Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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736 FXUS62 KRAH 282016 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 415 PM EDT Fri Jun 28 2024 .SYNOPSIS... High pressure will move off the New England coast tonight. A hotter and more humid airmass will become established across the area this weekend. A cold front will approach the area Sunday bringing the next chance of storms. && .NEAR TERM /THROUGH TONIGHT/... As of 243 PM Friday... High pressure to the north centered just of the New England coast is resulting in good onshore flow from the west this afternoon. A weak frontal boundary remains to the south and expected to wobble north this afternoon and overnight. As such a few isolated showers and storms developing along the coast could impact the Sandhills region later this afternoon. Later overnight as the warm front lifts to the north there is a chance that storms could develop across the region, with the best chance over the western Piedmont. Low stratus could develop early morning across the region with pockets of fog producing lower visibilities in some areas. Easterly flow this afternoon will shift overnight to a more south-southwesterly flow by Saturday morning. Temperatures this afternoon will top out in the upper 80s NW to low/mid 90s elsewhere. Lows overnight will generally be in the low 70s. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 415 PM Friday... Hot, seasonably humid, with a small chance of showers/storms on the wrn and ern flanks of cntl NC. Cntl NC will remain tucked between a couple of sub-tropical to lower mid-latitude mid-level highs/ridges centered over the srn Plains and w-cntl Atlantic, respectively. Poleward of this expansive zone of ridging, a compact mid-level cyclone now over nern MT will become an open wave trough while pivoting across the nrn Plains and upr MS Valley through 12Z Sat, then accelerate newd and across the Great lakes and QC through 12Z Sun. A trailing shortwave perturbation now over the cntl Canadian Prairies will dig sewd into the upr MS Valley and upr Great Lakes Sat and then follow a similar path as the first shortwave trough through Sun. In the intervening swly flow between these shortwave perturbations and the aforementioned ridges, a convectively-amplified mid-level trough will move across the OH Valley and cntl Appalachians Sat and the Middle Atlantic Sat night, the latter when weak mid-level height falls (10-20 m/12hr) will glance the srn Middle Atlantic. Weak mid-level lapse rates of less than 5 C/km will exist over cntl NC on Sat, with a slight increase to between 5-5.5 C/km, amid the aforementioned weakly falling heights, Sat night. At the surface, the remnants of a couple of fronts that have settled across the South Atlantic states during the past 24 hours will retreat nwd across the Middle Atlantic, on the wrn periphery of high pressure over the Atlantic basin. Broad sly flow will result throughout the South and Middle Atlantic states, while a lee trough will develop with diurnal heating over the srn Middle Atlantic and Carolina Foothills/wrn Piedmont. Weak confluence between the Atlantic high and lee trough will result over the Foothills and wrn Piedmont. A sea breeze will also retreat inland and across ern and e- cntl NC through the evening. While both temperatures and humidity levels will be on the increase as a result of the return to sly flow and the influence of the ridging aloft, afternoon/mixed surface dewpoints are likely to decrease into the upr 60s to around 70 F. Resultant heat index values, when factoring in high temperatures mostly 92-98 F, are likely to peak in the 100-105 F range over all but the nrn and nwrn Piedmont, where upr 90s will be common. Those mixed dewpoints will also result in a minimum of MLCAPE generally between 500-1000 J/KG over cntl NC, with slightly higher dewpoints in the lwr 70s, and MLCAPE between 1000-1500 J/KG, along and west of the Yadkin Valley and from the the far ern Coastal Plain to the coast. A 20-30 percent chance of showers/storms will consequently exist along the wrn/ern flanks of cntl NC. Overall coverage and strength of convection will be limited by the relative lack of buoyancy and forcing for ascent, aside from low-level convergence along the sea breeze and into the lee trough. After a lingering small chance of showers/storms over the srn/wrn Piedmont during the evening, it will otherwise be warm and muggy overnight, with lows 75-80 F. && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 255 PM Friday... Hot and stormy Sun/Sun