…Helene is forecast to make landfall as a major hurricane later Thursday
evening and bring life-threatening impacts to Florida and the Southeast
through early Saturday…
…Rare High Risks of excessive rainfall are in place for parts of the
Florida Panhandle where Helene will make landfall, and for the southern
Appalachians where catastrophic flash flooding and landslides are
expected…
…Above average temperatures and summer-like warmth forecast to stretch
from the Southwest to northern Plains…
Hurricane Helene, now a major hurricane, is moving northward through the
Gulf of Mexico this afternoon and forecast to make landfall later this
(Thursday) evening in the Florida Big Bend Region. Because Helene is a
large system and will initially move inland quickly, damaging and
life-threatening hurricane-force winds, especially in gusts, will
penetrate well inland over portions of the Florida Panhandle/Big Bend
region and into southwestern Georgia late Thursday and Thursday night
where Hurricane Warnings are in effect. Strong, tropical-storm force wind
gusts are also likely farther north across portions of northern Georgia
and the Carolinas late Thursday and into the day Friday, particularly over
the higher terrain of the southern Appalachians. Additionally,
catastrophic and deadly storm surge is expected along portions of the
Florida Big Bend coast, where inundation could reach as high as 20 feet
above ground level, along with destructive waves. There is also a danger
of life-threatening storm surge along the remainder of the west coast of
the Florida Peninsula. 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 bring catastrophic and life-threatening extreme rainfall
and flooding threats. Beginning ahead of Helene itself, tropical moisture
is being pulled north into the Southeast to southern Appalachians ahead of
a slow-moving upper trough/low and surface front, currently causing
rainfall and flooding that will continue through the next couple of days
as Helene moves inland. Heavy to extreme rainfall from yesterday has
already led to wet antecedent conditions in places where Helene will
track, contributing to the significance of the flooding threat with this
system. A rare High Risk (level 4/4) is in place in WPC’s Excessive
Rainfall Outlook (ERO) through Friday morning across portions of the
Florida Panhandle/Big Bend Region, Georgia, and into the southern
Appalachians. This threat will extend into at least mid-day Friday for the
southern Appalachians where upslope flow should increase rain totals and
varying terrain is likely to lead to landslides. Catastrophic and
life-threatening flash and urban flooding, including numerous significant
landslides in the Appalachians, is expected. A much broader Slight Risk
(level 2/4) is in effect over much of the Southeast and extending
northward into the central Appalachians and west through the Tennessee and
Ohio Valleys into the Mid-South where more scattered flash flooding is
expected through Friday. A more targeted Slight Risk continues into
Saturday over the Ohio Valley where areas of heavier rainfall and
scattered flash flooding may continue as the forecast extratropical Helene
and the upper-low interact over the region. Overall, Helene is forecast to
produce total rain accumulations of 6 to 12 inches over portions of the
Southeast, with isolated totals of 20 inches or more into the southern
Appalachians. Widespread significant river flooding and isolated major
river flooding are likely. Another weather hazard associated with Helene
to monitor is the tornado threat, 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, from the Florida Peninsula
north into the Carolinas through early Friday, continuing in the Carolinas
through early Saturday.
Elsewhere, showers and storms are also possible farther north in the
eastern U.S. along the northern part of the frontal system for portions of
New England though Friday, and as tropical moisture interacts with the
front over the Mid-Atlantic through Saturday. A couple of fronts passing
through the Northwest should lead to some precipitation there and gusty
winds. 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
low 110s, which has prompted Excessive Heat Warnings from south-central
Arizona into the high deserts of southern California. Much of the interior
West including the central California Valleys and Great Basin will see
highs into the low 90s. Highs into the mid- to upper 80s and even the low
90s are forecast for the northern Plains, with low 80s stretching into the
Upper Midwest. Record warm temperatures are possible for both morning lows
and afternoon highs.
Putnam/Tate
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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