Mainland South Florida Tropical Briefing Mon Sept 27 10 AM

1
Mainland South Florida Tropical BriefingMon Sept
27 10 AM

• Rob Molleda
• National Weather Service
• Miami/South Florida
• Forecast Office

2
Area of Disturbed Weather in Caribbean Sea
Remnant of Matthew
3
Deep Moisture
EXTREMELY HIGH atmospheric moisture content
4
Model Forecast 8 AM Wednesday

• 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

5
Model Forecast 8 PM Wednesday

• Low moves north of area.
• Moisture lingers over area, although heaviest
  rainfall begins to shift north of region.

6
Rainfall Forecasts

• Average of 3-4 inches over much of South
  Florida.
• Isolated areas typically could see as much as
  twice that amount.

8 AM Tuesday 8 AM Wednesday
7
Rainfall Forecasts

• Average of 2-3 inches over eastern half of South
  Florida.

8 AM Wednesday 8 AM Thursday
8
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.

9
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.

10
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.

11
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.

12
Questions?

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