night, then generally quiet and mostly dry through the work week. Near normal temps Mon-Tue will once again give way to intensifying heat for July 4th and into the weekend. Sun-Sun night: Expect hot and muggy conditions with high rain chances as a potent mid level trough deepens with a positively tilt as it shifts through far SE Canada/St Lawrence Valley into the Northeast states. Just ahead of this trough axis and its associated surface front, anomalously high PWs near 2.5" will spread in areawide, with mid level moistening and cooling resulting in an erosion of mid level stability, as steepening lapse rates through the column and prefrontal afternoon heating push SBCAPE to 1000-2500 J/kg, according to the latest LREF. Mid level flow and deep layer bulk shear will remain somewhat muted much of the day, however, peaking at just 15-25 kts, highest near the border Sun evening/night as the stronger cyclonic flow aloft dips into our latitude with trough axis passage. This will also result in the better upper divergence holding off until after dark, and this lack of temporal juxtapositioning of buoyancy and dynamic forcing for ascent could limit our severe threat. But given the forecast SBCAPE and deep mixing with elevated DCAPE, the threat of a few strong wet microbursts seems realistic. Will continue with high pops, peaking at likely at some point over the entire CWA. Sun is likely to be another day of dangerous heat, with very warm morning temps and highs mostly in the mid 90s, giving heat indices again around 100- 105 over most of the area. The surface front should drop slowly SE through the area (more likely, jumping into a prefrontal trough or convective outflow) Sun night, with some lower dewpoints expected to start arriving into the north sections overnight. Lows in the upper 60s to mid 70s. Mon-Fri: The front and deep moisture may still be lingering across southern sections Mon morning, so will maintain good chance to low likely pops there early. But as the front settles to our S and drier air works in from the N amid briefly gusty NE winds Mon, and within ridging both at the surface and aloft, expect a trend to no pops late Mon, lasting through mid week as high pressure noses in from the N. Expect temps to be near to even slightly below normal Mon/Tue, with dewpoints in the 50s and 60s, making it feel quite pleasant. Then, as the mid level trough extending down through the Mid Atlantic early Mon shifts offshore and ridging builds further from the S Plains/Lower Miss Valley into the Carolinas, with the surface ridge pushing out over the open NW Atlantic, rising humidity and thicknesses will bring a return to oppressive heat. Highs should be in the low to mid 90s Wed and mid 90s to near 100 on July 4th and Fri, as thicknesses climb to nearly 20 m above normal. With mid level warm/stable air beneath the strong ridge aloft and limited deep moisture flux into the area, rain chances will remain low Wed, then will have a trend toward climo pops for Thu/Fri, just 25-35% chance at most with those higher values focused on the extreme NW where mountain convection could drift late each day. -GIH && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 200 PM Friday... VFR conditions currently across the region with some mid and high clouds moving over the region. Later this afternoon some isolated showers or storms could develop around KFAY reducing visbys/ceilings at times with stronger storms. Up slope flow in the NW Piedmont could also generate some storms but not until later this evening. There is a good chance of low stratus and/or fog at all sites early morning. MVFR or even IFR conditions are possible by 06z at KINT, KGSO, and KRWI. As the low stratus develops and spreads south, KRDU and KFAY could see MVFR or IFR conditions by 08/09z. By 15/16z Saturday morning all sites are expected to return to MVFR. Outlook: Sub VFR conditions will be possible area wide Sun morning with IFR stratus, followed by a good chance of mainly afternoon- evening showers/storms Sunday. VFR conditions are expected early to mid week next week. && .CLIMATE... Record High Temperatures: June 30: KFAY: 102/2012 July 4: KGSO: 98/1970 KRDU: 101/2012 KFAY: 98/2019 Record High Minimum Temperatures: June 28: KRDU: 76/1952 KFAY: 78/1914 June 29: KGSO: 74/2010 KRDU: 78/1914 KFAY: 76/1969 June 30: KGSO: 74/1936 KRDU: 80/1936 KFAY: 79/1936 July 1: KRDU: 75/2012 KFAY: 76/1990 July 4: KGSO: 73/2018 KRDU: 79/1902 KFAY: 78/1913 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CA NEAR TERM...CA SHORT TERM...MWS LONG TERM...Hartfield AVIATION...CA CLIMATE...RAH