01:12 Tropical Storm Beta Drifting Around the Northwestern Gulf of Mexico Tropical Storm Beta has stalled in the western Gulf of Mexico, which will eventually set the storm up for a slow scrape of the Texas coast into next week. Beta poses a major threat of rainfall and coastal flooding to the Texas and Louisiana coasts.

At a Glance Irma will lead to major coastal flooding along parts of the Georgia and South Carolina coasts.

The worst flooding may occur during a high tide around midday Monday.

In some locations, the peak coastal flooding could top what was seen during Matthew last October.

Irma, now a tropical storm, is continuing its destructive strike on parts of Florida, but its impacts will also be felt in Georgia and South Carolina, among other states.

In addition to a threat of tropical-storm-force winds, some locations in Georgia and South Carolina may see worse coastal flooding from Irma than they did with last October's Hurricane Matthew , despite Matthew's center tracking much closer than Irma.

Here's how that's possible.

(MAPS: Track Hurricane Irma's Current Conditions )

Swells and Setup

First, large swells propagated well ahead of Irma last week toward the Southeast coast, from the Outer Banks of North Carolina southward.

You can see this in the animation from NOAA's Wave Watch model Sept. 7-9, showing the higher significant wave heights propagating toward the coast.

<img class="styles__noscript__2rw2y" src="https://s.w-x.co/wave-watch-irma-setup-7-9sep17.gif" srcset="https://s.w-x.co/wave-watch-irma-setup-7-9sep17.gif 400w, https://s.w-x.co/wave-watch-irma-setup-7-9sep17.gif 800w" >

With repeated swells propagating northwest toward this east-facing curved part of the coast, water levels couldn't fall completely back to normal levels. This is what meteorologists call wave setup.

Irma's Fetch

With that as a backdrop, increasing east, then southeast, then southerly winds on the east side of Irma's impressively large wind field will only act to pile more water toward the Georgia and South Carolina coasts Monday, lingering into Tuesday.

As a result, coastal flooding will only ramp up with the peak water levels expected to occur with the midday Monday high tide at both Ft. Pulaski, Georgia (near Tybee Island), and Charleston Harbor.

At Ft. Pulaski , water levels may top record levels set during Hurricane Matthew.

(MORE: Irma's Extremes, So Far )

<img class="styles__noscript__2rw2y" src="https://water.weather.gov/resources/hydrographs/fpkg1_hg.png" srcset="https://water.weather.gov/resources/hydrographs/fpkg1_hg.png 400w, https://water.weather.gov/resources/hydrographs/fpkg1_hg.png 800w" > Current water levels (in blue) and the forecast tide levels at Ft. Pulaski, Georgia, (NWS-Charleston, SC) (NWS-Charleston, SC)

At Charleston Harbor , peak tide levels may top Matthew and would be the highest since Hurricane Hugo in 1989.

Some residual coastal flooding may persist in Charleston into Tuesday before Irma finally winds down.

(INTERACTIVE: Latest NHC Storm Surge Inundation Forecast )

Rain, Too ...

If that wasn't enough, Irma will also wring out heavy rain over the very same areas subject to coastal flooding through at least Monday.

Anywhere from 3 to 7 inches of additional rain is possible from the Lowcountry of South Carolina to the Georgia coast.

As long as onshore winds continue to pile water in from the ocean, rain-swollen rivers won't be able to drain, worsening flooding which could last well into the week ahead.

(MORE: Irma City-By-City Timing/Impact Forecast )

Water – either from storm-surge flooding or rainfall flooding – claims the majority of lives in tropical cyclones.

Heed all evacuation orders from local government officials, and never drive into floodwaters.