166 FXUS61 KOKX 182119 AFDOKXArea Forecast Discussion National Weather Service New York NY 519 PM EDT Thu Sep 18 2025
.SYNOPSIS... Weak low pressure continues to move farther away to the northeast through tonight. Meanwhile a cold front approaches from the north and west. This cold front moves across early Friday. High pressure moves in from Southeast Canada thereafter through the weekend and into early next week. A weak front will move through Tuesday night, then return north as a slow moving warm front Wednesday into Thursday.
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.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Numerical weather prediction models show that mid levels exhibit not much height change, ridge to the west and trough to the north. Surface, a cold front approaches from the north and west. This will move through the area early on Friday.
Winds will be light, SW to NW direction tonight, becoming all NW overnight into Friday morning as the cold front moves across. Clouds will be minimal with the front with winds staying up slightly to limit radiational cooling.
NBM appeared to be too warm and leaned more towards relatively cooler MOS for the forecast min temperatures for locations that are more rural and cool off more rapidly. Used the MAV/MET MOS blend instead. Lows range from the lower 50s to upper 60s.
A few locations within the outlying and rural sections could develop some fog late tonight into early Friday morning with radiational cooling and very light winds. Left as some patchy fog in forecast grids.
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.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... The cold front to start the short term is expected to be southeast of the region with all NW flow for early Friday. NW flow expected to remain through the day, as surface high pressure builds in from the north and west. The center of high pressure will be in Ontario Friday and heading into Quebec Saturday.
With NW primary mode of wind direction during the day, downslope will be effective at allowing coastal locations to be just as warm if not slightly warmer than interior locations. NBM was adjusted a degree warmer along CT and NYC/LI southern coastlines. Upper 70s to mid 80s range of high temperatures forecast.
For Friday night, models convey a strengthening of the high pressure moving in. The high pressure continues to build into the local area but with an increase in pressure gradient. This will allow for an increase in NE flow, which will mitigate radiational cooling. Used a blend of MAV and MET MOS along with NBM with greater weight towards MAV and MET, with each 40 percent weight. Forecast lows range from mid 40s to near 60.
Ridging in the mid levels Saturday through Saturday night. This will help promote subsidence and keep cloud coverage minimal.
For Saturday, the NE flow continues with gusty winds for the day closer to the coast, near 20 mph. Gusts subside towards the end of the day and at night. The flow becomes more easterly. A much cooler day is expected with forecast max temperatures mostly in the lower 70s. Lows Saturday night, while partially mitigated with the easterly winds, are still expected to drop near slightly cooler values than those of Friday night, mid 40s to upper 50s. Temperatures for Saturday and Saturday night followed the NBM.
Will have to watch for potential low stratus and/or fog development Saturday night with the easterly flow continuing. Have areas across the northern parts of the region with patchy fog late Saturday night.
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.LONG TERM /SUNDAY THROUGH THURSDAY/... The period starts off with an elongated sfc high pressure ridge extending westward from the north Atlantic into New England and the Mid Atlantic states, with weak ridging aloft, while the troughing that has persisted off the SE coast for some time finally lifts out into the Atlantic. We should see fair wx during this time, with a general E flow on Sunday, becoming SE-S on Mon. Temps on Sunday will be a little on the cool side, with highs in the upper 60s/lower 70s, then moderating close to normal for Mon with highs in the 70s throughout.
On Tue, a nrn stream trough will send a weak front toward the area, that should move through Tue night. The front will be fairly moisture starved, so have forecast only slight chance PoP for some showers late day Tue into Tue night. Temps will be above normal on a SW flow, with highs in the lower 80s for the NYC metro area and most of the interior.
Model guidance diverges somewhat later in the week but either way suggests a blockier pattern unfolding, with the ECMWF forecasting a rex block over the central states as ridging builds into central Canada and a closed low forms over the souther Plains, while the GFS has more of an omega block from the northern Plains and central Canada over to New England. Either way this setup suggests sfc high pressure over central/ern Canada, with some energy undercutting the general blockiness to send a sfc warm front slowly toward the area Wed into Thu. Have forecast chance PoP for Wed night for NYC north/west and Long Island, and slight chance otherwise for Wed night into Thu. Temps during this time frame should remain above normal.
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.AVIATION /21Z THURSDAY THROUGH TUESDAY/... VFR as a cold front approaches tonight and then moves across on Friday.
Made some amendments to go with a stronger sea breeze at KJFK/KISP and to delay its arrival at the other NYC metros. Sea breeze should be through KLGA by 22Z and may make it into KEWR/KTEB/KHPN for a brief period after 00Z. Outside of sea breezes, winds should become SW less than 10 kt after 00Z-01Z, then shift around to the NW overnight and into Friday. Speeds approach 10 kt by late morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Sea breeze may briefly make it to KEWR/KTEB/KHPN between 00Z-02Z.
.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday afternoon through Tuesday: VFR.
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.MARINE... Conditions are forecast to remain below SCA thresholds through Saturday night. The conditions get relatively close to SCA thresholds in ENE flow late Fri night into early Sat, with gusts up to 20 kt and ocean seas building to near 4 ft.
Persistent E flow on should keep ocean seas at 3-4 ft on Sunday. Thereafter the wave height forecast is uncertain, and will depend on the future track and intensity of TS Gabrielle well out in the Atlantic. Attm NWPS suggests potential for sets of 5-ft SE swells from Mon afternoon into Tue.
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.HYDROLOGY... There are no hydrologic concerns attm.
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.TIDES/COASTAL FLOODING... With a 2-ft/8 sec swell and mostly offshore flow 10 kt or less, perhaps some late afternoon SW sea breezes at the same speeds, have forecast a low rip current risk for Fri. As ENE flow after a cold frontal passage increases to around 15 kt Sat morning and seas build to 4 ft/5 sec (more favorable for longshore currents), the rip current risk should become moderate on Sat.
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.OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None.
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SYNOPSIS...JE NEAR TERM...JE SHORT TERM...JE LONG TERM...JE AVIATION...20/BG MARINE...JE HYDROLOGY...JE TIDES/COASTAL FLOODING...
NWS OKX Office Area Forecast Discussion