Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 181839 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 239 PM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure will remain across the Mid Atlantic through the rest of the week and this weekend. A low pressure system may affect the region early next week. && .NEAR TERM /THROUGH TONIGHT/... Surface high pressure will continue sliding southward through the remainder of the day and tonight as a weak system pushes through the Great Lakes. At the same time a weak upper level trough will cross the area overnight into early Thursday morning. All this means for us is that there will likely be some cirrus clouds tonight and a light southerly flow. In addition, dew points are 5-10 degrees higher than at this time yesterday. Therefore, while temperatures will be seasonably chilly, they are not expected to be quite as cool as previous nights, with lows from the mid/upper 30s in the cooler locations to around 50F in the urban centers and along the Chesapeake and tidal Potomac. There may be some patchy frost in those coolest locations, but where the growing season remains, it is not expected to be widespread enough for any advisories. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Surface high pressure center will remain generally to our south and southwest Thursday into Thursday night as the tail end of a decaying cold front/low level trough over New England clips the area Thursday night. This will bring little more than a few clouds and a wind shift to the northwest. The upper level pattern will amplify (west coast trough/east coast ridge) Friday into Friday night, with the surface high expanding back to the north and east. Temperatures will continue to warm through the period, with highs Thursday in the low 70s, and low to mid 70s on Friday. Lows will be generally in the 40s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... High pressure system centered to our northeast on Saturday will keep dry conditions and light winds over our area. This system will slowly move offshore into Sunday as flow becomes more southerly over our area. High temperatures will be in the mid to upper 70s for most areas. A cold front approaches from the west on Monday with a wave of low pressure tracking northeast along it. Guidance suggest that precipitation associated with the cold front could start sometime on Monday but there is still uncertainty on how early. Afterward, guidance is in agreement with an upper level trough amplifying behind the front over the eastern CONUS Tuesday into Wednesday bringing some upslope precipitation to areas west. High temperatures on Monday will be between the low to mid 70s decreasing into the upper 50s on Wednesday. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... High pressure will remain in control through the end of the weekend. Predominantly VFR expected, but can`t rule out a brief period of fog/br at MRB/CHO the next few mornings. Otherwise only passing cirrus is expected with winds less than 10 kt. A frontal system will approach the region on Monday, and precipitation could bring sub-VFR conditions at times beginning late Monday. && .MARINE... High pressure will remain nearby through Thursday with light southerly winds developing. A weak front will pass by to the north Thursday night, which will turn winds to the northwest. Potential for Small Craft Advisory conditions will be dependent on mixing, so the greater chance would be over the more open waters. Winds will subside during the day on Friday as high pressure moves back overhead, which will then generally persist through the weekend. Southerly flow will begin to increase on Monday ahead of the next frontal system. && .TIDES/COASTAL FLOODING... Anomalies remain around one-half to three quarters of a foot above normal. This should keep water levels below minor flood thresholds but it will be close for the sensitive sites of Straits Point, Annapolis, and Washington DC. Water levels will need to be monitored. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...MM NEAR TERM...MM SHORT TERM...MM LONG TERM...IMR AVIATION...MM/IMR MARINE...MM/IMR TIDES/COASTAL FLOODING...MM

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