Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
456 AM EDT Tue Sep 27 2022

Valid 12Z Tue Sep 27 2022 - 12Z Thu Sep 29 2022

...Major Hurricane Ian is forecast to make landfall on the west coast of
Florida late Wednesday/early Thursday; slow forward motion of Ian will
likely prolong impacts from high winds, heavy rain, and flooding even for
areas further inland...

...Heavy rain expected downwind of the lower Great Lakes today, gradual
tapering off on Wednesday...

...Cool and unsettled weather expected to persist across the Northeast and
Great Lakes through at least mid-week...

...Well above average temperatures across much of the West, with excessive
heat continuing over parts of southern California, followed by arrival of
rain and cooler temperatures over the Pacific Northwest later on
Wednesday...

All eyes are now on Hurricane Ian as it took center stage after
intensifying to major hurricane intensity just before making landfall over
western Cuba early this morning.  The outer rainbands are now streaming
across the Keys and into southern Florida.  Ian is forecast to move
generally northward through tonight, passing to the west of the Keys
before turning gradually toward the north-northeast on Wednesday.  Heavy
rain will become more frequent as winds are forecast to reach hurricane
force near the west coast of Florida late on Wednesday where Ian makes
landfall.  Ian is forecast to slow down its forward motion as it begins to
interact with a stationary front settling across northern Florida.  This
interaction will likely prolong the threat of heavy rain and high winds
near and to the northeast of where Ian makes landfall.  How fast/slow Ian
moves will partly depend on how fast/slow an amplified upper trough
retreats into eastern Canada as well as how fast/slow Ian interacts with
the front.  Meanwhile, heavy rain will become increasingly focused to the
north of the front, possibly shifting northward into northern Florida by
Thursday morning.  A Moderate Risk of Excessive Rainfall is in place along
coastal portions of the southern Florida Peninsula, shifting northward to
the northern-central portion of the Peninsula on Wednesday.  As heavy rain
falls on top of already wet grounds, scattered to widespread instances of
flooding are expected.  In addition, the Storm Prediction Center has also
highlighted the same regions with Slight Risks for the threat of tornadoes.

Meanwhile, the amplifying upper-level trough as mentioned above is
forecast to continue bringing cool and unsettled weather from the Great
Lakes to the Northeast through mid-week.  The strength of the upper trough
will be maintained by reinforcing surges of cooler air diving across
central Canada.  This pattern will favor damp, dreary weather to persist
into Wednesday.  A Slight Risk of Excessive Rainfall remains in place
along Lake Erie and a Marginal Risk along Lake Ontario on Tuesday as cold
air aloft flowing across the warm waters of the Great Lakes will
destabilize the atmosphere and could lead to heavy lake-effect rain. In
addition to the threat for heavy rain, temperatures will remain
unseasonably cool across the Midwest and Northeast and spread into the
Southeast Wednesday.  Most of the Upper Midwest, Great Lakes, and interior
Northeast will see highs in the upper-50s and low-60s, with some locations
in the Upper Great Lakes only reaching the upper 40s Tuesday. There are
Frost Advisories in effect for portions of the Upper Mississippi Valley
Tuesday morning as lows will bottom out in the mid-30s.  Southern portions
of the Midwest as well as the coastal Northeast will see highs in the
mid-60s to low 70s. Temperatures across the Southeast will cool from the
upper 70s/low 80s today to the mid-70s Wednesday and Thursday.  

In contrast to the eastern half of the country, well above normal
temperatures are forecast to remain over much of the West as a strong
upper-level ridge passes over the region.  The hottest weather is expected
over the Southwest and southern California with highs in the mid-100s for
the interior deserts and in the 90s for all but coastal portions of
Southern California. Excessive Heat Warnings and Heat Advisories remain in
effect for the Greater Los Angeles/San Diego regions as well as adjacent
portions of the Sonoran Desert.  Elsewhere, well above normal temperatures
will stretch from the Intermountain West to the northern Rockies and
northern High Plains. Highs today and Wednesday are forecast to soar into
the upper 80s and low 90s.  By late Wednesday, moisture ahead of a Pacific
cyclone is forecast to reach the Pacific Northwest, bringing a period of
unsettled weather further inland as well as a general cool down to the
region.  Rain associated with the system is expected to reach the northern
Rockies Wednesday night/Thursday morning.  Some monsoonal moisture is
forecast to return near/west of the Four Corners region.

Kong/Putnam


Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php