Storm Survey for Southside Jacksonville (Duval County) EF-1 Tornado – April 25, 2015

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…NWS DAMAGE SURVEY RESULT FOR 4/25/15 SOUTHSIDE TORNADO IN DUVAL COUNTY…

NWS METEOROLOGISTS HAVE CONFIRMED A TORNADO DEVELOPED AND MOVED ASHORE IN THE SOUTHSIDE AREA OF DUVAL COUNTY JUST SOUTH OF RIVER
OAKS PARK AROUND 552 PM ON APRIL 25TH.

A SEVERE THUNDERSTORM PUSHED ESE THROUGH THE JAX METRO AREA AT ABOUT 50 MPH AND INTENSIFIED AS IT MOVED OVER THE ST. JOHNS RIVER. RADAR IMAGERY INDICATES A BRIEF TIGHT ROTATION DEVELOPED ON THE NORTH END OF A DEVELOPING DOWNBURST.

THE TORNADO MOVED ASHORE AND PUSHED JUST SOUTH OF HENDRICKS ELEMENTARY SNAPPING TREES AND POWERLINES. SEVERAL STRUCTURES WERE IMPACTED BY FALLING TREES AND LIMBS. INITIAL DAMAGE WAS TIGHTLY CLUSTERED WITH A PATH OF APPROXIMATELY 200 YARDS. AS THE TORNADO CROSSED PHILLIPS HIGHWAY SEVERAL BUSINESSES SUSTAINED ROOF DAMAGE. TRAILERS IN THE PINE OAKS MOBILE HOME PARK WERE DAMAGED AS WELL.

THE TORNADO BEGAN TO TURN MORE TO THE SOUTHEAST AS IT PASSED I-95 AND WIDENED TO 350 YARDS AS IT NEARED ENGLEWOOD HIGH SCHOOL.  AT ABOUT 5:58 PM THE TORNADO BEGAN TO WEAKEN AND DISSIPATE. A WIDE
SWATH OF STRAIGHT LINE WINDS CONTINUED TO CAUSE DAMAGE FURTHER TO THE SOUTH AND EAST OF THE PATH UNTIL SHORTLY AFTER 6 PM. THE PATH WIDTH VARIED FROM 200-350 YARDS ALONG A 3.45 MILE PATH. THE TORNADO
LASTED 5 OR 6 MINUTES WITH THE MAXIMUM WIND SPEEDS REACHING 104 MPH.

RATING:               EF-1
ESTIMATED PEAK WINDS: 104 MPH
PATH LENGTH/STATUTE:  3.45 MILES
PATH WIDTH/MAXIMUM:   350 YARDS
FATALITIES:           0
INJURIES:             0

START DATE:           APRIL 25 2015
START TIME:           552 PM EDT
START LOCATION:       4 MILES SOUTHWEST OF ARLINGTON
START LAT/LON:        30.2910/-81.6565

END DATE:             APRIL 25 2015
END TIME:             558 PM EDT
END LOCATION:         5 MILES SOUTH OF ARLINGTON
END LAT/LON:          30.2688/-81.6058

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Storm Survey for Palm Cay (Marion County) EF-1 Tornado – April 20, 2015

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NWS METEOROLOGISTS HAVE CONFIRMED A TORNADO ACROSS SOUTHWESTERN MARION COUNTY ON THE AFTERNOON OF MONDAY APRIL 20 2015. THE NATIONAL WEATHER SERVICE JACKSONVILLE WOULD LIKE TO EXPRESS APPRECIATION TO MARION COUNTY EMERGENCY  MANAGEMENT FOR ASSISTING OUR TEAM DURING THE SURVEY.

THE TORNADO TOUCHED DOWN SHORTLY AFTER 330 PM EDT MONDAY JUST EAST OF STATE ROAD 200 AT THE OAK RUN COUNTRY CLUB. SPOTTY EF-0 DAMAGE WAS NOTED THROUGHOUT THE OAK RUN COUNTRY CLUB NEIGHBORHOOD. THE TORNADO CONTINUED ON AN EAST TO EAST-NORTHEAST PATH INTO THE PALM CAY SUBDIVISION, REACHING ITS MAXIMUM INTENSITY OF EF-1.  SPOTTY EF-0 DAMAGE WAS NOTED JUST SOUTH OF SOUTHWEST 103RD STREET ROAD AT THE CONCLUSION OF THE TORNADO
PATH, WHICH WAS APPROXIMATELY 2 MILES IN LENGTH. THE DURATION OF THIS TORNADO WAS LIKELY LESS THAN 5 MINUTES.  MARION COUNTY EMERGENCY MANAGEMENT REPORTS THAT 55 HOMES WERE DAMAGED, WITH 10 OF THOSE HOMES DEEMED UNINHABITABLE.

