National Weather Service Miami FL
402pm EDT Thu Jun 13 2024
...New Long Term
.SHORT TERM... (Rest of today through Friday) Issued at 135pm EDT Thu Jun 13 2024
Conditions will continue to deteriorate this afternoon as a frontal boundary continues to sag southward towards our area.This boundary is moving into an area of significantly enhanced moisture (PWATs (Precipitable Waters) of 2.19 as of the 12Z MFL sounding), which has resulted in the development of a robust line of showers and storms on a NE-SW axis currently draped along the Lake region. This line has already produced 1-2 inches of rain over the past couple of hours; additional accumulations in the 4-8 inch range, with locally higher amounts of 10+ inches could be possible across much of South Florida as the line drifts southward.
A few things to note with this: 1) Even rainfall accumulations on the lower end of this range could be dangerous for areas that have already received 10+ inches of rain over the past couple of days. Flash flooding will be extremely likely, and ongoing flooding in areas were standing water was unable to drain overnight could be further exacerbated during this event.
2) Models were originally hinting at a faster progression for this line, but the line has been much slower in its approach over the region. This slower pace could mean that heavy rainfall sits over vulnerable areas for longer periods of time, leading to rainfall acumulations that are higher than our worst reasonable scenario.
3) Warm temperatures along the column will mean extremely efficient warm rain processes, which could further enhance accumulations through the afternoon hours.
To that effect, WPC has placed the whole I-75 corridor, including Fort Lauderdale and as far south as Tamiami Trail, under a HIGH RISK for excessive rainfall this afternoon. This means that there is at least a 70% chance that areas 25 miles away from any given spot could see flash flooding concerns. Additionally, there is a very marginal concern for funnel clouds or even weak tornadoes as this line progresses across the CWA. This risk will decrease as the line moves southward.
Heading into Friday, a mid level shortwave trough currently over the Gulf States will push further south into the Gulf of Mexico as well as South Florida. At the surface, the developing area of low pressure will push further to the northeast off of the Carolina coastline. At the same time, deep tropical moisture will continue to be funneled into South Florida along the south to southwesterly wind flow. Enough instability given the synoptic scale environment alongside the enhanced moisture plume will produce additional rounds of precipitation during the day on Friday. However, with the low departing from the area and the boundary pushing southward, convective coverage will be lower than what we've seen over the past couple of days, with scattered showers and thunderstorms being the more likely outcome for precip across the region. In general, additional rainfall amount of 2 to 4 inches will possible across most areas through Friday evening. Because of this, the Flood watch will remain in place across all of South Florida through Friday Evening. High temperatures will continue to be held down in the mid 80s across most areas on Thursday and Friday due to the increased cloud cover and rainfall across the region.
Long Term
(Friday night through next Wednesday) Issued at 313pm EDT Thu Jun 13 2024
This weekend: An upper level trough will still be the dominant synoptic feature over the area and it will come into phase with an amplifying trough over the eastern United States and Canada. As the surface low off the Southeast United States moves to the northeast, surface flow across South Florida will become easterly by Sunday afternoon which will be the start of a return to normalcy. Modeled PWATs (Precipitable Waters) will still remain at or above 2 inches Saturday and Sunday, which is at or above the 90th percentile for this time of year. It is possible we remain in the 'moisture tail' of the surface low through the weekend, with the most enhanced moisture draped across far southern portions of the area. Showers and storms are likely each day through the weekend before drier air finally begins to filter across the area on Monday. As the low continues to push further and further away from South Florida, the coverage of showers and storms is not expected to be as widespread or numerous as what we experienced earlier this week. Still, given the extremely wet conditions this week, the Flood Watch may need to be extended into the weekend.
Early Next Week
Surface high pressure will build across the region again late Sunday into Monday which should return us to a more typical summertime easterly regime. This will allow the eastern sea breeze to progress relatively far inland and keep the best chances for showers and storms across interior South Florida and Southwest Florida each afternoon.
Highs through the period will be in the upper 80s with heat indices in the upper 90s to lower 100s. With the return of the easterly regime, Southwest Florida will experience slightly warmer temperatures and heat indices each day.
Marine
Issued at 135pm EDT Thu Jun 13 2024
A moderate to fresh south to southwesterly wind flow will remain in place across the local waters through the end of the week. Seas across the Atlantic and Gulf waters will remain at 2 feet or less through Friday. Winds and seas could be locally higher in and around any shower or thunderstorm activity.
NOAA Miami FL Office: Watches - Warnings - Advisories
FL...Flood Watch through Friday evening for FLZ063-066>075-168- 172>174.
AM...None. GM...None.
