Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 231111

Area Forecast Discussion
National Weather Service Louisville KY
611 AM EST Tue Jan 23 2018

...Updated Aviation Discussion...

.Short Term...(Today through Wednesday)
Issued at 250 AM EST Tue Jan 23 2018

Upper low over western Illinois will make its way ENE into the Great
Lakes today. Flow overhead will remain cyclonically curved, keeping
us under plenty of cloud cover, but the better forcing for precip
will remain largely to our north. Still can`t rule out a few light
rain showers, and perhaps even a few ice pellets given the steep
lapse rates, so will include slight chance POPs along and north of I-
64, and extending southward from the Bluegrass region to Lake
Cumberland. Tight gradient and cold advection will give us a breezy
day with frequent gusts around 30 mph, and very little temp recovery
from morning lows around 40.

Seasonably chilly and somewhat raw conditions will continue into
Wednesday, as another upper wave swings through the Ohio Valley and
the low-level thermal trof takes its time lifting out. Could see a
few flurries or brief/light rain showers again, but even less of a
chance of measurable precip this time around.

.Long Term...(Wednesday night through Monday)
Issued at 250 AM EST Tue Jan 23 2018

Height rises should be underway Wed evening as the shortwave trof
departs, and upper ridging will bring milder temps for Thursday and

Look for deepening SW flow and increasing moisture starting on
Friday night as the pattern amplifies ahead of a progressive trof
digging into the Plains. Models are starting to diverge on the
timing of this system, but we still see enough of a signal to
support likely POPs for Saturday and Saturday night. We`ll be mild
enough to keep it mostly, if not entirely rain, but no mention of
thunder yet due to lack of instability.

The key to this forecast will be Sunday, as the GFS is progressive
enough to take the system cleanly off to our east, but the latest
ECMWF has come in slower and more amplified. This could create a
precip type issue on the very back end of the system if it slows
down enough, but at this point any wintry precip impacts (if they
even occur) will be well east of the I-75 corridor. For now will
hang on to chance POPs for Sunday, and run temps in between the
milder GFS and colder ECMWF.

Dry NW flow and surface high pressure will take hold by Sunday
night, knocking temps back to near normal for late January.


.Aviation...(12Z TAF Issuance)
Issued at 608 AM EST Tue Jan 23 2018

Plan on broken to overcast stratus through the TAF period at all
sites. VFR ceilings currently will lower to MVFR then fuel alternate
MVFR mid/late morning then persist through the evening hours.
Isolated/scattered rain showers expected around HNB and perhaps SDF
today. Westerly winds will remain gusty throughout the day, though
likely to be strongest through late morning. Some gusts 30 to 35
kts possible. By later this evening, stratus may begin to
lift/scatter, especially at HNB and BWG but likely to persist at
SDF and LEX within the deeper cyclonic flow.




Short Term...RAS
Long Term...RAS
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