Area Forecast Discussion
Issued by NWS Upton, NY

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978 FXUS61 KOKX 030554 CCA AFDOKX Area Forecast Discussion...CORRECTED National Weather Service New York NY 154 AM EDT Thu Jul 3 2025 .SYNOPSIS...
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A Canadian cold front approaches and passes this afternoon into evening. High pressure builds in behind the front tonight through Friday night, then offshore for Saturday into Saturday night. A cold front approaches from the Great Lakes Sunday into Monday, passing slowly across the area Tuesday or even stalling in close proximity.
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&& .NEAR TERM /THROUGH TONIGHT/... A few pockets of patchy radiational fog are possible through daybreak until mid-morning in some outlying areas. An upper-level polar low dives southeast through western Quebec today into tonight with its associated 1 std deep shortwave trough passing the area this afternoon & evening with a Canadian cold front. Model soundings show a well-mixed environment today. Mainly sunny skies are expected other than some lingering partly sunny skies for far eastern locales from a stalled front that washes out east of the area over the ocean early today. Light offshore flow in a sunny, well-mixed environment should allow temperatures to warm into the upper-80s for most with some spots at or just above 90 this afternoon in NE NJ and the NYC metro area. A warm, sunny, well-mixed environment in the early afternoon today will leave us well set for an active afternoon and evening of showers and thunderstorms. A Canadian cold front will pass the area mid-afternoon into early evening, providing lift for shower and thunderstorm development along with shortwave energy passing aloft. PWATs along and ahead of the front will be suitable rain to develop. 00Z CAMs are showing an unstable environment with good SBCAPE values and acceptable MLCAPE values for surface based convection along the passing cold front. With 35-50 kts of mainly unidirectional shear, any thunderstorms that do develop, could see scattered instances of strong to damaging wind gusts in the form of squall lines or bowing segments along the cold front. Low level lapse rates look potent. Despite the cap breaking just before midday, the mid-level lapse rates look too low for most of the morning and early afternoon for thunderstorm development. They do eventually climb to marginal values (6.5-6.9 C/km) with the approaching front helping with storm initiation in the mid/late afternoon to early evening. Given this, most storms will likely develop along the cold front rather than well ahead of it. 00Z CAMs have showers and thunderstorms timed to start around midday to our west, entering our area with the cold front 2-4 pm for NW interior locales then follow the cold front through the area west-to- east, exiting east by 7-9 pm. SPC has the entire area under a Slight Risk for severe thunderstorms. The primary risk will be for damaging winds, but isolated occurrences of hail can not be ruled out. N&W of NYC there may be scattered instances of strong to damaging winds, but as the line of storms track east with the cold front in the early evening strong to damaging winds may become more isolated. Following FROPA this evening, clouds clear by early in the night as cooler/drier Canadian air gets advected in, aided by the upper-level trough axis centering over the area. Lows will be in the mid-60s for coastal locations, upper-60s to low-70s in urbanized areas of NE NJ, NYC, and Nassau counties, and drop into the low-60s to upper-50s in interior locations. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... The upper-level trough axis shifts east on Friday and completely exits east by Friday night. At the same time, an upper-level ridge builds in from the west Friday through Saturday night. At the surface, high pressure builds in from the west Friday into Friday night, passing east offshore, but remaining in control, Saturday into Saturday night. Friday through Saturday will be dry and mainly sunny given widespread subsidence. Temperatures will be close to just above climatological norms with highs in the 80s and lows in the upper-50s to near 70. Ideal conditions are expected for Independence Day celebrations. Sunny, dry, warm weather for afternoon activities with temperatures falling into the 70s under clear skies in the evening. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... No significant changes were made to the extended forecast and stuck close to the NBM/previous Forecast. Key Points: * Warm and humid conditions expected Sunday and Monday . * A weak cold front moves into the area on Tuesday with a chance of showers and thunderstorms High pressure both aloft and at the surface will slide offshore Sunday and Monday. With an approaching upper trough trough over the Great Lakes Sunday into early next week, vertical temperatures profiles will be on the rise with 85h temps near 18C by Monday. In addition, a prolonged period of southerly flow will result in gradually increase humidity during this time. A weak cold front associated with the aforementioned upper trough approaches late Monday into Tuesday with increasing chances of showers and thunderstorms. Environment is weakly sheared, but moderately unstable ahead of the front. There is some uncertainty as to when the front pushes through, or if it simply washes out in close proximity Tuesday into Wednesday. This is reflected in some increasing spread for temperatures between the 25th and 75th percentiles. Once again, the NBM deterministic temperatures are generally at or below the 25th percentile during the forecast period. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A cold front will approach this afternoon and move across the area this evening and overnight. VFR to start. LIFR cigs are likely early this morning at KGON and KISP and may also impact KBDR/KJFK. SW winds may go light and variable for a few hours, before veering NW toward daybreak, then backing SW once again into late morning. Speeds increase to 10 kt, with gusts toward 20 kt possible after 18Z, though may be more occasional at some sites. Risk for TSRA late afternoon and early eve, mainly 20Z to 00Z Fri. Any TSRA could produce brief IFR conditions. Drier and VFR conditions expected tonight. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Can not rule out low cigs reaching KJFK early this morning. Gusts 20 kt possible this afternoon, may be more occasional. Timing of TSRA may be off by an hour or two. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... Thursday night: VFR conditions. Friday: VFR. NW winds G15-18kt. Saturday through Monday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Sub-SCA conditions are expected on all waters under a weak pressure gradient through Friday night. Tstms may pose a hazard of strong winds, lightning, heavy rain, and locally rough seas Thu aft/eve. Sub-SCA conditions are expected this weekend into early next week. Southerly flow on the ocean waters Sunday into Monday will feature G15-20kt with seas generally around 3 ft, possibly as 4 ft late Monday. && .HYDROLOGY... No widespread hydrologic impacts anticipated through early next week. && .TIDES/COASTAL FLOODING... A lingering southerly swell of 3 ft 6-7s will produce a moderate rip current risk on Thursday, and low to moderate on Friday. Surf looks to be around 3 ft Thursday and around 2 ft on Friday, possibly a bit higher across the SE Suffolk beaches. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BR NEAR TERM...BR SHORT TERM...BR LONG TERM... AVIATION...BC MARINE...BR HYDROLOGY...BR TIDES/COASTAL FLOODING...