CoCoRaHS

FLORIDA

A Community Collaborative

Rain, Hail & Snow Network

Fall 2024 Newsletter

Greetings from the Coordinators,

We are pleased to present the fall 2024 quarterly newsletter. In this latest issue, we share highlights from the network during the past few months, discuss the latest hurricane season outlook and peak into the fall season outlook. Summer brought plenty of rainfall, but the rain did not seem to mitigate summer heat. Summer 2024 (June - August) ranked as the warmest summer on record in Florida, and the 4th-warmest summer on record for the U.S. as a whole, dating back to 1895. This is impressive given the record breaking heat we experienced last July and August in 2023!

The average statewide summer precipitation ranked 53rd-wettest on record. An early tropical system in mid-June, called Invest 90L, never developed into a named storm but brought abundant rainfall to South Florida nonetheless. Hurricane Debby made landfall on August 5 near Steinhatchee and became the first named storm to impact Florida this season.

ENSO-neutral conditions currently exist in the tropical equatorial Pacific Ocean, but La Niña conditions are forecast to emerge later this fall. Whether it will emerge in time to strongly influence the rest of the Atlantic Hurricane season is still uncertain.

As always, your contributions to this network are greatly appreciated. Thank you for your continued support and dedication to the CoCoRaHS program. We hope you enjoy this newsletter, and feel free to reach out to us at any time.

Sincerely,

Emily Powell

epowell@coaps.fsu.edu

Ivetta Abramyan

ivetta.abramyan@fscj.edu

Florida CoCoRaHS Program Highlights

Over the summer, 57,471 reports were submitted through daily and multi-day reports. There were an additional 93 significant weather reports and 144 condition monitoring reports submitted during the summer months of June - August. Reports of local impacts are extremely useful during tropical cyclones like Hurricane Debby as well as during drought.

Summer Rainfall Departures and Rankings

Total summer rainfall varied across the state, with well above normal rainfall in Southwest Florida and below normal rainfall in the Panhandle and East-Central Florida. The map below shows the seasonal rainfall departures from normal for June 1 - August 31, courtesy of the High Plains Regional Climate Center. Areas right along the coast in southwestern Florida were as much as 15-20 inches above normal for the season.

West-Central and Southwest Florida saw repeat heavy rainfall, which contributed to well above average seasonal rainfall totals. The Sarasota/Bradenton area had its wettest summer on record with 47.98", which was 19.97" above normal, and Fort Myers had its wettest summer with 43.87" of rainfall for the season, which was 14.4" above normal. Tampa recorded its 2nd-wettest summer on record with a total of 38.52" of rainfall, which was 14.37" above normal. Venice and Naples also had their 2nd-wettest summer on record, with 37.69" and 39.94" of rain, respectively.

The map below shows the precipitation station rankings for summer (June 1 - August 31), courtesy of the Southeast Regional Climate Center. (Click on the map to view a larger image.)

Recent Rounds of Heavy Rainfall

Invest 90L

In mid-June, a system named Invest 90L brought warm, tropical moisture into the state, generating heavy rainfall across South Florida from June 11-14. Rainfall totals from this system were between 4 and 18+ inches, which led to flash flooding and inundated roadways. As a result of the system, drought in Central and South Florida ended and June 2024 became the wettest June on record in Fort Myers (120 years), 2nd-wettest in Fort Lauderdale (27 years) and Naples (23 years), 3rd-wettest in Sarasota (111 years), and 8th-wettest in Miami (88 years). Read more about this system and its impacts here.

Hurricane Debby

August was much wetter than normal for areas impacted by Hurricane Debby, which made landfall in Florida's Big Bend region near Steinhatchee on August 5 as a category 1 hurricane. The radar image below shows Debby at landfall at 7 a.m. EDT August 5.

The storm affected Florida's Gulf Coast as it moved north through the Gulf of Mexico, bringing torrential rainfall, flooding and storm surge to coastal areas and across North-Central Florida. Storm totals peaked at just under 20 inches of rain, with the largest amounts observed in the Sarasota area in Manatee County. Parrish 5.6 SE (MA-40) recorded 16.89 inches of rain from the storm, and Lakewood Ranch (MA-29) collected a total of 18.34 inches, of which 16.04 inches was observed in one day. Read more about Debby's impacts in Florida here.

As a result of Debby, along with typical summer weather, many stations accumulated impressive rainfall totals for the month of August. Select August monthly rainfall totals from the CoCoRaHS network are shown in the table below. View a map of monthly rainfall totals here.

