862 FXUS61 KOKX 130540 AAD AFDOKX Area Forecast Discussion...UPDATED National Weather Service New York NY 140 AM EDT Mon Sep 13 2021 .SYNOPSIS... A cold front gradually sinks south towards the region overnight and into the morning. The front may then remain stationary just to the south into Tuesday before lifting north as a warm front Tuesday night. A cold front approaches on Wednesday and stalls near the area by week's end. A weak low pressure system may pass southeast of the area on Saturday. High pressure builds back in on Sunday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... An MCS progressing across Lake Erie is forecast to weaken while passing north of the area toward daybreak. A shower or an isolated thunderstorm still can't be ruled out well inland, but seeming unlikely at this time. The latest CAMs and global models are in excellent agreement that this activity will pass well to the north overnight. The frontal boundary focusing the convection will sag slowly southward into the area by morning. Otherwise, mild temperatures in the upper 60s and lower 70s are forecast tonight. It will feel much muggier than previous nights as well with dew points in the middle to upper 60s. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Confidence continues to increase that the cold front will slowly shift south of the area on Monday. There is a growing consensus among the models for the front to stall across central NJ and just south of Long Island during the day. The flow aloft continues to be largely zonal with no well defined shortwaves or energy to develop any convection during the day time. Forecast soundings also reveal a strong capping inversion between about 800 and 600 mb. The low level flow should become NW, which will still give a boost to temperatures, with highs in the lower 80s inland and middle 80s near the coast. There will be a decrease in dew points, especially inland. It would not be surprising if dew points mix out a few degrees more than forecast, especially given the northwest flow. The surface boundary may meander near or just south Monday night. There is signal among the model guidance, including several CAMs, for another convectively induced vorticity maximum to traverse around the periphery of the ridging across the southeast. The energy may able to interact with the frontal boundary and develop some showers and thunderstorms Monday night. There is a decent amount of middle level flow, so any convection will be fast moving. Will have to monitor trends in the model guidance over the next 12-24 hours as the middle level flow could help organize the convection into a cluster or line segment. One main negating factor is there is evidence of a strong stable layer setting up Monday night leading to no surface based instability. However, elevated instability looks quite high and may be enough to support/sustain convection. The biggest question is whether or not this convection can produce any severe wind gusts. SPC has placed portions of the area in a marginal to slight risk. Our confidence at this time is low, and not enough to include in an HWO since the threat is highly conditional to whether or not the convection will be strong enough to break through the strong stable layer below 900 mb. One aspect to watch for is the positioning of the surface boundary. If the front ends up further north, then the convection may have a higher chance of producing a few severe storms. At the same time, if the front is further south, the convection could move further south and west limiting any threat of convection entirely. Due to the aforementioned uncertainty, have only increased PoP across the southwest half of the area to low chance. Any convection from Monday night dissipates before sunrise Tuesday. The convection could force the frontal boundary further south by Tuesday morning. There is also a signal for a high pressure to develop along the New England coast Tuesday. The surface ridging is tied to ridging building aloft. These factors have led to a lowering of PoPs on Tuesday with much of the area dry through the evening. Cannot completely rule out a shower late in the day across the interior, but this may even be aggressive given the recent trends in the modeling. Temperatures have also trended cooler and should end up closer to seasonal averages in the middle and upper 70s. Developing onshore flow around the high pressure and potential lingering low cloudiness should aid in keeping temperatures cooler. