Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 270020
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
820 PM EDT Tue Aug 26 2014
Issued at 810 PM EDT Tue Aug 26 2014
Slightly drier air has tried to push westward from eastern Kentucky,
as copious moisture remains pooled in west-central Kentucky and
southern Indiana. Focus for isolated T-storms remains north and west
of Louisville, albeit just barely so with an isolated cell just
across the river in Indiana as of 00Z. Still expect this isolated
convection to die out over the next couple of hours, but have had to
extend the slight chance POPs a little farther into the evening for
our Indiana counties. The zone forecasts remain unaffected, but
grids have been tweaked for the point-and-click and other
.SHORT TERM (Now through Wednesday Night)...
Issued at 320 PM EDT Tue Aug 26 2014
Very isolated showers have developed west of I-65 this afternoon in
an area of better low level moisture (higher Td`s). Will keep a 20%
mention across the western half of the CWA until sundown. Otherwise,
temperatures will peak in the upper 80s and low 90s, with mostly
sunny skies outside of any shower/storm.
Will watch as storms continue to build southward across central
Indiana late this afternoon, ahead of a frontal boundary. Will keep
the same thinking that these storms will dissipate with the loss of
peak heating before arriving in our southern Indiana counties later
this evening. Will monitor progress through the evening for possible
inclusion of precipitation chances. Otherwise, only real concerns
overnight will be fog potential. Have highlighted the area for best
fog where highest dew points will continue to be positioned, which
is generally along and west of I-65.
As we move into Wednesday, the frontal boundary will slide
southward, closer to the Ohio River as the upper ridge breaks down a
bit in response to a passing wave over the Great Lakes. This will
allow for isolated to scattered shower and storm development with
peak heating over our southern Indiana and extreme north central KY
counties. Basically, I-64 and northward. Highs should be similar to
today with temps topping out in the upper 80s and low 90s.
Will only mention some lingering sprinkles on Wednesday night as the
front sags more toward central KY. Will maintain mild lows in the
upper 60s to the low 70s.
.LONG TERM (Thursday through Tuesday)...
Issued at 314 PM EDT Tue Aug 26 2014
Persistence forecasting at play for the long-term as run-to-run
model consistency features the well-advertised upper-level ridge in
the SE CONUS shifting toward the FL/GA border along the Atlantic,
opening up opportunities for shortwaves/vort maxes to barge through.
The most notable large-scale feature is the cut-off low ejecting
out of the Rockies and into the central Plains, transitioning into
an open wave as it interacts with the tenacious ridge.
For most of the days throughout the upcoming period, there will be
plenty of moisture with PWATs generally around or greater than 1.5
inches. Friday is the exception as drier air briefly infiltrates the
forecast area, limiting precip chances. By Saturday, the surge of
Gulf moisture returns as it flows in around the ridge and ahead of
the approaching low. Current indications point to more organized
convection over the weekend with the better synoptic forces at
play. Bottom line is that the summertime pattern of
afternoon/evening convection will be possible with the highest
chances occurring over the holiday weekend with the aforementioned
Mid 80s to low 90s will be the rule of thumb for highs each day with
the cooler day looking to be Sunday, thanks to the cloudiness and
precip anticipated with the low. By early next week, the forecast
area`s temperatures should rebound to near normal. Lows will range
from the upper 60s to lower 70s and dewpoints will be similar
throughout the period.
.AVIATION (00Z TAF Update)...
Issued at 705 PM EDT Tue Aug 26 2014
Isolated showers that have been affecting far southern Indiana and
central Kentucky have remained north and west of SDF and BWG, more
in line with the best moisture pooling. Concerns for any convection
affecting the terminals this evening is now minimal and the
afternoon cu field is fading.
The challenge overnight will be whether enough low-level moisture
remains to form significant fog by Wednesday morning. With LEX
dewpoints dropping into the mid 60s in the heat of the afternoon and
an easterly component to this evening`s winds, do not expect any
restrictions to vis there. SDF should also stay VFR due to heat
island. BWG is the tricky one, as it remains to be seen whether
enough drier low-level air can filter in there. Will go prevailing
MVFR after midnight, with a low to moderate-confidence TEMPO for IFR
visibility around daybreak.
Expect VFR conditions and light NE winds from mid-morning onward on