Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
402 PM EDT Wed Sep 28 2022

Valid 00Z Thu Sep 29 2022 - 00Z Sat Oct 01 2022

...Major Hurricane Ian makes landfall on the west coast of Florida, with
catastrophic storm surge, destructive major-hurricane force winds, and
torrential rainfall ongoing...

...Ian's interaction with a front will likely prolong impacts from high
winds, heavy rain, and flooding even for areas further inland through
Thursday...

...Cool and dry weather for the rest of the eastern half of the country
but heavy rain and strong winds from Ian is forecast to edge toward the
Southeast U.S. on Friday...

...Well above average temperatures persist 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
today and into the northern Rockies on Thursday...

Category 4 major hurricane Ian has made landfall along the southwestern
coast of Florida near Cayo Costa, with catastrophic storm surge and
destructive major-hurricane force winds ongoing. The core of the hurricane
will continue to slowly move inland this evening into the early morning
hours, leading to a combination of hurricane force winds, storm surge and
torrential rainfall that will result in devastating impacts to coastal
communities. Meanwhile, Ian's forward motion is forecast to slow as it
interacts 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. Due to the slow forward movement speed and intense rainfall
rates in Ian's convective bands, a High Risk of Excessive Rainfall has
been issued for much of central Florida through Thursday, as rainfall
totals may reach 2 feet in isolated areas near and to the north of Ian's
track.

After tracking over the Florida peninsula, Ian is forecast to emerge into
the Atlantic as a tropical storm on Thursday evening. Albeit weaker, Ian
is expected to make a second landfall along the Georgia/South Carolina
coast on Friday afternoon, with the main threat being torrential rainfall
and coastal flooding, leading to a Moderate Risk of Excessive Rainfall
being issued for coastal South Carolina and Georgia, where much as 10
inches of rain may fall. Interaction with the aforementioned frontal
boundary north of Ian will help expand the heavy rainfall axis, allowing
for heavy amounts to fall well inland as the tropical system moves onshore.

Elsewhere, fall-like cool temperatures will continue across the Midwest
and Northeast through Thursday as a deep, upper-level trough moves
eastward. Highs in the upper-50s and low 60s are expected across the
region on Wednesday before slowly warming into the low-to-mid 60s on
Thursday and Friday, as the trough continues its eastward progression.
Freeze Warnings and Frost Advisories have been issued for parts of the
Great Lakes region through Thursday morning, as nighttime temperatures
will flirt with and drop below freezing.

Across the western U.S., above-average temperatures will remain over the
region as a strong upper-level ridge moves eastward. Temperatures are
forecast to soar into the 100s and 90s for the desert southwest and
interior southern California, with Excessive Heat Warnings and Heat
Advisories remaining in effect for the Los Angeles and San Diego metro
areas through this evening. Moisture ahead of a Pacific cyclone has begun
to move onshore in the Pacific Northwest, bringing a period of unsettled
weather inland as well as a general cool down to the region. Rain
associated with the system is expected to reach the northern Rockies
tonight and into Thursday morning. Another impulse of energy will keep the
rain over the northern Rockies later on Thursday with high-elevation wet
snow possible over northwestern Wyoming by Friday morning. Meanwhile, some
monsoonal moisture is forecast to return near/west of the Four Corners
region.

Russell/Kong


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