Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 261705
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
105 PM EDT Tue Aug 26 2014
...Updated Aviation Discussion...
Issued at 1125 AM EDT Tue Aug 26 2014
Forecast is largely on track this morning, although did make an
update to add some isolated showers or a storm west of the I-65
corridor. Current analysis shows dew points starting to pool in this
area on the western edge of the surface high. SPC mesoanalysis
moisture convergence parameter also confirms this. Additionally,
have support from the HRRR that isolated to widely scattered
showers/storms should pop up by early afternoon.
Forecast soundings indicate at least moderately strong instability
will be available this afternoon due to the very moist low levels
combined with steep low level lapse rates. Deep layer flow is quite
weak, so only expect localized gusty winds in the vicinity of
showers/storms and some brief heavy rainfall.
.SHORT TERM (Now through Wednesday)...
Issued at 317 AM EDT Tue Aug 26 2014
Morning IR satellite and surface observations reveal mostly clear
skies across southern Indiana and central Kentucky. Some patchy fog
has developed in the typical fog prone areas and in areas that
picked up a bit of rainfall Monday afternoon. Temperatures remained
quite mild with readings in the lower-middle 70s. Expect quiet
weather to continue through the remainder of the overnight hours
with overnight minimums dropping only a few more degrees or so.
For Today/Tonight, the short term multi-model consensus continues to
be in agreement with increasing the strength of the mid-level ridge
axis overhead. This should result in another mostly sunny and muggy
day across the region. With some additional mid-level warming and
slight drying of the column, current thinking is that convection
will be a bit more isolated. However, high resolution convective
allowing models suggest that storms will fire up to our north along
the periphery of the ridge axis. These could slide southward in the
afternoon and affect our far northern areas of southern Indiana.
Thus, have maintained an isolated storm chance up that way for the
late afternoon hours. Afternoon highs will be similar to Monday
with readings in the upper 80s to the lower 90s. Skies are expected
to clear back out tonight as any convection dissipates after
sunset. Overnight lows will cool into the upper 60s in the far NE
to the lower 70s in the central and southwest.
For Wednesday, the upper level ridge axis is expected to shift a bit
further to the south along with the surface ridge axis. This will
allow a surface frontal boundary to sag southward through central
Indiana. Convection is expected to develop during the afternoon
hours along this front and this activity may eventually spread
southward into southern Indiana and the northern half of KY. For
now, isolated-scattered PoPs still look like a good bet at this
time. Afternoon highs will be warm once again with readings topping
out in the upper 80s in the north with lower 90s in the south.
.LONG TERM (Wednesday Night through Monday)...
Issued at 307 AM EDT Tue Aug 26 2014
Ridging across the southeastern United States will slowly shift
eastward through the long term. As it does so a shortwave trough
will approach from the west, moving across the upper Midwest Sunday
and across the Great Lakes region by Monday morning. At the surface
a weak frontal boundary near the KY/TN border at the beginning of
the period will eventually push back northward as a warm front
For Wednesday night a few residual showers or storms may be ongoing
at the start of the period. However, these should dissipate
overnight with mostly dry conditions expected. Diurnal storms are
expected once again on Thursday and Friday, particularly in the
vicinity of the frontal boundaries. The better chance will be on
Thursday with scattered storms across the region. Friday`s storms
look to be more isolated in nature.
Rain chances will increase through the weekend as the upper level
trough nears and its associated surface low lifts north of the
region. The best chances for storms this weekend looks to be on
Sunday as precipitable water values rise to around 1.9 inches and we
become moderately unstable. Will keep chances in the 40-50% range
right now considering there is still some differences in the
development of the system between the model solutions. Monday will
see a return to the more summertime diurnal pattern of storms before
a cold front approaches towards midweek.
Temperatures will be in the upper 80s to lower 90s through Saturday
with lows in the upper 60s to lower 70s. With rain and clouds
expected Sunday into Monday we should see a bit of a cool down,
particularly on Sunday with highs in the lower to mid 80s expected.
This will not last however, as a return to upper 80s is expected by
.AVIATION (18Z TAF Update)...
Issued at 105 PM EDT Tue Aug 26 2014
A few showers have popped up around the BWG terminal early this
afternoon where the best low level moisture convergence is occurring
on the western edge of the surface high. Have included VCSH mention
at BWG through sundown. SDF would be the other site that could
experience a shower or two this afternoon/evening, however coverage
is less certain in this area so will leave dry for now. Expect
generally light and variable winds today with any noticeable
gradient out of the ENE. Expect only Sct Cu around 4 k feet.
Some fog will be possible at the TAF sites again toward dawn, with
light and variable winds and scattered clouds around 4 k feet once
again on Wednesday. Some showers may settle across SDF/BWG tomorrow
afternoon ahead of a frontal boundary.