Mainland South Florida Tropical Briefing Mon Sept AM Rob Molleda National Weather Service Miami/South Florida Forecast Office

Area of Disturbed Weather in Caribbean Sea Remnant of Matthew

Deep Moisture EXTREMELY HIGH atmospheric moisture content

Low pressure south of Keys moving northward. Caribbean moisture surges northward Purple and red colors indicate high 6-hour rainfall amounts of over 3 inches Model Forecast: 8 AM Wednesday

Model Forecast: 8 PM Wednesday Low moves north of area. Moisture lingers over area, although heaviest rainfall begins to shift north of region.

Rainfall Forecasts 8 AM Tuesday – 8 AM Wednesday Average of 3-4 inches over much of South Florida. Isolated areas typically could see as much as twice that amount.

Rainfall Forecasts 8 AM Wednesday – 8 AM Thursday Average of 2-3 inches over eastern half of South Florida.

Summary Tropical (or subtropical) system may or may not develop south of Florida. Regardless of what type of system impacts our area, the main threat is for torrential rainfall and potential for significant flooding.

Rainfall Forecasts Model forecasts and human-adjusted forecasts suggest 2-day average rainfall amounts of 5-8 inches over parts of South Florida from 8 AM Tue to 8 AM Thu. This type of weather pattern favors development of heavy rain bands which could produce even higher rainfall values.

Impacts Flooding: Significant flooding entering structures is possible, especially in historically flood-prone areas. Timing: Late Tuesday through Wednesday night. Too early to pin down with high confidence areas most likely to receive worst flooding. Present indications are that the SE Florida metro areas may be more likely to see greatest flood potential.

Impacts Flood Watch may be issued early tomorrow. This means that the potential exists for significant flooding affecting property. Tornado threat may be higher than normal, but right now not our primary concern.

Questions? Thank you for your time! National Weather Service Miami/South Florida Forecast Office