textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Increasing heat trends continue into next weekend. The Aviation section was updated for the 00Z TAF issuance.

KEY MESSAGES

1. Isolated showers possible again Monday afternoon across the NC mountains, with a decrease in coverage afterwards. 2. Hot and humid weather returns by Tuesday, with dangerous heat index values likely over the low terrain each afternoon this week.

DISCUSSION

Key message 1: Isolated showers possible again Monday afternoon across the NC mountains, with a decrease in coverage afterwards.

Pattern continues to trend drier as an amplifying ridge progresses eastward and decreases rain chances after Monday. Even Monday, shower activity looks isolated and mainly confined to the mountains. Somewhat drier dewpoints and stagnant air mass associated with the ridge keeps the chances for rain almost nonexistent. Model guidance starts to increase PoPs toward the end of the week, but this is mainly due to the ridge breaking down and a new trough developing. This is still too far out to nail down but the general pattern is drier for the next week. Bottom line is that the risk for impactful thunderstorms looks low for the next several days.

Key message 2: Hot and humid weather returns by Tuesday, with dangerous heat index values likely over the low terrain each afternoon this week.

Though rain chances decrease, the amplifying ridge brings another round of hot and humid weather. By Tuesday, the ridge looks to park over the southeast and increase temps through at least Friday. Model guidance has temps creeping back into the mid and upper 90s. Weak southerly surface winds also contribute higher dewpoints, meaning humidity is also returning for the hundredth time this summer. So, hot temps, elevated dewpoints, can only paint one picture: heat index values in the 100-106 range. This appears to occur in the eastern NC Piedmont and southern counties, as usual. Heat Advisories may be needed. Depending on how the pattern evolves, could see a break for the holiday weekend, but confidence is low at this point. Summer isn't done with the area yet, no matter how much we all want it to be.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Remaining isolated mtn showers should dissipate by 01Z. Otherwise, VFR at all terminals this evening, then after midnight another round of low stratus and fog is possible, though not as widespread and long lasting as last night. IFR and LIFR is likely in the mountain valleys after 09Z or so, and thus we hit KAVL the hardest with a prevailing LIFR. Periods of VLIFR would not be out of the question. The mtn valley fog may persist until an hour or two after sunrise. Other terminals should improve by around 12Z if they get any restrictions at all. After that, VFR at all terminals for the bulk of Monday, with scattered convective clouds at 040-050. Wind will be variable for most of the morning, and may settle in to something easterly by afternoon, which could present a problem at KCLT. No clear indication yet, so opted for VRB and will address in the next TAF.

Outlook: Isolated mountain showers and thunderstorms may develop again on Monday afternoon. Fog and low stratus will be possible each morning, especially in the mountain valleys.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.