Area Forecast Discussion

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Rain showers intermittently through much of the afternoon.

2) Colder air mass settles in early this week, with subfreezing temperatures likely outside the urban NYC metro Monday night.

3) Milder weather returns mid to late week.

DISCUSSION

.KEY MESSAGE 1...

Broad upper trough swings into the East. Additional rain develops supported by the rapidly falling heights as the trough comes in and an incoming 120 kt upper jet. The rain tapers from west to east late this afternoon into early evening.

QPF is relatively light, on the order of a couple of tenths for most, with highest amounts up to a half inch off to the north and west into the LoHud Valley. While a brief downpour cannot be ruled out, the bulk of the activity should remain light to moderate with no hydrologic concerns.

.KEY MESSAGE 2...

Temperatures will struggle to climb any higher than where they started the day, and more likely, fall several degrees into the 40s through the afternoon as colder air advects in on the NW flow behind the fropa.

CAA continues tonight with temperatures bottoming out in the 30s for most, and low to mid 40s in the NYC metro. Additional cloud cover develops early Monday AM as a secondary front approaches, and could help spur a few isolated snow showers into the LoHud Valley and rain showers along the coast after daybreak Monday as some hi-res CAMs are depicting. Cyclonic flow and steep lapse rates with the cold pool aloft should lead to plenty of stratocu Monday, as well as the continued possibility of isolated to scattered showers. Can't rule out some wet flakes across the far interior. The bulk of the day remains dry though, and much drier compared to the previous day.

The coldest temperatures early next week appear likely Monday night with clearing skies and light winds helping to efficiently cool the BL. Opted to blend in a bit cooler MAV/MET guidance given this setup, and a widespread freeze appears likely for most outside NYC. Freeze Watch hoisted for areas away from the urban metro. Lows range from the mid 20s across the interior to mid 30s in the city, or about 10 to 15 degrees below normal. Record daily lows are even in reach for a few sites, see Climate section below for detail.

Temperatures remain below normal on Tuesday with highs ranging from the upper 40s to mid 50s. High pressure overhead shifts offshore Tuesday night, setting up a weak return flow and a milder night compared to Monday night.

.KEY MESSAGE 3...

The high shifts offshore Tuesday night as a warm front lifts through the region. Chance for a few showers as it does into Wed AM, but coverage looks scattered at best. A weak cold front follows later Wednesday, but despite the fropa, temperatures nudge upwards into late week with downsloping NW winds.

Afternoon temperatures Wednesday jump 5 to 10 degrees from the previous day, with highs mostly in the upper 50s to mid 60s. Thursday likely the mildest day of the week with ridging building from the west; forecast highs into the 60s and 70s.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Another cold front follows last tonight into early Monday, followed by high pressure building from the west.

Mainly MVFR with showers to start, but conditions will improve from west to east. Showers end 20-22z with flight categories gradually prevailing VFR. VFR prevails this evening into tonight.

There is a chance for showers and MVFR, possible mixed with wet snow well NW of NYC terminals Monday morning. Have included a PROB30 for this potential.

NW winds around 15 kt with gusts around 25 kt this afternoon. Winds and gusts should start weakening after 19z, ending around 00z. WNW-NW winds fall below 10 kt tonight, then back to the SW early Monday morning.

NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty

Timing of improving flight categories may be off by 1-2 hours.

Peak gusts around 30 kt possible through 20z and end time of wind gusts this evening may be off by 1-2 hours.

Start time of gusts Monday may be off by 1-3 hours.

OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY

Monday: VFR. NW wind gusts 20 kt.

Tuesday: VFR.

Wednesday: Mainly VFR. Slight chance of showers in the morning.

Thursday-Friday: VFR.

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

MARINE

Increasing NW wind gusts behind a cold front passage. This should produce SCA wind gusts (25 to 30 kt) on the near shore ocean waters, LI Sound, LI Bays, and NY Harbor for the afternoon. Nearshore ocean seas will likely build to around 4 or 5 ft. Winds and seas subside this evening, and conditions then remain below SCA levels through at least midweek.

CLIMATE

Daily record low temperatures:

Tue, April 21

KEWR: 31/1981 KBDR: 29/1956 KNYC: 26/1875 KLGA: 33/1956 KJFK: 34/1956 KISP: 30/1965

OKX WATCHES / WARNINGS / ADVISORIES

CT...Freeze Watch from late Monday night through Tuesday morning for CTZ005>012. NY...Freeze Watch from late Monday night through Tuesday morning for NYZ067>071-078>081-177-179. NJ...Freeze Watch from late Monday night through Tuesday morning for NJZ002-004-103>108. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ331- 335-345-353-355. Small Craft Advisory until 9 PM EDT this evening for ANZ332- 338-340. Small Craft Advisory until 11 PM EDT this evening for ANZ350.