989 FXUS61 KOKX 060952 AFDOKX Area Forecast Discussion National Weather Service New York NY 552 AM EDT Mon Sep 6 2021 .SYNOPSIS... A cold front crosses pushes offshore this morning. High pressure then gradually builds in this afternoon through Tuesday. The high moves offshore Tuesday night as a warm front lifts north. A cold front moves works its way through Wednesday night into Thursday. High pressure builds back into the area heading into the weekend. Another cold front may pass through the region Sunday Night into Monday. && .NEAR TERM /THROUGH TONIGHT/... The cold front continues to move across the area early this morning. The bulk of the showers with the front remain along the Long Island coast and over the ocean. This trend will continue early this morning as the front slowly works its way offshore, with these showers ending by middle to late morning. Patchy fog is possible through around 8 am across the interior as well. Clouds will diminish from west to east through the morning, but mostly cloudy to overcast conditions likely persist longest across eastern Long Island and southeast Connecticut. A westerly, downsloping flow sets up behind the front today allowing temperatures to warm into the lower 80s for much of the area. The NYC metro and urban NE NJ could see highs reach the middle 80s. The westerly flow will also allow the atmosphere to dry out. This will prevent any showers from developing this afternoon as the upper trough swings across New England. High pressure builds towards the area late today into tonight. This will lead to a seasonably cool night with dry conditions across the region. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Tuesday will be dry and seasonably warm with high pressure in control through the day. Highs will be in the middle and upper 70s for most locations, with around 80 degrees in the NYC metro and urban NE NJ corridor. The surface high pressure does shift offshore in the afternoon as an upper ridge axis pushes east. The flow will become more southerly late the day as this occurs. A warm front lifts north of the area Tuesday night as a deepening upper trough takes shape over the Great Lakes region. The upper trough is likely to continue deepening into Wednesday as a cold front slowly approaches. The flow ahead of the front and around high pressure offshore will bring in a warmer and more humid air mass. The warm advection pattern could develop a few showers in the morning, but probabilities of increase in the afternoon, especially north and west of the NYC metro with a pre-frontal trough. Instability will increase with the more humid airmass and lowering heights aloft. A few showers and thunderstorms are possible along the pre-frontal trough in the afternoon and early evening. Greater coverage of showers/storms should hold off until the arrival of the actual cold front in the evening and at night. A band of showers and thunderstorms may work its way from west to east across the region with the front Wednesday night. Cannot completely rule out a strong to severe storm especially in the evening NW of the NYC metro given 1000-1500 J/kg of CAPE and 35-40 kt of bulk shear, but this appears to be an isolated threat given waning instability after sunset. The amplification of the upper trough may allow for a deeper moisture profile for any of the showers/thunderstorms to work with Wednesday evening and night. Specific details on rainfall amounts and possible rainfall rates in any convection are of low confidence at this time. Given recent rainfall, WPC has placed the NYC metro, NE NJ, and Lower Hudson Valley in a marginal risk for excessive rainfall/flash flooding. The front should be moving towards the coast late Wednesday night allowing for any lingering convection to shift across Connecticut and Long Island. However, there is some question as to whether the front will fully move offshore by Thursday morning since the handling of the upper trough is not well resolved by the models at this time. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Models in good agreement with mean troughing for the end of the week into the weekend, but model spread continues with the amplitude and progressiveness of a trough axis through the area Thu into Fri. The above mentioned trough evolution will determine progress of a cold front through the region Thu, and timing/location of wave development. A deeper and slower trough would cause slower movement of the front, while a shallower more progressive trough axis would allow for quicker movement of the front. The deeper solution would also point to better potential for surface wave development. Threat for locally heavy rain exists into at least Thu morning, particularly with slower solutions and potential wave development. Still quite a bit of model spread at this point, but threat for heavy rain late Wed into early Thu on extremely saturated grounds will have to be monitored with a favorable deep layered lift of a gulf/sub-tropical moisture plume ahead of a slow moving front, and possible enhancement in vicinity of a surface wave. Although rainfall could linger well into Thursday, heaviest rain threat should wane in the wake of the cold front as instability axis would be shifted east. Once the initial mean trough axis slides through during the late Thu to late Fri time period, model spread continues on timing of a couple of shortwave troughs within the mean trough this weekend into early next week. The latter shortwave, may bring next potential for shower activity for Sun Night/Monday time period. Before then, Friday through Sun continue to look like a seasonably mild and dry period as Canadian high pressure builds in through Saturday, and then offshore on Sunday. Good agreement on the synoptic setup helping steer Larry well east of the US East coast late week, but energetic swells arriving as early as Wednesday will likely bring high surf and dangerous rip currents Thu and Fri, gradually subsiding this weekend. See National Hurricane Center forecasts for the latest on Larry. Seasonable temperatures are expected during this time period, with comfortably less humid conditions Fri thru Sun. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... An approaching cold front will pass through this morning, with a second weak cold front passing through this evening. MVFR/IFR early this morning, improving to VFR from w to e through the morning push. SW winds 5-10 kt bcmg W early this morning, then increasing to 10-15 kt aft daybreak. Afternoon peak winds of gusts 20-25 kt. ...Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Conditions likely improving to VFR between 11z and 13z. W winds increasing to 10 to 15 kt after 12z, with gusts 20-25 kt for aft/early eve push. W winds and gusts subside after 23-01z. Winds should generally run left of 310 magnetic, but could range between 300 and 320 during the morning and evening push. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Tonight...VFR. .Tuesday...VFR. W winds AM, becoming S/SW PM/ .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. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... A cold front will work its across the waters this morning. Winds on the ocean have largely fallen below 20 kt. Seas may briefly build to 5 ft offshore of Moriches Inlet to Montauk Point, but overall conditions should remain below SCA levels this morning. Conditions will then remain below SCA criteria this afternoon through Tuesday night with high pressure in control. Southerly winds ahead of the next cold front increase on Wednesday and may reach 25 kt in the afternoon and evening, especially on the ocean waters. The winds will diminish to around 20 kt or less Wednesday night as the pressure gradient relaxes somewhat with the cold front nearing the waters. Ocean seas are likely to build to 5 to 6 ft Wednesday into Wednesday night. Seas on the ocean will likely remain at SCA levels through the late week into Saturday as energetic long period se swells (5 to 8 ft @ 15-17 sec period) from Larry likely move into the water Wednesday, peak Thu and Fri, and gradually subside through the weekend. && .HYDROLOGY... While water levels continue to fall, minor to moderate flooding continues along portions of the Passaic River. Water levels are expected to fall below flood stage late Monday into Tuesday. A cold front late Wednesday into 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 potential for a high risk of rip currents mid to late this week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...DS/NV NEAR TERM...DS SHORT TERM...DS LONG TERM...NV AVIATION...NV MARINE...DS/NV HYDROLOGY...DS/NV TIDES/COASTAL FLOODING...DS