New York/Upton, New York

Frost Advisory issued for coastal CT, southern Westchester, and eastern Long Island for tonight.

1) Widespread frost conditions expected outside of NYC/NJ metro area, with scattered freeze conditions possible, tonight into tomorrow morning. Otherwise, dry and increasingly mild conditions for early to mid next week.

2) The next chance of a wetting rain - late next week.

The driest stretch of the year so far persists thru midweek in response to confluent NW upper flow this weekend, giving way to east coast upper ridging thru midweek. At the surface, modified Canadian high pressure builds overhead through Sunday, and then gradually offshore through midweek.

Widespread frost conditions expected, scattered freeze conditions possible, across eastern LI, southern CT and southern Westchester county tonight into early tomorrow morning under good radiational cooling conditions. The one caveat will be the northeastward progression of a cirrus deck over the Ohio/Tennessee Rivers Valleys associated with shearing central US shortwave, and to a lesser extent and upper jet streak aloft and a weak northern stream shortwave moving through northern New England. Although frost- freeze conditions are expected across areas to the north of this, the frost-freeze program has already ended for these interior areas. The frost- freeze program will end for Suffolk, Northern Nassau, Southern Westchester, Coastal Connecticut, Eastern Bergen, Eastern Essex, Eastern Union Sunday morning. Latest model trend is for a slower progression of cirrus deck, giving more confidence in issuing a frost advisory for tonight. In addition, temps last night were colder than the deterministic and MOS guidances, resulting in temps falling into the mid to upper 30s across the advisory area. With better radiational cooling conditions tonight would expected temps even cooler tonight.

For Sunday, mostly sunny (although increasing cirrus deck may filter sunshine), dry and seasonably chilly. High temps will be slightly milder than today, generally be in the upper 50s to lower 60s on Sunday.

Slightly milder temps for Sun Night/early MOn AM as compared to tonight with return flow. This does bring potential for patchy fog in addition to patchy frost conditions for outlying areas.

Gradually moderating conditions for early to mid next week as heights rise aloft and high pressure slides offshore with return SW flow. High temps incrementally rising through the 60s each day, to near 10 degrees above seasonable (upper 60s/lower 70s) by Wed/Thu. Similarly, overnight lows rising from in the 30s and 40s Monday morning to 50s to near 60 by Thursday morning (close to normal high temps for parts of the area this time of year).

General NWP/AI model agreement in NW PAC troughing slowly moving east-southeastward into the central CONUS through the early-mid next week, but then considerable spread (even more than 24 hr ago) on trough evolution as it moves towards the east coast late week/weekend. Sensitivity lying in evolution of NW PAC trough and upstream Aleutian trough, and possibly partial phasing with offshore SE US trough/closed low. Scenarios range from the central US trough remaining influenced by the northern stream and approaching as a closed low towards the NE/Mid Atlantic US East coast late week/weekend, or base of central US trough detaching from northern stream and drifting across the SE US, or variations in between.

General agreement on a frontal system and/or low pressure system affecting the area late in the week into the weekend with a wetting rainfall, but inherently low predictability on timing and sensible weather details this far out. More details as the week progresses.

High pressure remains in control through the period.

VFR. Winds will be mainly NW 10 kt or less this afternoon with the exception of KJFK where a hybrid SW seabreeze has moved in. Winds will diminish this evening and back to a more northerly flow before becoming W/SW at less than 10 kt on Sunday.

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

SW flow at KJFK could persist into early evening before reverting back to the NW or may be in and out. Low confidence.

Sunday Afternoon through Wednesday: Mainly VFR.

Thursday: Chance of MVFR or lower with a chance of showers.

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

Sub-SCA conditions are on all waters through Thursday as high pressure maintains a weak pressure gradient.

CT

Frost Advisory from 10 PM this evening to 8 AM EDT Sunday for CTZ009>012.

NY

Frost Advisory from 10 PM this evening to 8 AM EDT Sunday for NYZ071-078>081.

NJ

None.

MARINE

None.