Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 020146

Area Forecast Discussion
National Weather Service Louisville KY
946 PM EDT Sat Oct 1 2022

.Forecast Update...
Issued at 930 PM EDT Sat Oct 1 2022

Remnant sfc low of Ian is moving slowly into southern Virginia, with
the cloud-level (read: upper-level) circulation over West Virginia.
Low-level dry air is winning for the most part, with precip limited
to far eastern Kentucky, and just mid/high clouds over portions of
central Kentucky and southern Indiana east of I-65. Cloud cover has
been trying to spread westward, but is really eroding as it runs up
against so much dry air.

Aside from tweaks to the hourly sky cover grids, the current
forecast looks to be in good shape. Temp forecast has lows in the
upper 40s most places that skies are clear, with lower 50s under the
clouds in the Bluegrass, and in the urban heat island of Louisville
even with mostly clear skies. Any bust potential comes from just how
far west the clouds extend.


.Short Term...(This evening through Sunday)
Issued at 315 PM EDT Sat Oct 1 2022

Synopsis...Little change is expected in the short term regarding the
mean position of the features at play in the mid-level pattern,
which favors a persistence forecast approach. Initially the remnant
circulation of Ian will be meandering around the Appalachians while
slowly creeping towards the Mid Atlantic. On the other hand, a ridge
will be extending from the Texas Gulf Coast through the Plains into
south-central Canada as strong upper-low will be spinning in the
Intermountain region. At the surface level, the occluded surface low
will follow its mid-level counterpart and move a few degrees
eastward at the same time it helps dragging a weak surface trough
across the Ohio Valley (currently observed over the northern Great
Lakes). Expansive surface high pressure will dominate by Sunday

Highlights...Sunny/clear conditions are expected for most of the
forecast area with the exception of counties along I-75 where mid-
level clouds in the wrap-around circulation can linger into the
evening. KY Mesonet observations and forecast soundings indicate
sufficient dry air below the current cloud deck; thus, have decided
to reduce PoPs over the area. The greatest contrast is being
reported in the temperature field (as previously stated) with 5-6
degrees difference between cloudy vs clear areas. Northerly winds
have picked up this afternoon with gusts reaching 20 to 25 mph at
times, but they will become lighter after sunset.

On Sunday morning, area-wide temperatures should be a few degrees
higher than earlier this morning and right around the climatological
average for this time of the year. The greatest change will be the
low-level moisture influx advected by the surface trough Sunday
morning. Although still placing low confidence given the lack of
consensus, some CAM models do indicate a solid stratus deck moving
from the Upper Ohio Valley. Daytime heating and mechanical mixing
will possibly erode the layer by noon; however, cloudy conditions
might still be ongoing during the afternoon for areas in the
Bluegrass and Cumberland regions. This will ultimately impact the
spatial distribution of high temperature since precipitation is not
expected at the moment. Finally, winds will gust once again Sunday

.Long Term...(Sunday night through Saturday)
Issued at 328 PM EDT Sat Oct 1 2022

As we head into the beginning of the work week, upper ridging
continues moving east into the Lower Ohio Valley. High pressure
centered over the Great Lakes will extend south keeping
northeasterly surface winds over southern Indiana and central
Kentucky. This will result in clear skies and high temperatures in
the low to mid 70s for Monday and Tuesday, but on Wednesday, the
surface high will slide to the southeast towards the Appalachians.
This will veer winds over the CWA towards the south, increasing warm
air advection. Highs will reach into the mid to upper 70s on
Wednesday, and on Thursday, a few areas, near Bowling Green, could
reach into the low 80s.

On Thursday, an approaching cold front will bring increased clouds
to southern Indiana and along north central Kentucky. There is a
slight, less than 10%, chance for precipitation through the evening
hours. During the overnight hours, winds will continue veering to
the north. This will limit high temperatures to the 60s for Friday
and Saturday. A few areas in southern Indiana and the Kentucky
Bluegrass may only see the upper 50s. At night, lows will drop into
the 30s and low 40s. This will increase frost/freeze potential.


.Aviation...(00Z TAF Issuance)
Issued at 645 PM EDT Sat Oct 1 2022

Gusty north winds continue between the strong sfc high over Upper
Ontario and the remnant low of Ian near the NC/VA border. Expect
gusts to diminish quickly around sunset, so will most likely
initialize with a steady 6-9 kt for the night, but we`ll see gusts
around 20 kt again for the mixy part of the day on Sunday. Skies
should remain clear aside from some cirrus blowoff from Ian getting
into SDF and enough for a cig at LEX, but will limit the mid-level
deck to scattered, and then just at LEX. Low-level moisture remains
too far east for any restrictions below VFR.




Short Term...ALL
Long Term...KDW
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