textproduct: Raleigh

WHAT HAS CHANGED

* The risk of an isolated tornado and damaging winds remains into mid to late morning across eastern portions of central NC.

* The risk of heavy rainfall across the Piedmont appears more likely into mid-morning.

* Chances of precipitation increase Monday with the passage of a frontal boundary.

KEY MESSAGES

As of 200 AM Friday...

1) Widespread showers into midday, with embedded strong storms capable of damaging winds. An isolated tornado cannot be ruled out.

2) Heavy rainfall expected across portions of the Piedmont into midday, with a swath of 2-4 inches possible.

3) Increasing rain chances for Monday-WPC issues Marginal Risk for flash flooding on Monday.

DISCUSSION

As of 200 AM Friday...

KEY MESSAGE 1... Widespread showers into midday, with embedded strong storms capable of damaging winds. An isolated tornado cannot be ruled out.

The remnants of Arthur will bring widespread showers across central NC, at least into midday. The remnant low is currently near northeast GA and upstate SC. On the forecast track, most guidance takes the system into the southern Piedmont and Sandhills by sunrise, then tracking into the Outer Banks by early afternoon. The system is moving rather fast, such that the window for rainfall will be from the early morning hours until midday. By the early afternoon, precipitation will have exited the majority of central NC, except the far eastern Coastal Plain. Clouds should lessen by the afternoon as well, with sunshine breaking out and temperatures reaching the middle to upper 80s, warmest in the west where the sun breaks out sooner.

On the severe front, a severe risk from SPC remains in place. The main severe risk, from a pattern recognition standpoint and some AI guidance, is from 4 AM until 11 AM to maybe as late as noon. During this time is when the overlap of low/deep-layer shear will combine with the instability. In fact, upstream VWP hodographs indicate strong low-level shear in SC, indicative of the environment coming into the area early this morning into late morning ahead of Arthur's remnants. Given these conditions, a damaging wind threat remains in place, but also an isolated tornado cannot be ruled out. That tornado threat appears greatest across the southern Piedmont, Sandhills, and southern Coastal Plain, however it cannot be ruled out near the Triangle as well. We will be closely watching the severe risk into this morning as a result.

Once the system exits toward the coast this afternoon, our rain chances will greatly diminish. But a small window of isolated convection may redevelop ahead of the southward moving cold front, across portions of the southern Piedmont and Sandhills to southern Coastal Plain. If some storms can get going, they do have favorable shear and instability to become severe, but most CAMs show limited coverage.

KEY MESSAGE 2... Heavy rainfall expected across portions of the Piedmont into midday, with a swath of 2-4 inches possible.

Along with the severe risk into this morning, the 00z high-res ensemble data and CAMs are increasingly showing the potential for a swath of heavy rainfall as the remnants of Arthur track through central NC. Combined with well above normal moisture of 2-2.5 inches in PW, this heavy rainfall threat appears warranted, despite being in an exceptional drought.

A look at the 00z HREF/REFS, the two separate ensemble solutions show remarkable agreement on a swath of heavy rainfall of 2-4 inches stretching from the Charlotte region, into the southern Piedmont and portions of the Triangle. It should be noted that models can be off by location of the heavy rainfall footprint by several hundred miles. Nevertheless, the agreement suggests isolated flash flooding will be a real possibility. The main heavy rainfall threat appears from the early morning hours into mid-morning over urban and poor drainage areas. Although there is this flood risk, we are not confident enough to go with a flood watch given the relatively short- fuse nature of this event, as well as the ongoing drought. If the forecasted rainfall totals come to fruition, this could be a welcomed relief given the extreme to exceptional drought over the region.

KEY MESSAGE 3... Increasing rain chances for Monday-WPC issues Marginal Risk for flash flooding on Monday.

The weekend will be dry with increasing rain chances on Monday, for which the WPC has already issued a Day 4 Marginal Risk of flash flooding across the entire CWA. Driven by a potent shortwave and low pressure system moving out of the Midwest into our area, this setup will drag an associated frontal boundary into the Mid-Atlantic, capable of triggering thunderstorms across the region. Confidence remains low-to-medium regarding the exact timing and placement of the heaviest rainfall and severe risk, though the latest AI-NWP convective models consistently show a 3045% chance of severe storms across our area. Because showers and storms are expected to hold off until the afternoon, Heat Risk values will reach the Major category (3 out of 4) across the Triangle and Sandhills. While actual temperatures will stay in the low-to-mid 90s, heat indices will range from the upper 90s to triple digits.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

As of 150 AM Friday...

As the remnants of Tropical Storm Arthur spread across the Carolinas early this morning, widespread adverse aviation conditions will arrive with widespread CIG and VSBY restriction from around 08Z through 14 to 18Z.

The rain along with some embedded heavier showers will overspread the region from southwest to northeast. The Precipitation will arrive in the Triad (KINT and KGSO) between 06 and 08Z and at KRDU, KFAY and KRWI between 07 and 09Z. CIGS and VSBYS will drop to MVFR range within an hour or two of the precipitation starting with occasional drops into IFR range during heavier rain episodes. A few thunderstorms are possible late tonight into the daybreak hours to the south and east of Raleigh although coverage and confidence are low so will exclude a mention in the TAF for now. The precipitation will exit the area from west to east during the mid morning to midday hours with KINT/KGSO expected to trend to VFR 14-16Z, KRDU between 16 and 18Z with KFAY/KRWI trending to VFR between 18 and 20Z. Low and mid clouds will clear out during the afternoon and evening with clear skies and VFR conditions expected overnight into Saturday morning with a veil of persistent high cirrus clouds. South to southwest winds at 5 to 10kts overnight will veer to southwest after daybreak and become northwest at around 8 to 12kts between 16 and 20Z with a few gusts to around 20kts during the afternoon. Light north winds are expected tonight at 6kts or less.

Looking beyond 06Z Saturday, generally fair weather with VFR conditions are expected for Saturday through Sunday. Some patchy daybreak stratus is possible on Sunday and especially Monday morning. An approaching frontal system will bring a risk of showers and storms and some gusty winds for Monday which may linger into early Tuesday.

CLIMATE

Record High Temperatures:

June 21: KRDU: 101/1933

June 22: KRDU: 100/2022 KFAY: 101/2022

Record High Minimum Temperatures:

June 19: KRDU: 73/2025 KFAY: 77/2017

June 22: KGSO: 75/1981 KRDU: 78/1933

June 23: KGSO: 74/2024 KRDU: 78/2024 KFAY: 77/2024

RAH WATCHES/WARNINGS/ADVISORIES