Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 210638 AFDOKX Area Forecast Discussion National Weather Service New York NY 238 AM EDT Fri Oct 21 2016 .SYNOPSIS... showers today as a cold front gradually approaches from the west and then moves through late tonight. Deepening low pressure will track across New England into Quebec this weekend bringing windy conditions to the Tri-State. A cold front will pass through on Monday, followed by building high pressure through the middle of the week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Areas of Dense Fog is expanding. May need an advisory after all for Suffolk County on Long Island and in the elevated areas of SE CT, the Hudson Valley and into NE NJ. Will issue a Statement and Upgrade to an Advisory if needed at 4 AM. Otherwise, Occasional drizzle with a few light showers through the overnight as seen on current KOKX WSR-88D. Winds continue to veer as diffuse warm front passes through. Temps are steady or rise slightly the rest of the overnight. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... Amplifying trough tracks east as it becomes negatively tilted, and cuts off tonight. At the surface, frontal boundary and wave of low pressure tracks east across the area this afternoon. Low pressure over the Atlantic lifts northward, passing to the east. The front moves slowly east of the area tonight as surface low develops across eastern New England and deepens. Coverage of showers remains in question, and axis of heavier rain is in doubt. However, latest 12Z model suite does look drier overall. Marginal CAPE could be enough for isolated thunder this afternoon as lift increases ahead of the trough. Temperatures will be warm, in the lower to mid 70s during the day, falling into the 50s at night. They could be lower depending on speed of the front, and any cooler air arriving late at night. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Windy and cooler weather expected this weekend as low pressure deepens over New England and Quebec on Saturday, then drifts toward Labrador Sunday night. The GFS, GEM and ECMWF are all very similar with the evolution of the system, suggesting a 500 millibar closed low develops over central Pennsylvania Friday night, tracks into upstate New York on Saturday, and then north of Quebec City on Sunday. For Saturday, the synoptic lift will be exiting the region. However, very steep low level lapse rates will develop. In fact, the GFS progs superadiabatic lapse rates in the approximately 15-21Z time period. This should result in at least broken cloud cover and scattered showers. Across the northern tier, there may be enough moisture to result in greater coverage and perhaps some periods of steady rain. This precipitation will have to overcome the downslope however on top of the synoptic subsidence, so limited the rain to scattered showers. Because of the expected cloud cover, this should help to temper wind gusts a bit. As a result, wind gusts were capped at around 40 mph. This is essentially full mixing from 950 millibars in the GFS. The best chance at this time for over-performing winds reaching advisory criteria looks to be Saturday morning as the pressure rapidly rises. The precipitation winds down Saturday night as the low and associated moisture gets too far away, but the gusty winds will continue right through Sunday with the low still in the 980s over Canada. A clipper type system will be racing towards the forecast area on Monday. This will allow winds to back to the southwest and may allow a quick warm up if the cold frontal passage is slow enough. The 12Z data however has the front coming through during the early afternoon at the latest, so high temperatures close to those expected on Sunday were forecast. The airmass that builds in for the Tuesday and Wednesday time period looks to be around 10 degrees below average, and will have the potential to produce a freeze across much if not all of the interior, possibly getting into some of the coastal zones. A frontal system of Pacific origin may reach the area on Thursday per the ECMWF. A slower timing is preferred for this type of a system this far out however, so precipitation chances were limited to slight chance. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... A warm front lifts to the north early this morning, followed by a cold front approaching from the west and a wave of low pressure approaching from the south today. SE/ESE winds of 5 to 10 kt through the day...becoming light and variable this evening. Early Morning: Conditions improving to mvfr...except local ifr interior wake of warm frontal passage between 06z and 08z. Then indications that conditions come back down to widespread ifr/lifr towards daybreak...but some uncertainty on timing. Late Morning/Afternoon: Improvement to mvfr vsby with ifr cigs as the morning progresses...continuing thru the afternoon. SHRA likely. Low prob of an isolated tsra. Evening: Potential deterioration to widespread LIFR or lower conditions this evening. SHRA likely. .Outlook for 06Z Saturday through Tuesday... .Late Tonight...Improvement to MVFR conditions in wake of cold frontal passage...with continued shower activity likely. NW winds G30-35KT developing. .Saturday...Becoming VFR. WNW-NW winds G25-30KT likely. .Saturday Night...Most likely VFR with very low chance of MVFR. WNW-W winds G30-35KT likely. .Sunday...VFR. W winds G25-30KT likely. .Sunday Night-Monday Night...VFR with isolated to scattered showers possible. WNW-NW winds g20-25 kt possible at eastern terminals Sunday night. NW winds g20-25KT possible Monday/Monday Night. .Tuesday...VFR with NW winds g20-25KT possible. && .MARINE... SCA out east on the Ocean through tonight as seas remain around 5 ft. A frontal boundary slowly moves across the waters today, as winds eventually turn toward the south. Expect a wind shift Friday night, generally after midnight, to the west. Seas build tonight, and a few gusts could approach 25 kt late at night. SCA in effect west of Moriches Inlet for this. Gales are likely over the weekend as deep low pressure spins north of the waters. A gale watch has been issued for Saturday and Saturday night, and gales may also extend into Sunday. A cold frontal passage on Monday will have the potential to produce SCA conditions though Tuesday, especially on the ocean where seas are likely to at least remain in the 3-5 ft range. && .HYDROLOGY... Showers are today and today night. Totals should average around 1/2 an inch. No hydrologic problems are expected. Less than a quarter of an inch of precipitation is expected over the weekend. Mainly dry weather is expected thereafter. && .TIDES/COASTAL FLOODING... The potential remains for isolated minor coastal flooding with this afternoon`s high tide cycles. Generally 1-2 ft departures are needed for minor flooding. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Watch from Saturday morning through late Saturday night for ANZ330-335-338-340-345-350-353-355. Small Craft Advisory from 6 PM this evening to 6 AM EDT Saturday for ANZ353-355. Small Craft Advisory until 6 AM EDT early this morning for ANZ350. && $$ SYNOPSIS...Tongue NEAR TERM...Tongue SHORT TERM...PW LONG TERM...JMC AVIATION...NV MARINE...JMC/Goodman/PW HYDROLOGY...JMC/PW TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.