The ingredients for the formation of a powerful low pressure system began to come together on Thursday and Friday - March 11-12, 1993. On Thursday, a cold front had made it to the Gulf coast region and the northern Gulf of Mexico and began to stall in advance of a strong, digging upper level trough. By early Friday (March 12), a reinforcing shot of cold air was arriving with the digging trough into the southern states, and a low was born along a strengthening temperature gradient in the northwest Gulf of Mexico. The combination of the approaching trough, increasing temperature gradients, and strongly divergent winds aloft (favoring strong rising motion) set the stage for explosive development of the non-tropical low on Friday and Friday Night.
By Friday evening the low was deepening rapidly, and in the early morning hours of Saturday March 13th, the powerful low was approaching the Florida Panhandle coastline. According to the NWS Service Assessment on the event, the low on Friday deepened at a rate of about 1-2 millibars per hour. According to the assessment: "[Friday] afternoon there had been ship and oil platform reports from off the Louisiana coast that showed sustained north winds up to 70 knots. There was also an extensive rain shield to the north of the low, with embedded heavy thunderstorms that may have produced wind gusts in excess of hurricane force over the northern Gulf of Mexico." The low eventually crossed the Florida Panhandle and south Georgia Saturday morning (March 13), and continued to intensify as it ejected up the Atlantic coast into the Carolinas later in the day.
When the low passed near Tallahassee, an all-time lowest atmospheric pressure reading was recorded for the station: 28.84 inches of mercury, or 976.5 millibars. Low pressure records fell at a number of other stations up the east coast of the United States as detailed in this NCDC archived report. Note that some of those records may or may not still be valid.
Here is a summary description of the event from the NWS Service Assessment:
"The Superstorm of March 12-14, 1993 was among the greatest nontropical weather events to affect the nation in modern times. Blizzard conditions were prevalent to the north and west of the storm center, while high winds, coastal flooding, and severe convective weather occurred to the south and east. Record cold temperatures followed the storm in all regions."
"The Superstorm adversely impacted over 100 million citizens during its lifetime and severely crippled economic activities in the eastern one-third of the U.S. Repercussions were felt nationwide in personal loss, travel, trade, and other commercial activity during the storm and for several days thereafter. For example, about 25 percent of scheduled airline flights were canceled nationwide on Saturday and Sunday with associated monetary losses to the airline industry estimated in the tens of millions. The Superstorm produced over $2 billion in property damage across portions of 22 states in the eastern part of the nation."
Impacts In Our Area
Storm surge flooding and inundation was one of the most significant impacts to the Florida Big Bend area from the 1993 Superstorm. As described in the NWS Service Assessment: "As the cold front from the low center passed across Apalachee Bay and slammed the Florida Gulf Coast about 3:30 am [Saturday morning], the winds shifted to the southwest, increasing to 50 mph or more with much higher gusts. These winds served to shove the mass of water that had been "piled up" in Apalachee Bay east onto the shores of Taylor County and the other counties bordering the Gulf of Mexico north of St. Petersburg".
The Apalachee Bay coastline over to the Suwannee River (including Taylor and Dixie counties) is particularly vulnerable to storm surge impacts due to the shape of the coastline and the shallow depth of water extending many miles offshore. The strong wind field associated with the Superstorm was also very large, which led to storm surge values far more severe than are normally recorded with non-tropical lows. The tide trace above from Cedar Key, Florida illustrates the storm surge with this event, which unfortunately coincided with a high tide cycle. The 8.9 foot stage reading was a record for the station in 1993, and the station had been in place since 1938.
You can click on the images above for larger versions. Both are from the previously mentioned NWS Service Assessment. The photo on the left shows a resident of Dekle Beach in Taylor County pointing to the height of the storm surge on his home. The graphic on the right was created for the assessment and shows reported storm surge heights along the Florida Gulf Coast. Some of the highest values were reported in Taylor and Dixie Counties, around 11-12 feet immediately along the coast.
The NWS Service Assessment states: "The single most deadly phenomenon associated with the Superstorm was the coastal flooding that occurred near sunrise Saturday in the Dekle Beach and Keaton Beach areas of Taylor County, Florida. To our knowledge, no winter storm has ever produced a deadly storm surge of such magnitude in the Gulf of Mexico."
Some other notable impacts include:
Other Offices' Writeups
NWS Wilmington, North Carolina
This writeup offers a comprehensive summary of the entire storm, not just the effects in their local area.
NWS Greenville-Spartanburg, South Carolina
A PDF file summarizing the storm, particularly the heavy snow and blizzard impacts to some of their local area.
NWS Tampa Bay, Florida
A 3-page PDF file detailing some local impacts of the storm including coastal flooding, damaging winds, and tornadoes.
NWS Huntsville, Alabama
The writeup discusses heavy snow and blizzard impacts to northern Alabama and south-central Tennessee.
NWS Technical Overview of the Event (Kocin et al)
A publication in the Bulletin of the American Meteorological Society, hosted on the NWS Wilmington web page. (PDF)
NWS Melbourne, Florida
Includes a radar loop of the squall line as it crossed the Florida Peninsula.
NWS Birmingham, Alabama - Technical Analysis
A technical writeup of the snowfall that occurred with the storm in central Alabama.
NWS Birmingham, Alabama
A less technical web page about the snowfall and blizzard in central Alabama.
NWS Charleston, West Virginia
A summary of snowfall and blizzard impacts in West Virginia.
NWS Louisville, Kentucky
A summary of snowfall and blizzard impacts in eastern Kentucky.
Interesting Images and Maps