Posted: 5:33 am Thursday, September 13th, 2018
By Kirk Mellish
HEAVY RAINBANDS WITH TROPICAL-STORM-FORCE WINDS SPREADING ACROSS THE OUTER BANKS AND COASTAL SOUTHEASTERN NORTH CAROLINA… LIFE-THREATENING STORM SURGE AND RAINFALL EXPECTED. A CATEGORY 2 STORM
A weaker but still dangerous storm will continue impacting coastal Virginia and the Carolinas today with outer rain bands and isolated tornadoes, conditions will deteriorate this afternoon and overnight as tropical storm conditions begin. The forecast track has moved a bit north after landfall.
Landfall of the eye looks to be somewhere between Bald Head Island to Jacksonville NC tomorrow night or early Friday morning… North of Wilmington.
The good news is its expected to weaken rapidly once the eye gets on land down to a Tropical Storm and then a Tropical Depression Saturday and Sunday as it moves West across Central South Carolina then heads Northwest ending up in Westernmost North Carolina by the wee hours of Monday. The bad news its still expected to slow to a crawl exacerbating the water and wave dangers pounding coastal areas of the Carolinas for 2 or 3 days! The storm has grown in size overnight.
Remember I’ve been pointing out since Saturday too much attention is paid by the public and news media to the headline wind number category. Most deaths from tropical cyclones are caused by water not wind! Water from the ocean and water from the clouds. CATEGORY does not equal impacts.
While storm surge is driven by wind, but the maximum value of the wind speed matters much less than the size of the wind field. Florence is huge, and will push perhaps greater than 10 feet of water ashore in some places, regardless of any “weakening” that has occurred.
Highly possible that parts of North and South Carolina will see more rain from Florence than with any other tropical system on record. NC record: 24.1″ from Floyd (1999); SC record: 18.5″ from T.S Jerry (1995).
Experimental power outlook University of Michigan Engineering:
FLORENCE IN GEORGIA:
For The Metro Atlanta area I expect little negative impact as of now. IN FACT the first significant effect will be a positive tomorrow. The rising air in Florence comes back down over us on the West side of the storm structure, a process know as subsidence. or sinking air. That gives us more sun and little or no rain chance tomorrow into Saturday morning.
Then just some showers and gusty breezes for the Atlanta area Saturday afternoon but mainly Sunday and Monday with ATLANTA winds expected to be 15-25 mph. Worse conditions NE mountains toward Athens to Savannah. ATHENS for example gets rain and wind gusts up to 35mph.
We need to monitor for any worsening of the forecast for Athens and Atlanta depending on the path and strength of Florence.
The Peachtree City National Weather Service explains it well:
Florence is expected to impact portions of the forecast area and the eastern portion the most with increased winds and rain chances late Saturday and Sunday and into Monday. How much wind and how much rain will depend on the actual track of Florence and how quickly it weakens. Florence is expected to make landfall the first half of Friday or so along the southern portion of the NC coast and track across SC into or near the mid to upper SAV River Valley late Sunday into Monday. This will put the strongest winds and greatest rain chances and rainfall along the east border of the forecast area with less chances and less wind as you go west. There will be a sharp gradient (cut-off) of 25 to 45 mph wind gusts and 2 to 4 inches if rain. Again, this is all dependent on the actual track of Florence. Please read previous blogs if you missed them. Follow me on Twitter @MellishMeterWSB.