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Global model continue to be in fairly good agreement with the overall upper level pattern through the end of the week. Weak ridging aloft shifts offshore Wednesday morning as a trough digs through the Great Lakes. This feature will bring a cold front near the CWA by Wednesday evening as the trough axis passes over the region on Thursday morning. Flow then becomes more zonal into Friday, stalling the front. Shortwave energy approaches from the southwest into Saturday and moves offshore by Sunday. Long wave ridging returns by the end of the weekend. The area remains in the warm sector on Wednesday, with southerly flow and increasing humidity as the cold front heads toward the area by the afternoon. The environment does look supportive of shower and thunderstorm development by Wednesday evening. Model soundings are indicating SBCAPEs near or above 1000J/kg (NAM has value approaching 2000-2500J/kg) with 20-30 kt 0-6km shear by 00Z Thursday. In addition, the region is near the right exit region of the jet. At this point, cloud cover from earlier in the day Wednesday may be the limiting factor for destabilization, and so northwest areas of the CWA are most likely to see any stronger storms as they move in from the west. PWATS do look to remain in the 1-1.5" range over this timeframe, and so any storms will have the potential for a period of isolated heavy rainfall. Thursday continues to look unsettled, as well, as front stalls just to our north as the upper flow flattens. Thus, have maintained chance PoPs via NBM. Thunder potential does look lower on Thursday with capping in place, and rain chances look to continue into Friday with the front nearby. For Friday and Saturday, we continue to monitor the potential for low pressure development off the southeast coast, which may approach the region. Both the 12Z deterministic GFS and EU move this weak low north along the western periphery of the subtropical ridge and curve it south of the 40/70 benchmark back to the east away from land as it gets picked up by a shortwave. It should also be noted that many members of both the GEFS and ECENS depict a weak system well to the south of the area. In addition, some model guidance is also showing both an interaction with the remnants of Nicholas as well as the aforementioned frontal system to the north, so there are many details to be ironed out over the next few days. As mentioned yesterday, this far out it is much too early to determine what, if any, impacts there may be to the region next weekend from this system. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR as high pressure off the Mid Atlantic will continue to work E across the western Atlantic, while a cold front slowly approaches from the NW overnight, and pushes through around or shortly after 12Z. A passing shower and/or isolated thunderstorm can't completely be ruled out at KSWF in the 08Z to 12Z timeframe. SW winds 5-10 kt early this morning, will gradually veer to the W-NW toward 12Z, increasing to around 10 kt. Occasional gusts 14-17kt possible during the late morning into mid afternoon. Winds will veer to the N or become light and variable around 00Z Tue at 5 kt or less. Another round of showers and possible thunderstorms will be possible Monday evening/overnight. Timing and placement of any storms still remains uncertain, but will cover this threat with a prob30 for TSRA for now. ...Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of wind shift around the morning push could be off by 1 to 2 hours with cold frontal passage. Winds will also be right around 310 magnetic for much of Monday, varying +/- 10 to 20 degrees on either side. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Monday night...Mainly VFR. Chance of brief sub VFR conditions in a shower or tstm, mainly after 06Z. .Tuesday...Mainly VFR. .Tuesday night...Chance of showers and possibly a few tstms with MVFR or lower conditions from the NYC metros north/west. .Wednesday...Mainly VFR, with a chance of showers and a few tstms in the afternoon and night. .Thursday...Chance of showers and possibly a few tstms with brief MVFR or lower conditions, mainly in the afternoon and evening. .Friday...MVFR possible at times with chance of showers and slight chance of tstms. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Winds should continue to subside tonight below 25 kt on most of the waters, except the ocean east of Moriches Inlet where 25 kt gusts are possible until early morning. Ocean seas will remain elevated tonight into Monday morning, lingering around 5 ft longest east of Moriches Inlet. The SCA east of Moriches Inlet has been extended until 15z, with the rest of the ocean SCA in effect until 10z. Sub SCA conditions are then expected Monday through Tuesday with a weak pressure gradient in place. SCA conditions are possible again on Wednesday afternoon into early Thursday morning over the ocean waters as a frontal system approaches. Seas may approach 5 ft and winds gust to 25kts. Sub SCA conditions are expected Thursday and Friday. Seas may begin to build again on Saturday to over 5ft, depending on the track and intensity of an approaching area of low pressure for the ocean zones. && .HYDROLOGY... No hydrologic issues expected. && .TIDES/COASTAL FLOODING... There is a moderate risk of rip currents at the ocean beaches Monday. However, with swells continuing to subside, the rip current risk likely lowers to low Monday afternoon. The rip current risk is low on Tuesday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT early this morning for ANZ353-355. Small Craft Advisory until 11 AM EDT this morning for ANZ350. && $$ SYNOPSIS...DBR/DS NEAR TERM...DBR/DS/DW SHORT TERM...DS LONG TERM...DBR AVIATION...BC/DW MARINE...DBR/DS HYDROLOGY...DBR/DS TIDES/COASTAL FLOODING...DBR