Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 241425 AFDOKX Area Forecast Discussion National Weather Service New York NY 1025 AM EDT Fri Mar 24 2017 .SYNOPSIS... A warm front moves across the region today, with an unsettled weather pattern continuing through the weekend and into the middle of next week. The warm front north of the region retrogrades back into the region as a back door cold front Saturday night and will be west of the area Sunday. The front returns to the region Sunday night into Monday and then passes east of the region Monday night. Another system approaches Tuesday and moves across Tuesday night into early Wednesday. High pressure returns thereafter. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Minor tweaks but no major changes made to the forecast. By the time the precipitation fully moves into the region and starts reaching the ground late this morning into early this afternoon, this will be mainly rain as temperatures will have risen to above freezing for most locations in the forecast region. Extremely dry air evident on 00Z soundings at OKX and ALY will be very difficult to saturate initially this morning, so have delayed the onset of precipitation. Isentropic lift associated with the warm front and a passing short wave will eventually lead to the development of light precipitation later this morning into the early afternoon. Initially cold temperatures may support a brief period of light snow, then perhaps ice pellets or minimal accumulation of freezing rain as warm advection above the surface rapidly increases amidst a strengthening low-level jet. Eventually surface warm/moist advection will lead to above freezing temperatures at all locations, and precipitation type transitioning to rain. A warming trend is expected today into Saturday, though high temperatures today will still be a few degrees below climatological normals.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Any precipitation will quickly taper off by evening as the short wave moves east of the area and the warm front moves to the north. Dry conditions will be short-lived overnight. By morning, an upper low approaches from the west, increasing forcing for ascent, and in combination with a back door cold front subsequently increases precipitation chances through Saturday evening. Temperatures tonight will be nearly steady as warm advection continues through the night amidst southwesterly flow. By Saturday afternoon temperatures will finally be close to climatological normals, though a cooling trend will be noted late in the day from northeast to southwest as the back door cold front begins to move through. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Overall, an increasingly maritime airmass will be getting entrained into the region from a persistent easterly flow. Rain will ultimately be intermittent with some drizzle from time to time for the remainder of the weekend. Not much of a diurnal temperature range expected for the remainder of the weekend either. Patchy fog is expected Saturday night through Sunday evening as boundary layer becomes saturated from the continuous easterly flow. Rain continues Monday with some more synoptic forcing ahead of the shortwave and surface frontal system moving in. The chances for rain lower Monday night as these aforementioned features move east of the region. Chances for rain are slow to drop off because of increasing uncertainty in the model precipitation fields this timeframe. Rain could linger longer early next week if the frontal system is slower. Aloft, there will be a flattening ridge with the polar jet moving farther north of the region Saturday night. The flattening ridge axis moves across on Sunday. An embedded shortwave on the back end of the ridge approaches Sunday night and moves across Monday. Brief ridging then takes place Monday night into Tuesday. There will be another shortwave moving across Tuesday night. A ridge to the west then starts to build in thereafter for midweek. Starting Saturday night, the surface features to note will be a front retrograding southwest within the region and strengthening high pressure building southeast from Quebec into Maine. The front is a back door cold front. On Sunday, the high pressure area will be moving into the Gulf of Maine and easterly flow will keep a cool marine airmass. The front moves east back into the area Sunday night into Monday with a weak low developing along the front. The flow becomes more southerly. The front and low along it move east of the region Monday night. Another frontal system approaches Tuesday afternoon and moves across Tuesday night. High pressure starts to build in thereafter for midweek. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... High pressure will slide further offshore today. Meanwhile, a warm front will lift to the north. Mainly VFR through the TAF period. There is the potential for some light precipitation late this morning into early this afternoon. The best chances of precipitation will be at KSWF, where some ice pellets may briefly mix in at the very start. Elsewhere, will use a TEMPO group to address any rain/showers. light and variable winds increase out of the S-SSW this morning to around or just over 10 kt. Gusts around 20 kt likely this afternoon. Winds diminish overnight. Conditions should remain fairly dry overnight. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Best chance of any precipitation will be between 16z-18z. Low chance for a brief MVFR cig. KLGA TAF Comments: Best chance of any precipitation will be between 16z-18z. Low chance for a brief MVFR cig. KEWR TAF Comments: Best chance of any precipitation will be between 16z-18z. Low chance for a brief MVFR cig. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Best chance of any precipitation will be between 16z-18z. Low chance for a brief MVFR cig. KHPN TAF Comments: Best chance of any precipitation will be between 16z-18z. Low chance for a brief MVFR cig. low chance precipitation could start off as a rain/ice pellet mix. KISP TAF Comments: Best chance of any precipitation will be between 16z-19z. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .Saturday morning...chance of sub-vfr in stratus Saturday morning. .Saturday afternoon-Monday...MVFR/IFR probable, possibly LIFR. .Monday night-Tuesday...MVFR or lower possible. && .MARINE... Winds and seas increase this afternoon with the pressure gradient tightening as high pressure moves east and an area of low pressure approaches from the northwest. Expecting all but NY Harbor to see SCA conds in the afternoon, with advisory conds continuing into the night for the ocean, Eastern Sound and Eastern Bays. Isolated gusts to 35 KT are possible east of Moriches Inlet for a brief period this afternoon, though will likely not be widespread enough for a Gale Warning. Lingering seas around 5 ft are possible on the ocean waters through Saturday afternoon. Initially Saturday evening features sub SCA conditions across the waters. However, SCA conditions resume for the ocean waters late Saturday night lasting through much of the remainder of the weekend for the ocean with easterly flow increasing. Other waters stay below SCA. Sub SCA conditions return Monday and Monday night and stay that way for non-ocean waters through Tuesday. The ocean will have a return to SCA conditions Tuesday ahead of the next frontal system. && .HYDROLOGY... Model run accumulation of rain could reach 0.75 to 1.5 inches with locally higher amounts possible for the period Saturday through early next week. This is over a long enough time period to not have too much excessive runoff. Therefore, not expecting flooding and there are no hydrologic concerns at this time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until midnight EDT tonight for ANZ330-340. Small Craft Advisory until 6 PM EDT this evening for ANZ335- 345. Small Craft Advisory until 2 PM EDT Saturday for ANZ350-353- 355. && $$ SYNOPSIS...MD/JM NEAR TERM...12/MD/JM SHORT TERM...MD LONG TERM...JM AVIATION...IRD MARINE...MD/JM HYDROLOGY...MD/JM

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