Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 130952

Area Forecast Discussion
National Weather Service Louisville KY
552 AM EDT Thu Aug 13 2020

.Forecast Update...
Issued at 553 AM EDT Thu Aug 13 2020

Satellite imagery and a few obs are showing more persistent spots of
dense fog across southern KY. Skies look to stay mostly clear in
that area through sunrise, so expect the visibility restrictions to
persist. Therefore, have issued a Special Weather Statement in
coordination with OHX. Fog should burn off by 10 AM EDT/9AM CDT


.Short Term...(Today and tonight)
Issued at 305 AM EDT Thu Aug 13 2020

Today`s forecast appears to be following a pretty similar template
to what we saw yesterday. The early morning hours should stay mostly
dry, with perhaps a few blips on radar across our SW. Otherwise, the
main concern this morning will be patchy and transient fog. There
have been some instances of locally dense fog across our southern
CWA, however given the variable cloudiness don`t expect fog to
become very widespread or persist in one place very long. Will keep
an eye on it.

Otherwise, expect another muggy day as highs top out in the upper
80s to around 90 in the presence of low 70s dew points. Given the
weak upper low in the area and perhaps some differential heating due
to variable cloudiness, expect to see showers and storms fire once
again this afternoon. The best coverage is still supposed to be
mainly along and west of the I-65 corridor, and across far southern
KY although can`t rule out at least an isolated shower or storm
anywhere. A very moist atmospheric column will be around generally
along and west of I-65 once again, where PWATs should exceed 2" this
PM once again. Given the moist column and slow movement of any
storms, some locally heavy rainfall amounts will once again be
possible. Given moderate instability and little to no shear, don`t
expect any real organization to storms. However, gusty winds will be
possible with stronger storms as we have seen with similar

Overall coverage should diminish later tonight with the loss of
heating, however with the upper low in the area and plenty of
moisture still can`t rule out some isolated to widely scattered
activity. Look for mild lows around 70 once again.

.Long Term...(Friday through Wednesday)
Issued at 300 AM EDT Thu Aug 13 2020

Friday through Sunday Night...

A generally unsettled weather pattern is expected through this
portion of the forecast period.  Upper level flow will feature a
baggy trough axis across the Ohio Valley with a developing ridge
over the western US.  This upper trough will move slowly through the
region Friday and Saturday bringing periods of showers and
thunderstorms to the region.  Overall coverage should be higher on
Friday and Saturday than what we`ve seen over the past few days.
Environmental shear is still forecast to be rather weak, with your
run of the mill afternoon instability values.  Some of the storms
could be on the strong side, but the main threats here will be
torrential rainfall, gusty winds, and lightning.  PWATs within this
airmass will be quite high (>1.8 in).  Training of cells could pose
some flooding issues in places that see repeated rainfall.

Secondary upper level wave over the Midwest is forecast to drop into
the region by Sunday.  Associated with this wave, a surface cold
front is forecast to push through the region late Sunday.  Another
round of showers and storms will accompany this front and quickly
push through the region.

Highs through the period will generally be in the mid-upper 80s with
overnight lows in the upper 60s to the lower 70s.

Monday through Wednesday...

Upper level pattern in this period will be very amplified with a
ridge out over the western US and a large/baggy trough over the
eastern US.  This will place the Ohio Valley in a northwest flow
configuration.  The main weather story here will be the cooler than
normal temperatures and much less humid conditions.  Monday will
likely be a transition day as the cooler air settles into the region
with highs mainly in the low 80s.  By Tuesday and Wednesday, highs
will generally be in the mid-upper 70s with a few of the urban spots
hitting 80.  Overnight lows will be quite pleasant and cool with
readings mid-upper 50s.  A few of the typical cool spots may be able
to drop into the low 50s Tuesday and Wednesday mornings.


.Aviation...(06Z TAF Issuance)
Issued at 131 AM EDT Thu Aug 13 2020

Expect a mostly quiet and dry early morning at the TAF sites, with
the main concern being fog potential. BWG/HNB have both gone down
below minimums at times, however these conditions have been somewhat
transient due to variable upper sky cover. Will keep some pretty
pessimistic conditions at these two sites through dawn, but it
should be stated that a wide range of conditions is possible through
sunrise given the variable nature.

Otherwise, today will be dominated by mid/high-level clouds, which
will keep ceilings solidly VFR and limit some of the diurnal cu
formation. Do expect storms to pop in the afternoon with an upper
disturbance in the area, which we`ll cover with PROB30 groups for
SDF, BWG, and HNB. Farther east, we can`t rule out a storm in LEX,
but probabilities are still fairly low.




Short Term...BJS
Long Term...MJ
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