Marine Weather and Tide Forecast for Columbia, SC

NEAR TERM /THROUGH 7 AM WEDNESDAY/
Key Message(s):

- Isolated showers and a few thunderstorms possible tonight.

There were a few showers and thunderstorms earlier this evening in parts of the Midlands, but that activity has diminished.
However, regional radar shows some isolated to scattered showers moving toward the CSRA and also the northern Midlands. Expect mainly light rain with these showers as they move through.

An outflow boundary continues trekking eastward at this hour with just a few weak showers remaining on it. Meanwhile, a seabreeze is moving more inland. As these features collide this evening, it could trigger some additional shower or thunderstorm development over the eastern Midlands. Otherwise, overall activity should decrease overnight.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
Key Message(s):

- Diurnal shower/storm chances continue Wednesday afternoon and evening with the front stalling out near the CWA

- These chances continue Thursday afternoon and evening as well with the diffuse front lingering.

Little change in the forecast for this period from the previous few days. A weak cold front will continue to sag southward and become diffuse over the next several days. The airmass should be characterized as moisture rich, with dewpoints in the mid 60s and mixing ratios in the 10-12 g/kg range. Mid and upper level flow is expected to relax over the next couple of days as the ridge weakens, allowing for weak shortwaves to pass northeastward in the upper level flow. Combine that with the sea breeze getting going in the evening hours and the set up is quite favorable for numerous showers and thunderstorms both Wednesday and Thursday afternoon. CAPE values look moderate across the area both days - with values of 1000-2000 j/kg expected by the afternoon/evening on both days. PWs should be in the 1.25-1.5" range, which should support heavy rainfall within this convection. Shear looks quite weak, with values less than 30 knots both days; however, there is some indication amongst guidance that 6km shear could be in the 20-25 knot range, which could result in loosely organized multi-cell clusters. Regardless, widespread severe weather is not expected either day. Strong to marginally severe storms are possible, though, with strong wind gusts and small hail the threats. In any storm, lightning and heavy rainfall are expected and these will be the primary threats. Highs both days should be in the low to mid 80s. Overnight, convection may hang around longer than normal as outflow boundaries and the sea breeze interact.

LONG TERM /FRIDAY THROUGH TUESDAY/
Key Message(s):

- The lingering frontal boundary is expected to move north Friday, but some more diurnal showers/storms may be possible.

- Stronger cold front moves in Saturday with another chance of showers and possible thunderstorms.

- Temperatures look to remain above normal into the weekend before possibly cooling slightly Sunday and Monday.

The diffuse boundary across the region on Wednesday and Thursday should either dissipate or begin to slowly lift to our north ahead of another cold front Friday. A moisture rich environment looks to remain in place by this point, with PWs still 15-180% of normal across the region. Instability looks like it could be a bit lower on Friday than it is expected to the prior couple of days but still should end up in the ~1000 j/kg range for much of the area. This supports another round of diurnal showers and thunderstorms developing Friday afternoon and evening, with guidance a bit more bullish today on rain chances than they have been the past couple of days. Saturday looks to have a better chance at more defined activity as a cold front pushes through the area. Strong storms are possible given expectation that CAPE will exceed 1000 j/kg ahead of the front, but shear looks to be a limiting factor with weak mid and upper level flow ahead of the front itself. Thereafter, ensembles and operational models indicate a surface high pressure settling into the eastern CONUS, with upper level ridging increasing early next week.
Weather should be benign in this period as PWs and temperatures return closer to normal values.

AVIATION /07Z WEDNESDAY THROUGH SUNDAY/
Occasional restrictions possible in showers and thunderstorms through the valid TAF period.

SCT-BKN high clouds through the period with SCT-BKN clouds 4-6k ft MSL through the period. Confidence in CIG restrictions this morning is low, but some patchy fog with occasional VSBY restrictions is not out of the question given increasing low level moisture and light winds. SCT -SHRA/-TSRA expected to redevelop this afternoon, but timing remains a question, so maintained PROB30 for a few hours this afternoon. Restrictions will be possible with the stronger storms.
Rainfall chances decrease somewhat overnight tonight. Winds remain light and variable through the period, though some erratic gustiness is possible within -SHRA/-TSRA.

EXTENDED AVIATION OUTLOOK...A front will stall over the region this week leading to convection and occasional restrictions through Saturday.

CAE WATCHES/WARNINGS/ADVISORIES
SC...None.
GA...None.