Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 221753
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
153 PM EDT Tue May 22 2018

...Updated Aviation Discussion...

.Forecast Update...
Issued at 1020 AM EDT Tue May 22 2018

Updated the forecast to tweak POPs for the day.  The broken line of
showers/storms south of the Ohio River should continue to slowly
drift east through the morning hours and gradually weaken.  Brief
heavy downpours will continue to be the main threats this
morning/early afternoon.

After a break in convection or perhaps just some isolated cells this
afternoon, another broken line of showers/storms is expected this
evening along the cold front as it pushes through. Some of these
storms could be strong with gusty winds and heavy rain the main
threats.

Afternoon highs should still reach the low to mid 80s.

&&

.Short Term...(Today and tonight)
Issued at 259 AM EDT Tue May 22 2018

Low pressure advancing from southern Michigan to New England over
the course of the Short Term will drag its attendant cold front
through the Ohio Valley this evening. Ahead of the front today in a
pool of warm (temperatures lifting into the 80s) and moist
(precipitable water >= 1.5") atmosphere, scattered shower and
thunderstorm development can be expected. As in recent days, locally
heavy downpours will be the main threat, with briefly gusty winds
and small hail possible in the strongest cells.

Clouds will gradually break up from northwest to southeast tonight
ahead of high pressure over Lake Michigan. As temperatures drop into
the 60s patchy fog will likely develop.

.Long Term...(Wednesday through Monday)
Issued at 245 AM EDT Tue May 22 2018

Cool Canadian high pressure settling over the lower Great Lakes will
provide a couple of drier, less humid days across the Ohio Valley
Wednesday and Thursday. Expect light easterly/northeasterly winds
with a mix of sun and clouds, and highs will still top out above
normal, in the mid 80s, but nighttime lows will be a bit closer to
normal, ranging from the upper 50s in the cooler, rural areas to mid
60s in the urban centers.

Moisture return from the Gulf begins to advect northward into the
lower Ohio Valley on Friday, with the operational GFS the most
aggressive and bullish with QPF by Friday afternoon. This might be a
bit overdone as model forecast dewpoints are in the low/mid 70s,
which seem too high. For consistency, will maintain a slight chance
of showers/storms Friday, mainly across the Bluegrass and south
central Kentucky.

The upcoming holiday weekend still features the possibility of
tropical moisture lifting northward from the Gulf, but there is
considerable uncertainty in the timing and placement. It now appears
that any influence from an Upper Midwest shortwave will stay largely
north. So, the model consensus will still show precipitation chances
Saturday through Monday, but it looks to be more diurnally driven
scattered showers/storms that would peak in the mid/late afternoon
then subside during the evening hours.

Temperatures Friday through Memorial Day will stay above normal, and
Friday looks to be the warmest day with mid/upper 80s likely then
trend more low/mid 80s for Saturday-Monday.

&&

.Aviation...(18Z TAF Issuance)
Issued at 145 PM EDT Tue May 22 2018

Isolated to scattered showers and storms will continue this
afternoon and evening ahead of an approaching cold front.  These
storms could produce MVFR conditions at the TAF sites periodically
through late evening.  The cold front is expected to pass through
the region form NW to SE between 2-9Z tonight.  Along this front, a
final round of storms may be possible at SDF/LEX along the front
late this evening.  After the front passes, convection chances will
end and winds will shift to the north.  Behind the front late
tonight, MVFR cigs and some fog may be possible behind the front.
Short range models vary on fog chances for late tonight into
tomorrow morning and this may need to be re-addressed with the
evening TAF issuances.  VFR conditions are expected after 12Z
tomorrow morning.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...AMS
Short Term...13
Long Term...ZT
Aviation...AMS


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