Questions remain for Dangerous Florence 

Posted: 11:11 am Tuesday, September 11th, 2018

By Kirk Mellish

The broad strokes are certain and have been for many days, longer than most non-meteorologists were aware of Florence. A dangerous hurricane will threat SOME part of the East Coast and the cone of uncertainty for location is slowly shrinking. But the devil is in the details and that’s were plenty of question marks remain.

FLORENCE EXPECTED TO RESTRENGTHEN LATER TODAY… …LIFE-THREATENING STORM SURGE POSSIBLE ALONG THE COASTS OF NORTH AND SOUTH CAROLINA

We don’t know exactly where the strongest wind will hit yet, or how strong the wind will be at that spot near where the eye goes ashore. We do know that the strongest winds will only be in a small fraction of the storm, lesser but still dangerous winds will extend out more widely. In the end the water not wind usually causes the most damage and death.

A shift in storm track of just 50 miles can mean the difference from a given location getting a few inches of rain or 2-4 feet of rain. Either way the threat of severe river flooding is high over the course of many days. It won’t be instantaneous.

On strike location and timing the model range is from as early as Thursday to as late as Monday. Depending on which model is right it could have impact of a day or two or 5!

IF it moves right inland and stalls it could be the equivalent of last years Harvey flooding in TX somewhere in the Carolinas and/or Virginia. Inland wind damage is probable in the mountains but river flooding will flow from the mountains to the sea.

Florence could easily reach the max of a CAT 5. But that doesn’t mean it has to be that at landfall. The forecast SLOW DOWN of its forward motion near and on land means a more prolonged lashing of wind, storm surge and waves than with a typical hurricane.

atcf_AL06_currentstorm_06_enseps_tcprob_64_atlantic_1

It’s worth noting the usually reliable European Ensemble is further South and West than the official NHC forecast:

ECMWF_06L_2018091100

The specifics of where the eye goes inland will not change the threat of severe flooding and wind damage across a large part of NC/SC/VA so no need to overly focus on that. The concern is that for at least some areas this will be a Katrina-Harvey like combo.

In some cases on the coast it may be historic storm surge, for some spots inland it may be historic catastrophic flooding, both are property and life-threatening.

It is should be a very dangerous, powerful hurricane at landfall. Even if the system were to weaken upon approach, widespread damaging impacts are still likely due to the size and intensity of the hurricane.

As a side note ONE run of the operational deterministic ECMWF has the storm back up into Georgia Sunday/Monday but this is currently discounted.

092646_5day_cone_no_line_and_wind092646_earliest_reasonable_toa_no_wsp_34092646WPCQPF_smScreen Shot 2018-09-11 at 11.09.52 AM

I have covered other issues in previous posts, can’t repeat everything every time or this would become a book not a blog. Please read previous blogs on Florence and tropics if you missed them.

5dayfcst_wbg_conus

Follow me on Twitter @MellishMeterWSB.

 

0 comments