Area Forecast Discussion

WHAT HAS CHANGED

Thunderstorms have pushed quickly down to the Santee River in South Carolina and dry weather is anticipated overnight for most of our area. Stiff east-northeasterly winds blowing across the very warm Atlantic will remain unstable and may develop new showers and thunderstorms overnight, possibly affecting the Grand Strand coastline south of Myrtle Beach. PoPs are being maintained at 30 percent from Murrells Inlet through Georgetown for this potential.

Over the coastal waters, post-frontal east-northeast winds are coming in almost 5 knots stronger than earlier forecasts indicated. Upward adjustments have been made to winds and seas through midnight before blending back down into the previous forecast by daybreak Sunday.

KEY MESSAGES

1) A period of unsettled weather will exist, especially Tuesday through Thursday with much cooler weather beginning Thursday.

DISCUSSION

KEY MESSAGE 1...A period of unsettled weather will exist, especially Tuesday through Thursday with much cooler weather beginning Thursday.

The mid/upper low invof FL is expected to open and lift toward the northeast Monday through Wednesday directed by a developing upper trough across the upper Midwest region. This trough will advance toward the OH Valley into the eastern U.S. Wednesday into Thursday. A CAD event will likely unfold Tuesday into Thursday as the surface low remains offshore with high pressure ridging southward into the Carolinas. Convection is likely at times Tuesday and Wednesday with good chances of rainfall after the CAD develops given the positioning of the upper trough. In the end, below normal temperatures are expected to arrive Thursday and persist through the end of the week. It seems reasonable that NBM high temperatures Thursday are too high unless the CAD is slower to evolve. Much lower PWATs are on tap for the end of the week.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Thunderstorms have pushed south of all local airports and VFR conditions are expected for the first half of the night. After 07-08z there is increasing potential for MVFR to IFR ceilings to develop across the area. The highest potential for impacts should exist at KFLO where ceilings and/or vis may dip into the IFR range by daybreak. There is moderate potential for MVFR impacts at KLBT, KMYR, and KCRE. KILM has a low (but not zero) chance for MVFR ceilings late tonight. New offshore showers and thunderstorms will make a run at the South Carolina coast overnight, but should remain south of KMYR.

VFR conditions should develop by 14z at all local airports as any early morning clouds burn off.

Extended Outlook...Showers and storms are most likely to cause flight restrictions Tuesday and Wednesday. Morning fog/stratus is possible each morning through Monday. The first cool season Cold Air Damming pattern may result in MVFR to IFR ceilings on Thursday.

MARINE

Tonight through Thursday: E-NEly winds will increase as a ridge builds southward through the remainder of the day into tonight with speeds around 15 knots (a touch higher Cape Fear northward). These winds will diminish during Sunday and veer to a SEly direction in the afternoon. Winds around 10 knots or less are expected Monday into Tuesday then low pressure is expected to develop off the SC during Tuesday. This low will be situated east of NC Tuesday night as a strong ridge builds southward into the Carolinas. This will lead to strengthening Nly winds Wednesday, with the potential for Small Craft conditions increasing.

ILM WATCHES / WARNINGS / ADVISORIES

NC...None. SC...None. MARINE...None.