Sarasota rainfall is nearly a 1-in-1,000 year event
It’s not very often that 8″+ of rain falls in 3 hours in the Tampa Bay area, but that happened early Tuesday evening in Sarasota. At the very least, that is considered the type of event… The rainfall in Sarasota, Florida, early Tuesday evening was nearly a 1-in-1,000 year event, according to the National Hurricane Center (NHS), which should only occur once every 500 to 1,000 years. The area experienced a significant rainfall of 8.29″ in 3 hours, marking the highest recurrence interval (rearal interval) in 1-200 years. This event also set a record for the most rain in one hour in Sarasot, with 3.93″ falling. The rainfall was caused by factors such as deep tropical moisture, a tropical disturbance named 90-L, a small low pressure, and a slow-moving persistent convergent band. Over the past 24 hours, 10 inches of rain has fallen in the Sarasota vicinity, helping to make up for a 25-inch deficit of rainfall since the beginning of 2023, the driest year on record for Sarasota.
gepubliceerd : 10 maanden geleden door Jeff Berardelli in Weather
It’s not very often that 8″+ of rain falls in 3 hours in the Tampa Bay area, but that happened early Tuesday evening in Sarasota. At the very least, that is considered the type of event which should only occur once every 500 to 1,000 years.
As seen from the NOAA graphic below, the purple bullseye shows the area where the 3-hour rain totals that fell from roughly 5 p.m. – 8 p.m. reached a recurrence interval, or return period, that peaks at the top of the scale: 1-in-200 years.
It was also the all-time record for the most rain in one hour in Sarasota with 3.93″ falling, as seen below.
The torrential downpours happened as a result of a few factors: deep tropical moisture, a tropical disturbance named 90-L by the National Hurricane Center, a small (meso) low pressure just off the Sarasota Coast and a very slow-moving stubborn convergent band.
If you look closely you can see how the stalled band was being fed from the south by very fast moving showers, crashing into the band, converging and causing fast rising motion. These are exactly the type of setups that cause Florida’s infamous localized floods.
Last year in April, Ft Lauderdale saw an astonishing 25″ inches of rain in about 12 hours, flooding the downtown with feet of water. This Sarasota event was nowhere near as large, mainly because it didn’t last as long.
The criteria for a 1-in-1,000 year event in SW Sarasota — where some of the heaviest rain fell — is 8.29″ in 3 hours. This event either matches that, or falls short by a very tiny amount. The red X below indicates the rainfall amount and the curves tell us the rarity of that amount over 3 hours. You can see it falls along the 1-500 or 1-1,000 year curve.
A 1-in-1,000 year event does not mean it happens once every 1,000 years. It means the chance of it occurring any given year in Sarasota is .1% — a very rare event.
Over the past 24 hours, 10″+ of rain has fallen in the Sarasota vicinity. Another few to several inches is possible the rest of the week.
That goes a long way in making up for the 25″ inch deficit of rainfall (below image) Sarasota has seen since the beginning of 2023 — the driest year on record for the city.
The area has been in an extreme soil drought for weeks. Ironically ,the extremely dry soil in Sarasota likely helped limit flooding, as the soil was able to absorb much more rain than normal.