Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 110236 AFDOKX Area Forecast Discussion National Weather Service New York NY 936 PM EST Mon Dec 10 2018 .SYNOPSIS... High pressure builds into the region tonight and weakens Tuesday. A cold front moves across the area Tuesday night through Wednesday morning. This will be followed by a weak upper level disturbance on Thursday. A frontal system and associated low pressure will then impact the area over the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... The forecast is mainly on track. Made some adjustments to hourly temperatures to capture the latest trends. The main upper level jet remains south of the region tonight into early Tuesday. For tonight, continued subsidence will allow for clear sky conditions to continue. The winds will continue to decrease in response to a decreasing pressure gradient. High pressure will continue to build in from the west. A series of lows will be moving along a cold front well out into the Atlantic. Lower teens for Pine Barrens and interior locations to near 30 for NYC will be the range for the low temperatures. The conditions will be ideal for radiational cooling with the light winds and clear sky conditions. Used a blend of MET and ECS for low temperatures, favoring relatively colder guidance. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... The main upper level jet remains south of the area Tuesday through Tuesday night. For Tuesday, high pressure weakens with surface winds becoming light and variable. The winds will eventually settle to a SW direction by mid to late Tuesday afternoon. Weakening low pressure approaches from the Great Lakes late in the day with an associated cold front. This cold front moves across Tuesday night with winds becoming more NW behind it. Temperatures Tuesday will be near to slightly colder than the previous day with limited vertical mixing and some more clouds contributing to the decreasing trend. The weather remains dry Tuesday through Tuesday night with just an increase in clouds Tuesday afternoon into Tuesday night. Mostly westerly flow in the atmosphere will limit the amount of moisture available to the low pressure moving across. A shortwave will be moving across from northwest to southeast. The low pressure and front will move across with the pressure gradient remaining weak. Forecast lows Tuesday night were a blend of MAV/MET/ECS, ranging from the lower 20s to lower 30s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Complex interaction between multiple streams and Pacific energy will make for a challenging forecast with respect to the timing and intensity of a frontal system that will impact the area for the upcoming weekend. Thermally, guidance is all in good agreement that whatever scenario pans out it should be an all rain event. Differences arise amongst the global models due to wavelength spacing between Pacific energy moving into the west coast at the end of the week and an upper low over the Lower Mississippi Valley. In addition, a northern stream shortwave passing to the north across eastern Canada poses some influence as well. Rain from this system will work into the area late Friday and continue into Saturday. The overall evolution and timing of this system will also dictate how much of a player it could be on Sunday, but emphasis at this time is on the first half of the weekend. Prior to that, an exiting northern branch shortwave will send a reinforcing cold front through the area Wednesday morning. On its heels, warm advection ahead of another shortwave trough may produce flurries on Thursday. This feature though dampens out in the building ridge ahead of the aforementioned storm system. Temperatures remain below normal through Thursday. Warm advection then ensues Thursday night through Saturday as temperature return to above normal values. Cold advection on the backside of the departing low Sunday into Monday will bring temperatures back to seasonable. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Mainly VFR conditions through the TAF period. Some sct-bkn clouds around 3000 ft are possible aft 00z Wed. Winds lgt and vrb tngt. Around 16z on Tuesday, winds shift to SW and increase to near 10kt. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .Tuesday Night-Thursday...Mainly VFR. .Friday...VFR, then a chance of Sub-VFR late in rain. .Saturday...IFR Likely in Rain. E-SE Gusts to 25 kt possible. && .MARINE... Conditions on all waters are below small craft advisory thresholds. Ocean seas tonight are forecast in the 2 to 4 ft range. The pressure gradient will continue to remain weak tonight through Tuesday night keeping winds well below SCA thresholds. Seas on all waters are expected to remain below small craft advisory thresholds through Tuesday night. Winds and waves will continue to remain below SCA criteria Wednesday through Friday with high pressure over the waters during this time frame. A frontal system and associated low pressure will approach the area Friday into Friday night. SCA may be needed by late Friday night into Saturday. && .HYDROLOGY... Mainly dry conditions are expected through Friday. Potential remains for a moderate to heavy rainfall event Friday night into Saturday with an inch or more. && .EQUIPMENT... NYC Central Park winds are out of service until further notice. Loss of data is due to a severed cable. Parts are on order. NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JM/DW NEAR TERM...JC/JM SHORT TERM...JM LONG TERM...DW AVIATION...JMC/IRD MARINE...JM/DW HYDROLOGY...JM/DW EQUIPMENT...

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