Significant flood threat materializing Monday for South Florida

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Flood Alerts - Right Now (WPEC)

A very complex weather pattern is setting up for the next couple of days across South Florida, and significant flooding could become an issue.

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New tonight, a moderate risk for flash flooding, the second highest level you can have issued, is now in place for those along and east of I-95 on our Monday. This includes a place like Sebastian and Vero Beach all the way south through Delray and Boca Raton.

Flood Watches were issued area wide earlier today. They continue through Monday night for our entire viewing area. They also extend south through Miami-Dade and mainland Monroe county, as well as along the Space Coast.

All of this, as a complex area of several lows meanders through the Gulf of Mexico and eventually onshore through the Florida peninsula. These areas of low pressure are bringing significant tropical moisture to the state. In fact, this system is bringing nearly 2 to 3 times more moisture than we typically see this time of the year. That is a substantial deviation from normal, so significant heavy rains aren't just likely on Monday - they're expected.

On top of the heavy rain and flooding threat, a very fast low-level jet will set up about 5,000 feet above our heads. This jet stream not only brings speed shear - a change in wind speed as you go up in height through the atmosphere - but also directional shear, as the wind direction is expected to change with height.

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On our Sunday, we had several reported funnel clouds and even a few waterspouts near the Keys. Only marginal conditions supported these waterspouts and funnel clouds on Sunday, but conditions are slated to become more favorable on Monday. Because of the amount of waterspouts and funnel clouds we saw today, the risk for a tornado or waterspout on our Monday has increased. It still remains low, but not zero. The most likely location for a brief tornado will exist along the coastline of east Florida, and especially for Miami-Dade and mainland Monroe counties.

The Storm Prediction Center has issued a marginal risk for severe storms on our Monday. That's the lowest risk category you can have. They agree that the risk of a tornado is small, but not zero. The risk for a few strong damaging winds, should any thunderstorms form, is also a possibility for south Florida.

The timing of the rain, according to our latest hi-res futurecast model, shows the rain beginning tomorrow morning during the morning commute. Be aware, roads will already be wet with ponding from Sunday's rainfall, so plan some extra time for that commute. Rain will steadily pick up, becoming moderate to heavy at times after the lunchtime hour.

Rounds of moderate to heavy rain is likely through the afternoon and evening hours, and certainly heading into the overnight period as well, as the tropical wave exists south Florida.

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If any training occurs, or storms with very heavy rainfall moving over the same location for several hours, expect flash flooding to become a threat very quickly. Remember, turn around, don't drown.

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The general consensus on how much rain will fall continues to increase from each model run. Right now, the current thinking is much of our area will receive between 2 to 4 inches of rain, with some areas that see rounds of repeated heavy rain topping out between 6 and 10 inches. Some of the higher end solutions show over a foot of rain in some locations, but those models continue to be outliers.

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Remember, you should always treat flooding as seriously as you would any severe weather event. If you see a flooded road, do not drive through it. Be ready to evacuate should flood waters create an unsafe environment for you and your family at your residence. Your CBS 12 StormTrac Weather Team will be tracking this event all day Monday. The next update to this Weather Blog will come Monday morning.

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