Marine Weather and Tide Forecast for Walhalla, SC

NEAR TERM /THROUGH TUESDAY/
As of 820 PM: Water vapor imagery indicates mid-level dry slot has pushed through the CWA this evening...and this has been associated with reduced coverage of showers across most of the area. However, ample instability (sbCAPE of 1000-1500 J/kg) to our west...around the periphery of residual cold air damming air mass...has resulted in some strong...even severe convection across north GA this evening. Some of this activity has made its way into the lower SC Piedmont in the form of a line of vigorous cells. Since these cells are aligned with the mean flow...conditions are favorable for training cells and isolated flash flooding across the Upstate as this activity lifts north through the evening...with some considerable flash flooding possible if the line of cells moves over an urban area. Meanwhile, more general light/moderate/occasionally heavy showers continue to feed into the eastern Blue Ridge escarpment in response to upslope flow. General additional amounts of up to 1.5" there could result in some duration-type flooding, but the potential for flash flooding remains, especially if some of the higher rainfall rates over the Upstate manage to make their way into the escarpment.

Slow northward movement of stacked low pressure system will steadily veer low-level winds tonight, weakening moisture flux and weakening upslope lift. Shear parameters and attendant tornado threat will continue to steadily diminish...and the threat should be pretty much done by late evening. PWATs decline from west to east between approx. 03z-09z tonight as the dry slot expands over the area. The heavy rain threat likely will taper off in that timeframe as well.
There won't be much of a wedge erosion mechanism, so whatever is left could remain into morning until diurnal insolation can work to that effect. The closed portion of the 500mb low will drift north over TN/KY by that time, so we will see 700-500mb lapse rates increase to near 7C/km during peak heating Tuesday. Profiles will not be saturated thru a deep layer like today/tonight, but should be supportive of deep updrafts. For now have kept PoPs mostly in the scattered to low likely range (the latter over the mountains). Can't completely rule out severe weather, with 0-6km shear of 30+ kt supportive of multicells producing a wind or marginally severe hail threat.

SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
As of 1225 PM Monday: The upper low will be departing from the area at the beginning of the short range period with ridging asserting itself across the region by Thursday. This will lead to a shift in the low level flow to more westerly/southwesterly and more diurnal showers/storms each day with overall lighter rainfall amounts. High temperatures are expected to be around normal on Wednesday climbing to several degrees above normal on Thursday.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
As of 1235 PM Monday: The upper ridging pattern will shift quickly to the east by Friday and then off the coast by the weekend. An upper low over the Great Lakes states will create an active storm pattern across the Ohio and Tennessee Valleys for Friday into the weekend. A northwest flow pattern that will set up between the low and ridging to our southwest, causing some of these storms to make a run at our area during the extended period. Thus, will maintain the chance of showers/storms through the extended period.

High temperatures through the extended period look to average around 5 degrees above normal.

AVIATION /01Z TUESDAY THROUGH SATURDAY/
At KCLT and elsewhere: With drier air aloft pushing in from the west this evening, coverage of showers has decreased across the Terminal Forecast Area. However, intensity of convection has increased across portions of upstate SC...as ample instability and low level moisture persists. Prob30s for TSRA are still warranted at most sites through about 06Z...while a tempo for TSRA lingers at KAND through 02Z.
Otherwise, tempo SHRA will continue for the next few hours...
tapering to VCSH shortly after midnight. Cigs are primarily IFR early this evening...and are expected to settle to 003-005 at all sites by around midnight. LIFR cigs will linger until late morning or so...with further improvement to VFR expected by mid-afternoon.
Generally MVFR/IFR visby is expected during the overnight...but can't rule out periods of lower visby in light of the drying aloft.
Instability and moisture will remain sufficient to support diurnal convection Tue afternoon and evening, but coverage of showers and storms will be considerably less than today. Prob30s for TSRA are carried at all sites during the afternoon. General ESE winds at around 10 kts this evening will steadily diminish through the night.
Winds are expected to become light southerly Tue afternoon.

Outlook: Chances for diurnal scattered showers and storms will continue through the week. The potential for organized complexes of thunderstorms to move into the area from the TN and OH Valley will increase late in the week into the weekend...although much uncertainty surrounds timing and track of these complexes. Morning fog and low stratus will be possible each morning...primarily in the mountain valleys and in areas that receive appreciable rainfall the previous afternoon/evening.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...Flood Watch until 8 AM EDT Tuesday for NCZ033-035-049-050- 063>065-501>510.
SC...Flood Watch until 8 AM EDT Tuesday for SCZ102-103.