Station Name	August Monthly Total Rainfall (in inches)	Station ID
Lakewood Ranch 3.5 E	30.60	FL-MA-29
Parrish 5.6 SE	28.93	FL-MA-40
The Meadows 6.2 NE	28.44	FL-MA-32
Desoto Lakes 4.2 NNE	28.35	FL-MA-43
Bradenton 10.8 SE	28.06	FL-MA-10
Englewood 0.2 ENE	25.04	FL-SS-82
San Mateo 2.5 SE	24.65	FL-PT-24
Pinellas Park 1.7 ENE	24.08	FL-PN-90
Osprey 1.1 ESE	23.16	FL-SS-88
Largo 3.1 SE	22.78	FL-PN-94
Sarasota 5.9 NE	22.58	FL-MA-41

So far, September has brought more extreme rainfall. From September 1-19, parts of North Florida have already logged 14" or more of rain in just a couple of weeks, some have seen over 20" of rain. During this period, the Jacksonville International Airport ranked 5th-wettest on record and Daytona Beach ranked 3rd-wettest on record. Some locations have already collected more rainfall than they typically do in an entire year, with year-to-date rainfall totals over 10" above normal in Tampa, Sarasota, Ft. Myers, Naples, and Jacksonville.

The highest CoCoRaHS rainfall totals so far in September are shown below. View the map here.

Station Name	Total Rainfall September 1 - 19 (in inches)	Station ID
Navarre 4.1 ENE	16.71	FL-SR-30
Orange Park 5.9 ENE	17.04	FL-DV-133
Jacksonville 9.6 SE	17.82	FL-DV-79
Fernandina Beach 2.4 S	19.66	FL-NS-21
Fernandina Beach 6.3 SW	19.72	FL-NS-14
Sawgrass 0.0 E	25.33	FL-SJ-29

Summer Drought Patterns

The CoCoRaHS Condition Monitoring (CM) chart below really helps tell the story of how drought and extreme rainfall changed throughout the summer. The chart displays observers' reports of on-the-ground conditions as a percentage of the total number of reports submitted each week. In early June, most local CM reports indicated moderately to severely dry conditions, with drought affecting much of the Peninsula. As summer progressed, more CM reports indicated near normal or wet conditions. And by early September, nearly all CM reports indicated wet conditions.

Condition Monitoring Reports Submitted by CoCoRaHS Observers

(May 28, 2024 - September 17, 2024)

CoCoRaHS-condition-monitoring-chart-06012024-09172024 image

Unlike the rest of Florida, the western Panhandle saw a dearth of rainfall over the summer, especially in August. Pensacola recorded less than an inch of rain for the entire month of August, which was 6.5 inches below normal and the 2nd-driest August on record. By early September, severe drought (D2) had developed affecting 6.2% of the state, and moderate drought (D1) affected 9% of the state.

Summer Extremes Across Florida CoCoRaHS

Between 1 June 2024 and 31 August 2024:

Highest seasonal rainfall total: 56.02" in Lakewood Ranch, Manatee Co. (MA-29)
Lowest seasonal rainfall total: 7.12" in Midway, Leon Co. (LN-18)
Highest daily rainfall total: 16.04" on August 5 in Lakewood Ranch, Manatee Co. (MA-29)

*based on stations with at least 90% completeness

Significant Weather Reports

Between 1 June 2024 and 31 August 2024, there were:

93 total Significant Weather reports submitted.
34 reports of Minor flooding.
16 reports of Unusual flooding.
1 report of Severe flooding.

Observer Comment Corner

Observer comments are encouraged! Thanks to the many who regularly post comments with their reports. Comments provide valuable context to observations, which can be very helpful to those who later use the observations. Below are a select few of the comments shared during the past few months. We’ll continue to share your comments in these newsletters.

1. 13 June, Palm City 1.4 NW, Martin County (MT-31) - 5.85 inches:

"This was much needed rain. It replenished our local catchment lakes and ponds. No violent or extreme weather. Neighborhood streets had minor short term flooding, not out of the ordinary."

2. 13 June, Miami Lakes 0.3 NNW, Miami-Dade County (MD-26) - 6.24 inches:

"New record for me. Catastrophic numbers. Flooding on the main street, Fairway. Miami Dade County doing a poor job of draining the canals in anticipation of this event. The golf course is flooded... Many cars flooded and abandoned at the Adventura mall. Significant flooding in the northeast part of the county. You cant get to the Mall because of flooding and flooded cars. Tow trucks are working to clear things up. More storms expected at 1pm."

3. 14 June, Cypress Lake 1.2 SE, Lee County (LE-79) - 6.74 inches:

"All creeks and ponds in and around complex at max. Nothing into buildings. 4-day storm total is 16.45 inches."

4. 1 July, Inverness 1.6 SE, Citrus County (CT-45) - 3.82 inches:

"Heavy thunderstorm began around 5:35 pm and lasted for around 2 hours, ending at around 8:00 pm."

5. 1 July, Inverness 1.6 SE, Citrus County (CT-45) - 3.82 inches:

"Heavy thunderstorm began around 5:35 pm and lasted for around 2 hours, ending at around 8:00 pm."

