…Helene is forecast to rapidly intensify to a major hurricane in the
Gulf and bring life-threatening impacts to Florida and the Southeast
through Friday…
…A rare High Risk of Excessive Rainfall is in place for the southern
Appalachians through Thursday night 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 is currently entering the southeastern Gulf of Mexico
this afternoon and is forecast to become a major hurricane on Thursday
before making landfall over the Florida Panhandle sometime Thursday
evening. A Hurricane Warning is in effect over the Florida Big Bend and
extending inland into southwest Georgia for damaging hurricane-force
winds. The damaging wind threat is also expected to stretch even further
inland towards the southern Appalachians and much of Georgia as the storm
races northward through Friday, with Tropical Storm Watches posted. 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, central and
eastern sections of the Florida Panhandle (including the 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 through 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 rare High Risk
(level 4/4) is in place in WPC’s Excessive Rainfall Outlook (ERO) across
portions of Georgia into the southern Appalachians tonight, in addition
Slight Risks (level 2/4) of flash flooding have been issued in parts of
the Florida Peninsula and west coast of Florida as Helene approaches.
Today’s rainfall is forecast to create numerous instances of flash
flooding while also leading to wet antecedent conditions that should
likely overlap heavy rain along Helene’s track Thursday-Friday. Thus a
High Risk of excessive rainfall is also delineated on Thursday across the
southern Appalachians where upslope flow should increase rain totals and
varying terrain could lead to landslides. Additionally, a separate area of
extreme rainfall is also likely near the core of the storm as it passes
over the Florida Panhandle, where a separate High Risk of Excessive
Rainfall is in effect. Overall, 6 to 12 inches of rain with isolated
totals around 18 inches is forecast over the Southeast and southern
Appalachians. Catastrophic and life-threatening flash and urban flooding,
including landslides, is expected across portions of the southern
Appalachians through Friday. Considerable to locally catastrophic flash
and urban flooding is likely for northwestern and northern Florida and the
Southeast through Friday. Widespread minor to moderate river flooding is
likely, and isolated major river flooding is possible. 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, on Thursday into Thursday night for parts of northern 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 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. High into the 90s are possible in the northern
High Plains, with 80s stretching into the Upper Midwest through the end of
the week. Some record warm temperatures are possible for both morning lows
and afternoon highs.
Snell
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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