textproduct: Charleston

WHAT HAS CHANGED

All Key Messages and sections have been changed.

KEY MESSAGES

- 1) A cold front will bring an increased risk for showers and thunderstorms to the region Thursday into Saturday.

DISCUSSION

KEY MESSAGE 1: A cold front will bring an increased risk for showers and thunderstorms to the region Thursday into Saturday.

Forecast confidence for Thursday into Saturday is low. A potent shortwave is forecast to dig across the Ohio and Tennessee Valleys Thursday which will help push a cold front into the Southeast states. The front will interact will building moisture and instability to produce showers/tstms. The degree of lift and resulting coverage of convection will be largely driven by how strong and progressive the shortwave will be. This is the primary source of forecast uncertainty and is a key factor on how far the south the front will progress before stalling. The various ensemble guidance packages are showing a number of possible outcomes with the majority of GFS ensembles favoring a more progressive, drier solution Friday into Saturday with the front stalled well to the south while the ECMWF is a bit weaker, slower with the majority of its members highlighting wetter scenarios with the front stalled closer to or directly across the Lowcountry and Southeast Georgia. Hopefully, the ensemble and operational solutions will begin to converge on a more consistent, consolidated solution over the next day or two as additional data and upper air observations are ingested. Guidance is the most consistent with the evolution the surface pattern for Thursday and the highest pops (50-80%) were maintained consistent with the 04/13z NBM. Elevated pops were also maintained for Friday and Saturday to try and account for the spread in the guidance due to ongoing uncertainty. Additional adjustments, possibly significant, are likely to be made as confidence increases on how the pattern will evolve.

AVIATION /18Z MONDAY THROUGH SATURDAY/

04/18z TAF Discussion: KCHS/KJZI/KSAV: VFR through 05/12z.

Extended Aviation Outlook: Flight restrictions from showers/tstms are possible Thursday and Friday as a cold front moves through the region.

MARINE

Southerly flow will strengthen ahead of an approaching cold front Thursday. There could be period of 25 kt winds and 6 ft seas over portions of the Charleston nearshore and Georgia offshore waters Thursday afternoon/evening. Small Craft Advisories may be needed.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.