…Potential Tropical Cyclone Nine is forecast to pass not too far from
the Florida Keys Wednesday night as a hurricane before skirting up the
West Coast of Florida by Thursday morning…
…Much needed rainfall from the Ohio Valley into the central to southern
Appalachians, Upper Tennessee Valley and Mid-Atlantic…
…Much above average temperatures continue across the West into the
Northern Plains and across the Gulf Coast into the Southeast…
A relatively benign mid- to upper-level trough that will likely bring
beneficial rainfall for the eastern U.S. is forecast to deepen when
another upper-level trough over the northern Plains drops southeast and
merges with the lead trough. The resulting trough amplification will be
instrumental in pulling the tropical moisture as well as Potential Cyclone
Nine (PTC9) northward into the eastern portion of the Gulf of Mexico by
the end of the short-range forecast period on Thursday morning.
The initial impacts from the lead trough will be in the form of an
expanding area of moderate to heavy rainfall potential from the Midwest
into the lower Great Lakes, Ohio Valley, upper Tennessee Valley, central
to southern Appalachians into the Mid-Atlantic near and ahead of a low
pressure wave. Much of these areas are currently experiencing severe to
exceptional drought conditions, with the expected 1 to 1.5 inch plus
rainfall amount over the next two days bringing some relief to these
drought conditions. With the dry conditions across these areas, river
flooding will be unlikely. However, there is still at least a marginal
risk of isolated flash flooding with the expected heavy rainfall amounts,
especially if they occur over urbanized regions.
As the above-mentioned amplifying pattern develops over the northern
Plains and dips toward the Deep South, PTC9 is forecast to track more
toward the north and intensify rapidly as it moves across the Yucatan
Channel on Wednesday and then pass not too far from the Florida Keys
Wednesday night. The Florida Keys can expect strengthening winds with
more frequent passages of squally downpours Wednesday night as PTC9 is
forecast to pass to the west as a hurricane. Computer models indicate
that the circulation of PTC9 will expand as it interacts with the
deepening upper trough in the Deep South. Given a more robust convective
structure concentrated more on the east side of the storm, the West Coast
of Florida could begin to see more frequent and intense squalls with winds
further strengthening by Thursday morning. Please refer to the National
Hurricane Center for the latest updates on this system.
The amplifying upper ridge across the interior West will be supporting
widespread much above average temperatures over the next few days across
nearly all of the West and into the Northern Plains. High temperatures
across these regions are forecast to be as much as 10 to 20 degrees above
average. Above average temperatures also likely across the Gulf Coast and
into the Southeast. While temperatures are forecast to be much above
across these areas over the next few days, there are not expected to be
many record highs. However, more numerous record high morning
temperatures are possible both today and Wednesday morning along the West
coast and from portions of the southern Mid-Atlantic into the Southeast
and Florida. Across the Pacific Northwest, the cold front associated
with a Pacific cyclone centered over the Gulf of Alaska will only bring
some rainfall into the region by Wednesday.
Kong/Oravec
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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