…Helene is forecast to rapidly intensify to a major hurricane in the
Gulf and bring life-threatening impacts to Florida and the Southeast late
today through Friday…
…A rare High Risk of excessive rainfall is in place for the southern
Appalachians Thursday-Thursday night where considerable flash/urban/river
flooding and landslides are possible…
Current Tropical Storm Helene is forecast to quickly become a hurricane
today and become a major hurricane before making landfall on Thursday. A
Hurricane Warning is in effect over the Florida Big Bend for damaging
hurricane-force winds. Helene will grow in size as it strengthens,
spreading its impacts to much of Florida and the Southeast. There is a
danger of life-threatening storm surge along the entire west coast of the
Florida Peninsula and Florida Big Bend. The highest inundation levels are
expected along the coast of the Florida Big Bend. Prepare now and heed
instructions from local officials about evacuations in these areas. Please
refer to the National Hurricane Center for the latest updates on the track
and timing of Helene.
Helene will also cause significant rainfall and flooding threats. Even
ahead of Helene itself, tropical moisture will be pulled north into the
Southeast to southern Appalachians today and tonight ahead of a
slow-moving upper trough/low. This moisture will pool along and ahead of a
stalling front at the surface and lead to excessive rainfall. A Moderate
Risk is in place in WPC’s Excessive Rainfall Outlook (ERO) across portions
of Georgia into the southern Appalachians today into tonight within a
broader Slight Risk, in addition to Slight Risks of flash flooding in
parts of the Florida Peninsula and West Coast as Helene approaches.
Today’s rainfall is forecast to create wet antecedent conditions that
should likely overlap heavy rain along Helene’s track Thursday-Friday.
Thus a High Risk of excessive rainfall is delineated across the southern
Appalachians where upslope flow should increase rain totals and varying
terrain could lead to landslides. Overall, 5 to 10 inches of rain with
isolated totals around 15 inches is forecast over the Southeast.
Considerable flash and urban flooding is expected across portions of
Florida, the Southeast, southern Appalachians, and the Tennessee Valley
Wednesday through Friday. This includes the risk of landslides across the
southern Appalachians. Widespread minor to moderate river flooding is
likely, and isolated major river flooding is possible. Additionally, there
is a tornado threat with Helene, especially on the eastern side of the
track. The Storm Prediction center is indicating a Slight to Enhanced Risk
of severe weather, primarily for tornadoes, on Thursday into Thursday
night for parts of Florida into Georgia and South Carolina.
Elsewhere, showers and storms are also possible farther north in the
eastern U.S. along the northern part of the frontal system over the next
couple of days. A couple of fronts passing through the Northwest should
lead to some precipitation there. Meanwhile the rest of the western U.S.
stretching into the north-central U.S. can expect dry conditions with
warmer than average temperatures. The Desert Southwest will see highs well
into the 100s, and 90s are possible in the northern High Plains. Some
record temperatures are possible for lows and highs.
Tate
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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