Area Forecast Discussion
Issued by NWS Upton, NY

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029 FXUS61 KOKX 220246 AFDOKX Area Forecast Discussion National Weather Service New York NY 1046 PM EDT Tue Mar 21 2017 .SYNOPSIS... A cold front will move across tonight. High pressure moving into the Great Lakes on Wednesday will then build across on Thursday, and pass east Thursday night. A warm front will approach on Friday and remain nearby 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/... A digging trough will approach, with dry cold fropa late tonight, followed by strong CAA/NW winds heading into daybreak. Lows generally falling into the 20s interior and near freezing for the coast tonight, with wind chills falling into the teens by daybreak. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Upper trough will pivots through, as the front pushes offshore. Brisk NW flow expected through the day with deep mixing and tight pressure gradient between high pressure and a developing Canadian Maritimes low. Frequent gusts 35-40 mph likely, with isolated 45-50 mph gusts potential based on winds at top of mixed layer. Scattered afternoon instability Cu likely under the shortwave late tonight through Wed morning, but downslope flow and diminishing instability over the Great Lakes do not support maintenance of flurry/snow shower activity locally. Unseasonably cold temps expected on Wednesday, struggling to rise much from morning lows during the day as cold air moves in. Highs generally from the upper 20s to mid 30s. Upper trough slides east Wed Night with high pressure building from the west, with winds gradually diminishing. A well mixed boundary layer should limit radiational cooling, but still expect temps to fall to around 20 NYC metro and into the teens elsewhere. If decoupling occurs, temps would likely drop well down into the single digits inland with snow pack. && .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 /03Z WEDNESDAY THROUGH SUNDAY/... A cold front will move southeast across the area late tonight. Canadian high pressure will follow on Wednesday. VFR. BKN mid and upper level clouds will precede the cold front`s arrival overnight. NW winds will increase to 15-20kt with G30kt following the CFP overnight. The strongest winds will occur from 14Z-23Z Wed when NW winds will be sustained near 25 kt with gusts to 35 kt. Wind directions within 20 degrees of 320 degrees. Timing of the CFP with wind gusts within 2 hours overnight. .OUTLOOK FOR 00z THURSDAY THROUGH SUNDAY... .Wed...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... Gales expected early Wednesday AM into Wednesday evening due to tight pressure gradient and strong CAA in wake of cold frontal passage late tonight, with building to 4-7 ft on the ocean and3-5 ft on Long Island Sound. Winds should gradually diminish through advy levels Wed night into Thu morning, and then remain below through Thursday night. Thereafter, gusts 25-30 kt are possible late Friday into Friday night for the ocean waters as a warm front approaches. 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. Seas below 5 ft through Friday should build up to 6 ft on the ocean Friday night, then diminishing below advy criteria by Saturday morning. Ocean seas close to advy levels are also possible from Sunday night and beyond. && .FIRE WEATHER... NW winds of 15-25 mph with gusts 35-40 mph and min RH in the 20s should help dry fine fuels across the snow barren grounds of Long Island coastal SE CT. This will enhance the threat for brush fire spread in those areas. && .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...GC MARINE...JP/NV FIRE WEATHER... HYDROLOGY...JP/NV CLIMATE...

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