Flash Flood Guidance
Issued by NWS
Issued by NWS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
959 AWUS01 KWNH 122127 FFGMPD FLZ000-130325- Mesoscale Precipitation Discussion 0429 NWS Weather Prediction Center College Park MD 525 PM EDT Wed Jun 12 2024 Areas affected...South Florida Concerning...Heavy rainfall...Flash flooding likely Valid 122125Z - 130325Z SUMMARY...Catastrophic and life-threatening flash flooding is expected to continue into the evening hours across south Florida with an emphasis on the highly urbanized and densely populated I-95 corridor from Fort Lauderdale south through Miami and Homestead. DISCUSSION...An extremely high-impact flash flood event is ongoing across south Florida with a particular focus on the highly urbanized I-95 corridor of southeast Florida involving Broward and Miami-Dade County, with also significant flooding concerns noted farther west back into parts of Collier and Monroe County where there continues to an elongated west-southwest to east-northeast band of very strong convection with extremely high and life-threatening rainfall rates. Dual-pol radar in conjunction with local gauges continue to show rainfall rates reaching well into 3 to 5 inch/hour range, and while the higher end of these rates has tended to be over the Everglades over the last few hours, these extreme rates have been continuing to train over the same area and have also been advancing through the densely populated and highly sensitive urban corridor from Fort Lauderdale south down through Miami. GOES-E IR satellite imagery shows very cold convective tops persisting with this training band of convection with multiple overshooting tops reaching on the order of -75 to -80C. An elongated axis of very strong moisture convergence working in tandem with deep tropical moisture and instability is expected to maintain extreme rainfall rates potential over the next few hours. PWs are locally over 2.5 inches with MLCAPE values of 2000 to 3000 J/kg are seen pooled up over far south Florida. However, there is also 30 to 40+ kts of effective bulk shear in place, and the combination of all of these ingredients suggests a persistence to the well-organized nature of the convective band. Gradually a southeastward advance of the convection, albeit slow, is expected over the next few hours. Unfortunately, this means a persistence of extreme rainfall rates over the highly urbanized areas of southeast Florida. Widespread flash flooding, with catastrophic impacts are ongoing from near Fort Lauderdale down through Hollywood, but the situation is expected to worsen for areas farther south involving Miami and eventually even Homestead farther down the I-95 corridor. An additional 4 to 8 inches of rain with isolated 10+ inch amounts will be possible going through the early to mid-evening hours. For some locations, this will bring multi-day storm totals upwards of 15 to 20+ inches. Significant and life-threatening flash flooding is ongoing and is expected to continue as a result over the next several hours. Orrison ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...KEY...MFL... ATTN...RFC...SERFC...NWC... LAT...LON 26438020 26167981 25358018 25108088 25548140 25828183 25898181 26058123 26238069