Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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722 FXUS62 KRAH 070203 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1003 PM EDT Sat Jul 6 2024 .SYNOPSIS... A subtropical ridge will continue to extend across the eastern Gulf of Mexico and Florida into early next week. A cold front will slowly move southeast into Virginia and the Carolinas over the weekend and then dissipate. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of 1000 PM Saturday... A surface boundary is currently situated roughly along I-85 in the northern Piedmont, with dew points in the upper-60s to lower-70s to its NW and dew points in the mid-to-upper-70s to its SE. SPC mesoanalysis still depicts MLCAPE of 1500-2500 J/kg and PW values of 2-2.5 inches ahead of the boundary across the Sandhills and Coastal Plain, which is where scattered showers and storms continue. A second smaller area of showers and storms (including a stationary cell over KGSO) is over the far NW Piedmont associated with higher effective bulk shear of 20-30 kt. Storms this evening have produced very heavy rainfall rates as much as 2 to 3 inches per hour, and with weak southwesterly flow aloft and converging outflow/sea breeze boundaries they have been slow to move and training. So flash flooding has been a concern, but storms are exhibiting a weakening trend which will continue over the next few hours with loss of daytime heating. An MCV upstream over GA/SC and a continued very moist airmass may result in some additional light rain/showers overnight, particularly across southern parts of central NC where slight chance POPs linger. An isolated storm can`t be ruled out, but instability will be limited. Lows tonight will be in the lower-to- mid-70s, still mild with widespread cloud cover, but not quite as mild as last night. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... As of 230 PM Saturday... * Showers and storms expected again on Sunday * Still hot and humid but heat indices will be a bit lower Sunday`s weather will mirror today`s (Saturday) with a similar airmass in place featuring 2.25 to 2.5 in PW`s in place, weak steering flow, and MLCAPEs around 1000-1500 J/KG. In response to today`s convection, a weak surface trough will be deposited across the area and should serve to trigger another round of showers and storms across the area. Meanwhile upstream convection across portions of AL, SC, and GA and their remnant MCVs could serve to focus additional convection across the area during the day tomorrow. The 12Z HREF is suggesting storms could get going early in the day (15-16Z) especially across the western Piedmont before blossoming and slowly expanding eastward. As is the case today, storm motions will likely be slow and convection is likely to be dominated by pulse-type clusters producing periods of heavy rain and isolated sub- severe wind gusts. Hard to pin down any specific area for heaviest rainfall potential but much (if not all) of central NC shares a similar 50-70 percent chance of precip during the day. Given the broad area and low confidence in pinpointing a specific area, I will hold off on Flood Watches. Showers are likely to linger into early evening before dissipating around midnight. Thicknesses should be a bit lower and with storms potentially developing earlier in the day, cloud cover should also be on the increase. Temps should run about 5 degrees cooler than today with highs only reaching the low to mid 90s. Heat indices should remain at or just below triple digits, with the only exception being portions of the southern Coastal Plain where readings may try and take a brief run toward 100-103 before clouds, convection, and outflows bring temps back down. Lows falling into the low/mid 70s. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 230 PM Saturday... * Typical summer pattern expected with hot/humid conditions * Daily diurnal thunderstorm chances, with greatest rain chances late in the week The mid level pattern for much of next week will feature broad southwesterly flow as the NC becomes positioned between longwave troughing over the Great Lakes and an offshore ridge. It`s worth pointing out that there will also be an upper low that lingers off the NC coast for a period of time this week, but nearly all guidance suggests it will be drawn southward away from our area and should not be a player in our weather across central NC. Embedded within the southwesterly flow aloft will be a series of weak perturbations, all of which are difficult to track and time their arrival into NC, but will ultimately promote daily afternoon/evening shower and thunderstorm chances with areas across the Sandhills and western Piedmont favored any given day. PW`s next will generally range from 1.75 - 2.25 inches during this time (90-95th percentile) with little day to day variation while afternoon MLCAPEs should easily climb into the 1000-1500 J/KG range. In short, precip chances next week will closely mirror a typical climatological distribution for early/mid July. An influx of additional moisture aloft late in the week should support somewhat higher than normal precip chances and PoPs have been trended upward slightly. Hot/humid conditions will once again be the theme next week, although values should be a bit lower than what has been observed recently. Afternoon highs should reach the low to mid 90s, with the highest values of the week possible Tuesday into Wednesday. The arrival of additional moisture (and presumably cloud cover) should hold temps back a bit (upper 80s to lower 90s) to close out the week although heat indices could still approach the triple digits given the humid airmass. Mild overnight lows in the low to mid 70s will also be common. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 815 PM Saturday... 24-hour TAF period: Scattered showers and storms continue across the Coastal Plain and eastern Sandhills, including near FAY and RWI. They could be accompanied by brief IFR or MVFR ceilings and visibilities, along with gusty winds. Convection will gradually diminish this evening, but periods of light rain will be possible anywhere across central NC through the overnight hours. Low stratus is expected to develop overnight, and MVFR or IFR ceilings can`t be ruled out at any of the TAF sites. Guidance differs on how widespread the low stratus will be, but the best chance appears to be over the Sandhills and southern Piedmont, including at FAY. Low stratus may linger for much of the morning across the south. Scattered showers and storms will then begin popping up around midday, becoming most widespread from mid afternoon into early evening. Once again, sub-VFR conditions and gusty winds will be possible with any storms. Outlook: A rather typical summer pattern of scattered afternoon and evening showers and storms along with some late night and early morning stratus and fog are expected through the period with the coverage of storms and restrictions expected to uptick on Wednesday into Thursday. && .CLIMATE... Record High Temperatures: July 6: KRDU: 102/2022 KFAY: 99/1990 Record High Minimum Temperatures: July 6: KGSO: 76/1999 KRDU: 79/1900 KFAY: 76/2017 July 7: KGSO: 73/2019 KRDU: 77/1900 KFAY: 78/2017 July 8: KGSO: 76/2010 KRDU: 78/1986 KFAY: 79/2012 July 9: KGSO: 76/1987 KRDU: 74/2014 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Blaes NEAR TERM...Danco SHORT TERM...DL LONG TERM...DL AVIATION...Danco/Blaes CLIMATE...RAH