'93 Superstorm
This month is the 25th anniversary of the March 12-14, 1993 Superstorm dubbed The Storm of the Century.
The storm was also known as the '93 Superstorm, The No Name Storm, or the Great Blizzard of 1993. It was a large cyclonic storm that formed over the Gulf of Mexico on March 12, 1993. The storm was unique and notable for its intensity, massive size, and wide-reaching effects; at its height, the storm stretched from Canada to Honduras. The cyclone moved through the Gulf of Mexico and then through the eastern United States before moving on to Canada. The storm eventually dissipated in the North Atlantic Ocean on March 15, 1993. Along its path it spawned blizzards, storm surge, tornadoes, high winds and hail—all felt in Florida and along the U. S. East Coast.
The amount of snow and rain that fell during the storm was almost biblical—44 million acre-feet— "comparable to 40 days flow on the Mississippi River at New Orleans," according to a National Climatic Data Center report.
One of the strongest mid-latitude cyclones on record, the "Superstorm of '93" would become one of the most costly weather events of the 20th century.
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Sunny skies rule Florida this March
Above, the solitude of the Ocala National Forest extends to the roads that cross the wildlands
This March is a little different in Florida. Cool, very dry, and endlessly sunny conditions prevail as a waning La Niña can no longer be blamed for our current drought conditions.
Dry conditions have left the Alexander Spring Creek only a couple of feet deep and clogged with lyngbya. This birds-eye view was captured yesterday, high above the now-shallow creek.
Superstorm of '93
The Setup
A slow-moving cold front stalled over Central FL in the early hours of March 12, while a developing low off the southern coast of Texas moved east into the Gulf of Mexico. Over the next 6 hours, this low be-gan to rapidly intensify over the central Gulf, with sufficient warmth to spark convection in the area.
By sunset on March 12, the center of a mature low pressure system was positioned just southeast of the Mississippi Delta, where wind speeds over 50 knots and heavy rain were observed. Not only did this system feature a strong center of low pressure, but also a broad squall line, extending deep into the southern Gulf of Mexico. This squall line would later produce significant, dam-aging weather across the Florida peninsula.
Late-Night Landfall
Shortly after midnight, the center of low pressure made land-fall along the FL Gulf Coast near Panama City, with the lowest pressure reading near 977mb.
As this low pressure center tracked northeast across southern Georgia, a very broad squall line extending from north Florida to the Yucatan Peninsula advanced rapidly across the state. Most of the significant weather impacts across Florida occurred in the pre-dawn hours, when most residents were sleeping and may have been unable to receive severe alerts. Also, in 1993 cable news was not as ubiquitous as it is today.
The derecho spawned by the storm moves across Central Florida in this radar image.
Florida Impacts
It was an exceptional storm system. For this latitude, it was probably one of the strongest in terms of extra-tropical cyclones. There have been lower pressure centers move across the northern latitudes, but for Central Florida, it was an extraordinary event.
The Superstorm impacted Florida for nearly an 18 hour period beginning on March 12. The most intense weather occurred from 11pm to 5am, as a squall-line moved across the Florida peninsula, causing unprecedented severe weather. As the line raced through the state, significant wind damage occurred from wind gusts measured from 70 mph in Central Florida, to as high as 96 mph in the Tampa Bay area.
Small scale bowing segments of the squall line also produced tornadoes, with 11 tornadoes occurring within 2 hours. The strongest confirmed tornado occurred in Levy County (F-3), killing 3 people and destroying numerous homes in Chiefland. The longest track tornado was an F-2 and left a path of damage 31 miles long from central Lake County to Deland. This tornado killed 1, an infant inside a mobile home. A total of 7 lives were lost due to 15 confirmed tornadoes in the state.
The most unexpected impact was an unprecedented 9-12 ft storm surge along the Gulf Coast, severely inundating Taylor County and areas south to Tampa Bay. Major flooding in these areas caused 13 deaths, while high wind and seas up to 20 feet in the Gulf capsized boats, drowning 11 people.
Cold air behind the severe squall line moved into the Florida Panhandle on Saturday, producing nearly 5 inches of snowfall in areas from Pensacola to Crestview.
In total, 44 deaths were attributed to the Superstorm in Florida, nearly one-third of the direct deaths across the nation. Destruction from high seas, tornadoes, storm surge, and coastal flooding created a property damage estimate of $1.6 billion, one of the most costly disasters of the 20th century.
National Impacts
While Florida received a majority of the severe weather from the 1993 Superstorm, the entire East Coast felt impacts from the intense system. High winds continued across the Appalachians and Deep South, downing trees and power lines and leaving thousands of residents without power. Intense winds were also recorded in the Northeast, where a peak wind gust of 144 mph was measured at Mt. Washington, New Hampshire.
Blizzard conditions were seen from North Georgia to Maine, with 43” of snow measured in Syracuse, NY and 56” in Tennessee. Over 200 hikers became stranded in the Appalachians due to blizzard conditions and heavy snowfall. March 1993 also recorded the most weather related flight cancellations in history to this point.
In total, 270 people were killed in 10 states along the East Coast from effects of the Storm of the Century.
The Death of La Niña
“It appears La Niña is on its last legs,” noted Mike Halpert, director of the NOAA/NWS Climate Prediction Center, in an online video last week. Although NOAA’s La Niña Advisory was continued in the agency’s monthly diagnostic discussion on March 8, the oceanic and atmospheric fingerprints of La Niña are quickly fading. The decline has been hastened in recent weeks by a strong Madden-Julian Oscillation in the equatorial Pacific, where upper-level winds at the 200-millibar level are now mostly from the west and subsurface waters are warming.
The Australian Bureau of Meteorology declared La Niña officially over in the March 13 installment of its biweekly report. The bureau uses a more stringent threshold than NOAA for defining La Niña: sea-surface temperatures in the Niño3.4 region of the tropical Pacific must be at least 0.8°C below average, vs. the NOAA benchmark of 0.5°C below average.
This is the second consecutive winter of La Niña. The second winter of a La Niña can lead to an enhanced risk of drought over the southern U.S., especially the Southwest and Southern Plains. Events over the last few weeks have fallen in line with this relationship. The fraction of the U.S. covered by severe to exceptional drought (categories D2-D4) has grown from 2.9% in mid-November to 16.3% as of March 13, according to the U.S. Drought Monitor. Most of the Four Corners states, plus Kansas and western Oklahoma and Texas, are now firmly entrenched in severe drought or worse.
According to NOAA’s outlook, below-average precipitation is favored this spring southwest of a belt from Oregon to Louisiana—roughly the same area that’s been running dry all winter. Any warmer-than-usual temperatures this spring would exacerbate the drought’s impact by increasing the evaporation from soils and vegetation. Unfortunately, that’s just what is expected. Unseasonably warm temperatures are predicted to prevailacross all of the nation except Montana and western North Dakota, where moist soils and ample mountain snowpack should help tamp down spring warming.
As noted in NOAA’s long-lead outlook, issued Thursday, “The greatest confidence in the [April-June] 2018 outlook is across the southern tier, where influences from La Niña, overwhelming consistency in dynamical model guidance and statistical tools, long term trends, [and] soil moisture deficits all coincided and favor warmer than normal conditions.”
See Weather Underground's post from March 9 for background on how the departing La Niña and other factors could influence U.S. severe weather this spring.