Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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291 FXUS62 KRAH 070657 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 255 AM EDT Sun Jul 7 2024 .SYNOPSIS... A weak frontal zone will remain stalled just east of the Appalachians through early Monday. This front will weaken further and dissipate Monday, as mid level high pressure builds over the Southeast states and Carolinas Monday through Tuesday. && .NEAR TERM /TODAY AND TONIGHT/... As of 255 AM Sunday... Fairly high coverage of convection is expected once again today. A very warm and deeply moist air mass remains over central NC, east of a diffuse frontal zone stretching SW-NE over the E slopes of the Appalachians, according to the latest surface analysis. The vast majority of the area saw rainfall yesterday (much needed, given the ongoing dry/drought conditions, although a bit too much/too fast in some spots). This ground moistening has led to some light/isold fog/stratus development early this morning, although this should be limited by both considerable higher debris clouds (esp in the W) and by relatively dry air just off the ground, noted on 925 mb progs. Persistence will largely be the rule today: The weak surface front should hold in place while slowly weakening, with weak low level flow to its east over central NC and anomalously high PWs (150-175% of normal) likely to linger across the area. Central NC will also remain within weak mid-upper level flow, in a col area between SW steering flow from the S Plains across the Ohio Valley and an upper low spinning well off the Carolina coast, while through the lower levels, the subtle trough noted on the 07/00z 925-850 mb UA analyses across GA and the Carolinas will likely hold in place with no mechanisms to dislodge it. All told, today`s convection pattern should behave much like yesterday, except perhaps a bit earlier initiation. Moderate SBCAPE is again expected, but with modest deep layer shear, so we may again see a few strong cells with the potential for downbursts, and the slow-moving water-laden cores will present a threat of heavy downpours and localized flooding as well. Recent CAM runs from various modeling systems have frankly been rather poor, fairly to accurately depict current/00H precip over its last several runs, going back to last evening, and they aren`t in very good agreement with each other. As such, have gone with a precip pattern not far off Saturday`s, most closely replicated by the 00z HREF mean. Expect coverage to peak at numerous/likely pops mid afternoon into early evening, with again a slow decline in coverage through tonight as elevated CAPE very slowly wanes, similar to last evening/early this morning. Expect highs today in the upper 80s to mid 90s, with clouds tempering heating a bit amidst thicknesses near to just slightly above normal. This will also keep heat index values below heat advisory criteria, although areas south and east of the Triangle may still see a few hours of 100-104F. Lows in the low-mid 70s. -GIH && .SHORT TERM / /... As of 230 PM Saturday... To be updated shortly. && .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 /06Z SUNDAY THROUGH THURSDAY/... As of 1230 AM Sunday... Adverse aviation conditions are likely to dominate across the Piedmont terminals (INT/GSO/RDU) through mid morning, with scattered showers and isolated storms expected to persist here through around 09z, with just isold showers thereafter through the morning. These sites will also see variable sct-bkn IFR/LIFR cloud bases topped by bkn-ovc VFR decks through mid morning, although the highest chance of IFR/LIFR cigs will be 09z-12z. There will be less of a chance of IFR/LIFR cigs at FAY/RWI. Any fog this morning should be MVFR at worst and focused in the SW Piedmont, S and W of INT/GSO/RDU. As cloud bases rise slowly this morning, VFR conditions should return by 15z areawide, but redevelopment of scattered to numerous showers and storms is expected by 16z-18z starting first in the W Piedmont before quickly expanding across all of central NC, lasting through the afternoon and evening, and aviation interests can expect a risk of storms, with periods of sub-VFR cigs/vsbys and gusty/erratic winds, across all terminals during this time, although coverage should begin to decrease toward 04z. Outside of any storms, surface winds will be light and variable, mainly from the SW at RDU/FAY/RWI. Looking beyond 06z Mon, there is a high chance of IFR cigs and MVFR vsbys in fog developing areawide shortly after 06z, forming first at INT/GSO then expanding E. VFR conditions should return by 15z. Another round of scattered showers and storms is expected Mon, with coverage slightly lower than today. The general pattern of scattered to numerous showers and storms each afternoon through evening will continue through Thu, with at least some chance of early-morning sub- VFR clouds/fog each day. -GIH && .CLIMATE... Record High Minimum Temperatures: 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...Hartfield NEAR TERM...Hartfield SHORT TERM... LONG TERM...DL AVIATION...Hartfield CLIMATE...RAH