6. 5 August, Ellenton 6.6 E, Manatee County (MA-6) - 12.50 inches:

"Periods of T-storms, moving south to north, with heavy rain and wind gusts to at least 40 mph as feeder band from Hurricane Debby remained in our area past 24 hours. Heaviest rain since we moved here in 2005."

7. 5 August, St. Petersburg 2.5 S, Pinellas County (PN-81) - 5.00 inches:

"TS Debby passed about 75 miles west of us today. Rained hard all day and night. Winds 25 to 50 MPH. A lot of limbs down in my area. Since I live in a high area no street or yard flooding."

8. 6 August, Fernandina Beach 2.4 S, Nassau County (NS-21) - 3.32 inches:

"Rain from Hurricane Debby, now Tropical Storm Debby. It’s been constantly raining since yesterday and our yard is a soggy flooded mess with standing water. We also have a lot of palm fronds and other debris in the yard from the wind."

9. 5 September, St. Petersburg 6.5 WNW, Pinellas County (PN-4) - 4.24 inches:

"Unusual Flooding around area that I have not seen before. Standing water in yard still this morning; ground completely saturated."

10. 10 September, Palm Coast 4.6 NW, Flagler County (FL-53) - 3.61 inches:

"Gauge Flooded. Heavy rain, no wind, no lightning no thunder. At 7:00 still raining. Ground saturated no surprise. Minor flooding we are on mostly sand here."

What's Going on with the Atlantic Hurricane Season?

Several groups, including the National Oceanic and Atmospheric Administration (NOAA) and Colorado State University (CSU), released mid-season updates for the Atlantic Basin Hurricane Season Outlook in early August. NOAA's mid-season update, shown just below, is similar to its initial outlook issued in May. They continued to call for a very active, above-average Atlantic hurricane season.

So far this season, there have been 7 named storms (Alberto, Beryl, Chris, Debby, Ernesto, Francine, and Gordon), including 4 hurricanes. However, from August 13 to September 3, no named storms developed in the Atlantic basin. The last time there were no named storms during this period in the Atlantic basin was 1968. With the recent lull in activity, we are now slightly behind climatology. Typically by mid-September, the season would have produced 9 named storms on average.

Factors influencing this year's forecast include: 1) above-average sea surface temperatures in the tropical Atlantic Ocean and Caribbean Sea, 2) reduced vertical wind shear and the possibility of La Niña developing during the hurricane season, 3) weaker tropical Atlantic trade winds, and 4) an enhanced west African monsoon. Read more about the season so far in a discussion recently released by CSU.

NOAA Issues La Niña Watch

La Niña conditions, the cool phase of the El Niño Southern Oscillation climate pattern in the tropical equatorial Pacific Ocean, are likely to develop in the coming months (71% chance during September-November 2024). However, forecasters are uncertain whether it will arrive in time to exert a strong influence on the Atlantic Hurricane season. Once it emerges, it is favored to persist through the Northern Hemisphere winter, January - March 2025.

Fall Season Outlook

The NOAA Climate Prediction Center's outlook for this fall is leaning toward a warmer than normal fall and early winter on average, October through December, in Florida and nearly the entire U.S. Fall precipitation has equal chances of being above, below, or near normal across Florida.

Important Reminders

Peak Hurricane Season is Here.

The graph shows tropical cyclone activity, in terms of named storms and hurricanes, that occurs in the Atlantic basin on each calendar day between May 1 and December 31, showing the number of hurricanes (yellow area), and combined named storms and hurricanes (red area) that occur on each calendar day on average. (Source: NOAA/National Hurricane Center)

We have reached the peak of hurricane season and typically the bulk of activity occurs during the second half of the season. So we are not in the clear yet. Currently, there is a system in the Caribbean that has a moderate chance of development next week. Keep an eye out for potential development through the National Hurricane Center - https://www.nhc.noaa.gov/, which is the leading authority and best source of information on active and potential storms.

A New Rain Gauge Option for CoCoRaHS

In case you missed it, a new approved rain gauge, the Tropo rain gauge from Climalytic Instruments, is now available to CoCoRaHS observers. This is a "premium" alternative to the Stratus gauge manufactured by Productive Alternatives. These are the only two gauges approved for CoCoRaHS (along with the NWS 8" standard rain gauge).

While not required, the Tropo gauge incorporates many suggestions made by CoCoRaHS observers over the years for improving the overall gauge. Some of the improvements include a handle that slides into the mounting bracket to aid in pouring into the inner measuring tube, and it holds about 13" of water vs. 11" for the Stratus. Read more about the new gauge and the differences here.

CoCoRaHS WeatherTalk Fall Webinar Series Kicks Off this Month

Mark your calendars for the first talk in our fall webinar series on September 26th at 1:00 PM Eastern. The topic will be "Measuring beyond precipitation. How is your forest responding to drought?" Register and view recordings of past webinars at: https://www.cocorahs.org/Content.aspx?page=wxtalk.