Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 201918
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
318 PM EDT WED JUL 20 2016

.SHORT TERM (Now through Thursday Night)...
Issued at 300 PM EDT Wed Jul 20 2016

...First Significant Heat of the Summer Coming...

Big story this period will be our going into a heat wave. Already
have had some hot temperatures today, despite a cloud shield over us
from earlier and current convection. Temperatures have reached 90 at
all of the main climate sites. Tomorrow low-level thicknesses
increase, and with more sunshine expected, we should see high
temperatures go more into the low to mid 90s. Dewpoints solidly in
the low to mid 70s along and west of the I-65 corridor, this should
mean heat indices jumping to near 105 in some spots. Debated about
holding off on a heat advisory to Friday, but with the possible
prolonged nature of this event, decided to go ahead with the
headline.

A lobe of the ridge aloft should suppress convection tomorrow, so
went ahead and removed noticeable storm chances. Of some concern to
the heat forecast is what the WRF-NMM and ARW both show dropping
down late Thursday night, an MCS. The other models are not showing
such a system, but the flow aloft, being from the north by then
would make sense. Will have to keep an eye on updates to see how
this system evolves in the model domain.

.LONG TERM (Friday through Wednesday)...
Issued at 245 PM EDT Wed Jul 20 2016

...Continued Hot and Humid Likely Through This Weekend...

The WRF`s mentioned above drop that system down quickly Friday
morning. Even if it should develop and come through here, the added
humidity and sunshine later in the day likely will keep heat indices
into the Advisory range, so went ahead and pushed the expiration
time to 00Z Sunday, after coordination with neighboring offices.

That system dropping down should christen us for isolated to widely
scattered storms the next few days...either from systems moving
around the periphery of the ridge or just airmass diurnally driven
thunderstorms. Have storm chances of 20-40 percent through the
weekend, which could provide some cooling relief.

Monday, a frontal boundary will drop into the region. How far south
it gets before stalling is in question. Rain chances should be
highest Monday, with that boundary aiding in storm development and
expansion. After that, rain chances are based on a blended forecast,
and that keeps isolated to widely scattered storms through midweek.
Thicknesses do go down for the work week, but added humidity will
keep heat indices at least in the 90s outside of storms.

&&

.AVIATION (18Z TAF Update)...
Issued at 1211 PM EDT Wed Jul 20 2016

A few thunderstorms near BWG/SDF will be the main near-term concern.
A few storms have developed across west-central KY well west of BWG
and SDF.  Have timed these showers and a few rumbles of thunder into
SDF with a TEMPO group, but will leave any TEMPO group out of BWG
for now given that convection may just stay off to the west.
Outside of any storm, expect passing mid/high clouds with generally
light and variable winds.

Any storms will wane tonight, leaving just some passing mid/high
clouds.  Winds will be light, thus think we could see some fog
development at BWG, especially if it rains there this afternoon.
Otherwise expect a dry day tomorrow with just scattered cu/high
clouds and light winds.

&&

.LMK Watches/Warnings/Advisories...
KY...Heat Advisory from noon EDT /11 AM CDT/ Thursday to 8 PM EDT /7
     PM CDT/ Saturday for KYZ023>030-045-053-061>063-070>075.

IN...Heat Advisory from noon EDT /11 AM CDT/ Thursday to 8 PM EDT /7
     PM CDT/ Saturday for INZ076>078-083-084-089>092.

&&

$$

Short Term........RJS
Long Term.........RJS
Aviation..........KJD


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