Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261831 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 231 PM EDT Thu May 26 2016 .SYNOPSIS...Bermuda high pressure will extend over the area through Friday. Meanwhile, a storm system will develop over the sub-tropical Atlantic and drift toward the Southeast U.S. coast through the holiday weekend. && .NEAR TERM /through tonight/... As of 1025 AM Thursday... A slightly unstable low level air mass this afternoon with sbcape values of 1000-1500 j/kg will interact with a weakening disturbance aloft to possibly trigger a few showers and t-storms late this afternoon and this evening. This potential appears best west of highway 1, with the greatest threat along the western periphery of our forecast area. Have adjusted/expanded slight chance pops to encompass most of the southern Piedmont and the western sandhills. At this time, atmosphere does not appear that it will support any severe storms as the shear is very weak/non-existent and instability weak. Thicknesses this afternoon projected to be near or slightly warmer than those observed Wednesday. Thus, max temps this afternoon should be comparable to yesterday, ranging from the mid 80s in the nw Piedmont, to the upper 80s/near 90 elsewhere. -WSS The surface ridge axis, accompanied by lower theta e air, will begin to slowly shift back west over eastern NC tonight, allowing for good radiational cooling conditions and a range of lows from 61-65 (coolest in the east). -BLS && .SHORT TERM /Friday through Friday Night/... As of 340 AM Thursday... Strengthening of the upper ridge and shifting of the surface ridge overhead will lessen the prospects of convection on Friday, compared even to the little chance there is today. If there is a chance it will again be int he northwest Piedmont, but even then the steering flow should keep any convection confined to the higher terrain. H10-H85 thicknesses will be around 1415m, yielding highs of 85- 90. Lows mostly in the lower 60s. && .LONG TERM /Saturday through Thursday/...
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As of 230 PM Thursday... The main forecast concern for this period continues to be the potential tropical/sub-tropical development of an area of low pressure between the Bahamas and Bermuda this weekend. The upper level ridge responsible for the recent quiet weather will break down as the coastal low develops. To the west, an upper level trough will linger for the weekend. A shortwave will progress from the southern Rockies northeastward along the trough axis toward the Great Lakes. As the upper level short wave moves through the Great Lakes, the northeastward moving coastal (tropical) low will progress toward the SC coast. As of the most recent runs, the models indicate these two features interacting Sunday night/Monday. The upper level shortwave could absorb the coastal low (possible tropical system) on Monday. There is still a fair amount of uncertainty on whether the low will move up the Mid-Atlantic coast or hand out along the Carolina coast before slowly moving inland. Regardless of this, the majority of this period appears to be fairly unsettled, with chances for convection, highest in the aft/eve, everyday. Much of the coverage, duration, and timing of convection will depend on how the system evolves and thus confidence is still somewhat low. With the strong advection of Atlantic moisture into the region on the northern edge of the low, expect increasing clouds from the east on Saturday, though much of the day will remain dry. Cloudy skies could persist through much of the period. Temperatures through the period: with the increasing clouds and chances for rainfall, expect highs to decrease from the mid 80s on Saturday, to upper 70s to low 80s Sunday. Highs should slowly moderate back into the mid 80s by the middle of the week. Overnight lows will remain fairly steady in the mid to upper 60s.
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&& .AVIATION /18Z Thursday through Tuesday/... As of 115 PM Thursday... It`s highly likely that VFR conditions will persist across central NC through Friday. The exception will be a small risk for early morning fog, limiting the visibility to MVFR criteria for a brief period. In addition, isolated convection late this afternoon through this evening, and again Friday afternoon through the evening, will produce instances of MVFR ceiling and visibility. Aviation conditions on Saturday will vary between VFR and MVFR criteria as increasing moisture results in lowering cloud bases and an enhanced threat for afternoon and evening scattered convection. Sub VFR conditions appear more likely Sunday and Memorial Day due to an area of low pressure projected to be positioned off the GA/SC coast. Circulation around this feature could send abundant moisture into central NC, resulting in widespread cloud cover and scattered to numerous showers and thunderstorms. Aviation conditions may slowly improve by Tuesday, though periods of MVFR conditions are probable. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL/BLS NEAR TERM...WSS/BLS SHORT TERM...BLS LONG TERM...KC AVIATION...WSS

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