Area Forecast Discussion
Issued by NWS Upton, NY

Current Version |  Previous Version |  Text Only |  Print | Product List |  Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
560 FXUS61 KOKX 181938 AFDOKX Area Forecast Discussion National Weather Service New York NY 338 PM EDT Sat May 18 2024 .SYNOPSIS...
-- Changed Discussion --
A couple of upper troughs will be in the vicinity through tonight, otherwise surface high pressure will be in place through Monday. The high gradually slides farther out into the Atlantic through midweek. A frontal system approaches from the west Wednesday night. The associated cold front approaches Thursday and moves across Thursday night. Brief weak high pressure returns towards the end of the week.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
-- Changed Discussion --
High pressure will slowly build into the region from the northeast tonight. At the same time, a couple of shortwaves will be nearby, triggering some showers for parts of the forecast area, primarily into the evening hours. After midnight, looks like any chance of additional showers will be east of the city with a mid-level shortwave still nearby. Low temperatures a few degrees above normal with plenty of cloud cover around.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
-- Changed Discussion --
Surface high pressure along the new England coast remains in control during this time. A lingering shower still possible for eastern zones in the morning, and although another shortwave may arrive here during the afternoon, moisture will be more shallow. Will therefore go with a dry forecast for the afternoon. Partly to mostly cloudy conditions in the morning, then probably at little less in the way of clouds during the afternoon. Highs near normal in the upper 60s to lower 70s. Heights rise aloft Sunday night into Monday. It could start out mostly cloudy in the morning for coastal areas, but anticipating mostly sunny conditions across the entire area during the afternoon. Based on mixing up to around 925mb, deterministic NBM looked reasonable for high temperatures. Highs ranging from near 80 for parts of the Lower Hudson Valley, to the mid 60s for eastern LI and the SE coast of CT, which will have cooling onshore winds during the afternoon.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --
Large scale numerical weather prediction models convey the upper level jet as weak across the local region early into midweek. Then, jet stream level winds increase as a quasi-zonal jet streak moves into the area Thursday into Friday before shifting northeast of the region next Saturday. At the surface, high pressure moves farther offshore early into midweek. 850mb temperatures are warming during this time period. Synoptic pattern will be favoring low level warm air advection with more SW to W flow. Dry conditions are forecast Monday night through Wednesday. Low pressure weakens and moves north of the Great Lakes Wednesday night into Thursday. Its associated cold front approaches the local region from the west. The cold front moves across the local region Thursday night. Shower and convective activity is forecast to decrease in coverage as the front moves farther east. There is forecast of the potential showers and thunderstorms, slight chance Wednesday night into early Thursday, higher chance Thursday into Thursday night. Higher instability is forecast across the interior and less to the east across the more marine low level environment Thursday into Thursday evening. Therefore, locations near NYC and to the north and west will have the higher chances of seeing any rain showers and thunderstorms. 850mb temperatures do not change as much between Wednesday and Thursday. The local region will then be in between two low pressure systems for Friday and Saturday of next week. The ECMWF recently trended farther south and weaker with a wave of low pressure for next Saturday. There is uncertainty in this timeframe and some fluctuations of the low positions and thereby some rain potential for the local area are possible with subsequent forecasts. Forecast currently has slight chance of rain showers for much of the region but some areas forecast to have relatively higher chance late Friday night and Saturday but only between 25 and 30 percent. Surface high temperatures are forecast to range from the upper 60s to lower 80s for a majority of the region Tuesday, Wednesday and Thursday. Relatively cooler high temperatures are forecast along the immediate shore and the Twin Forks of Long Island, more within the 60s. High temperatures are forecast to trend downward slightly for Friday (more in the 70 to 80 range) and next Saturday (mostly in the upper 60s to mid 70s).
-- End Changed Discussion --
&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/... Weak high pressure remains along the northeast coast and into the mid Atlantic through Sunday afternoon. A weakening trough of low approaches from the west, and dissipates late tonight. Conditions remained varied across the region, with MVFR east of the New York City terminals, and VFR at the New York City terminals and north and west. There is a chance of MVFR at the western terminals with scattered light rain into early this evening. During the early evening MVFR is expected to develop throughout the area, with KGON becoming IFR. Brief IFR will be possible at KISP toward Sunday morning. Areas of rain and drizzle will be possible this evening and into early Sunday morning. Conditions may begin to improve toward 18Z Sunday. Moderate confidence in the forecast, with timing uncertainties with ceilings lowering. Winds generally remain 10kt or less from the northeast ..NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Scattered MVFR ceilings are possible late afternoon with light rain, then becoming MVFR. Moderate confidence with the timing of lowering ceilings this evening. OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... Sunday afternoon...MVFR early, then becoming VFR, except KGON remaining MVFR. Becoming MVFR at night. Monday...MVFR early morning, then VFR. Tuesday-Wednesday...VFR. Thursday...VFR, a chance of MVFR with showers and thunderstorms. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE...
-- Changed Discussion --
Sub-advisory conditions currently anticipated across all local waters through the middle of next week. However, with an approaching cold front Wednesday into early Thursday and its passage Thursday night, wind gusts will be reaching around 20 kt. Ocean seas forecast will be in the 3 to 4 ft range. Conditions could trend more rough in subsequent marine forecasts with higher ocean seas and higher wind gusts. Therefore would not rule the possibility of SCA conditions in this time period of Wednesday through Thursday night.
-- End Changed Discussion --
&& .HYDROLOGY... There are no hydrologic issues through the middle of next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/JM NEAR TERM...JC SHORT TERM...JC LONG TERM...JM AVIATION...MET MARINE...JC/JM HYDROLOGY...JC/JM