Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 191741 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 140 PM EDT Tue Sep 19 2017 .SYNOPSIS... Weak high pressure centered over southern Quebec will extend south into the southern Appalachians through Wednesday. Tropical Cyclone Jose will continue to move northward well offshore of the DELMARVA peninsula today, and off the southern New England coast on Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 10 AM Tuesday... Abrupt dissipation of stratus will result in mostly sunny skies for the remainder of the day. Meanwhile, with low-level flow backing from NELY to a more NWLY component, afternoon temperatures will be 2 to 3 degrees warmer than Monday, averaging in the mid 80s. Tonight, expect mostly clear skies as the low level flow will back to a more west-nw direction, advecting a slightly drier air mass which should inhibit the formation of widespread low clouds and fog. Overnight temperatures mainly in the mid 60s. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 340 AM Tuesday... Wednesday, a disturbance dropping sewd across the TN Valley will continue to gradually strengthening as it moves into the western Carolinas Wednesday night. The lift provided by the system, interacting with an atmosphere that will be slight-moderately unstable, will support the development of a few showers and t-storms Wednesday afternoon-early evening, primarily west of highway 1. Some model guidance suggesting coverage close to 40-50 percent coverage over the western Piedmont by late Wednesday. This seems a bit overdone so will cap PoPs at 25-30 percent across the western periphery for now. Strong heating Wednesday coupled with a wly low level flow will push temperatures well into the 80s to around 90. With dewpoints projected to be well into the 60s, it will feel very summer-like with heat indices likely in the low-mid 90s across most of central NC (excluding the Triad region). The progression sewd of the upper disturbance Wednesday night will likely maintain a slight chance for a few showers across the sw half of central NC. The patchy cloudiness and a warm air mass will result in min temps in the mid-upper 60s. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 255 AM Tuesday... Central NC will be under the influence of high pressure through much of the extended forecast period, resulting in a predominantly dry forecast. A weak trough over the region could result in some showers on Thursday and Friday, primarily in the southwest, but chances are no more than slight. Also, expect skies to be mostly sunny/partly cloudy through the period. Temperatures will be highest on Thursday/Thursday night with highs in the mid to upper 80s and lows in the mid to upper 60s. Expect gradually decreasing temperatures thereafter as a result of increasing northerly flow and possible advection of some cooler air. The forecast for Sunday onward remains highly uncertain as it will depend on the track of Maria, which will depend on what happens with Jose. As a result, very low confidence in the forecast for Monday and Tuesday. The more interesting features of the extended period will be the tropics and what happens with Jose and Maria. Jose is progged to meander off the NE U.S. coast through the week, with increasing uncertainty through the weekend. Meanwhile, Maria will be moving through the Caribbean, northwestward toward the CONUS. As mentioned above, Maria`s impacts from Sunday onward are still highly uncertain as they will depend heavily on Jose and if/how the two systems interact with one another. The medium range models continue to have significantly different solutions in that regard, making forecast confidence very low. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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As of 140 PM Tuesday... Low-level flow will becoming increasingly westerly this evening and overnight, which will inhibit the formation of widespread low clouds and fog overnight. The exception will be at fog-prone sites like KRWI. Isolated to widely scattered showers and possibly a few storms will accompany an upper level disturbance moving into the area Wednesday afternoon. Coverage/pops are expected to be too low to mention in TAFS at this time. Beyond 24 hours: Additional showers and isolated thunderstorms may occur Thursday and into Friday as the disturbance stalls across the region. Low-level easterly flow could support widespread fog/stratus across the area late Thursday night/Friday morning. Otherwise, dry VFR conditions are expected through the weekend.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...CBL/WSS SHORT TERM...WSS LONG TERM...KC AVIATION...CBL

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