000 FXUS61 KOKX 180530 AFDOKX Area Forecast Discussion National Weather Service New York NY 130 AM EDT Thu Apr 18 2024 .SYNOPSIS... A slow moving warm front approaches from the southwest and moves through the area into Thursday. High pressure briefly builds in for Thursday night into Friday before a cold front passes through Friday night into Saturday morning. High pressure then follows from Saturday afternoon through early next week. A weak frontal system will impact the region mid week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Made some adjustments to POPs for rain showers as well as dewpoints. Also pushed back timing of slight chance thunder to just the overnight period from west to east. Temperatures are mainly on track. An approaching warm front will lead to isentropic lift in association with overrunning moisture with rain showers across the region going into overnight. Instability will continue to be the challenge with the overall thunder potential but given that there has been some lightning upstream the forecast still includes a slight chance of some embedded thunderstorms overnight. Confidence is low (15%) on the likelihood of widespread mention of thunder especially with a modest low level inversion keeping much of the area stable. The 12z suite of CAMs still indicated the potential for some short lived embedded heavier showers moving through southwestern portions of the forecast area overnight tonight within the New York City metro area. During the overnight expect the shower coverage to increase although decrease in intensity. As the WAA lift decreases, showers will transition from potentially heavy at times to more of a steady light rain. Temperatures are expected to be near normal for this time of year. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... Shower coverage looks to lower Thursday as isentropic lift weakens over the area and high pressure building in from the northeast brings in a cooler and drier air mass in the lower levels. The high building in with the weak low to our south will mean a strengthening easterly flow develops across the area that starts to increase late tonight. It does not look to be overly windy, with sustained winds of 15 to 20 mph and gusts to 25 mph by Thursday morning. Winds start to decrease Thursday afternoon as the high continues to nose into the region, with the weak low well out to sea by this point. The easterly flow will also mean cooler than normal temperatures for Thursday, with highs only in the upper 40s to lower 50s. Mainly dry conditions from Thursday night (except perhaps some lingering showers for eastern areas) through Friday morning with high pressure over the region. The chances for showers increase Friday afternoon and Friday night as the associated cold front approaches and begins to move through late Friday night. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Little change in the long term and stuck fairly close to the previous forecast/NBM. A cold front approaches and passes through Friday night into Saturday morning. Moisture will deepen along with a chance of showers with its passage. High pressure then builds in behind the front with dry weather for Saturday afternoon. The high will continue to build into the region through the rest of the weekend and remain in control of the weather through Monday. High temperatures near normal on Saturday, but cooling off slightly for Sunday. Temperatures rebound a few degrees on Monday. A 500mb trough then shifts through the Great Lakes on Tuesday with an associated weak surface low and cold front. It appears that we should by dry through the day, but cannot rule out a shower for western zones by the end of the day. Rain chances increase Tuesday night into Wednesday. Temperatures remain in the lower and middle 60s. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... Persistent pattern during the TAF period with low pressure and a warm front approaching but staying south and west of the region with high pressure to the northeast of the region. MVFR or IFR everywhere to start with more widespread IFR towards the second half of the night and into Thursday morning. Rain showers are intermittent but eventually will become more steady for the second half of the overnight period. Also, the rain may be locally moderate to heavy at times. Can not rule out an isolated embedded thunderstorm as well, however timing and confidence too low to include in the TAF. Rain showers will remain in the forecast through at least 18z, however, they may be more intermittent. Rain chances lower further this afternoon. Mainly IFR conditions are expected, however improvement to MVFR late can not be ruled out. Conditions start to improve late this evening and overnight to MVFR then VFR for most terminals. Timing however amendments are likely to adjust the timing. Wind direction will be E to ENE for much of the TAF period. Wind speeds will be near 10 kt tonight and then increase Thursday to near 12-15 kt with gusts mainly in the 20-25 kt range. KSWF expected to have lower winds near 10 kts or less without gusts during the TAF period. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Amendments likely for changing flight categories. OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... Thu night: Showers end with slowly improving conditions Thursday night. Improvement to MVFR then VFR expected. Fri: VFR early, then MVFR afternoon and at night with a chance of showers. Sat: MVFR with showers ending in the early morning, becoming VFR. W-WNW wind gusts 15-20 kt. Sun through Mon: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... No changes to the winds and seas at this time. Winds and seas remain below SCA criteria. However, easterly winds will increase tonight as strengthening high pressure builds in, and by late tonight will likely reach 25 kt on the ocean waters and the entrance to the harbor. A few hours later, all waters will see SCA wind gusts by early Thursday. A SCA is in effect for all waters for Thursday. LI Sound and LI Bays have SCA just for Thursday and other marine zones (ocean and NY Harbor) have SCA begin at 06Z Thursday and go through the day Thursday. Winds gusts diminish Thursday night as the high continues to build in over the area. Non ocean waters will likely drop below 25 kt early Thursday night. The ocean waters will likely have SCA gusts hang on for the first few hours of Thursday night before they also come down below 25 kt. Seas build to 4 to 7 ft on the ocean by Thursday morning into the afternoon, diminishing thereafter. However, they remain above or right around 5 ft Thursday night, so an extension to the SCA over the ocean may be needed for Thursday night and perhaps into Friday with a persistent, though slowly weakening easterly flow. Waves finally drop below 5 ft on the ocean by Friday night. High pressure building over the area waters Saturday through the first part of next week should keep conditions sub-advisory waters through at least Tuesday night. Conditions may build back to SCA levels for Wednesday with the next low pressure and associated cold front to approach. && .HYDROLOGY... There is the potential for 0.25" to 0.75" of rainfall through Thursday afternoon. Although a brief heavy shower is possible, no hydrologic impacts are expected with this event and thereafter through the first half of next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 6 AM this morning to 6 PM EDT this evening for ANZ331-332-335-340-345. Small Craft Advisory until 6 PM EDT this evening for ANZ338- 350-353-355. && $$