A Gulf storm producing a heavy rain event is becoming more likely this weekend, but model differences still exist thus there is decreased confidence in the exact locations that could see the heaviest rain. A closed 500mb low (roughly 18,000 feet above sea level) over east Texas will dip sharply southeast across Louisiana into the northeast Gulf of Mexico on Saturday, Dec 21, 2019.
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| Radar Simulation for 6 am Sunday, December 22, 2019 showing strong storm centered over Florida panhandle whipping energy (storms) into the Central Florida peninsula. |
The models diverge on the timing of this storm event with the ECMWF currently 6-12 hours slower than the GFS. Rapid mid level height falls (rapid low pressure event) will induce strong vertical motion with a surface low developing in the eastern Gulf of Mexico. The low will become vertically stacked (quite strong) as it gets captured and pulled north by the parent 500mb feature.
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| The potential rainfall from the forecast storm is significant: 3-5 inches over a large part of Florida. |
At this time, the potential for heavy rainfall in Central Florida appears to be greatest from Tampa to Kissimmee to Titusville northward, and for areas along the immediate Space and Treasure Coasts. The track of the surface low will determine where the heaviest rain falls.
The ECMWF indicates a track north into the FL panhandle and across southern Georgia, above, centering the storm just off shore of Georgia-South Carolina at noon on Monday, December 23, 2019. In this scenario there is significant rain and wind event ongoing in Central Florida.
The GFS currently tracks the low more or less across the same path but now slower than the ECMWF.
Warm Front Triple Point Danger Exists
Additionally, forecasters will be monitoring the position of the warm front associated with the low and any other "spin up" lows that may develop. Robust upglide will likely overspread the central peninsula of Florida with the approach of the warm front through early Sunday, with all the global models indicating a secondary triple point low (resembling a northern stream event) developing over the central peninsula. The messy dual-lobed deep layer low then proceeds to slide slowly east across the peninsula and into the Atlantic by Monday night.
A triple point in meteorology refers to the intersection point between two boundaries (dry line, outflow boundary, cold front, etc.), often a focus for thunderstorm development. Triple point also may refer to a point on the gust front of a supercell, where the warm moist inflow, the rain-cooled outflow from the forward flank downdraft, and the rear flank downdraft all intersect; this point is a favored location for tornado development (or redevelopment). There is currently no forecast for tornadoes with this system but in Florida winter storms are always capable of significant spin.
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| 3-7 inches of rain are currently forecast across the Central Florida peninsula and the Florida panhandle over the week preceding Christmas 2019 |
The currently forecast period of heaviest rainfall is from Saturday night into Sunday with total amounts ranging up to 8-inches. This is very welcome news for lake and spring lovers in Central Florida but will be problematic for developers and new residents who have moved into flood prone areas in recent dry years.
El Niño is not to blame
El Niño conditions are currently neutral.
After 10 years of relatively dry weather in Florida and massive, uncontrolled development there are many areas of Central Florida that will be in for an unwelcome surprise when "normal" weather patterns return, including the occasional rainy and stormy winter. It should be noted, however, that rainy, stormy winters are more common in Florida during El Niño years.
After 10 years of relatively dry weather in Florida and massive, uncontrolled development there are many areas of Central Florida that will be in for an unwelcome surprise when "normal" weather patterns return, including the occasional rainy and stormy winter. It should be noted, however, that rainy, stormy winters are more common in Florida during El Niño years.
Parts of Central Florida received over 3-inches of rain a couple of days ago in another such stormy, rainy, windy event.
After the storm passes warm, balmy weather will dominate making for a warm and sunny Christmas Day (temperatures should be near 80°(27°C) across Central Florida on Christmas).