Area Forecast Discussion
Issued by NWS Louisville, KY

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476
FXUS63 KLMK 262353
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
753 PM EDT Thu Apr 26 2018

...Updated Forecast and Aviation Discussions...

.Forecast Update...
Issued at 745 PM EDT Thu Apr 26 2018

Current radar has some light rains across Lake Cumberland. On the
edge of the cloud shield however, some boundary mergers have allowed
for some taller cells to develop.  These should weaken as the night
continues and we lose surface heating. Still we will carry rain
chances in our south and east to late evening. After that, we will
wait and see how the sky cover allows for fog development overnight,
especially thanks to the rain development. Have expanded the patchy
fog wording a little more north and west of what previous forecast
had. Rest of the forecast looks on track.

&&

.Short Term...(This evening through Friday night)
Issued at 300 PM EDT Thu Apr 26 2018

(Tonight) - Rain moves out of the CWA, but a chance of fog lingers.

An upper low will continue to track northeast from the Tennessee
River Valley and pick up speed through Virginia. This will carry the
light rain chances, circling the low, through south central Kentucky
and eastward. Shortly after midnight, the rain should be out of the
CWA. Clearing skies will follow from the northwest across southern
Indiana into Kentucky. Temperatures will drop across the area to the
mid 40s.

Spotty fog is possible in the southeast part of the CWA as light
winds and some high humidities are likely. Sky cover is the one
factor that could limit radiative cooling to hamper fog development.

(Friday - Friday Night) - Mostly sunny with more afternoon clouds.

Sunshine is expected Friday morning, but by afternoon, with highs
near 70, a shortwave on an upper trough axis will likely bring some
extra cloud cover across the area. Winds will increase during the
day to 10-15 mph and gusts to near 20 mph. Areas east of Interstate
65 had a small chance of light rain or sprinkles in the forecast for
the afternoon and evening, but due to a lack of moisture,
precipitation chances have been lowered and rain removed from the
forecast. After the quick passage of the system, skies are expected
to clear during the overnight hours.

.Long Term...(Saturday through Thursday)
Issued at 326 PM EDT Thu Apr 26 2018

(Saturday - Sunday) - Sunny skies with frost Sunday morning.

A large surface high centered over the plains quickly heads to the
southeast towards the Ohio River Vally. This pushes a surface low
over Lake Erie to the east while compressing the pressure gradient
between them. A north wind of 10 to 15 mph over the CWA will
be the result during the day Saturday.

Saturday night, the winds drop off and high pressure subsidence
provides clear skies for radiative cooling to drop temperatures down
to the low to mid 30s. The Bluegrass region and south-central
Kentucky will likely see the best chance for frost during the early
morning hours on Sunday.

(Monday - Tuesday night) - Clear skies and much warmer.

As an upper ridge axis nears the CWA and a surface high moves past
the CWA a strong southerly wind will funnel warm air into the Ohio
Valley raising temperatures on Monday to around 70 for highs.

As the ridge drifts east, temperatures on Tuesday will feel like
summer reaching near 80 degrees. Lows Tuesday night will stay near
60.

(Wednesday - Thursday) - Gulf moisture provides next large precip
chance.

The strong southerly flow that brings the warm temperatures also
brings Gulf of Mexico moisture. Precipitable water values of over
1.7" currently look possible. With this moisture in front of an
upper trough precipitation is likely. Current instability in the
models is mild but will likely enhance as we near the event.
Thunderstorms are expected and in the forecast. Timing and rainfall
amounts will be tuned in coming forecasts.

&&

.Aviation...(00Z TAF Issuance)
Issued at 753 PM EDT Thu Apr 26 2018

VFR expected through this forecast cycle. Only concerns this evening
are some lingering stronger showers near BWG. At this point, don`t
expect them to impact the terminal, but will mention VCSH for a few
hours at the start. These showers are developing on lingering
boundaries evident on current radar imagery, so a few more could pop
up before diminishing this evening.

Otherwise, expect light and variable winds overnight with some
potential for some reduced visibility in fog toward dawn, mainly at
LEX or BWG.

A steady W wind picks up tomorrow with a scattered layer of clouds
developing around 5 K feet by midday. A few gusts up around 20 mph
are possible.

&&

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

$$

Update...RJS
Short Term...KDW
Long Term...KDW
Aviation...BJS



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