Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 211729
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
129 PM EDT Sun May 21 2017

...Updated Aviation Discussion...

.Forecast Update...
Issued at 900 AM EDT Sat May 20 2017

Showers have developed along the cold front in southern Indiana this
morning. The cold front is quickly approaching the northwest CWA, as
seen on surface observations. Surface winds are now W/WNW in
Evansville and far SE Illinois. Winds should be veering soon in
Owensboro and Huntingburg. No lightning in the region as of this
writing, with the closest activity down in Arkansas. Instability is
fairly meager at the moment and will be slow to build today given
widespread cloud cover and morning shower activity ahead of the
front. Model guidance suggests that 500-1000 J/kg MLCAPE will be
realized this afternoon east of I-65, but values approaching 1000
would be restricted to the far southeast CWA. Still, convection will
likely intensify along the cold front this afternoon, with
lightning, heavy showers, gusty winds, and perhaps small hail. Rain
chances will diminish from west to east from early afternoon through
the evening.

&&

.Short Term...(Today through Monday)
Issued at 316 AM EDT Sun May 21 2017

A low pressure system currently residing over Minnesota will slowly
work its way off to the northeast through the short term period. The
cold front associated with this system should finally work its way
through the forecast area this afternoon to early evening, bringing
an end to the rain for at least a brief period.

Before that, however, showers and storms will continue today. Rain
has redeveloped along and west of I-65 this morning and some strikes
of lightning are showing up in this activity. Most of the high
resolution guidance shows this activity shifting to the east and out
of the area through mid morning. There then may be a brief lull in
precipitation before storms start to develop along the cold front
this afternoon. The best coverage of storms along the cold front
will be east of the I-65 corridor this afternoon. Soundings do show
CAPE climbing to around 1000 J/kg across east central KY this
afternoon. However, shear will be weak. So while a few strong storms
will be possible, numerous severe storms are not expected at this
time.

Rain will come to an end this evening as the cold front pushes
through. High pressure will build in for Monday bringing drier
weather. Temperatures will be cooler today and Monday with the cold
front moving through. Lows will dip into the 50s tonight with highs
in the lower to mid 70s tomorrow.

.Long Term...(Monday night through Saturday)
Issued at 331 AM EDT Sun May 21 2017

The dry weather will be short lived as a trough digs into the upper
Midwest. Across the Ohio Valley we will be under southwesterly flow
aloft. Scattered showers and a few storms will be possible on
Tuesday into Tuesday night. However, the better chance will come
Wednesday as an area of low pressure and a cold front swing through
the region. The upper level trough will swing through the lower Ohio
Valley through Thursday. Light showers and perhaps a few
thunderstorms will continue into Thursday as it does so.

High pressure will once again bring dry weather for Thursday night
into at least Friday morning. Thereafter, a shortwave moving through
the upper level flow will bring yet another chance for showers and
storms Friday evening into Saturday morning.

Temperatures this week will be much cooler than last week. This will
be especially true on Wednesday and Thursday with highs likely
staying in the 60s. We should then see a warm up into the weekend
with highs jumping back up into the 80s.

&&

.Aviation...(18Z TAF Issuance)
Issued at 125 PM EDT Sat May 20 2017

Have a line of broken showers nearing SDF this hour, and some
lighter development in the BWG/LEX area. The first line may yet get
to the point of bringing some thunder to the LEX vicinity late this
afternoon. Otherwise, expect a wind shift behind this line, with
ceilings improving within an hour or two behind it. Model time
height sections indicate some low level moisture around daybreak
Monday, but think the dry air building in will prevent fog
formation.

&&

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

$$

Update...EBW
Short Term...EER
Long Term...EER
Aviation...RJS



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