It finally rained in Florida Monday, but the areas that needed it the most missed out.
Many Florida cities have had little or no rain in over a month, resulting in an expansion of drought conditions across most of the Florida Panhandle and sections of North Florida.
A nearby weak weather system triggered numerous rounds of showers and thunderstorms Monday, but they primarily affected areas farther south.
Radar estimates and numerous ground-truth reports indicate that 3 to 5 inches of rain fell over portions of the Jacksonville metro area Monday, with 5.36“ observed at the Mayport Naval Station gauge. Pockets of heavy rain were also observed across the rest of the peninsula from Gainesville to Orlando Monday afternoon. The National Weather Service in Jacksonville tweeted a lengthy list of preliminary reports at 9:15 pm ET.
Penascola and Tallahassee received no measurable rain at their official climate reporting sites during the month of September. Gainesville had a top 10 driest month. Even places over the Florida Peninsula, which had a wet summer, saw a noticeable drop off in rain during the second half of the month. For example, Orlando, Tampa, Miami, and Fort Myers all officially received between 0.90“ and 1” of rain during that same period. Meanwhile, on Florida’s southwest coast, a measly 0.04“ fell in Naples. All of these numbers are a fraction of what these cities typically receive during late September.
Those who are looking for additional rain in South Florida will likely receive their wish this week, but the wetter pattern will not extend to the areas that need it the most. A weak area of low pressure will move across the southern half of the state Tuesday, while at the same time, a cold front will slowly approach from the north. These two weather systems are forecast to produce anywhere from 1/2“ to as much as 2” of rain over central and southern sections of the Peninsula, according to the latest forecast from NOAA’s Weather Prediction Center.
The center says a few pockets of flash flooding are not out of the question over the metro areas of South Florida through Tuesday, particularly if heavy showers pass over the same areas frequently.
The Florida Panhandle and Big Bend — which need the rain most of all — are expected to have the least in the coming days. The last few drought monitors have seen a notable worsening of the drought conditions. Much of the I-10 corridor is in a “moderate drought”, and pockets of “severe drought” conditions have cropped up near Lake City and Tallahassee based on NOAA’s most recent update.
Rainfall amounts over the next week are projected to be less than 1/2“ in these areas. There is a distinct possibility that a few places will go another week with no rain at all, which would lead to a worsening and expansion of the ongoing drought.
Even though the dominant heat ridge that has been producing record highs over North Florida is flattening and weakening, the upper air winds are forecast to blow from the west over a long distance. These winds effectively cut off the Florida Panhandle from a consistent moisture feed from the Gulf of Mexico. The main storm track from the mid-latitude westerlies is likely to stay well north of the state, which means there are no signs the drought will break any time soon.
A moderate drought is now affecting much of the Florida Panhandle, and some cities haven’t received a drop of rain in more than four weeks. This comes as Florida’s rainy season ends early and the driest months of the year are still to come.
Rainfall has been below average for the entire state this month, and in some spots, non-existent. As of Thursday, Pensacola and Tallahassee had not received any measurable rain in September. Average rainfall for the month in Pensacola is 5.98 inches, with Tallahassee receiving 4.69 inches on average. A similar situation has developed on the other side of the state in Miami, where there is a September rainfall deficit of 6.62 inches.
Monthly rainfall accumulations as of Sep. 26, compared to normal September values, are provided below.
|CITY||RAIN SO FAR||SEPT. NORMAL|
The departures from normal may look extreme, but it must be noted that average rainfall numbers in September are often skewed by tropical storms or hurricanes.
The National Drought Mitigation Center (NDMC) at the University of Nebraska publishes a weekly Drought Monitor Index to assess how severe the conditions are. In their update Thursday, all of north Florida was considered to be at least “abnormally dry”, and 21% of the state - nearly all areas along and north of I-10 - was classification as being in a “moderate drought”. The NDMC identifies the situation as a “flash drought”, which is used to describe a period of abnormally high temperatures and increased evaporation rates that exacerbated the drought.
Climatology alone would suggest drier days are in Florida’s future, as the rainy season typically ends over the next couple of weeks. However, it seems to have concluded early this year thanks to a quasi-persistent wind pattern that promotes warm temperatures and little rain.
State Climatologist David Zierden says this pattern can be traced back to the beginning of September, when Hurricane Dorian decided to turn north and miss Florida.
“When you get a big, strong, big storm that is that strong, it can kind of pull in dry or air from the north and enhance the ridging,” he says. Zierden is referring to an area of high pressure that causes sinking air and suppresses precipitation. “And then we had Humberto, that didn't come as close, but it still had much the same effect on pulling in a dry and warmer air mass,” he adds.
Recent forecast data also suggests the dry pattern will continue through at least the beginning of October, as yet another ridge of high pressure is set to build across the Southeast. Above average temperatures and dry air accompanied by the high will likely persist, allowing the drought to continue or even become more severe.
It would appear the only change for significant rain in Florida’s near future might be from a tropical weather system, which is not expected in the next five days. However, tropical weather activity is still very possible over the next few weeks, based on historical data that suggests the height of hurricane season continues through mid-October.