Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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094 FXUS62 KRAH 271752 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 150 PM EDT Thu Jun 27 2024 .SYNOPSIS... A mid-level disturbance and surface cold front will move across NC today. The front will linger across the southern and eastern Carolinas through early Friday, before lifting back north as a warm front. A stronger cold front will approach the area on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 1118 AM Thursday... After updating temperatures and dew points for this afternoon with the latest model data and current observations, thresholds for the Heat Advisory are no longer expected to meet in the areas that were previously thought to be in the advisory. With that, cancelled the Heat Advisory for Scotland, Hoke, Harnett, and Wake counties. The far SE counties still could reach Heat Advisory criteria as dew points remain in the mid 70s. Temperatures this afternoon will range from upper 80s NW to low/mid 90s SE. While showers are continuing to move across the NW Piedmont region today, as the boundary shifts southeast it will move into a more unstable environment in the southeast where we could expected more isolated to scattered thunderstorms develop. Some stronger storms across the far south eastern portion of the CWA could become severe later this afternoon and early evening. Conditions are expected to begin to dry out beginning in the NW by early evening and continue that trend southeast through the overnight hours. As of 445 AM Thursday...A positive tilt, convectively-amplified mid- level trough, one which includes a prominent MCV now over nern TN, will move east and across the srn Middle Atlantic and Carolinas today, then offshore tonight. At the surface, 08Z data depict a lee trough from cntl NC swwd through a ~1007 mb lee low over the Upstate of SC and nrn GA. An outflow boundary, and focus for isolated to widely scattered shower/storm development, has intersected the trough and extended from near ASJ to TTA to VUJ in cntl NC. These two features will merge and become an effective cold front, and nwrn bound of severe storm potential, that will move sewd and across cntl and ern NC today. Meanwhile, a couple of synoptic cold fronts stretched from 1) the lwr Great Lakes wswwd across the OH and mid MS Valleys, and 2) the nrn Middle Atlantic coast swwd through a ~1007 mb low over cntl MS, to the lwr MS Valley, respectively. The two will merge in the post-effective frontal regime over the Middle Atlantic and move swd in backdoor fashion across VA and nrn NC tonight. A combination of morning stratus over cntl NC, now developing in both the rain-cooled, post-outflow regime over the nrn NC Piedmont and in the maritime tropical (70s dewpoints) ahead of it, and also a multi-layered mid/high-level cloud band accompanying the approaching mid-level trough, will result in cloudy or mostly so conditions to start the day. A differential heating zone will probably develop along the sern edge of these clouds from cntl SC to sern NC and contribute to additional frontogenesis along the aforementioned effective frontal zone (merged lee trough/outflow), with the hottest (mid 90s) , most humid, and unstable conditions preceding it through early this afternoon. Scattered, deeper convection will likely develop along and ahead of this boundary and congeal into line segments or a broken line with strong to locally damaging wind gusts as it moves through the Coastal Plain/ern Sandhills and to the coast through early-mid afternoon, augmented by lift ahead of the approaching MCV and mid-level trough. As that activity moves toward the coast, partial clearing will probably result wwd across cntl and wrn NC later this afternoon; and this will allow for stronger diurnal heating into the upr 80s to lwr 90s and weak late day destabilization there. Isolated to widely scattered showers and storms will probably result in that regime and continue through early tonight. Overall, the combination of clouds and convection/outflow will favor less hot than previously forecast temperatures; and when factoring in mixed dewpoints that will again decrease into the mid 60s to around 70 F this afternoon, also lower than previously forecast, the risk of reaching or exceeding Heat Index values of 105 F appears low except for perhaps in Cumberland, Sampson, and Wayne Co. It will nonetheless be hot, with Heat Index values around 100; and given the consecutive days of heat with Heat index values having been consistently 102-110 F, and still with moderate to major HeatRisk, the Advisory will remain in place. A slightly cooler and less humid airmass behind both the effective front of today and synoptic front tonight will favor low temperatures in the upr 60s to lwr 70s for most. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 315 AM Thursday... Cannot rule out a stray thunderstorm Friday morning across southern counties, but the chance for a thunderstorm should spread across the entire region Friday afternoon as today`s cold front lifts back to the north. In addition, an upper level shortwave still appears poised to bring a chance of thunderstorms across western counties overnight. In the northwest, highs should be similar to today`s values, in the upper 80s to lower 90s. In the southeast, highs should be about 5 degrees cooler than today, reaching the lower to mid 90s. Heat index values should peak near 100. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 315 AM Thursday... Sat/Sun: Increased pops Saturday afternoon as ensembles have become a bit more generous with coverage of precipitation, although deterministic models are a little more reluctant to do so. Pops settle down Saturday night before increasing again as a cold front moves from the Ohio River Valley southeast across the state. Have continued with likely pops, and this front appears as if it may be the best chance for rain in the next seven days. Highs will be well into the 90s each day along with heat index values over 100 degrees. The values should be highest on Sunday, although the arrival of showers/thunderstorms could temper these readings. Mon/Wed: The front will be reluctant to move through, and have maintained chance pops across generally the southern half of the forecast area Monday afternoon and just slight chances across southern tier counties Tuesday afternoon. As the front slides south, a surface high will build in from the north, allowing for flow out of the north and a brief relief from the heat. The predicted high at RDU on Monday, July 1 is 87 degrees, which would break a forecast 18 day string of 90+ highs. By Wednesday, the high moves offshore, allowing a southerly wind to develop again and raise highs back into the 90s everywhere. && .AVIATION /18Z THURSDAY THROUGH MONDAY/... As of 150 PM Thursday... VFR conditions currently across the region as cold front moves east over the SE portion of NC. While conditions are expected to remain VFR over the Triad for the TAF period a brief period of MVFR conditions could be possible as the showers move across the region. At KRDU, showers are moving in and expected to bring reduced ceilings and visibility at times with any heavier showers. Have a TEMPO for thunderstorms early this afternoon but looks like all the thunderstorms development will stay to the southeast. MVFR conditions are expected early Friday morning as low stratus develops over the region before sunrise and burns off. At KFAY, While the lines of storms are just to the south of the terminal more thunderstorms are developing to the southwest and expected to impact flight restrictions at the terminal. Have MVFR conditions possible this afternoon then becoming VFR for a short period of time before low status and or fog develops across the Sandhills early Friday morning. VFR conditions will return for Friday. At RWI, VFR conditions will continue with VCSH over the next few hours as the boundary moves across the region. MVFR conditions are possible however, at RWI early Friday morning with development of low stratus across the Coastal Plains. VFR conditions expected to return just after sunrise. Outlook: Sub VFR conditions will be possible area-wide Sat-Sun mornings, followed by a good chance of mainly afternoon-evening showers/storms Sunday. VFR conditions are expected early to mid week next week. && .CLIMATE... Record High Temperatures: June 27: KFAY: 102/1998 June 30: KFAY: 102/2012 Record High Minimum Temperatures: June 27: KGSO: 76/1969 KRDU: 76/1952 KFAY: 77/1998 June 28: KGSO: 76/1969 KRDU: 76/1952 KFAY: 78/1914 June 29: KGSO: 74/2010 KRDU: 78/1914 KFAY: 76/1969 June 30: KGSO: 74/1936 KRDU: 80/1936 KFAY: 79/1936 July 1: KGSO: 77/1970 KRDU: 75/2012 KFAY: 76/1990 && Heat Advisory until 5 PM EDT this afternoon for NCZ042-078-088- 089. && $$ SYNOPSIS...MWS/Blaes NEAR TERM...CA SHORT TERM...Green LONG TERM...Green AVIATION...CA CLIMATE...RAH