... A weak stationary front from west to east across our region will slowly dissipate into mid week. Hot and dry high pressure will prevail from Wednesday until Friday when a cold front arrives from the north. Expect mainly afternoon showers and thunderstorms during the weekend. Another cold front should arrive from the north to start next week.
NEAR TERM /THROUGH WEDNESDAY/... As of 200 PM EDT Tuesday: Convection has begun to break out, mainly across the NC mountains. A few cells have begun to shift east of the Blue Ridge Escarpment much as anticipated. A weak, increasingly diffuse frontal zone is draped across the southern SC Upstate, south of I-85. Although this morning's fog and a persistent high-level ceiling over parts of the lower Piedmont initially hindered destabilization, SBCAPE has still managed to crest 2500 J/kg across most of the CWA. Categorical PoPs are forecast across the mountains this afternoon and into the early evening, with likely PoPs stretching across Upstate and Piedmont. Expecting to see convection initiation here within the next hour or two.
Although instability isn't quite what it was yesterday, a handful of pulse severe storms cannot be ruled out, particularly across the southern tier of the CWA. The larger concern, however, will once again be locally excessive rainfall. Model profiles indicate warm cloud depths of at least 10-11 kft for much of the afternoon, and although MBE vectors are a hair larger than they were yesterday, they're still small enough to warrant a risk of localized flash flooding. Moreover, some areas have been primed by yesterday's rainfall such that it will not take much precipitation to push them into risky territory. CAMs have significantly dialed back the overall coverage of convection, with the latest HRRR and NAMnest in particular being unimpressed by the setup. Still, several models keep scattered showers and storms in the forecast through perhaps 01-02Z, at which point stabilization and dry northerly flow inhibit further convection.
Overnight, the upper levels experience significant drying, paving the way for intense radiational cooling. Thus, tomorrow morning carries another chance of some fog or low stratus, though a less-saturated boundary layer and somewhat steadier surface winds should keep it becoming as dense or persistent as this morning's event. Instead, low clouds will scatter out within the first hour or two after sunrise, giving way to clear, dry weather leading into the late morning. With this drying, CCLs will be considerably higher tomorrow afternoon than they have been the last two days. Although some convection isn't out of the question, fairly confident it won't be as widespread or intense as we have seen in recent days.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 225 PM EDT Tuesday: the short-term forecast picks up at 00z on Thursday with broad upper trofing centered over the NE CONUS and steep upper ridging still in place over the rest of the CONUS. This pattern is expected to persist thru the period and into the extended. At the sfc, weak high pressure will be centered over our area as the period begins late Wed/early Thurs with a moist frontal bndy to our south. Another weak cold front will track out of the Ohio Valley on Thursday and drop into our CWA late Thurs/into early Friday. The front will be slow to move thru the fcst area, with most of the latest guidance placing the bndy over our southern tier of zones (or just south of them), as the period ends Friday evening. As for the sensible fcst, broad subsidence should keep things dry on Thursday with more typical summertime PoPs returning for Friday. Temps will remain well-above climo thru the period with triple digit heat indices likely across most of the lower terrain both days.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 205 PM EDT Tuesday: the extended forecast picks up at 00z on Saturday with broad upper trofing centered over New England and steep upper ridging still in place over the west. This pattern is expected to persist through the period with the upper trof amplifying again early next week and shifting at least slightly west. At the sfc, a weak frontal bndy and associated lee trof will be lingering somewhere just to our south as the period begins. Most of the long-range guidance has the bndy lifting back to the north gradually over the weekend. By early next week, broad high pressure from Canada will push southward and move over the Great Lakes as the period ends. This will likely provide some drying at least across our northern zones, however the above-mentioned moist bndy will persist just to our south and may shift back northward as the period ends. Temps will start out just above climatology on Sat, and cool to below climo by early next week.