Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 180704 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 303 AM EDT TUE OCT 18 2016 .SYNOPSIS... High pressure at the surface and ridging aloft will keep conditions warm and dry for the next few days before a frontal system approaches for the end of the week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 300 AM Tuesday... Fog may be a problem this morning but compared to previous days forecast soundings look a little drier at the surface and dewpoint depressions are generally larger. If fog were to occur it would most likely be in the east. HRRR, SREF, and RAP solutions are not bullish on fog so have kept it out of the TAFs at this time and will adjust as needed. Another warm day is expected and persistence suggests temperatures climbing into the low to mid 80s by this afternoon as high pressure continues at the surface with ridging aloft. Southwesterly return flow around the back side of the surface high will help to bring a little warm air advection to the area. No precipitation is expected and clouds should be at a minimum, thus helping insolation bring those afternoon highs up. Low temperatures in the upper 50s.
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As of 300 AM Tuesday... Wednesday will most likely be the warmest day of the week as high pressure continues to dominate the surface pattern. Thicknesses suggest high temperatures topping out in the mid 80s which for GSO is near record levels but we could end up just below on the day. Light southerly flow will again prevail with little cloud cover. Low temperatures in the low 60s.
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&& .LONG TERM /WEDNESDAY THROUGH MONdAY/... As of 255 pM Monday... Wednesday and Wednesday night...a ridge aloft centered over southern AL/GA will ridge northeast into the Carolinas while surface high pressure over the western Atlantic will ridge west into NC/VA. A dry and rather warm air mass across the region will be characterized by low precipitable water values of around 1.0 inches and morning low-level thickness values of 1395-1400m. The result will be mainly clear skies with a period of early morning fog/stratus possible across the Coastal Plain. High temperatures will warm into the mid 80s in most locations, which will be around 15 degrees above normal. Record highs for Wednesday (10/19) include 86 at GSO, 86 at RDU, and 90 at FAY. Lows Wednesday night will fall back into the lower 60s. The weather pattern will become more active for Thursday through Friday night as northern stream energy drops into the central Plains on Thursday and heights begin to fall across the Carolinas. NWP guidance in fairly good agreement that a higher amplitude trough sets up near the central Mississippi river on Thursday evening. Guidance then diverges in the handling of this system with the 12Z ECMWF aggressively pushing the trough and the associated cold front across central NC Friday morning with little/no precipitation while the GFS is slower, more amplified with the upper trough, eventually pushing it across the Carolinas in a negatively tilted fashion with a few tenths of an inch of precipitation. Further complicating things is an upper level low pressure system near the Bahamas that the National Hurricane Center now notes has a 60% chance of developing into a tropical or subtropical cyclone late in the work week as it moves slowly north or northwest. A slower arrival of the upper trough (per the operational GFS) would allow this system to get closer to the Southeast coast and possibly bridge some moisture into the area. WPC prefers the more progressive (ECMWF) solution which would result in a more benign system for central NC. Given this we have lowered PoPs a bit with a low chance or slight chance of showers in the forecast for Friday and Friday night. Highs on Thursday will range in the lower 80s and highs Friday will range in the lower and mid 70s with lows Friday night falling into the upper 40s to lower 50s. Quiet but cooler weather arrives for the weekend and Monday as northwest flow aloft develops on Saturday and persists into Monday. Surface high pressure will slowly build into the region on Sunday and Monday. It will be chilly on Saturday with highs in the lower to mid 60s along with cool northwest wind at 10 to 15 MPH with gusts up to 25 MPH. It will turn quite chilly on Saturday night with lows in the lower to mid 40s expected. Temperatures could be even chillier if the winds relax and optimal radiational cooling conditions develop. Fair weather and a slow moderation of temperatures is expected on Sunday into Monday with Monday`s highs ranging near normal from 69 to 74. -Blaes && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 130 AM Tuesday... 24 Hour TAF period: Fog will once again be the primary concern this morning although less confidence in it happening this morning as compared to previous days. Short term models are not showing much in the way of fog development and forecast soundings are drier at the surface then they have been the last few days. Dewpoint depressions in the observations are also larger than they have been but if fog were to occur it would be at KRWI or KFAY. Otherwise another day of light southwesterly winds with no precipitation and mostly clear skies. Long term: VFR conditions are largely expected through Friday or so when the next frontal system will approach from the west and bring a chance for sub-VFR aviation conditions. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Ellis NEAR TERM...Ellis SHORT TERM...Ellis LONG TERM...Blaes AVIATION...Ellis is the U.S. government's official web portal to all federal, state and local government web resources and services.