RATING: EF-1
ESTIMATED PEAK WINDS: 85-90 MPH
PATH LENGTH/STATUTE: 2.0 MILES
PATH WIDTH/MAXIMUM: 350 YARDS
FATALITIES: 0
INJURIES: 0

START DATE: APRIL 20 2015
START TIME: 331 PM EDT
START LOCATION: 11.8 MILES SOUTHWEST OF OCALA
START LAT/LON: 29.06087/-82.27132

END DATE: APRIL 20 2015
END TIME: 335 PM EDT
END LOCATION: 10.2 MILES SOUTHWEST OF OCALA
END LAT/LON: 29.06900/-82.24051

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We thank Marion County Emergency Management and WCJB-TV in Gainesville for providing the following photos of the damage caused by this EF-1 tornado:

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The National Weather Service in Jacksonville issued a severe thunderstorm warning for Marion County at 3:31 PM.  As you can see from available base reflectivity and storm relative velocity data from the JAX Doppler Radar near the Jacksonville International Airport at that time,  the lowest available elevation for that radar to sample data in southwestern Marion County is at nearly 10,300 feet above ground level (agl).  Most tornadoes that form from rotating wall clouds exhibit strong rotation in the Storm Relative Velocity data (image to the right on the slide below) below 10,000 feet. The velocity data below displayed broad mid-altitude rotation (right image) embedded within a strong reflectivity core (left image).

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The radar that is able to sample the lowest elevations in southwest Marion County is located in Ruskin, FL (Tampa Bay region).  However, even this radar is unable to sample data below about 8,500 feet.  This Storm Relative Velocity data image from a few minutes before the tornado (image below) depicts broad rotation and converging winds at 8,500 feet, with green returns indicating winds blowing towards the TBW Doppler Radar site located to the south-southwest, while red returns indicate winds blowing away from the TBW radar.  Futhermore, the National Weather Service in Ruskin was dealing with severe weather impacting their area of responsibility and thus chose a scanning pattern that focused closer in on their local area, providing limited velocity data for much of Marion County. This is evident by the purple data region, which is known as range folding.  This tornado essentially formed within a range folded, or “no available velocity data” region, rendering use of the Ruskin Doppler Radar data suspect for issuing warnings despite being slightly closer in geographic range to southwest Marion County.

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This scenario underscores several facts:

1) Marion County and much of north central Florida is not adequately sampled amongst JAX, TBW, and MLB (Melbourne, FL) Doppler Radars in situations where tornado formation is considered, given that much of the precursor low level rotation prior to a tornado touchdown occurs at elevations below which these Doppler Radars are able to scan.

2) Storm Spotters are vital in these severe weather situations when locations are too far removed from Doppler Radar data for reliable detection of low level rotation.  A severe thunderstorm watch was issued for much of north and north central Florida by the Storm Prediction Center at 11 am EDT on April 20 (http://www.spc.noaa.gov/products/watch/ww0086.html) , meaning that available Storm Spotters were activated to provide vital ground truth.  National Weather Service offices throughout the nation provide basic and advanced storm spotter training sessions in-person and sometimes virtually.

3) This tornado formed, touched down, traveled about 2 miles on the ground, and then lifted back into the clouds within the span of about 5 minutes.  Even with perfect available velocity data, it is difficult for meteorologists manning a Doppler Radar to issue a tornado warning with lead time for such a short-lived event. Even at its shortest scanning mode, National Weather Service Doppler Radars take approximately 4 minutes to complete a full data scan.  This is why it is so important for the public and first responders to be aware of the potential for severe weather during the watch phase, particularly in a state like Florida where short-lived tornadoes are the norm rather than the larger, longer lived twisters that are found in the Midwest.

