textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated aviation discussion with the 00z TAF issuance.

Updated PoP trends tonight based on current radar and latest CAM guidance.

KEY MESSAGES

1. Rain chances increase tonight through Tuesday, including a marginal risk for locally heavy rainfall and severe storms Monday. 2. Dry conditions return with cooler than normal weather through mid-week, with a warming trend beginning Thursday.

DISCUSSION

Key message 1: Rain chances increase tonight through Tuesday, including a marginal risk for locally heavy rainfall and severe storms Monday.

Drier air gets pushed out of the area as surface high pressure slides off the east coast and winds swing back to the south. Moisture creeps up from the south and increases dewpoints and rain chances through tonight. Current CAMs depict shower activity increasing for northeast GA and Upstate SC this evening, with a few showers developing over the far western NC mtns. Looking at the environment for the afternoon and evening timeframe, there looks to be a struggle for any instability to develop given the lingering dry air and cloud cover. Cannot rule out a shower or thunderstorm, but nothing suggests an environment supporting anything severe. For Monday, severe chances go up a tick with a marginal risk (1 of 5) as increased PWATs, 25-35kts of mid-level shear and 500-1000 J/kg of sbCAPE, increases confidence for the chance of an isolated strong to severe thunderstorm. However, not expecting widespread severe, just a few storms that have the potential to reach severe criteria. Given the W/NW upper flow, expect showers and thunderstorms to approach and develop mainly over the mountains before moving eastward.

By Tuesday, the next frontal boundary looks to head toward the area. Ahead of it, guidance depicts another round of showers, mainly concentrated over the mountains Tuesday afternoon, before drier air once again cuts off the chances. Overall QPF response is rather low through Tuesday, with only a 40-50% chance of total amounts measuring over 0.5". However, depending on where a storm setsup, could produce an isolated area with locally heavy rainfall. So not seeing much in the way of hydro concerns for this system. Additionally, much cooler temps should stick around through at least Wednesday.

Key message 2: Dry conditions return with cooler than normal weather through mid-week, with a warming trend beginning Thursday.

Temperatures are expected to remain below normal through at least Wednesday as a trough starts to migrate eastward. An amplifying ridge over the central CONUS begins to shift eastward, with height rises across the southeast Thursday and onward. High pressure shunts the majority of rain chances through the remainder of the week and into the weekend. Temperatures slowly tick up through the end of the forecast period to values more conducive for summertime. Winds should remain out of the north before turning south by the weekend. Southerly winds increases moisture transport and raises dewpoints. So, expect humidity to settle in by next weekend but, not seeing a signal for any heat index concerns at this time.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Widespread MVFR cigs at the SC sites will creep north toward KCLT and KAVL through the evening, but may never make it to KHKY. Winds remain S to SE, light and variable at KAND, through the evening as well. Scattered showers will move southeast across the area through the overnight, but TSRA look unlikely. IFR cigs and MVFR vsby expected at KAND overnight. KAVL sees IFR vsby and cigs. IFR possible elsewhere but looks unlikely now. Low clouds scatter out after daybreak with increasing N to NW wind. W wind at KAND. Scattered convection develops during the afternoon, have PROB30s for that.

Outlook: Showers possible Tuesday, but this is more uncertain. A drier pattern should set up by Wednesday and continue through the rest of the week.

GSP WATCHES/WARNINGS/ADVISORIES

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