963 FXUS61 KOKX 062347 AFDOKX Area Forecast Discussion National Weather Service New York NY 747 PM EDT Mon Sep 6 2021 .SYNOPSIS... High pressure builds in from the Ohio Valley tonight through Tuesday. A warm front approaches the area on Tuesday evening and passes to the north early Wednesday. A cold front moves through Wednesday night into early Thursday morning. High pressure builds back towards the area heading into next weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Lowered POPs north and west of NYC as there is nothing on currently seen on radar, despite what mesoscale models were advertising earlier. Otherwise, minor changes made to reflect current conditions. Upper trough axis currently over eastern PA swings through this evening as weak ridging builds in its wake through the overnight. Light winds and mostly clear skies will allow for efficient radiational cooling overnight. Lows are forecast to be mid and lower 60s for NYC and LI, and in the mid to upper 50s across CT and northern NJ. A few spots across the Lower Hudson Valley and eastern Long Island may see some temperatures in the lower 50s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... A dry day is expected on Tuesday as ridging aloft and surface high pressure remain in control. Temperatures should be similar to Monday, maybe a degree or two cooler given the lower temperatures to start, but still seasonable, upper 70s and lower 80s. By Tuesday night and into Wednesday morning, the ridge axis pushes east of the area as a more potent upper low takes shape over the Great Lakes and deepens as it moves east. Clouds will be on the increase by late Tuesday night into Wednesday morning as a warm front approaches, and moves north of the area, increasing the southerly flow along with a more humid airmass. PWATs will begin to increase for the area as a result, to 1-1.5". Model guidance has trended a bit slower with the onset of precipitation on Wednesday, though some light warm advection type shower activity looks possible later on Wednesday morning. With the area solidly in the warm sector, showers and thunderstorms are expected to approach the area by early evening in advance of a surface cold front. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... The cold front will continues its approach Wednesday night and begins to move through the forecast area late Wednesday night into Thursday morning, as an amplifying upper level trough moves over the Great Lakes region into the day Thursday. Will have to monitor for the potential for flash flooding Wednesday night as PWAT values increase to 1.5" to 2" across the area. Low level southwesterly winds will increase during this time frame, becoming nearly parallel to the cold front. Additionally, Conditions have been very wet lately and many rivers and streams remain at elevated levels, so flash flood guidance will be low and it won't take much rain for additional flooding. Weak low pressure may form along the frontal boundary, adding more in the way of lift. Finally, The Weather Prediction Center has placed portions of NYC, northeast NJ, and southwest CT in a marginal risk for excessive rainfall. Cannot rule out flash flooding in any of these locations, and there is still uncertainty in where and how much rain will fall, but as of now, the best chances look to be north and west of NYC. High pressure builds in behind the front for Thursday through Friday. However, there may be some lingering showers for eastern Long Island and southeast CT Thursday as weak areas of low pressure ride the frontal boundary off shore. With the upper trough axis moving through Thursday night, this should help steer Larry away from the coast. However, energetic swells will likely bring potential for high surf and dangerous rip currents to end the week. See National Hurricane Center forecasts for the latest on Larry. High pressure pushes off the mid-Atlantic coast on Saturday, as another frontal system approaches from the west for the second half of the weekend. However, there is a good deal of uncertainty for any precipitation next Saturday night into Sunday, though any precipitation looks to be light at this time. Seasonable temperatures are expected for this time period. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... On the heels of a morning cold frontal passage, a second cold front will pass through this evening. High builds in overnight into Tuesday morning, then offshore Tuesday afternoon. VFR. W winds increasing to 10-15 kt with gusts up 20 kt this afternoon. Winds and gusts subside this evening, with light W-NW winds overnight. Winds will then veer to the S/SW late morning into the afternoon at 5-10 kt. ...Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Winds should generally run left of 310 magnetic. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... .Tuesday Afternoon...VFR. .Wednesday into Thursday morning...Chc MVFR or lower in shra/tsra, mainly late afternoon into Thu AM. S/SW gusts 20-25 kt, shifting to W/NW on Thursday. .Thursday Aft and Friday...VFR. Gusty NW winds. .Saturday...VFR. S winds. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Conditions will then remain below SCA through Tuesday, though occasional gusts to 20 kts remain possible into this evening. SCA conditions look probable again on Wednesday, especially for the ocean waters, as southerly winds ahead of the next cold front may reach 20-25 kt in the afternoon and evening. By Wednesday evening, winds will remain below SCA criteria. However, waves will remain elevated on the ocean (5 to 6 ft) due to cold frontal passage and cold air advection behind the front on Thursday, then build again Thursday night with swells from tropical cyclone Larry moving into the coastal waters. Waves begin to diminish Friday night, but should remain above 5 ft through Saturday morning. Thereafter, waves should remain below 5 ft. && .HYDROLOGY... Minor to moderate flooding continues along portions of the Passaic River. Water levels are expected to fall below flood stage Tuesday into Wednesday. A cold front late Wednesday night brings a chance for heavy downpours and thunderstorms. Given wet antecedent conditions from recent rainfall, WPC has placed NYC metro, NE NJ, and the Lower Hudson Valley in a marginal risk for excessive rainfall/flash flooding. Localized flash flooding of urban and poor drainage areas, as well as already swollen quick responding small rivers, streams, and creeks cannot be ruled out. Otherwise, no widespread hydrologic concerns are anticipated this week. && .TIDES/COASTAL FLOODING... There is a moderate risk of rip currents through Tuesday with 2 to 3 ft S/SW swells. There is a high risk of rip currents for Wednesday and possibly into the end of the week as swells from tropical cyclone Larry affect the area. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JP/DBR NEAR TERM...JP/DBR SHORT TERM...DBR LONG TERM...JP AVIATION...DW MARINE...JP/DBR HYDROLOGY...JP/DBR TIDES/COASTAL FLOODING...JP