Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 191137 AFDOKX Area Forecast Discussion National Weather Service New York NY 637 AM EST Sun Feb 19 2017 .SYNOPSIS... A weak cold front moves through today, followed by a stronger one tonight. High pressure then builds in Monday before shifting offshore on Tuesday. A warm front will approach Tuesday night followed by a weak cold front becoming nearly stationary in our vicinity Wednesday through Friday. A separate cold front approaches from the west Friday through Saturday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The forecast is mostly on track so far. Updated hourly temperatures and dewpoints to reflect the latest trends. A shortwave to our south with a weak surface reflection will bring some mid/high level clouds to the area this morning. Additionally, a weak cold front or trough slowly moves through the forecast area this morning into early afternoon with some cirrus ahead of it. Moisture is not deep enough for any shower activity. The tricky part of the forecast will be high temperatures. Cold air advection during the day is on the weaker side and there is a tendency for MOS guidance to underestimate high temps in a setup like this in spite of progged cooling temps at the top of the mixed layer. Mixing across the CWA will be deeper than yesterday with a W- NW flow, and there will be a little contribution from compressional heating due to this downsloping wind. So in spite of some cloud cover, thinking is that most of the southern zones reach the 60s as the offshore flow should be just strong enough to hold off or at least temper sea breezes for a good portion of the day. Even many spots across the northern zones should be around 60. Record high temperatures are being forecast in some instances. See the climate section below for the records. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... Stronger cold advection occurs tonight with a stronger cold front moving through. Again, moisture is lacking so expect a dry passage. For Monday, surface high pressure builds in with slow ridging aloft. Sunny with cooler temperatures, but still above normal. MAV and NAM MOS look too warm given temps at the top of the mixed layer, so went with SuperBlend. Good radiational cooling conditions then set up for late Monday night with a clear sky and light to calm winds as the surface ridge axis shifts into the region. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure ridge drifts offshore during Tuesday. Overrunning PCPN ahead of a warm front to the west may sneak in by late over the westernmost zones. Otherwise, expect increasing clouds with highs near normal. CHC PoPs for Tuesday night as a warm front/cold front combination approach the region. Good model agreement in that the elevated warm layer will be warm enough for primarily rain, except for a chance of sleet across the northern zones during the evening. With clouds increasing and warm air advection with a lack of a cold air damming pattern, thinking is that temps remain above freezing through the night everywhere. Have therefore removed the chance of freezing rain across the northern zones. With the trailing cold front departing in the morning, it looks like a dry day for most if not all of Wednesday. The exception would be lingering chances of rain over the eastern zones in the morning. Cold air advection behind the front is not strong, and temperatures are expected to be well above normal. Will maintain previous PCPN forecast for Thursday/Thursday night at this time, although might need to include low chance PoPs in association with a weakening cold front. Did however bump up high temp forecast based on temps aloft. An onshore flow will keep coastal sections cooler, but all areas once again will have high temps above normal. A low pressure system then approaches late in the week with increasing chances of rainfall. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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A weak cold front moves across the region today. High pressure builds in late. Anticipate VFR conditions through the TAF period with mainly high clouds forecast. Light west/southwest winds of 10 kt or less early this morning will shift to the west/northwest after 10-12Z. Northwest winds can be expected during the afternoon, and a few gusts in the 15 to 20 kt range are possible, especially across NYC metro terminals. Across NYC, wind directions around 310 Magnetic are expected in the afternoon. Northwest winds diminish somewhat at night. .OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY... .Monday...VFR. NNW gusts near 20kt. .Monday night-Tuesday evening...VFR. .Tuesday night-Wednesday...MVFR possible in rain. .Thursday...VFR.
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&& .MARINE... Low pressure will pass well north of the waters today. Winds and seas will remain below Small Craft levels. A cold front will push across the area waters this evening and overnight, building seas to 4 ft and providing some occasional gusts to 25 kt into Monday morning. Will hold off on any headlines at this time, thinking that any SCA conditions may only last for a few hours, if they occur at all. No precipitation is expected with the frontal passage. Following the cold frontal passage and as canadian high pressure builds southeast across the area. The next potential chance of marine impacts will be late in the week on Friday/Saturday as winds strengthen ahead of an approaching low pressure system. && .HYDROLOGY... No hydrologic impacts are anticipated through the next 7 days. && .CLIMATE... The following are record high temperatures for today: Central Park...66 (1997) LaGuardia Apt...65 (1997) JFK Apt...66 (1997) Islip Apt...60 (1997) Newark Apt...66 (1997) Bridgeport...61 (1997) && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/MD NEAR TERM...JC SHORT TERM...JC LONG TERM...JC/MD AVIATION...BC MARINE...BC/MD HYDROLOGY...JC/MD CLIMATE...

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