Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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116 FXUS62 KRAH 050623 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 223 AM EDT Fri Jul 5 2024 .SYNOPSIS... A subtropical ridge will continue to extend across the South Atlantic states ahead of a cold front that will move into and stall over the southern Middle Atlantic and Carolinas this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 835 PM Thursday... * Scattered storms diminishing by late evening * The strongest storms capable of wind gusts of 35 to 45 mph. Radar trends the last few hours depict a few features worth noting for the near term update. A well-defined outflow boundary currently stretches from the far western Piedmont, east into Siler City and into RDU, then northeast into eastern Franklin and central Halifax Counties. Earlier convection that moved into the Triad has since showed dissipating trends both on radar and via satellite with diminishing instability. Gusts in the Triad ranged between 35 and 38 kts at GSO/INT. Another report of 36 kt was observed at Burlington with the line of storms/outflow. Storms will continue to weaken in the Triad and northwest Piedmont owing to stable conditions behind the rain-cooled air. Further to the east-southeast over the Triangle and northern Coastal Plain, isolated to scattered storms will be possible into late evening, between about now and 11 pm, as storms fire along the outflow. While instability is waning, there is still some 1500 J/kg of CAPE east of the boundary. An inland moving sea- breeze could also bring a few spotty storms over the central Coastal Plain. All storm activity should wane by midnight or so as forcing wanes. The strongest storms tracking ESE will be capable of gusts of 35-45 mph, owing to some dry air at low-levels favoring high DCAPE. Overnight lows will remain muggy in the low to mid 70s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... As of 310 PM Thursday... * Heat Advisory is in effect for Friday with dangerously hot conditions expected. * Widespread heat index values of 105 to 109 are expected for several hours during the afternoon. * Temperatures wont fall back into the lower 80s until around midnight. The mid and upper level ridge across the Deep South will persist but deamplify a bit on Friday as a broad trough and embedded closed low move across the northern Plains. At the surface a lee tough will extend south across the western Piedmont of VA and the Carolinas. A cold front will advance slowly east into the eastern OH and TN Valleys on Friday afternoon. The air mass across the Carolinas warms additionally on Friday with morning low level thickness values ranging in the 1420 to 1428m range along with 850 mb temperatures that climb to between 20 and 24 C Friday afternoon. This air mass should support highs in the mid 90s to around 100 with low 100s expected in some of the typically hotter locations such as KRDU, KFAY, and KMEB. Combining the hot temperatures with elevated dew points will result in widespread heat index values of 105 to 109. Scattered thunderstorms are apt to develop across western NC during the afternoon and slowly push east into the western Piedmont late in the afternoon and especially during the evening. Other more widely scattered thunderstorms may develop across the northern Coastal Plain. The airmass across central NC will be moderately to strongly unstable with MLCAPE values ranging from 1500 to 2500 J/kg. Profiles suggest a primary threat of damaging winds with steep low level lapse rates and elevated DCAPE. The convection is apt to continue into the evening before dissipating overnight. Outside of the thunderstorm cooled areas, temperatures are likely to linger in the upper 80s to lower 90s through at least mid evening and wont fall into the lower 80s until around or a little after midnight. Low temperatures should eventually fall into the mid to upper 70s by daybreak Saturday. -Blaes && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 226 PM Thursday... Saturday may offer an opportunity for above-climo PoPs with scattered showers/tstms as a prefrontal trough moves into our area ahead of an upper s/w trough moving NE across the eastern Great Lakes region. The rain will be welcome due to recent dryness, but also to limit the intensity of the daytime heating, particularly across our western and Triad zones where rain will arrive earlier in the afternoon. There, highs in the lower 90s...vs upper 90s east where rain will arrive later in the day. The aforementioned trough will weaken and stall Saturday night with a broad pressure trough lingering over the Piedmont for Sunday. This pattern will yield another round of afternoon/evening scattered showers/tstms with highs a bit lower than prev days (in the lower 90s) given the anticipated cloud cover and scattered showers/tstms. Next week`s pattern will be very near climo, both daily PoPs and daytime high temps, given an active daytime Piedmont trough which will result in scattered showers/tstms each afternoon and evening and resulting clouds, rain, and outflows which will keep temps in- check near, or just above climo values. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... As of 215 AM Thursday... IFR-MVFR visibility restrictions are expected at INT/GSO this morning, amid mainly clear and calm and where around a half an inch of rain cooled the air and wet the ground Thu evening. VFR conditions are otherwise expected until scattered showers/storms redevelop with afternoon heating. A slightly better chance (than recent mornings) of stratus and fog will exist late tonight-Sat morning, as low-level moisture and humidity values gradually increase. Outlook: A good chance of morning stratus and fog and mainly afternoon-evening showers/storms will exist through early-mid next week, as a surface trough/front settle into the region and interact with an unseasonably moist air mass in place. && .RAH WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ007>011- 021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...MWS NEAR TERM...Kren SHORT TERM...Blaes LONG TERM...NP AVIATION...MWS