Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 202332
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
732 PM EDT Tue Oct 20 2020

...Updated Aviation Discussion...

.Short Term...(This evening through Wednesday)
Issued at 300 PM EDT Tue Oct 20 2020

A weak stalled frontal boundary over the region will lift north
early this evening as a sfc low and upper trough move east/northeast
across the Midwest. Isld-sct showers with a few rumbles of thunder
will continue over southern Indiana as a result into tonight.  Late
tonight into Wed morning, a cold front associated with the low
pressure will push into southern Indiana again bringing a chance for
showers/storms Wed morning into early Wed afternoon.  Though there
is still some uncertainty with the exact location of these
boundaries tonight and Wednesday, it looks as if central KY will
stay mainly dry.  Any change or shift in the forecast locations of
these boundaries could result in either a dry forecast for southern
Indiana also or rain chances for southern Indiana and north central
KY. Any locations that receive rain tonight/Wed should stay under a
half inch of rainfall.


Expect low temps tonight in the upper 50s to around 60s.  High temps
tomorrow will warm into the 70s.

.Long Term...(Wednesday night through Tuesday)
Issued at 258 PM EDT Tue Oct 20 2020

Wednesday Night through Thursday...By Wednesday evening, a brief
zonal pattern will become more meridional as a shortwave ejects out
of the PNW, deepening the longwave mid-CONUS trough and resulting in
deep SW flow over the OH Valley. At the surface, the wavering yet
persistent boundary is still progged to be draped along the OH River
with a 1025mb high pressure center located over the spine of the
Appalachians. Light southerly winds at the surface, mostly sunny
skies, and deep layer WAA will allow daily highs to reach into the
upper 70s to lower 80s.

Friday and Saturday...Aforementioned shortwave will push through the
Plains and into the Great Lakes while trailing a surface cold front
that will bring rain back to the region Friday and Saturday. Expect
rain chances to begin as early as Friday morning and increasing in
the afternoon into evening hours. FROPA will occur sometime
overnight, but light rain and possibly drizzle will likely persist
through Saturday morning. Most locations should go dry by Saturday
afternoon, though slight chance of showers will linger. Do expect
embedded thunder Friday afternoon through early Saturday morning as
model soundings have shown an increase in CAPE with values between
1500-2000 J/kg. Modest atmospheric moisture availability (PWATs <
1.40") and a lack of strong dynamical support will limit QPF to less
than 0.15 inches across the CWA. Friday, ahead of the front, daily
highs will again reach into the upper 70s. But expect much cooler
conditions Saturday behind the front, as modified cPa air will keep
max temps in the upper 50s across southern Indiana and in the mid
60s across central KY.

Sunday...Brief influence of high pressure behind the front will keep
most of Sunday dry albeit mostly cloudy. Expect morning min temps in
the mid 40s to mid 50s across the region with highs in the 60s. Rain
chances will return late Sunday evening as another front approaches
from the west.

Monday and beyond...This next cold front should push through the
region sometime late Monday resulting in a wet beginning to next
week.

&&

.Aviation...(00Z TAF Issuance)
Issued at 730 PM EDT Tue Oct 20 2020

Ceilings have gradually improved throughout the evening as the
frontal boundary slowly pushes northward, with all TAF sites now
VFR. Around sunrise, some lower cigs may push back into
southern IN/northern KY as the front sinks back southward. However,
have only included mention of MVFR cigs at HNB for the time being as
confidence remains low. Winds will generally remain out of the SSE
overnight before turning more southwesterly during the day
Wednesday.

&&

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

$$

Short Term...AMS
Long Term...CG
Aviation...JML


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