Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211946 AFDOKX Area Forecast Discussion National Weather Service New York NY 346 PM EDT Tue Mar 21 2017 .SYNOPSIS... A polar front crosses the region tonight. High pressure moves into the Great Lakes Wednesday and then over the area Thursday and pushes offshore Thursday night. A warm front approaches Friday and remains in the vicinity through Saturday. A backdoor cold front moves through Saturday night. Another frontal system affects the region for the beginning of next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Weak trough pushes through late this aft/early evening...with mild westerly flow across the region. Digging polar trough approaches tonight...with polar front crossing the region late tonight. Passage is expected to be dry...with main impact strong caa on strengthening NW winds heading into daybreak. Lows generally falling into the 20s interior and near freezing for the coast tonight...with windchills falling into the teens by daybreak. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Polar trough pivots through the region on Wednesday...with polar front pushing offshore. Breezy NW flow expected through the day with deep mixing and tight gradient between polar high and developing Canadian Maritimes low. Frequent gusts of 35 to 40 mph likely...with isolated 45-50 mph gusts potential based on winds at top of mixed layer. Scattered aft instability cu likely under the shortwave late tonight through Wed AM...but downslope flow and diminishing instability over the lakes do not support maintenance of flurry/snow shower activity into the area. Unseasonably cold temps expected on Wednesday...with temps struggling to rise much from morning lows during the day as polar air advects into the region. Highs generally in the lower 30s to 35 city/coast and upper 20s to 30 for the interior. Polar trough slides east Wed Night with high pressure building in from the west. A gradual subsiding of winds expected as a result. The mixed low-levels should limit radiational cooling...but still expecting temps to fall down into the teens for most of the region...except around 20 NYC metro. If decoupling occurs...temps would likely drop well down into the single digits across interior with snowpack. && .LONG TERM /THURSDAY THROUGH TUESDAY/... There is some uncertainty in this time frame, especially Saturday and Sunday with placement of a warm front/back door cold front. Thereafter, there is uncertainty with an area of low pressure that rides a frontal boundary for the beginning of next week. High pressure moves over the region and pushes off the East Coast Thursday into Thursday night. This will allow a warm front to move toward the region on Friday. Ridging aloft over the Western Great Lakes region Thursday night flattens as it moves east. The warm front remains in the vicinity on Saturday. As previously mentioned, there is some uncertainty with where the warm front will be late Friday into early Saturday, which could lead to uncertainty in temperature forecasts and amount of precipitation. However, the warm front should move back south as a back door cold front Saturday into Saturday night. Thereafter, weak surface low over the mid-West moves toward the region, riding along the cold front, then passes well south of the region. 12Z Canadian and 00Z ECMWF are in good agreement with this feature in placement and timing, while the 12Z GFS is too far north and redevelops a second low offshore a bit too late. With the frontal boundaries in the vicinity as well as a weak area of low pressure passing south of the area, it will be fairly unsettled for this time period. Temperatures should average below normal, with the exception of Saturday when we will see slightly above normal temperatures with the warm front north of the area. Again, there is some uncertainty with temperatures due to exact placement of the front. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... A trough of low pressure exits east this afternoon followed by a cold front tonight. VFR. Winds around 10 kt or less this aftn varying mostly SW to NW depending on the terminal. Winds WNW-WNW this evening. Sea breezes east of city terminals. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Shift to WNW might be an hour or two off. KLGA TAF Comments: No unscheduled amendments expected. KEWR TAF Comments: No unscheduled amendments expected. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: Chance that sea breeze retreats and winds shift back to SW briefly at some point before 23z. .OUTLOOK FOR 18z WEDNESDAY THROUGH SUNDAY... .Weds...VFR. NW Gusts 30-35 kt. .Thursday..VFR. .Friday...CHC PM shra/mvfr. SW gusts 25 kt. .Saturday...Mainly VFR. .Sunday...MVFR/IFR and rain. E gusts 20-25 kt. && .MARINE... Gale conditions expected early Wednesday AM into Wednesday evening due to tight gradient and strong caa in wake of polar frontal passage late tonight...with ocean seas building to 4 to 7 ft and 3 to 5 ft on LI Sound. Winds should gradually fall through SCA Wed night into Thu morning and remain below through Thursday night. Thereafter, gusts 25 to 30 kt are possible late Friday into Friday night for the ocean waters as a warm front approaches the waters. Winds should fall below SCA criteria Sat through Sunday. SCA winds are possible on the ocean waters late Sunday night through Monday night as weak low pressure passes south of the waters. Waves will remain below 5 ft through Friday. Waves build up to 6 ft on the ocean waters Friday night, diminishing below SCA criteria by Saturday morning. Thereafter SCA waves are possible from Sunday night through the beginning of next week. && .FIRE WEATHER... NW winds of 15 to 25 mph with gusts 35 to 40 mph and min RH`s in the 20s should help dry fine fuels across the snow barren grounds of LI and Coastal SE CT. This will enhance the threat for brush fire spread. && .HYDROLOGY... Between 1 and 2 inches of QPF is possible this weekend into early next week. However, this will fall over an extended period of time and no hydrologic concerns are anticipated. && .CLIMATE... The following are record low temperatures for Thursday March 23, 2017 along with the forecast low temperatures. Record Low Temperature Forecast Low Temperature ---------------------- ------------------------ Central Park........12 (1875) 18 LaGuardia...........20 (1959) 21 Kennedy.............20 (1959) 20 Islip...............15 (2004) 15 Newark..............13 (1934) 17 Bridgeport..........19 (2004) 15 && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Warning from 6 AM Wednesday to 2 AM EDT Thursday for ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...JP/NV NEAR TERM...NV SHORT TERM...NV LONG TERM...JP AVIATION...JC MARINE...JP/NV FIRE WEATHER...NV HYDROLOGY...JP/NV CLIMATE...JE is the U.S. government's official web portal to all federal, state and local government web resources and services.