Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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775 FXUS62 KRAH 142306 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 705 PM EDT Sun Jul 14 2024 .SYNOPSIS... A strong subtropical ridge will remain over the Southeast through early to mid-week. A cold front will approach from the northwest on Wednesday and stall out over the region into the weekend, resulting in unsettled weather to close out the week. && .NEAR TERM /THROUGH TONIGHT/... As of 120 PM Sunday... Heat indices along and east of US-1 are currently between the lower 100s and 108-109, highest in the Sandhills to southern Coastal Plain. The Heat Advisory will remain in effect until 7 pm as the continued heat will pose a risk for those without effective cooling or hydration. West of US-1, dewpoints have mixed out as expected in the upper 60s, with some middle to low 60s in the Triad. This has led to heat indices largely in the upper 90s. Satellite imagery reveals two areas to watch for shower/storm development. Visible satellite shows that one area is along the Foothills tied to a lee trough, where some isolated storms have already developed. The second area is along the southern Piedmont, Sandhills, where some agitated cumulus have developed perhaps along a subtle moisture boundary separating the low/higher dewpoints. The latest CAMs show that nearly any location could see a spotty isolated storm into early evening. However, the more focused chance (30-percent) would appear over the west/northwest Piedmont along the lee trough, as well as over the Sandhills to central Coastal Plain along the subtle boundary and where instability is highest. While we do not expect any organized severe into the evening, with some 20 kts of deep layer shear, cannot rule out an isolated storm putting out some brief strong gusty winds with high DCAPE (900-1200 J/kg) over the region. Any storms will die out around sunset with the loss of heating. Overnight lows will be quite mild and muggy with mid to upper 70s, except low 70s in outlying areas of the Piedmont. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 240 PM Sunday... ...Heat advisory has been issued for the Coastal Plain, Sandhills, and northeast Piedmont for Mon afternoon from 11 AM to 8 PM... Dangerous heat will be the main hazard to start the work week. Central NC will be situated between a weak mid/upper level trough over the TN Valley and mid/upper level anticyclone positioned just north of the Bahamas. This will direct a fetch a deep layer of southwesterly flow over central NC and promote continued rises in low-level thicknesses and 850mb temperatures, supporting highs in the upper 90s to around 100. Surface dew points should start to mix out once again into the mid 60s across the NW Piedmont, but remain in the low/mid 70s from US-1 eastward. The combination of daily record heat and rich surface moisture, heat indices will quickly rise above 105 by late morning and peak between 105-109 through the afternoon. Reminder, this will be heat index values in the shade, conditions will feel worse in the direct sun. With little overnight recovery expected from Sun night and again Mon night, with this level of rare and long duration extreme heat will affect anyone without effective cooling and/or adequate hydration. An Excessive Heat Warning may be needed for eastern Sandhills and portions of the Coastal Plain and NC Piedmont where heat indices may approach/eclipse 110 degrees. It is also worth noting that wet-bulb globe temp (WBGT) is forecast to exceed 88 degrees and Heat Risk reaches 3 to 4 (Major to Extreme categories) in these regions as well Mon afternoon, which highlights especially dangerous heat will be possible and can affect anyone. Diurnal showers/storms will again be possible along the lee trough and the seabreeze with isolated development possible as convective temperatures are reached. Severe storms are not expected, but strong wind gusts may be possible if deep convection is able to develop within the environment with deep inverted-V thermo-profiles and DCAPE > 1000 J/kg. && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 200 PM Sunday... The forecast for Tuesday has trended higher with regard to PoPs, as it now appears that the combination of a Piedmont trough coupled with a weak upper disturbance moving by just to our north will result in widely scat showers/tstms developing over the higher terrain to our west and will move east into our CWA during the afternoon. The coverage won`t be enough to limit temps, so we still have an opportunity for heat advisory criteria heat indices Tuesday afternoon, esp across our eastern zones where any shower/tstm activity will arrive later in the day. Daily (mostly diurnal) PoPs for the rest of the long term period will be higher than climo as an upper trough deepens and moves across the Great Lakes and Northeast regions and a cold front slowly drifts south across the mountains and approaches us from the northwest during the Wed-Thu time frame, and eventually stalling and lingering across our region Fri-Sun. High-chance to low-likely PoPs are warranted Wed-Sun, which when coupled with increased cloud coverage should subsequently result in temps at least closer to climo, if not a few degree cooler than climo during the wettest days, which right now appears to be Thu and Fri. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 705 PM Sunday... VFR conditions are mostly expected over the next 24 hours at all terminals. A few decaying showers/storms remain near KRWI and KFAY, but these should diminish over the next hour or so. Otherwise, overnight convection should be limited. Isolated to scattered showers/storms will develop again Monday afternoon, with best chances near KFAY as convection along the sea breeze penetrates inland. Additionally, mountain showers/storms may trickle near KINT/KGSO later Monday afternoon. However, confidence was not high enough to include precipitation anywhere expect at KFAY with this TAF package. Outlook: Isolated storms remain in the forecast early this week, but generally VFR is expected. A better chance of widespread showers and storms, and thus flight restrictions, occurs in the Wed-Fri period as a front settles into the region. && .CLIMATE... Record High Temperatures: July 14: KRDU: 101/1954 July 15: KGSO: 97/1974 KRDU: 99/1997 July 16: KGSO: 99/1915 KRDU: 101/1887 KFAY: 103/1937 July 17: KRDU: 100/1887 KFAY: 102/1932 Record High Minimum Temperatures: July 14: KGSO: 77/1981 KRDU: 77/2017 KFAY: 80/2017 July 15: KGSO: 74/2019 KRDU: 76/1992 KFAY: 78/2015 July 16: KGSO: 75/2010 KRDU: 77/2010 KFAY: 78/1992 July 17: KGSO: 75/2013 KRDU: 80/1887 KFAY: 77/2019 July 18: KGSO: 76/1986 KRDU: 79/1887 KFAY: 77/2019 July 19: KGSO: 75/2016 KFAY: 77/2023 && .RAH WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM EDT this evening for NCZ008>011- 025>028-040>043-075>078-084>086-088-089. Heat Advisory from 11 AM to 8 PM EDT Monday for NCZ008>011- 024>028-040>043-075>078-084>086-088-089. && $$ SYNOPSIS...Kren NEAR TERM...Kren SHORT TERM...Swiggett LONG TERM...np AVIATION...Luchetti/Kren CLIMATE...RAH