textproduct: Raleigh

WHAT HAS CHANGED

* Updated Aviation discussion.

KEY MESSAGES

As of 330 AM Sunday...

1) There is a threat of both severe storms and excessive rainfall this afternoon and evening, with primary hazards of damaging straight-line wind gusts and locally heavy downpours.

2) A significant heat wave will likely develop across cntl NC mid to late next week into the holiday weekend.

DISCUSSION

As of 330 AM Sunday...

KEY MESSAGE 1... There is a threat of both severe storms and excessive rainfall this afternoon and evening, with primary hazards of damaging straight-line wind gusts and locally heavy downpours.

Hi-res guidance still suggests the MCV (currently over KY) will continue ewd downstream of the developing mid/upper level ridge during the next few/several hours, then dive sewd across the region today. This will be the primary forcing mechanism for convection across the area. Some convection is already moving across the NC mtns, while trailing convection should reinvigorate over KY this morning before moving into the area this aft/eve. The early convection and associated cloud cover could limit destabilization and severe potential across the nw, while any remnant outflow or differential heating boundaries could be a focus for storms later today. For this aft/eve over the Triad, forecast soundings from various hi-res models have SBCAPE of 500-1000 J/Kg with 0-6 Km bulk shear around 20 kts. Farther east, the bulk shear remains around 20- 30 kts but instability increases, with 1000-1500 J/Kg at KRDU and KRWI and 1500-2000 J/Kg at KFAY. PWATs range from around 2 inches over the Triad, to around 2.2 inches at points east. Damaging wind gusts will be the primary severe threat, with potential for locally heavy rainfall. The SPC has all of central NC in a Marginal Risk (level 1 of 5) for severe storms. The WPC has most of the NC Piedmont in a Marginal Risk (level 1 of 4) and the Coastal Plain in a Slight Risk (level 2 of 4) for excessive rainfall to potentially lead to flooding.

KEY MESSAGE 2... A significant heat wave will likely develop across cntl NC mid to late next week into the holiday weekend.

An unusually strong mid and upper-level high/anticyclone, with standardized height anomalies in the 500-250 mb layer forecast to reach 3-4 sigma, will become established from the OH and TN Valleys early to mid week and srn Middle Atlantic by the end of the week and into at least the start of the holiday weekend.

While NWP guidance and particularly the NBM have displayed a high bias with maximum temperatures in recent days, including observed ones this past Fri-Sat, the percentage of the top 15 analogs in the CIPS analog database exceeding 100 degrees increases over cntl NC from around 20% on Wed to between 40-50% by Thu. Given that historical context, and as noted in previous discussions, it appears likely that high temperatures are likely to increase into the mid 90s to around 100 on Wed, then upr 90s to 100-105 Thu through Sat, and probably highest on Fri. A sea breeze may provide slight relief to the oppressive heat each evening, but convective chances will be very low at least until the weekend, when there is some indication in model guidance that the ridge may weaken/dampen.

AVIATION /14Z SUNDAY THROUGH THURSDAY/

As of 1010 AM Sunday...

Update: Minor tweaks were made to the 12z TAFs. Given the pattern and typical level of uncertainty surrounding summertime convection with an hourly resolution, VCSH/VCTS were removed and PROB30s have been tightened to the most likely timing based on 00z HREF and 06z REFS. However, both of these ensemble solutions show two different scenarios; the 00z HREF depicts a similar scenario as yesterday with late morning to mid afternoon convection near RDU, FAY, and RWI that could stabilize them throughout the remainder of the day. The 06z REFS however depicts a significant lull in convective coverage until the early/mid afternoon when two separate areas of convection develop (NC/VA border sinking south towards RDU/RWI as well as a separate cluster of storms over upstate SC into western NC near CLT shifting towards FAY by late afternoon into the evening). Further updates and refinements will be made based on observations and as the 12z guidance becomes available.

Still relevant information from the 640 AM discussion follows... Convection should move out from W-E between 00Z and 06Z Mon. Low stratus is expected to spread ssw into central NC tonight/Mon morn, most likely at KRWI and KRDU.

Outlook: Largely VFR conditions expected to prevail from Mon afternoon through mid-week. However, if showers impact KRWI and/or KFAY Mon aft, there could be some early morning restrictions Tue morn.

CLIMATE

All-time High Temperature Record and Most Recent Date of Occurrence:

KGSO: 104/1914-07-27 KRDU: 106/2024-07-05 KFAY: 107/2007-08-09

Record High Temperatures:

July 1: KGSO: 99/2012 KRDU: 103/2012 KFAY: 104/1959 July 2: KGSO: 98/1954 KRDU: 101/1954 KFAY: 106/1931 July 3: KGSO: 98/1911 KRDU: 101/2012 KFAY: 102/2019

All-time High Minimum Temperature Record and Most Recent Date of Occurrence:

KGSO: 80/2007-08-09 KRDU: 80/2025-07-18 KFAY: 84/1928-06-22

Record High Minimum Temperatures:

July 1: KGSO: 77/1970 KRDU: 78/2025 KFAY: 76/1990 July 2: KGSO: 76/2018 KRDU: 78/1931 KFAY: 77/1931 July 3: KGSO: 76/2018 KRDU: 79/2023 KFAY: 76/2023

RAH WATCHES/WARNINGS/ADVISORIES

None.