Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 220724

Area Forecast Discussion
National Weather Service Louisville KY
324 AM EDT Thu Jun 22 2017

.Short Term...(Today through Friday)
Issued at 300 AM EDT Thu Jun 22 2017

It`s about to get fairly humid. East/west boundary of 2 inch
precipitable water now lies over central Tennessee and is forecast
to cross into southern Kentucky by 12Z. It should reach our southern
Indiana counties by mid afternoon. Rain chances will not be too far
behind that surge, with scattered showers/storms moving to the I-64
corridor by lunchtime. Think there will be a slight break behind
this leading edge of rain chances, but coverage should fill in with
any type of heating.

With the tropical airmass in place, any showers/storms that develop
will be capable of heavy rainfall. Another threat is gusty low-level winds do pick up in the afternoon to the 40-50
kt range at 850 mb (at least per NAM/RAP soundings). These winds
look valid as latest VWP from the Deep South do show these stronger
winds aloft. Cannot rule out a brief spinup given the low-level
shear in place.

We still should see a lull in the evening hours, with loss of
heating, but then models continue to show a well-defined deformation
band of heavier precip forming somewhere along the Ohio River late
Thursday night into Friday morning. A majority of model guidance
place this band just north of the river before 12Z, with some
hinting at additional weaker bands over central Kentucky. Given the
moist airmass in place, it will not take much instability to spark
new showers overnight, and again these will have potential to dump
some quick heavy rains. Briefly considered a flash flood watch for
these areas, but given some uncertainty in exact placement, and
after collaboration with neighboring offices and WPC, decided to
hold off for now and continue mentioning the threat in our outlook

Assuming that band sets up over southern Indiana, any heating over
Kentucky during the day Friday should allow for new storm
development. In addition, the remnants of Tropical Storm Cindy will
be approaching our border with TN, providing extra forcing for deep
tropical rain showers. The period from Friday afternoon through
evening should provide the best chance for any flash flood
potential, with a relatively quick 2-4 inches of rain possible in
that period.


.Long Term...(Friday night through Wednesday)
Issued at 300 AM EDT Thu Jun 22 2017

The surface low pressure that are the remnants of TS Cindy should
move into western Virginia a little after midnight Friday night. By
this point it will be absorbed into a cold front that will swing
through our region that evening. Model guidance now brings an
earlier end to precip, clearing our eastern zones by daybreak
Saturday. Rainfall totals for the event should easily range from 2-4
inches, but would not be surprised to see some 6"+ amounts.

High pressure building into the region behind this low should bring
several days of dry weather and cooler conditions. A couple of
hiccups in the dry air may come over our Bluegrass and southern
Indiana zones as upper troughs swing by to the north later in the
day Saturday and then again Monday.


.Aviation...(06Z TAF Issuance)
Issued at 1240 AM EDT Thu Jun 22 2017

Showers and thunderstorms currently over the Gulf Coast states are
gradually moving northward toward the region this morning. Expect
most of the activity to reach south-central Kentucky around or
shortly after sunrise and gradually move into north-central Kentucky
and southern Indiana by late morning to mid afternoon. MVFR to
isolated IFR cigs/vis will be common with the showers and
thunderstorms. Should see a lull in precipitation by late afternoon
or early evening, starting in south-central Kentucky, which will
allow visibilities to improve to VFR, but ceilings will remain MVFR.
Another round of showers and thunderstorms could impact the region
overnight into early tomorrow morning bringing reduced cigs/vis,
though timing of the second round remains uncertain at this time.




Short Term...RJS
Long Term...RJS
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