to pass NE to SW thru the entire area Sun Night, before working back north as a warm front Monday Night. So despite deep SW flow aloft and 850hpa temps rising into the mid to upper teens, air temps on Monday will likely be notably cooler than Sunday for the city/coast with onshore flow off the lower 50 degrees waters. Temps along the south and east coast may be cooler than currently forecast, and struggle to get out of the 60s/lower 70s. Areas farther west of the Hudson R should still be able to reach well into the 70s/lower 80s.

Potential for warmest day of the year so far (particularly away from the south coasts) on Tuesday with deep SW flow and mixing down of 850 hpa temps in the upper teens. Temps could rise into the lower 90s-95 across the NYC/NJ metro and 80s elsewhere. Tds appear to still be in the lower 60s, which should keep HI near air temp.

Temperatures rising to 10-15 degrees above seasonable Sat thu Mon and potentially 15-20 degrees above normal on Tue.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY

Thursday: Showers with possible thunderstorms. MVFR or lower conditions possible.

Friday: Chance of showers. MVFR or lower conditions possible. NW wind gusts 15-20 kt.

Saturday: VFR. SW wind gusts 15-20 kt afternoon into evening.

Sunday: VFR. NW wind gusts 15-20 kt in the afternoon.

Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90

MARINE

Southerly flow increases today ahead of approaching cold front. This will lead to small craft conditions developing quickly this morning and lasting through this evening for all waters and likely through late tonight for the ocean for southerly wind waves. Marginal gale conditions are likely for the entrance of NY harbor and adjacent ocean waters and south shore bays this afternoon and early evening with hybrid synoptic/seabreeze circulation.

Weak low pressure will be developing over the waters Thursday resulting in a lighter pressure gradient and a return to sub advisory winds.Generally sub advisory winds should continue for Friday into Sunday, although marginal nearshore SCA gusts are possible Fri afternoon and Sun for offshore flow.

SCA ocean seas are possible Thu Night into Friday in response to E/SE swells from offshore low and exiting coastal low.

OKX WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 2 AM EDT Thursday for ANZ331-332- 335-340. Gale Warning until 11 PM EDT this evening for ANZ338-345-353- 355. Small Craft Advisory until 8 AM EDT Thursday for ANZ350.