textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No major changes.

KEY MESSAGES

1. Severe threat remains low through Tuesday morning before increasing Tuesday afternoon into Tuesday night ahead of a cold front. Storms may linger into early Wednesday. A warming trend is expected through Tuesday, with slightly cooler highs and lower humidity returning by Wednesday behind the front.

DISCUSSION

Key message 1: Severe threat remains low through Tuesday morning before increasing Tuesday afternoon into Tuesday night ahead of a cold front. Storms may linger into early Wednesday. A warming trend is expected through Tuesday, with slightly cooler highs and lower humidity returning by Wednesday behind the front.

Persistent upper troughing will continue over the eastern United States while a large upper anticyclone dominates over the central and western United States. This "Ring of Fire" pattern will allow storm complexes to round the norther/eastern periphery of the upper anticylcone, diving towards the GSP forecast area overnight tonight and again tomorrow night. Confidence on these storm complexes holding together each night/morning remains low as 06Z CAMs depict them gradually weakening as they push farther south towards the southern Appalachians. As a result, confidence on the severe threat with these complexes remains low, especially overnight tonight into early Monday morning. The SPC Day 2 Severe Weather Outlook has the northern and western tiers of the GSP CWA in a Marginal Risk for early Tuesday morning but again confidence low on whether activity will hold together well enough to lead to a damaging wind threat. Otherwise, only isolated showers and storms are expected this afternoon and early evening with the severe risk remaining low. Mostly dry conditions are expected Monday afternoon and evening but cannot entirely rule out an isolated shower or thunderstorm developing.

The severe threat ramps up Tuesday afternoon and evening ahead of a cold front. However, confidence remains low regarding the severe potential with this front as it will depend on how well the storm complex Tuesday morning holds together as it tracks southward. If the complex weakens significantly and leaves behind less debris cloudiness, then we would have more time for the atmosphere to destabilize during peak heating, allowing for severe storm development. If the complex does not weaken significantly and leaves behind more debris cloudiness, then we would have less time for the atmosphere to destabilize during peak heating as it would take longer for the debris cloudiness to lift. The SPC Day 3 Severe Weather Outlook has a Slight risk in place across western NC, the northern SC Upstate, and extreme northeast Georgia with a Marginal risk in place across a portion of the southern SC Upstate and portion of northeast Georgia for Tuesday. This appears reasonable as if we are able to destabilize enough during peak heating then strong to severe storms can be expected, especially with an abnormally high amount of deep layer shear (30-45+ kts) in place for this time of year. The severe threat could linger into late Tuesday night or even early Wednesday morning but confidence is low as 06Z CAMs do not go out far enough to capture the full event.

The cold front will stall across the Southeast Wednesday through Friday as surface high pressure builds in behind it. This will allow drier conditions to return for the rest of the workweek. Shower and thunderstorm chances look to return over the weekend as the front lifts back northward.

A warming trend is expected ahead of the front through Tuesday, with cooler and less humid conditions returning behind the front starting Wednesday and lingering through the rest of the period. Tuesday still looks to be the hottest and most humid day of the week, especially east of the mountains where heat indices could flirt with Heat Advisory criteria (which starts at 105 degrees). However, confidence on reaching heat advisory criteria is low as lingering debris cloudiness could limit both afternoon temperatures and heat indices.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

At KCLT and elsewhere: Seeing quicker improvement regarding restrictions today compared to this time yesterday. A mix of MVFR to VFR cigs as of 18Z, with any lingering MVFR cigs lifting in the next hour (if not sooner). VFR should prevail outside of the potential for TSRA this afternoon across the SC terminals and the low stratus and/or patchy fog potential overnight across the NC terminals. Maintained PROB30s across the SC terminals as isolated storms may develop this afternoon. Have TEMPOs to account for IFR/MVFR vsbys and SCT IFR to LIFR cigs across the NC terminals overnight into daybreak Monday. A weakening line of storms should will sink southward towards the terminals overnight into early Monday morning but confidence was too low to add a mention of SHRA/TSRA as the bulk of activity should remain west of the Carolinas. Winds will be mostly light and VRB through the period, with the exception of KAVL where winds will remain NW.

Outlook: Showers and thunderstorms may impact the terminals Tuesday morning but confidence is low. Strong to severe storms and breezy SW winds are possible Tuesday afternoon/evening ahead of a cold front. Storms could linger into early Wednesday morning, but confidence is low at this time. Low stratus and/or fog will be possible each morning, mainly in the mountain valleys.

GSP WATCHES/WARNINGS/ADVISORIES

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