Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 191448
Area Forecast Discussion
National Weather Service Louisville KY
Issued by National Weather Service Paducah KY
1048 AM EDT TUE JUL 19 2016
Issued at 1048 AM EDT Tue Jul 19 2016
Early morning convection down across southern KY has dissipated and
skies were mostly sunny across the region. Temperatures had warmed
into the lower to middle 80s and highs this afternoon will warm into
the lower 90s. Dewpoints this morning were running in the mid to
upper 70s but these should mix out a bit during the afternoon.
Nonetheless, with highs in the lower 90s and dewpoints in the lower
to mid 70s, this will produce heat indices into the 95-100 degree
range this afternoon.
As for convective chances this afternoon. Agree with the previous
forecast of less than 20 percent coverage. With the surface
boundary to our south and the lack of any type of forcing mechanism,
pure convective processes would be the sole mechanism. Convective
allowing models show rather sparse convective coverage with no
particular organization. So for now, plan on leaving dry forecast
.SHORT TERM (Now through Wednesday)...
Issued at 300 AM EDT Tue Jul 19 2016
The synoptic pattern early this morning features an expansive ridge
strengthening across the nation`s midsection, with a trough sliding
into the Northeast. This has placed the Ohio Valley within
generally weak northwesterly flow aloft, a pattern which will
transition to more ridging aloft through the period.
Convection from yesterday has helped to push an effective boundary
just southwest of the forecast area this morning. This boundary
currently resides from west-central TN northwestward to portions of
western KY, southern IL, and eastern MO as is indicated by the
surface theta-e gradient. While an isolated shower/storm will be
possible along this boundary early this morning as the very weak low-
level jet veers atop it, just don`t see much synoptic or even
mesoscale support to warrant any mentionable pops at this time. Area
webcams do not show much in the way of fog as of yet, but obs to the
north of the region have already began to fall. Some of this fog
will develop southward into the region early this morning, thus will
include in the grids.
For this afternoon/evening, have gone ahead and dried out the
forecast. It appears with the boundary dipping just to the south of
the region, enough surface ridging and "drier" low-level air will
combine to promote a dry forecast. Can`t completely rule out a few
stray storms across southern KY in closest proximity to the front,
but think coverage will be less than 20 percent. A good amount of
sunshine will help temperatures climb into the upper 80s to low 90s
despite weak northerly surface flow.
On Wednesday, upper-level ridging will begin to take more of a hold
on the region. While once again an isolated storm or two will be
possible, coverage is not expected to be high enough to warrant any
inclusion into the forecast given the building capping aloft. Highs
will be smilier to today, with upper 80s and low 90s expected with
heat indices likely pushing 100 degrees in places.
.LONG TERM (Wednesday Night through Monday)...
Issued at 313 AM EDT Tue Jul 19 2016
...Dangerous heat possible late this week into this weekend...
The synoptic pattern at the start of the long term period will
feature an expansive ridge across much of the nation`s midsection, a
regime which will persist through the majority of the long term
period. This will bring hot temperatures to the region, along with
a mainly dry forecast.
Thursday through at least Sunday will feature very warm
temperatures, with the worst of the heat expected Friday and
Saturday. It is during this time that temperatures will climb into
the middle to even upper 90s. Have continued to go with the idea
that limited turbulent mixing due to a very weak surface pressure
gradient and seasonably green conditions will keep numbers from
getting too out of hand as some of the raw guidance suggests.
However, mid to upper 90s in the typically warm spots seem like a
good bet Thursday through at least Sunday, with heat indices from
100-110 each afternoon. These values could approach the warmest
temperatures since 2012, thus people who are forced to be outdoors
are urged to use caution and drink plenty of fluids.
Given the northern bias in synoptic-scale guidance of MCS
tracks/effective boundaries over the past month or so, have gone
ahead and kept pops in the forecast Thursday through the rest of the
period. Tough to really pin down any real synoptic feature to focus
higher pops, thus have stuck with slight chance/chance wording as we
expect most areas to remain dry. If we are lucky enough to get some
storms through here, obviously they will help cut down on the heat.
.AVIATION (12Z TAF Update)...
Issued at 624 AM EDT Tue Jul 19 2016
Light fog at BWG will linger through about 12-13z before burning
off. Otherwise, look for VFR conditions at the TAF sites for the
period. A stay shower or storm is possible at BWG but chances are
too low to mention in the TAF for now. Winds will be light/variable
the become out of the north/northeast 7-10 kts by afternoon along
with a scattered cu deck with bases 4 to 5 kft.