Josephine made landfall in the eastern Apalachee Bay, Florida
area as a 60-knot
tropical storm.
a. Synoptic History
The origin of Josephine does not appear to be directly related to a
tropical wave. On 29-30 September, a front,
which had moved over the southwestern Gulf of Mexico, stalled over that area. A
broad area of cloudiness and showers was noted over the southwest Gulf beginning
around this time. This disturbed weather appears to have been caused mainly by
the front, but could also be partially ascribed to a tropical wave which passed
over the extreme southern Gulf on 29 September. This wave led to the formation
of Hernan in the eastern Pacific. A broad area of low
pressure developed near the Bay of Campeche on 1-2 October, but
upper-tropospheric winds were only marginally favorable for development, and the
associated deep convection was not persistent until the 3rd. The surface
circulation became better defined on the 4th, on which day the system received
its initial Dvorak classification
from the Tropical Analysis and Forecast Branch
(TAFB). Meanwhile, the strong pressure gradient between the low and a large high
pressure system centered near the Great Lakes began to produce strong winds
across the northern Gulf of Mexico.
An
Air Force Hurricane Hunter
plane was dispatched to the system on the afternoon of the 4th and data from
the aircraft indicated that a tropical
cyclone, Tropical Depression Ten, had
formed. Based on aircraft, surface and satellite data, the estimated time of
genesis is 1800 UTC 4 October. The post-analysis
"best track" is shown in
Table 1 and Figure 1
(125K GIF). Initially, steering currents were weak and the depression moved
slowly north-northeastward on the 4th and 5th. Southwesterly shearing was
present over the system and there was no significant increase in organization
until the 6th. Even though the depression did not intensify during the first
couple of days of its existence, the strong pressure gradient persisted over the
northern Gulf, producing gale to
storm force winds over that area. By midday
on the 6th, aircraft observations indicated that the central pressure had
dropped to 1001 mb. Banding features on satellite images became better defined
and it is estimated that the cyclone
strengthened into Tropical Storm Josephine at 1800 UTC 6 October.
A strong mid-latitude, deep-layer trough began to dominate the eastern half
of the United States, and on the 6th and 7th the tropical storm was steered
eastward to northeastward, at an increasing forward speed, on the southeast
flank of this trough. Early on the 7th, Josephine strengthened significantly
and was nearing hurricane intensity.
This development trend proved to be temporary, however, as vertical shear began
to increase over the northeast Gulf. Josephine's cloud structure became more
asymmetric, with nearly all of the deep convection northeast of the center. The
storm's intensity leveled off at 60 knots. The center
moved over Apalachee Bay on the evening of the 7th, and crossed the coast in a
relatively uninhabited region of north Florida, in Taylor County, at about 0330
UTC on the 8th of October.
Josephine was already beginning to lose its tropical characteristics when it
crossed the coast, since temperature at Keaton Beach dropped about 6C in one
hour shortly after the storm moved inland. The system became an
extratropical cyclone by the time it entered
Georgia at 0600 UTC 8 October. The cyclone's forward speed increased
dramatically, to near 40 knots, and the extratropical low raced northeastward
near the U.S. east coast, passing close to Cape Cod at 0600 UTC on the 9th. The
low traversed Nova Scotia and Newfoundland on 9-10 October, and then emerged
over the north Atlantic. It moved eastward for a day or two, slowing its
forward speed. Then the system tracked counter-clockwise within a deep-layer
cyclonic flow regime over the northeastern Atlantic on the 12th through the
15th. Finally, the extratropical remnant of Josephine merged with a larger
extratropical cyclone in the vicinity of Iceland on 16 October.
b. Meteorological Statistics
Figures 2 (22K GIF) and
3 (23K GIF) depict the curves
of minimum central sea-level pressure and maximum one-minute average "surface"
(10 meters above ground level) wind speed, respectively, as a function of time.
