Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 160900 AFDOKX Area Forecast Discussion National Weather Service New York NY 400 AM EST Mon Jan 16 2017 .SYNOPSIS...
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A warm front approaches Tuesday night and then moves offshore Wednesday morning as low pressure develops near the Tri-State. This low gradually moves offshore late Wednesday into Thursday. Weak high pressure builds into the Thursday into Friday, before retreating north of the region Saturday. A wave of low pressure may pass just south Saturday before a more significant low approaches the end of the weekend.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Clear skies and calm winds will allow temperatures to fall further this morning bringing a cool start to the day. Temperatures will rebound fairly quickly after sunrise with dry and sunny conditions expected for today under high pressure. Temperatures will rise close to or slightly above climatological normals, with most sites around 40 degrees. Winds will generally remain light.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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Warm/moist advection will allow for the gradual development of light precipitation late ahead of an approaching short wave. With the area starting off initially very dry, moisture increase will be very slow. Temperatures outside of the NYC metro and surrounding suburbs will most likely be below freezing at the onset of any precipitation, so there is a short period in the morning where freezing rain will be possible, particularly to the northwest of NYC. Very little accumulation is expected. Rain will increase in coverage and intensity through the day, but after temperatures have risen above freezing.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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Warm advection ahead of an approaching warm front will bring a steady rainfall Tuesday night. Parent low pressure moving across the Great Lakes early will gradually transfer to a secondary low along the warm front. It does not appear the warm front will fully move across the region rather will move offshore as the secondary low develops. Rainfall amounts should average around a half inch with this system. Coverage of rain should become much lower by Wednesday morning. However, a potent piece of energy within a positively tilted 500 mb shortwave is progged to approach Wednesday morning and then move offshore in the afternoon. Deterministic models differ in the amplitude of the shortwave as well as positioning of the energy with the 00z GFS furthest south and less amplified. The 00z NAM, ECMWF, and CMC are more amplified and further north. Most of the 21 members of the GFS ensemble are dry Wednesday morning. Have continued with chance pops in the morning to reflect the potential for some showers with this shortwave, and then as it moves offshore PoPs lower to slight chance. High temperatures are above normal in the middle and upper 40s. Models are in good agreement on ridging building Wednesday night through Thursday across the eastern states as the trough moves offshore. As ridging continues to build into Friday, another upper trough will dig towards the north Atlantic from SE Canada. With this pattern aloft, high pressure will build over the region Thursday into Friday. Above normal temperatures continue in the middle and upper 40s. Some readings near 50 are possible in the NYC metro. The warmest air in this pattern appears to stay well to the south of the Tri-State as we will be under the influence of NW flow aloft and light N to NE flow at the surface. Energy from slow moving upper trough across the SW US and Plains is progged to eject out towards the Ohio Valley on Friday and then get caught underneath strengthening ridging aloft. This energy may approach Friday night and bring enough moisture for precipitation. However there is a large amount of spread on the amount of lift available as well as the strength of the energy as it gets to the coast. Despite this potential energy bringing a brief chance of precipitation Friday night, anomalous ridging continues to build aloft. The ridge axis may move offshore Sunday as a more significant upper trough and low pressure approach from the west. Temperatures 5- 10 degrees above normal continue this weekend.
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&& .AVIATION /09Z MONDAY THROUGH FRIDAY/...
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High pressure over the terminals moves east of the DELMARVA this afternoon and moves to the south tonight. A warm front approaches from the southwest late tonight, toward 12Z Tuesday. VFR through the TAF period. Light and variable wind will become WSW-SW 15Z to 16Z, less than 10KT. Winds become light and variable again late afternoon into the early evening. ...NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: no unscheduled amendments expected KLGA TAF Comments: no unscheduled amendments expected KEWR TAF Comments: no unscheduled amendments expected The afternoon KEWR haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: no unscheduled amendments expected KHPN TAF Comments: no unscheduled amendments expected KISP TAF Comments: no unscheduled amendments expected .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Late Tuesday night...VFR. There is a slight chance of rain and freezing rain toward 10Z across the NYC metro terminals and into the Lower Hudson Valley. .Tuesday...MVFR early in the morning, then IFR conditions developing. There is a chance of freezing rain across the Lower Hudson Valley and into southern Connecticut soon after 12Z, with a slight chance at KISP. Freezing rain transitions to plain rain 12Z through 16Z. Rain continues through the day. .Tuesday night-Wednesday...IFR or lower in rain. Conditions improving late Wednesday. .Wednesday night-Friday...VFR.
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&& .MARINE...
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Forecast remains on track with light winds and seas generally 1-2 ft. Winds and seas will remain below Small Craft Advisory criteria through Monday night due to a relaxed pressure gradient over the area. Sub-SCA conditions are likely on the waters Tuesday into Tuesday night with a weak pressure gradient. Winds on the ocean may approach 20 kt on the ocean late Wednesday into Wednesday night as low pressure gradually intensifies offshore. The low will slowly move to the east Thursday into Friday. Ocean seas should stay below SCA levels, but could approach 4 ft the end of the week. Otherwise, a weak pressure gradient continues to bring Sub-SCA winds on all waters for the end of the week.
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&& .HYDROLOGY...
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No hydrologic impacts are anticipated with around a half inch of precipitation late Tuesday through early Wednesday.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JMC/JM NEAR TERM...MD SHORT TERM...MD LONG TERM...DS AVIATION...MET MARINE...MD/DS HYDROLOGY...MD/DS

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