Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281512
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1112 AM EDT Fri Jul 28 2017

.Forecast Update...
Issued at 1051 AM EDT Thu Jul 27 2017

Slow moving frontal boundary remains oriented along the Ohio River
this morning.  Drier air was pushing into central OH/IL/IN this
morning, but lower 70s dewpoints still reside south of the I-70
corridor.  An area of surface low pressure was located just
southwest of the Louisville metro area.  This feature will slide
east-southeast this morning and into the afternoon hours.

Short range model solutions suggest that convection will ramp up in
the next few hours in areas south and southeast of this low pressure
center.  Strong shortwave trough continues to migrate through the
Great Lakes this morning with the help of a 90-100kt jet max.  Large
plume of deep moisture continues to reside over the region.  With
the front pushing slowly southeast, add in some daytime heating
along with the short wave passing by to the north, should result in
more widespread convective development this morning and particularly
this afternoon.  Current thinking is that axis of heaviest rainfall
will like fall along and southeast of a line from roughly Hartford
to Lexington.  Abundant cloud cover will likely prevent widespread
destabilization this morning.  However, some thinning of cloudiness
may result in more destabilization across the southern half of KY
this afternoon.  Model proximity soundings do show a decent amount
of instability available along with large PWAT values.  Wind shear
values are not all that great.  So the main threats with these
storms would be torrential rainfall, some gusty winds here and
there, along with plenty of CG lightning strikes.

Not all areas are going to pick up heavy rainfall today.  However,
those areas that get in on the action could see some locally higher
amounts.  Would not be surprising to see some 3-4 in/hr rainfall
rates in some of the storms which may end up dropping 1-2 inches
locally.  This may result in some localized flooding in low-lying
and poor drainage areas.  Overall thinking is that the best threat
of more widespread flood problems will exist a bit to the east of
the I-75 corridor across the coalfields of SE KY.

For this forecast update, have generally lowered highs slightly in
the central and SE sections due to anticipated cloud cover and
precipitation.  Temperatures will probably be a bit warmer over our
northern sections of our southern IN counties where drier influx of
air makes it in this afternoon resulting in more sunny conditions.
Drier conditions from north to south are expected late this
afternoon and into the evening hours with most precipitation expected
to end in the 29/01-02Z time frame.

&&

.Short Term...(Today through Saturday)
Issued at 245 AM EDT Fri Jul 28 2017

One more day of showers and storms is in store for the region, then
a change to cooler and drier weather for the weekend. The cold front
bringing this change is currently just to the north of the forecast
area, stretching across central IN. This front will sink south
through southern IN and central KY this morning into the afternoon.

Current radar has mainly showers ongoing across the region with just
a few lightning strikes showing up. Showers and storms will continue
off and on through the early evening hours, with some precip
possible even behind the front today. The latest high resolution
guidance shows a relative lull after sunrise with more storms
developing this afternoon in association with the daytime heating.

Soundings do show the region becoming moderately unstable this
afternoon and a few strong storms with gusty winds will be possible,
mainly across central KY. Additionally, precipitable water values
will remain in the 2" range. Heavy downpours and the potential for
some localized flooding issues will continue through the afternoon.

Precipitation should come to an end fairly quickly through the
evening as the drier air behind the front really begins to work in.
Dewpoints will fall into the upper 50s to lower 60s tonight with
lows in the lower to mid 60s. Highs Saturday will be quite nice for
this time of year, topping out in the upper 70s to lower 80s.

.Long Term...(Saturday night through Thursday)
Issued at 251 AM EDT Fri Jul 28 2017

The long term period will be relatively quiet. Aloft we will have
ridging to the west and troughing to the east. Surface high pressure
will be in place through mid week. This will bring dry weather
through Wednesday. Another cold front will move in towards the end
of the work week bringing the next chance for showers and storms.

The long term will start out relatively cool with lows on Sunday
morning in the mid 50s to around 60. A warming trend is then in
store through mid week. Dewpoints will be on the rise with
temperatures warming back up to near normal for this time of year.

&&

.Aviation...(12Z TAF Issuance)
Issued at 636 AM EDT Fri Jul 28 2017

Moisture rich air mass ahead of an approaching cold front will bring
scattered showers and lower ceilings to the terminals this morning.
Current observations show ceilings in the 800 to 2000 ft range
across southern Indiana and central Kentucky. With baggy surface
winds and scattered showers around, expect the IFR to low-end MVFR
conditions to persist through mid morning. By late morning and in
the afternoon, some improvement in ceilings is likely but also will
introduce the chance of thunderstorms with daytime heating.

Cold front and northerly wind shift will pass through the TAF sites
this afternoon, last at BWG this evening. Much drier air and
improving conditions are expected to develop in its wake. By the end
of the TAF period, high pressure nosing down into the region will
usher in much drier air with north breezes.


&&

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

$$

Update.......MJ
Short Term...EER
Long Term....EER
Aviation.....ZT



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