Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 180704

Area Forecast Discussion
National Weather Service Louisville KY
304 AM EDT Wed Jul 18 2018

.Short Term...(Today and tonight)
Issued at 301 AM EDT Wed Jul 18 2018

Early morning IR satellite imagery reveals partly cloudy skies
across the region this morning.  Only clouds are just some high
cirrus spilling southeastward across the area.  KY Mesonet and NWS
showing temperatures in the lower to mid 60s over the eastern half
of the state.  Mainly west of I-65, temperatures were in the lower
70s.  For the remainder of the overnight, we expect quiet weather
with temperatures dropping a few more degrees before bottoming out
just before sunrise.

For today and tonight, a northwest flow aloft will remain in place
as a surface high shifts from the Great Lakes into western New
England.  This feature will keep skies mostly sunny with a light
northeasterly flow.  Highs this afternoon look to warm into the 82
to 87 degree range in many areas.  Mostly clear skies are expected
tonight with lows cooling back into the low-mid 60s.


.Long Term...(Thursday through Tuesday)
Issued at 302 AM EDT Wed Jul 18 2018

...Strong to Severe Storms Possible Friday...

Thursday - Thursday Night...

Upper ridging begins to move off to the east on Thursday, but will
still hold enough influence over the area to keep the forecast dry.
Highs should be in the mid to upper 80s. By Thursday night, an
anomalously strong shortwave trough will move into the upper
Midwest. As deeper moisture arrives into our area ahead of this
feature, look for increasing shower and storm chances after Midnight
Thursday night.

Friday - Friday Night...

Shortwave troughing will remain over the Great Lakes and Ohio River
Valley region during this time, with the left exit region of a 70
knot upper jet nosing into the lower Ohio Valley area. At the same
time, low level moisture return will be occurring with dew points
expected to pool into the low 70s. A strongly unstable airmass
should develop as the rich low level moisture pools beneath
steepening lapse rates aloft. In fact, latest SREF guidance suggests
high probabilities of greater than 2000 J/KG of CAPE, likely higher
especially west of I-65. Given stronger than normal deep layer shear
values and the expected strong instability, strong to severe storms
will be possible Friday into Friday night. There is some question as
to what role morning convection could play on the ability to
destabilize in the afternoon, nevertheless models tend to agree that
multiple rounds of strong storms could be possible. At this time,
the greatest threat looks to be west of I-65 where the best
instability/shear values line up, but many details still need to be
worked out before confidence can grow in more specific
timing/placement. SPC Day 3 Outlook looks good. Highs Friday should
top out in the 85 to 90 degree range.

Saturday - Sunday Night...

Scattered to numerous showers and storms should continue through the
end of the weekend as an anomalous closed low slowly wobbles through
our area. Convective activity should be mostly diurnal in nature,
but will still have to keep some low chances in for the overnight
periods. Highs should be in the low to mid 80s on Saturday, and only
around 80 by Sunday. Lows should be in the mid to upper 60s each

Monday - Tuesday...

Pretty low confidence to start the new work week as models diverge
on possible solutions. Regardless, will have to keep at least some
chances for showers and storms in the forecast as either the closed
upper low will still be in the region or reinforced troughing will
drag another front toward the area. A few model solutions show a dry
forecast, but the majority have at least some precipitation around
during this time. Look for highs mostly back in the mid 80s.


.Aviation...(06Z TAF Issuance)
Issued at 114 AM EDT Wed Jul 18 2018

High pressure will continue to build into the region and provide the
area with VFR conditions.  Combination of dry air and a light north
to northeasterly wind flow is expected to preclude fog development




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