Area Forecast Discussion

WHAT HAS CHANGED

The Freeze Watch for Nassau tonight has been cancelled.

KEY MESSAGES

1) A colder air mass settles in, with near freezing temperatures inland early this morning with areas of frost, and sub-freezing temperatures for much of the area outside NYC and the nearby suburbs tonight.

2) Milder weather returns mid to late week, before turning more unsettled into the weekend.

DISCUSSION

.KEY MESSAGE 1... A Frost Advisory remains in effect through 800 AM EDT for coastal Connecticut and the outlying NY/NJ suburbs with light winds and temperatures in the mid 30s. Temperatures across the interior will be near to sub-freezing by early this morning, however the growing season starts Tuesday, April 21.

Light precipitation is possible with a secondary cold frontal passage this morning with light showers across much of the region, with snow showers across portions of the Lower Hudson Valley.

Behind this cold front will be the coldest air of the week. High pressure will be building over the region today into tonight, with clearing skies, and winds becoming near calm. Temperatures across most of the area will be sub freezing and a Freeze Warning remains in effect. In addition with the light winds and clear skies areas of frost will be likely. The Freeze Watch for Nassau county was cancelled as temperatures there are expected to remain above freezing tonight. Record daily low temperatures will be approached or may be set for a few climate stations Tuesday morning. See the Climate section for details.

Temperatures remain several degrees below normal Tuesday, and then return to near normal levels Tuesday night as high pressure moves off the coast with a return flow. In addition warm air advection sets up as a warm front approaches and moves through Wednesday morning. Lift along the front increases Tuesday night, and light rain showers will be possible. Also, a weak low will pass across the area early Wednesday keeping a chance of showers late Tuesday night into Wednesday morning.

.KEY MESSAGE 2...

The cooler regime is short-lived as the upper trough exits offshore and ridging attempts to build in from the Midwest.

Afternoon temperatures Wednesday jump 5 to 10 degrees from the previous day for most, with highs in the mid 50s to mid 60s, though remaining a bit cooler across SE CT. Thursday is likely the mildest day of the week, downsloping off NW flow helping temps get into the upper 60s to low 70s from NYC and points north and west, with low to mid 60s along the coast. Temperatures then begin to gradually cool down late week, though not as cold as earlier in the week.

Still a bit early for the fine details, but pattern appears to turn more unsettled into the weekend. Decreasing forecast confidence in this period with diverging solutions in guidance. Shortwave energy looks to drop down along the eastern side of the ridge, helping carve out an upper low near the Canadian Maritimes. This should block further advancement of the ridge and help break it down, with a nearby frontal boundary likely serving as focus for showers at times. Placement and timing of these features, as well as any frontal waves, will determine exact impacts and extent of unsettledness, but doesn't appear to be a washout. Will continue to carry chances for rain through the weekend and into early next week, with a bit cooler conditions.

AVIATION /06Z MONDAY THROUGH FRIDAY/

A cold front passes through today, followed by high pressure building from the west.

Mainly VFR thru TAF period. Brief MVFR possible with isolated to widely scattered rain showers around late this morning and into the afternoon. There is a chance the showers mix with snow NW of the NYC terminals.

Light WNW-NW flow backs to the SW early this morning. Winds become NW again by 15Z for most terminals, with gusts aoa 20 kt in the afternoon and early evening. Flow lightens as it gradually veers NNW into early Tuesday AM.

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

PROB30 timing Monday morning may be off by 1-3 hours.

OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY

Late Monday night: VFR. NNW winds under 10 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

Winds and seas remain below advisory levels today through Friday night.

CLIMATE

Daily record low temperatures for Tue Apr 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 Warning from midnight tonight to 9 AM EDT Tuesday for CTZ005>012. Frost Advisory until 8 AM EDT this morning for CTZ009>012. NY...Freeze Warning from midnight tonight to 9 AM EDT Tuesday for NYZ067>071-078>081. Frost Advisory until 8 AM EDT this morning for NYZ069>071- 078>081. NJ...Freeze Warning from midnight tonight to 9 AM EDT Tuesday for NJZ002-004-103>108. Frost Advisory until 8 AM EDT this morning for NJZ002-004-103- 104. MARINE...None.