Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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009 FXUS62 KRAH 230145 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 945 PM EDT Sun MAY 22 2016 .SYNOPSIS...Unsettled weather will continue through Monday, as a strong upper-level low pressure system holds over the region. This disturbance will shift offshore and move away from the area on Tuesday. In its wake, high pressure will build into the Carolinas during the middle of the week. && .NEAR TERM /through tonight/... As of 935 PM Sunday... Interesting weather this evening with batches of strong to severe storms, driven in part by vigorous dynamic forcing for ascent associated with strong mid level DPVA and focused upper divergence in the presence of good deep layer bulk shear (eff shear near 30 kts) and marginal instability. Several cells generated small hail, reasonable given the somewhat low freezing level around 8 kft, and we also received a few reports of low level rotation, also reasonable considering the 20 kts of 0-1 km shear and radar indications of weak rotation up through the mid levels. Mid level lapse rates remain elevated at 6.5 C/km, although the loss of heating has allowed the initially quite steep low level lapse rates (over 8.0 C/km) to begin a downturn. Nevertheless, the -10C to -30C CAPE remains around 200 J/kg with favorable bulk Richardson numbers of 20-35 and 400-500 J/kg of MLCAPE (although CINH is encroaching with nightfall), so the risk of a strong storm or two will linger for another few hours, until the strong dynamics push to our south and nocturnal cooling facilitates stabilization. Will however leave a mention of isolated showers on through the late night over the eastern CWA where PW will stay above normal and MLLRs elevated beneath the core of the mid level low. Lows in the lower to mid 50s under partly to mostly cloudy skies. -GIH && .SHORT TERM /Monday and Monday Night/... As of 325 PM Sunday... Upper level low begins to pull away from our region by Monday afternoon, and exits offshore Monday night. Perturbations rotating around this feature will trigger scattered showers...mainly across the ne half of central NC, with a few thunderstorms possible during peak heating. With loss of heating, shower coverage expected to diminish with bulk of showers dissipated prior to midnight. High temp Monday highly dependent upon cloud coverage. With peeks of sun this afternoon, temps responded by climbing quickly into the mid 70s. May see a similar scenario Monday though presence of 850mb thermal trough over the region may dampen recovery a tad. Currently forecast temps near 70 far northeast to the mid 70s southwest. If clouds and showers more extensive than current thinking, then max temps may end up being 3-4 degrees cooler across the ne piedmont/northern coastal plain. Subsidence behind the exiting low and advection of a drier air mass should cause clouds to diminish over central NC, departing last over the ne counties. Residual low level moisture may allow areas of fog to develop, though confidence not high enough to mention in the forecast at this time. Min temps comparable to tonight in the mid 50s. && .LONG TERM /Tuesday through Sunday/... As of 235 PM Sunday... Conditions are expected to dry out on Tuesday as the upper low pulls further away and shortwave ridging builds over the region. As the low pulls away, the building ridge will keep the main storm track to our north and west, resulting in mostly dry conditions through the majority of the long term period. There are indications that the ridge may weaken some towards the end of the forecast period, allowing an uptick in mostly diurnal type convection. However, given the model disagreement (the GFS, which is known the break ridges down too quickly, breaks down the ridge, while the ECMWF holds strong), will just show a little increase in cloud cover and will bring in a slight chance of precip at the very end of the forecast period. Otherwise, temps will gradually warm up to above normal, from mostly lower 80s on Tuesday to mid/upper 80s for the remainder of the period. && .AVIATION /00Z Monday through Friday/... As of 755 pm Sunday... 24 hour TAF period: Scattered showers and thunderstorms this afternoon mainly across the western half of the CWA. Some stronger storms moving across the VA border at this time do not appear to be a threat to any TAF sites at this time. A thunderstorm currently in the vicinity of KFAY will quickly move south of the area. All sites except for KRWI should continue to have some threat of showers and thunderstorms through much of the evening. As far as ceiling and visibility restrictions overnight...some MVFR visibilities are possible at the eastern three TAF sites. A bigger story could be some IFR ceilings with the biggest threat at KRWI and possibly KRDU before sunrise. Conditions should return to VFR later Monday morning or early afternoon. Showers may once again be prevalent Monday afternoon at least at eastern TAF sites. Winds are expected to be northerly at around 10 knots. Long term: After showers move out of the area Monday evening...A period of VFR conditions should persist through much of the work week. A threat of rain in the NW Piedmont may exist for Thursday and Friday but models are not real clear on the details yet. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...KS NEAR TERM...Hartfield SHORT TERM...WSS LONG TERM...KRD AVIATION...Ellis

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