Tropical Storm Isaias Should Return To Hurricane Overnight Still Tacking To Maryland

Saturday August 1 2020

The storm known as Isais (ees-ah-EE-ahs) weakened to a tropical storm during the afternoon, but is expected to return to hurricane intensity tonight. It already looks healthier on the satellite loop. Winds were only down to 70 mph, and the peak forecast is likely to keep this a Category 1 storm. So it’s just a matter of naming it.

Tropical storm force winds over 39 mph extend 105 miles form the center. It is not a big storm right now. When the winds do increase, the hurricane force will be a small area right around the eye. This is important to consider with the track of the center, and influence farther away.  But locally the day of concern will be Tuesday between eastern North Carolina through Maryland and Delaware.

Tropical Storm Isaias Satellite

 

Satellite Loop

 

 

Forecast Maps

The expectation for this to intensify to a hurricane as it gets close to Florida’s east coast is why a hurricane warning is still in place for Boca Raton to the Volusia/Flagler County Line Florida. Their time window is Sunday.

Monday: Jacksonville FL until landfall at night near the SC/NC border.

Tuesday: Eastern North Carolina through Maryland and Delaware.

Notice the path still curves along with the US coastline but makes landfall between South and North Carolina. This path inland would further weaken the storm, but may expand how large of an area it covers.

 

 

Looking Closer

Since last night, the forecast models have wobbled a bit, but consistently keeps Maryland in sight.  There is still a wide cone of uncertainty.  But there will be impact in Maryland, most likely with heavy rain on Tuesday.  Winds near the center may be 40 to 50 mph, but inland it may behave like a Nor’easter. Near the center, and east there could be some severe weather with EF0 and EF1 tornadoes.

 

Forecast Animation

Here is a look at the HWRF Model tracking the center of the storm up the coast. See the still maps below.

 

Still Maps Model Comparison 

HWRF Model shows the Low crossing the lower Chesapeake Bay at 2 PM on Tuesday.

GFS Model at the same time shows the center of the storm over Delaware. This is pretty close and in general agreement with the HWRF.

 

ECMWF (European) Model is slower. This hold the core of the storm back a few hours until 8 PM

 

What does this mean for us?

Most likely heavy rain!  While a tropical system is usually strongest on the east side of the center, it can be different when interacting with land. In this case, the heaviest rain may interact with terrain and a frontal boundary to drop the heaviest just west of the center. That is why tracking is critical.

Here we see agreement among the models for a 3 to 5 inches rainfall region in central Maryland and across the Bay. Any shift in this track can move the heavy rain region, but most of us should be in on it if this track holds.

 

Notes:

Since this will be in inland storm, it will be a tropical storm or even a depression when it reaches our region.  The spin of the storm can result in smaller vorticies that can drop isolated tornadoes within the rain bands. The impact on the water should be minimal, but behaving like a strong Nor’easter.

The good news is that the storm should be gone by Wednesday.

 

Also See:

July 2020 The hottest on record. Will it hint at snow this winter?

 

 

Related Posts

2020 Tropical Storm and Hurricane Names and Naming History

 

Atlantic Tropical History: Maps of Origin Regions Every 10 Days