Marine Weather and Tide Forecast for Barnwell, SC

KEY MESSAGES
- 1. Active weather increasingly likely to end the work week due to system from the Gulf moving across the region, with potential for locally heavy rainfall and isolated damaging winds.

- 2. Scattered showers this morning move out and dry conditions return into Thursday ahead of the active weather from Key Message 1.

DISCUSSION
Key Message 1: Active weather increasingly likely to end the work week due to system from the Gulf moving across the region, with potential for locally heavy rainfall and isolated damaging winds.

Potential Tropical Cyclone 1 (PTC 1) has moved off the TX coast and into the northwest Gulf. While over the warm waters, it is forecast to intensify briefly before making landfall in the lower Mississippi Valley and weakening. Guidance continues to show that the upper wave associated with this system moves along a stalled boundary over the Gulf Coast states and toward the Southeast. Although there is better agreement in timing, there is still some discrepancy between model solutions, with the ECMWF still being the strongest with the associated surface low.
Regardless of how the upper wave and surface low evolve, confidence is increasing that we'll see active weather Thursday afternoon/evening into Friday.

In addition to the upper wave along the Gulf coast, a cold front is forecast to start moving southward from the Midwest late in the week. As a result, the pressure gradient is expected to tighten, causing breezy to gusty winds Thursday afternoon.
There is a moderate chance (50-60%) of wind gusts exceeding 25 mph. Increased moisture is also expected as the upper wave pulls Gulf moisture into the region, with PWATs over 2" likely everywhere in the forecast area. Forecast soundings also look moist adiabatic Thursday evening into the overnight hours.
Latest QPF amounts have increased as well, so the combination of these factors indicate the threat for locally heavy rainfall is increasing. Despite the increased threat for locally heavy rain, confidence isn't high enough that it will be widespread enough to warrant a Flood Watch at this time. The heaviest rain from this system is forecast to remain to our southwest. Lastly, ahead of the heavy rain, there should be sufficient CAPE (~1000 J/kg or greater) and 0-6 km shear (~20-25 kts) to support an isolated strong to severe storm or two with damaging winds being the main threat.

Key Message 2: Scattered showers this morning move out and dry conditions return into Thursday ahead of the active weather from Key Message 1.

A weak shortwave translating across the South is bringing scattered showers to the forecast area early this morning, but a majority of the activity remains south of the area. Expect shower chances to continue ahead of this shortwave, which is weaker than forecast, leading to less activity than anticipated previously. Once this shortwave passes, dry conditions can be expected for the rest of today and into Thursday ahead of the system discussed in Key Message 1. Temperatures are expected to rebound to near average for today and tomorrow as well.



AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
Restrictions expected to overspread the terminals, although guidance has been a bit aggressive so far.

Regional radar showing some scattered showers moving through the region associated with an upper disturbance that will cross the are later this morning. Cigs have been intermittent between low VFR and MVFR but all guidance suggesting restrictions would be expected through much of the night into late morning. Will carry prevailing MVFR cigs most terminals and have a tempo for IFR cigs 09z-13z time frame. Will carry VCSH for persistent passing showers but they should end by mid morning with drier air moving in this afternoon with improving cigs back to VFR. Winds expected to be southwesterly 5 to 10 knots then pick up to around 10 knots after 15z with some afternoon gusts to 20 knots.

EXTENDED AVIATION OUTLOOK...Diurnally favored convection possible each afternoon, favoring the southern Midlands and CSRA. Breezy conditions expected Thu/Fri with increased chances of rain as a Gulf coast system approaches the area.

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