textproduct: New York

WHAT HAS CHANGED

Increased wind speeds for Wednesday afternoon into early evening. Gale warning issued for Wednesday aft/eve for entrance of NY harbor, Great South Bay, and nearshore western ocean waters.

Rainfall amounts increased for Thursday.

KEY MESSAGES

1) Breeze conditions Wed afternoon/evening ahead of approaching frontal system. Unsettled weather Wednesday Night into Friday, with slow moving frontal system 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 tonight into Wednesday and closing off over the region Thu into Friday. At the surface, resultant low pressure moves thru the Great Lakes and SE Ontario tonight into Wednesday, with it trailing cold front approaching late Wednesday/Wed Night. 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 on Wednesday, 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 Wed aft/eve. Isolated gusts to 45 mph possible for NYC/NJ metro and western LI with strong coastal jet development. Winds gradually subside Wed Night into Thu morning as pressure gradient weakens.

Isolated rain showers possible for northern portions of the area late tonight into Wednesday morning as a warm front moves north. This will be followed by increasing likelihood for showers from w to e Wed eve/night ahead of a slow moving cold front that stalls over the area Wednesday night into Thursday morning. Southern shortwave and developing offshore low pressure will shunt WCB offshore 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 Thu Am into Thu eve. 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 Thu afternoon/early eve. WPC URRD indicating potential for brief 1/2 to 1" hourly rates later Thu morning into afternoon as diurnal/cold pool instability develops. Generally expecting basin average of 0.50- 1" of rainfall through Thu Night, mostly falling early Thu AM into Thu 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 24-36 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 18Z WEDNESDAY THROUGH SUNDAY

Wednesday afternoon: VFR. Chance of showers in the early evening at KSWF. S winds increase to 15-20 kt with gusts 25-30kt, highest gusts up to 35 kt at south facing the coastal terminals. LLWS possible late in the afternoon at KISP with S winds 45 kt at 2 kft AGL.

Wednesday night: Showers becoming likely. IFR possible after midnight, otherwise MVFR expected. Slight chance of thunder in the evening at KSWF and at the NYC metros after midnight. S winds G20- 25kt mainly before midnight. LLWS possible in the evening at KISP/KGON with S winds 40 kt at 2 kft AGL.

Thursday and Thursday night: Showers with possible afternoon tstms. IFR cond possible mainly in the morning and with any tstms, otherwise MVFR cond expected. Mainly light NW winds, otherwise SE winds through early afternoon at KISP/KGON.

Friday: Slight chance of showers and thunderstorms with brief MVFR cond possible, otherwise VFR. NW winds G15-20kt.

Saturday: VFR. SW winds G15-20 kt in the afternoon.

Sunday: VFR. W winds up to 10 kt.

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

MARINE

High pressure will be in control along the coastal waters through tonight, although late this afternoon into early evening marginal small craft wind gusts are likely occur for the entrance of NY harbor and adjacent ocean waters and south shore bays. Otherwise, sub advisory conditions should prevail through much of tonight. Southerly flow increases ahead of approaching cold front during Wednesday. This will lead to small craft conditions developing quickly Wednesday morning and lasting through Wednesday evening for all waters and likely through late Wednesday night 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 Wed aft/eve 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 fro 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 from 8 AM Wednesday to 2 AM EDT Thursday for ANZ331-332-335-340. Gale Warning from 6 AM to 11 PM EDT Wednesday for ANZ338-345- 353-355. Small Craft Advisory from 6 AM Wednesday to 8 AM EDT Thursday for ANZ350.