…NWS DAMAGE SURVEY RESULT FOR 4/19/15 COFFEE COUNTY TORNADO EVENT…

NWS METEOROLOGISTS HAVE CONFIRMED A TORNADO ACROSS CENTRAL COFFEE COUNTY GEORGIA FROM THE AFTERNOON OF SUNDAY APRIL 19 2015. NWS JACKSONVILLE FLORIDA WOULD LIKE TO EXPRESS APPRECIATION TO COFFEE COUNTY EMA DIRECTOR FOR ASSISTING OUR TEAM DURING THE SURVEY WHERE HE WAS INSTRUMENTAL IN OUR RURAL COMMUTE ACROSS SATURATED DIRT ROADS OF THE COUNTY AND HELPING US IDENTIFY AND PIN POINT DAMAGE ALONG THE TORNADO PATH LIST BELOW. ALSO…THANK YOU TO THE COFFEE COUNTY GEORGIA POLICE SCANNER FACEBOOK PAGE FOR SOME OF THE PHOTOS FROM THE TORNADO.

THE TORNADO WAS SPAWNED AND MIGRATED OVER WEST CENTRAL COFFEE  COUNTY IN THE RURAL OUTSKIRTS WEST OF THE CITY OF DOUGLAS GEORGIA BY A SHORT-LIVED SUPERCELL THUNDERSTORM. THERE WAS DAMAGE TO HOUSE SIDING, SHALLOW ROOTED PINES WERE PUSH OVER, LARGE BRANCHES WERE BROKEN OFF TREES, MINOR ROOF DAMAGE, AND LOSS OF WOOD AND METAL PANELS ON SMALL FARM OUTBUILDINGS.

RATING:                                             EF-0
ESTIMATED PEAK WINDS:  75-85 MPH
PATH LENGTH/STATUTE:     4.0 MILES
PATH WIDTH/MAXIMUM:   60 YARDS
FATALITIES:                                     0
INJURIES:                                         0

START DATE:                     APRIL 19 2015
START TIME:                     201 PM EDT
START LOCATION:       6 MILES SSE OF AMBROSE
START LAT/LON:           31.514679/-82.960982

END DATE:                       APRIL 19 2015
END TIME:                       205 PM EDT
END LOCATION:         5 MILES SSW OF BROXTON
END LAT/LON:              31.547234/-82.906651

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…Tornado Watch through 8 pm for SE Ga and portions of NE FL…

…Strong to Severe Storms and a Few Tornadoes Possible through this mid-evening…

Synopsis & Timing

Broken bands of showers and thunderstorms will continue to impact SE Georgia and the Suwannee River Valley of NE Florida this afternoon with a more consolidated line of showers and thunderstorms just east of the aforementioned region that will continue to track east across the region this late afternoon and early evening.  There is markedly less activity across our SE Florida zones at this time. Even outside of thunderstorm activity, showers can produce wind gusts of 30-40 mph at times.  Some storms are exhibiting rotation over Southeast Georgia and it is important to remain vigilant with a weather eye to the sky through the remaining afternoon hours and this evening.

Remember, a watch means that severe storms or tornadoes are possible in and near the watch area, and to stay alert for possible warnings as storms near your location.

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Northeast Florida and Southeast Georgia Impacts:

Tornadoes:   At this time, the threat for isolated tornadoes appears to be increasing with the low level jet strengthening and the approach of the consolidated squall line.  Brief tornadoes could quickly come to fruition along or ahead of the squall line/convective line this late afternoon through mid- evening. Please utilize media, internet, smart phone and tabular apps and NOAA weather radio to keep abreast of the latest warnings from the National Weather Service.

Winds:  While the main threat from any thunderstorms that form will be strong winds in the neighborhood of 40-50 mph, the potential exists for a few stronger storms capable of higher wind speeds of 50 to 70 mph. Damaging straight line winds in excess of 58 MPH will be possible and are more likely along and ahead of the squall line this evening as storms track eastward.

Hail:  The threat for severe hail will be limited with some of the stronger storms having hail near the size of quarters.

Rainfall: Rainfall amounts of 1″ to 2″ will be possible with isolated higher pockets of 3” likely with rain efficient thunderstorms, especially along and west of a line from Jesup, Georgia to Lake City, FL.

Please call us directly with any specific questions and/or concerns for your local area.

Best regards,

Scott Cordero

 

Additional Information Resources:

NWS Jacksonville Webpage:  weather.gov/jax

NWS Jacksoville Facebook:  facebook.com/US.NationalWeatherService.Jacksonville.gov

NWS Jacksonville Twitter:   twitter.com/NWSJacksonville

AHPS River Forecasts:  water.weather.gov/ahps2/index.php?wfo=jax