Also plotted are the observations on which the curves are based, consisting of
aircraft reconnaissance data from the
U.S. Air Force Reserves (the Hurricane Hunters),
Dvorak-technique estimates (from the
TAFB, the
Synoptic Analysis
Branch, and the U.S. Air
Force Global Weather Center) using satellite imagery, and
fixes from synoptic weather map analyses.
The minimum central pressure reported in Josephine, by the
Hurricane Hunters,
was 981 mb at
1135 UTC 7 October. Highest flight-level (850 mb) winds near that time were
66 knots. The maximum flight-level wind reported by
reconnaissance aircraft was 74 knots at 0050 UTC 8
October. Josephine's maximum surface winds were estimated to be 60 knots from 1200 UTC on the 7th up to landfall 16 hours
later. Aircraft observations indicated that, at most, a partial eyewall was
present on three center fixes during the above period.
Table 2 lists ship reports of tropical storm force
winds associated with Josephine. There were additional reports (not included in
this table) of gale to storm force winds from ships over the northern and
western Gulf of Mexico that were estimated to be not within the circulation of
the tropical cyclone. Table 3 lists selected surface
observations from Florida.
Storm surge heights were "significant"
from the Tampa area northward to eastern Apalachee Bay. County officials
estimated storm tides (storm surge plus
astronomical tide) ranged from up to 9 feet in Levy county to 4 to 6 feet in
Pinellas and Hillsborough Counties, and 3 feet as far south as Lee County.
These tides produced widespread flooding of roads, dwellings, and
businesses.
According to reports from National Weather
Service Offices, at least 16 tornadoes occurred in association with
Josephine over northern and central Florida. These caused mostly minor damage,
primarily to trees. One tornado, however, had a 7 mile long, 400 yard wide
track across Edgewater in Volusia County. It severely damaged 30 homes, while
100 others had minor damage.
Rainfall amount of up to 8.5 inches were reported over northern Florida in
association with Josephine.
c. Casualty and Damage Statistics
Total insured losses from Josephine in Florida, Georgia, South Carolina,
North Carolina, and Virginia are estimated to be $65 million. This gives a
rough estimate of $130 million for the total storm damage. There were no deaths
that could be directly attributed to Josephine. A woman suffered a heart attack
during a tornado in Edgewater, and a surfer suffered a broken leg in Pinellas
County.
d. Forecast and Warning Critique
There were some large track forecast errors for Josephine; the number of
cases was rather small, however. The average 12-, 24-, 36-, 48-, and 72-hr
official forecast errors were 70, 131, 203, 266, and 401 n mi respectively.
These are 41% to 49% larger than the most recent 10-year average track
errors. The sample size was only 8 cases for 12 through 48 hours, and 7 cases
for 72 hours. The intensity forecasts were generally off by 10 knots or less
for all time periods.
Table 4 lists the various watches and warnings that
were issued for Josephine. There was about 19 hours between the issuance of the
tropical storm warning and landfall in
Taylor County.
Table 4. Watch and warning summary, Tropical Storm Josephine, October
1996.
Date/Time
(UTC) | Action | Location |
| 7/0300 |
tropical storm watch issued |
Apalachicola to Venice, Florida |
| 7/0900 |
tropical storm warning issued |
Apalachicola to Venice, Florida |
| 7/1200 |
hurricane warning issued |
Apalachicola to Anclote Keys, Florida |
| tropical storm warning issued |
west of Apalachicola to Fort Walton Beach, Florida |
| 7/1500 |
tropical storm warning issued |
Cape Canaveral, Florida to Little River Inlet, South
Carolina |
| 8/0300 |
hurricane warning downgraded to
tropical storm warning |
Apalachicola to Anclote Keys, Florida |
| tropical storm warning discontinued |
west of Apalachicola to Fort Walton Beach, Florida |
| 8/0900 |
tropical storm warning changed to
gale warning |
Cape Canaveral, Florida to Little River Inlet, South
Carolina |
| tropical storm warning discontinued |
Apalachicola to Venice, Florida |
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