Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
SPC AC 100533
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Sun Sep 10 2017
Valid 101200Z - 111200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TODAY ACROSS
INTERIOR AND ATLANTIC COASTAL AREAS OF THE FLORIDA PENINSULA BETWEEN
THE GREATER MIAMI METROPOLITAN AREA AND ORLANDO/MELBOURNE...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING
AREAS OF EASTERN AND SOUTHERN FLORIDA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN
PORTIONS OF THE FLORIDA PENINSULA AND GEORGIA/SOUTH CAROLINA COASTAL
Hurricane Irma will impact much of the Florida Peninsula into
northeastern Florida today and tonight. Among the potential
hazards, associated thunderstorm activity will be accompanied by a
risk for tornadoes, particularly across interior and coastal areas
between Miami and Orlando.
As upper troughing progresses east of the northern Atlantic Coast,
models indicate that the mid-latitude westerlies will become
generally confined to areas near and north of the Canadian/U.S.
border during this period. To the south, a much weaker but more
amplified belt of subtropical westerlies will prevail, with one
embedded closed low remaining more or less stationary west of the
southern California coast. More significantly, a downstream impulse
is in the process of digging across the central/eastern Gulf Coast,
and this is contributing to the gradual north/northwestward
acceleration of Hurricane Irma, toward the lower Florida Keys. Irma
is expected maintain hurricane strength through today and tonight
while continuing to migrate north of the Keys, near the west coast
of Florida, into Florida's Nature Coast by late tonight.
...Florida and adjacent south Atlantic coastal areas...
The northward forecast track of Irma, along (near and just west of)
Gulf coastal areas, could allow for an appreciable risk for
longer-lived supercells across at least the interior peninsula and
Atlantic coastal areas, with northward/northwestward storm motions
tending to be aligned with the major axis of the peninsula. North
through east of the center of Irma, lower/mid tropospheric
hodographs are forecast to be large to extreme in size, with
considerable clockwise curvature, more than supportive of potential
for sustained low-level mesocyclones, and the risk for tornadoes
within the more moist and potentially unstable boundary layer air.
The extent of this potential will considerably hinge on boundary
layer warming between the stronger convective bands pivoting around
the circulation center of Irma. This remains unclear at the present
time, but at least a few tornadoes appear possible, particularly
during the daytime hours within a corridor between the Greater Miami
metro area and Orlando/Melbourne.
Continuing tornado potential late this evening into daybreak Monday
becomes more unclear farther to the north, particularly across and
inland of Georgia/Carolina coastal areas, where near-surface wind
fields may maintain a northerly component, emanating from a
dry/potentially cool environment associated with expansive surface
ridging centered over the lower Great Lakes region.
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