Area Forecast Discussion
Issued by NWS Louisville, KY

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684
FXUS63 KLMK 192331
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
731 PM EDT Thu Apr 19 2018

...Updated Aviation Discussion...

.Short Term...(This evening through Friday night)
Issued at 245 PM EDT Thu Apr 19 2018

Thinning strato-cu deck and persistent cold advection are making it
feel a lot more like February today, as a 1034mb sfc high builds in
from the Upper Midwest.

Main challenge in this forecast is the potential for frost/freeze
tonight. By Friday morning the surface high is still centered over
NE Iowa/SW Wisconsin, with a decent E-NE gradient over the Ohio
Valley keeping winds up around 5 kt. Temp forecast is not as cold as
previous, but there remains decent potential for sub-freezing temps
in some of the sheltered valleys in the Bluegrass region. Even the
frost potential is limited given the winds and temp/dewpoint
spreads, which leave a freeze-or-nothing scenario for many. Best
chance for frost will be south of the Bluegrass Parkway and east of
Interstate 65. Bottom line is that any widespread frost or freeze
appears unlikely, but with surrounding headlines and still a non-
zero chance for frost/freeze conditions, will just tone down the
wording of the existing Freeze Warning and Frost Advisory.

More sunshine and milder temps on Friday as upper ridging builds
from the southwest. However we will remain on the low side of climo.
Another chilly night on Friday night, but impacts will be limited to
patchy frost potential across the Bluegrass region.

.Long Term...(Saturday through Thursday)
Issued at 245 PM EDT Thu Apr 19 2018

After a chilly start, Saturday looks fairly mild and tranquil, with
temps just on the low side of climo. Could see increasing mid/high
clouds through the day, which will mainly serve to slow the fall in
temps after sunset. From afternoon highs in the mid 60s, temps
should only drop off by a few degrees by late evening.

Closed upper low dips into the southern Plains early Sunday and then
slowly makes its way into the Tennessee Valley by Monday. Precip
shield will expand into south central Kentucky late Sunday or Sunday
night and then overspread the rest of the region on Monday.
Unsettled weather will continue well into next week as another
system drops into the Ohio Valley on Wednesday, leaving a broad and
lingering upper trofiness. Have limited POPs in any given period to
50-60%, as timing will depend heavily on any impulses pinwheeling
around either of the upper lows. Temps should actually run near
normal, but with some smaller diurnal ranges given intervals of
clouds and precip.

&&

.Aviation...(00Z TAF Issuance)
Issued at 730 PM EDT Thu Apr 19 2018

Dry weather is expected through this TAF period as high pressure
builds in from the north. Skies should turn mostly clear this
evening through tomorrow morning.  Winds overnight will be 4-6 knots
out of the north to northwest, shifting to easterly tomorrow
morning.  A few upper level clouds are possible in the region
tomorrow afternoon.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Freeze Warning from 1 AM to 10 AM EDT Friday for INZ076>079-083-
     092.

     Frost Advisory from 1 AM EDT /midnight CDT/ to 10 AM EDT /9 AM
     CDT/ Friday for INZ084-089>091.

KY...Freeze Warning from 1 AM to 10 AM EDT Friday for KYZ031>037-
     039>043-047>049-056-057.

     Frost Advisory from 1 AM EDT /midnight CDT/ to 10 AM EDT /9 AM
     CDT/ Friday for KYZ023>030-038-045-046-053>055-061>067-
     070>078-081-082.

&&

$$

Short Term...RAS
Long Term...RAS
Aviation...AMS



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