Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 190738 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 340 AM 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/...
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As of 340 AM Tuesday... Little change to our weather pattern through tonight translates to a continuation in the warm and dry conditions across central NC in the near term. Areas of low clouds and patchy fog beginning to develop along the VA/NC, timed fairly well by the near term models. This area of low clouds should develop/spread south to encompass most of the northern Piedmont and northern coastal plain through daybreak. Still some uncertainty how far south the low clouds will get. Will continue to monitor and adjust as necessary. Once the low clouds lift/dissipate, expect abundant sunshine with afternoon temperatures near or slightly 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.
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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 summerlike 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.
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&& .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 /06Z TUESDAY THROUGH SATURDAY/... As of 145 AM Tuesday... A deck of low stratus is expected to materialize and drift southward across most of the Piedmont and the northern coastal plain early this morning with widespread IFR/LIFR ceilings expected and MVFR visibilities due to fog. Some uncertainty whether the adverse aviation parameters will make it as far south as KFAY. Conditions are expected to improve after 13Z, with VFR parameters expected areawide by 15Z. Sfc winds, at less than 10 kts, will gradually back to a nwly direction this morning as Jose` moves northward well offshore of the Outer Banks and the DELMARVA peninsula. VFR parameters generally expected across central NC Wednesday through Saturday, though a few showers may occur Thursday into Friday as a weak upper disturbance and associated sfc front crosses the region. A brief instance of MVFR ceilings/visibility will occur in vicinity of the isolated showers. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...KC AVIATION...WSS is the U.S. government's official web portal to all federal, state and local government web resources and services.