Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 251737 AFDOKX Area Forecast Discussion National Weather Service New York NY 1237 PM EST Sat Feb 25 2017 .SYNOPSIS... Mild with showers and scattered thunderstorms with a cold frontal passage this evening. Cool high pressure then builds south of the area through Monday. A warming trend on Tuesday gives way to another cold frontal passage during the middle of next week. && .NEAR TERM /THROUGH TONIGHT/...
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Have adjusted back the dense fog advisory and will likely cancel the remaining section shortly based on latest satellite imagery and surface observations. Will turn main focus now to convection. Cold Front associated with fine line on Radar just passed Rochester and Johnstown PA. Showers developing ahead of the front over NE PA and Central NY. While there`s plenty of shear, there`s limited thermodynamics suggested in the latest HRRR sounding. Though in SE PA, the 17Z SPC Meso Analyses shows 1000 J/Kg of SBCAPE and LI`s of -3 C. Storms of interest are those over Central VA as of 17Z that are tracking NE at 60 KT. These should continue to grow as they feed on the instability. That would put them into the Newark area around 2230Z. Will add slight risk of Severe west of the Hudson to the Hazardous Weather Outlook. The rain ends quickly overnight and northwest winds usher in a more seasonal airmass.
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&& .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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Mixing temperatures down on Sunday from 850 millibars yields upper 30s to around 40. Add a few degrees for the super adiabatic lapse rate near the surface and this yields highs right in the guidance ballpark, which was subsequently used for the forecast. Initially, clear skies should allow for decent radiational cooling Sunday night. The challenge will be whether high clouds overspread the area early enough to keep temperatures from completely bottoming out, and how quickly the winds subside. For now, the forecast leans milder due to these two potential limiting factors, however the end result could play out 5 degrees or more colder.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/...
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The system currently off the Pacific Northwest brings some dynamics through Monday and Tuesday. The airmass is modeled to be very dry limiting chances for precipitation at least through Monday. Thereafter, warm air advection aloft will increase chances for some rain as a warm front develops and lifts north of the Tri-State Region. The GFS and ECMWF both bring a cold front through on Thursday, so chances for rain remain until the frontal passage. The model consensus breaks down on Friday. The GFS brings a clipper through, with the ECMWF holding off until the weekend. No changes have been made during this period, although the GFS suggests colder and snowier.
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&& .AVIATION /18Z SATURDAY THROUGH THURSDAY/... A cold front approaches from the west into this afternoon, then crosses the area this evening. High pressure then builds in behind the front late tonight. Conditions expected to be vastly different between KEWR, KTEB, KSWF and terminals to the east. These three particular terminals will have MVFR/VFR conditions through the afternoon while to the east, dense VLIFR fog will eventually lift, leaving IFR conditions with perhaps some brief improvement to MVFR before the cold front arrives this evening. In terms of the category forecast, amendments are likely to better refine the timing of categorical changes. A line of showers/with embedded thunderstorms (possibly IFR - most likely from city terminals on west) should pass early this evening from W to E. Conditions improve to VFR at all terminals by mid evening. Winds increase out of the SE-S this morning, become S at 10-15kt throughout by mid-late afternoon with some gusts possible to 20 kt before cold front arrives. Winds become gusty out of the WNW behind the front this evening, with gusts of 20-30KT expected. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .Sunday...VFR. NW winds G20-25KT likely. .Sunday night-Monday evening...VFR. W-SW winds G15-20KT possible. .Late Monday night-Wednesday...Chance of MVFR or lower. && .MARINE... A combination of swells and winds increasing from west to east will bring seas to SCA levels over the two western zones this morning, and then on the eastern most coastal ocean zone this afternoon. Winds then increase on all waters tonight to small craft levels and continue on Saturday in response to low level cold advection. Looking at low level winds and they appear to generally stay below 35 kt, so do not have confidence in anything other than maybe some isolated 35 kt gusts on the coastal ocean waters. As a result, have converted the gale watch to a small craft advisory on the coastal ocean waters for tonight. I then extended the small craft advisory through the day on Sunday for all marine zones. SCA conditions could linger into Sunday night on the coastal ocean waters, eastern Long Island Sound and the bays of Long Island, and maybe into Monday for the coastal ocean waters east of Moriches inlet. The pressure gradient relaxes over the waters Monday night and remains fairly light into Wednesday, so sub-small craft conditions are expected from Monday night through at least Wednesday morning. There are some indications that small craft conditions could return to at least the coastal ocean waters by late Wednesday if the pressure gradient tightens over the waters as currently predicted. && .HYDROLOGY... Around a half inch of rain with locally higher amounts can be expected through tonight. There will be chances for rain throughout next week, however widespread heavy precipitation is not expected at this time. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Dense Fog Advisory until 2 PM EST this afternoon for CTZ009. NY...Dense Fog Advisory until 2 PM EST this afternoon for NYZ071. NJ...None. MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EST Sunday for ANZ330-335-338-340-345. Small Craft Advisory until 6 PM EST Sunday for ANZ353-355. Small Craft Advisory until 6 PM EST Sunday for ANZ350.
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&& $$ SYNOPSIS...12 NEAR TERM...Tongue SHORT TERM...12 LONG TERM...12 AVIATION...Maloit/JM MARINE...Maloit HYDROLOGY...12 CLIMATE...

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