Area Forecast Discussion
Issued by NWS Upton, NY

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186 FXUS61 KOKX 221401 AFDOKX Area Forecast Discussion National Weather Service New York NY 1001 AM EDT Thu Jun 22 2017 .SYNOPSIS... Weak high pressure will slide across today, followed by a warm front passing through tonight. An upper level disturbance will approach on Friday. A series of fronts will then move across the area through the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast is on track. Only minor adjustments needed to T/Td and sky this morning. Weak high pressure will slide across, providing a mostly sunny day, though there could be an increase in high and mid level clouds late as a mid level vort max spills over the upper ridge to the west. Deep mixing under mostly sunny skies with H8 temps 13-14C should result in another warm day, with temps in the lower/mid 80s. There is a moderate risk for the development of rip currents at the eastern Suffolk ocean beaches.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... A warm front passing through tonight could produce an isolated shower late tonight, with the better chances across SE CT as isentropic lift with the front strengthens a little. Some hi-res guidance indicates potential for some low stratus and/or patchy fog late as well. Low temps should range from the mid 60s across easternmost Long Island/CT, to the lower 70s in NYC metro. A lead mid level trough well in advance of any remnants of Tropical Storm Cindy will be approaching on Friday, accompanied by a substantial increase in low level moisture in the morning, with dewpoints in the lower 70s. Best forcing for any convection should arrive late morning or early afternoon, and while instability appears meager, with CAPE 500 J/kg or less, winds aloft may make up for this and lead to a few strong tstms, especially from NYC metro north/west. Had been concerned initially about a potential tropical predecessor rainfall event with the area on the poleward side of an upper jet streak approaching from the west, but think this potential will be greater to the west at least through daytime Friday. Temps will only be a tad less warm than those fcst for today, with upper 70s to mid 80s expected. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... NWP is in agreement that a broad upper level trough will remain east of the Rockies through much of the forecast period. The trough begins to sharpen early next week, but there are differences as to when the trough axis pushes east. Could see some heavy rainfall Fri night into Sat if the stronger NAM 50-60 kt LLJ verifies. GFS is much weaker, around 30 kt, and EC is around 40 kt. Increasing theta-e advection and an approaching short wave/pre-frontal trough should support rain moving in during the evening, generally west of the city, although may be too aggressive with likely PoP and it may hold off until after midnight. PW should increase to 2+ inches Fri Night into Sat as deep tropical moisture advects into the area. There appears to be enough elevated instability for some non-severe tstms, which could also aid in heavy rainfall potential. Rain continues Sat morning as the remnants of TS Cindy are forecast to ride along an approaching cold front. The front will be slow to move through, but the heavy rain threat should push east during the aftn. Weak ridging then builds in into Monday providing dry and seasonable weather. The 00Z EC has started to waver from other guidance on the progression of the upper trough over the eastern US early next week. After a dry cold frontal passage Sun night, another will approach on Mon with the potential for aftn/eve convection. Will need to monitor trends for the rest of the forecast period as a slower trough progression could keep unsettled weather into the middle of the week. Current forecast reflects trof axis moving through on Tue with a chc for showers. Have kept thunder out due to limited instability. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...
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Weak high pressure builds over the area today. A warm front crosses tonight. VFR through the evening push. Sea breezes pushing through late this morning into early aftn, increasing 10-15 kt. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Winds could prevail more southerly before 16z. KLGA TAF Comments: Timing of shift from NE winds to S could be off by 1 to 2 hours. KEWR TAF Comments: Chance that winds waver between a SE seabreeze and SW winds for a few hours starting near 20z. Higher confidence that SE prevails. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Winds may waver between a SE seabreeze and SW winds this afternoon. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .Friday-Friday Night...MVFR or lower in shra/tsra. S/SW winds G20- 25KT possible Friday afternoon. IFR of lower conditions possible in stratus/fog for eastern terminals Friday Night. .Saturday...MVFR or lower possible in shra/tsra. S/SW winds. .Saturday night-Sunday Night...VFR. NW winds...becoming W/SW. .Monday...VFR. Chance of afternoon shra/tsra. S/SW winds.
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&& .MARINE...
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Quiet conditions expected into Friday morning. S-SW flow increasing to 15-20 kt should push ocean seas to 5-6 ft Fri afternoon/night. An inversion over the waters should keep winds below 25 kt, though there could be a brief period Fri eve where gusts reach this level, again only on the ocean waters. These hazardous ocean seas could linger into Sunday.
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&& .HYDROLOGY... There is the potential for heavy rain Fri night into Sat as the remnants of Cindy move through. At this time expect at least flood advisories to be issued. It is too early to tell if flash flooding will occur due to the lack of instability. This potential could be added to the HWO in subsequent forecasts. && .TIDES/COASTAL FLOODING... Astronomical tides will be running very high, especially during the evening high tide cycles through Saturday. Less than 1 ft of surge is needed during these evening high tide cycles for minor flooding, and in some cases less then 1/2 ft. The expected S/SW flow is not favorable for surge, but a background anomaly will likely be enough for minor coastal flooding of the most vulnerable coastal locales along the south shore bays of Western Long Island, along Jamaica Bay, and along western Long Island Sound during this time. && .EQUIPMENT... KOKX weather radar is scheduled for maintenance starting Friday June 23rd for a period of 3 days. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Goodman/24 NEAR TERM...Goodman/PW SHORT TERM...Goodman LONG TERM...24 AVIATION...JC/NV MARINE...Goodman/24 HYDROLOGY...Goodman/24 TIDES/COASTAL FLOODING... EQUIPMENT...

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