Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 231048

Area Forecast Discussion
National Weather Service Louisville KY
648 AM EDT Sun Jul 23 2017

...Updated Aviation Discussion...

...Forecast Update...
Issued at 515 AM EDT Sun Jul 23 2017

MCS activity continues across southern Indiana and northern Kentucky
this morning. There have been multiple observed wind gusts over 40
mph, including 48 mph at SDF. The potential for damaging winds,
however, is low and decreasing as low levels stabilize.

Many areas continue to receive very beneficial rainfall, but MRMS 3-
hourly radar estimates are around 3-4 inches in portions of Dubois,
Orange, Crawford, Perry, Washington, and Harrison counties in
Indiana. Rainfall estimates are up to around 2 inches in Meade and
Breckinridge counties in KY. Scattered to numerous storms continue
to develop upstream. Storm motion to the east will continue to
result in training in some areas, and minor flooding is possible. An
axis of 1.9-2.2 PWATs is oriented along the low-level boundary.
Despite antecedent dry conditions and high FFG, this prolonged
period of training convection may result in localized flash
flooding. Remember, NEVER attempt to drive through standing or
flowing water.

.Short Term (Now through Monday)...
Issued at 315 AM EDT Sun Jul 23 2017

Steady mid and upper level height falls have set in and will
continue today as a synoptic scale trough swings southeast over the
Great Lakes. Modest flow aloft will finally become cyclonic as the
upper ridge continues to establish itself over the Four Corners. At
the surface, a convectively-reinforced boundary was oriented east-
west across southern Indiana.

Two separate MCSs were ongoing early this morning, one over southern
IN/northern KY and another impacting southern OH/northeast KY. These
clusters of thunderstorms were moving to the ESE at 30-35 kts. The
strong convection over the northern CWA has pushed out an outflow
boundary, which was moving south through Bullitt, Hardin, Meade, and
Breckinridge counties, extending back northwest into Perry Co, IN.
Numerous thunderstorms will continue across mainly southern IN and
the northern half of central KY through 11-12z. While the convection
will become increasingly elevated, an axis of 1500-2500 J/kg MUCAPE
and a very warm, moist boundary layer should allow for robust
convection for another 2-3 hours. Convection is expected to
gradually diminish by 12z.

Isolated activity can`t be completely ruled out after 12z, but in
general, a lull in precipitation looks likely into the early
afternoon. With fairly strong heating once again today,
redevelopment over central KY along remnant boundaries is expected
during the second half of the day. Storms this afternoon and evening
could quickly become strong, capable of very heavy rain, frequent
lightning, and gusty winds. The strongest updrafts may produce small

A Heat Advisory remains in effect generally along and west of I-65,
where heat indices will peak in the 100-106 range. The hottest
conditions are expected in the southwest, including Bowling Green
and surrounding areas.

Rain and storms will push southeast late this evening into the
overnight period, with most areas dry after midnight. Lows will fall
into the upper 60s to lower 70s behind the cool front. Highs on
Monday will be near climatological normals, in the mid 80s to around
90 degrees. Models continue to suggest weak convergence associated
with the stalled boundary on Monday, so we may see isolated to
scattered showers/storms.

.Long Term (Monday Night through Saturday)...
Issued at 325 AM EDT Sun Jul 23 2017

Tuesday will feature mid-level height rises, with surface high
pressure over the Great Lakes. We`ll likely see mostly sunny skies
with a light northeast wind here in central KY and southern IN.
Highs will be in the mid to upper 80s. We`ll likely see a stretch of
dry weather and normal summertime temps that continues through
Wednesday night. Highs on Wednesday will likely warm to around 90.

The passage of a shortwave trough and its associated cold front
bring showers and thunderstorms back into the forecast for Thursday
and Thursday night. Post-frontal upper troughing, along with
Canadian high pressure, may provide some downright "cool" weather
Friday into the weekend. Highs in the low to mid 80s look possible,
with lows in the 60s.


.Aviation (12Z TAF Update)...
Issued at 648 AM EDT Sun Jul 23 2017

A complex, challenging forecast.

First order of business is early morning storms. Convection from the
pre-dawn hours has decreased, but new convection is coming in from
southeast Illinois. Will use radar to time the new storms into SDF.
There is some question about whether or not they will make it all
the way to LEX...feeling right now is that they will have reduced to
scattered showers by the time they get that far east. This is a low
confidence forecast, though, so changes may be needed. BWG will stay
south of the early morning storms.

Then this afternoon new storms are expected to fire along various
boundaries left over from the morning convection plus a weak
synoptic surface trof. The models are hitting southern Kentucky the
hardest with new storms, and this has been a consistent solution
over the past several runs of local models. So, will go with this
idea in the TAFs.

Clearing tonight may lead to patchy fog.


KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for

IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for INZ083-



Short Term.....EBW
Long Term......EBW
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