Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 301923
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
323 PM EDT Wed Jul 30 2014
.SHORT TERM (Now through Thursday Night)...
Issued at 250 PM EDT Wed Jul 30 2014
The synoptic pattern this afternoon features an unusually amplified
pattern for late July, with a large trough across the Great Lakes
region and an upstream ridge across the western CONUS. This pattern
will persist through the short term period, keeping seasonably cool
conditions in place.
A PV anomaly was diving through the mean upper trough this afternoon
across IN and northern Ohio. The ascent associated with this
feature has helped to trigger some showers and thunderstorms across
portions of central Indiana and southern Ohio. As the system
continues to dive southeast, it may just be enough to spark an
isolated shower or rumble of thunder across the Northern Bluegrass.
However, given only marginal low-level moisture and the main upper
cold core off staying off to the north, think most places will
Clouds will diminish with sunset this evening, resulting in another
clear and cool night. Went close to persistence for low
temperatures tonight, which once again puts them in the mid to upper
50s, with the heat-island cities staying in the lower 60s.
On Thursday and especially into Thursday night, we will likely see a
bit more upper-level cloud cover push into southern and central KY.
This cloudiness will be in association with a weak system meandering
across the Southeast. Given the dry airmass remaining in place near
the surface, think any precip that may fall in the warm-air
advection regime Thursday night will likely not reach the ground,
thus will continue with a dry forecast.
.LONG TERM (Friday through Wednesday)...
Issued at 300 PM EDT Wed Jul 30 2014
August weather begins looking just like much of July with below
normal temperatures and little significant accumulation of
Despite some decay of the persistent upper level western U.S. ridge
and eastern U.S. trough, little in the way of active weather will
occur during the extended period. That doesn`t mean there will be
no precipitation, but don`t look for widespread moisture to fill the
accumulated precip deficit that`s starting to show up across much of
Shower/thunder chances will first return by midday Friday, then
linger through Saturday night. The highest POPs during this time -
are Saturday night as the long wave trough axis starts to press
eastward. All models are in decent agreement on this, but with the
standard variations on timing and location, will only go with a
broadbrush of 30-40 POPs for now. Given recent trends, it would not
be surprising to see this go through the forecast area without a
drop in some locations, while a few lucky sites get enough to keep
Partly to mostly cloudy skies will cover the forecast throughout the
period, and while dewpoints will rise into the lower to mid 60s,
they should not go any higher, so the dog days of August will be
late to arrive. Temperatures will hover just below seasonal norms,
which run from the mid to upper 60s for lows and the mid to upper
80s for highs this time of year.
.AVIATION (18Z TAF Update)...
Issued at 100 PM EDT Wed Jul 30 2014
High pressure will keep mainly VFR conditions through the TAF
period. Scattered cu will continue to develop this afternoon. Some
of these could gain some vertical depth near KLEX, thus cannot rule
out a stray shower there, but will continue to leave the forecast
dry as think most activity will remain off to the north. Otherwise,
cigs/vsbys will remain VFR at all sites through this evening.
Skies will go partly cloudy tonight as winds go mostly calm.
Despite there not being any light fog the past couple of nights,
think there may be a slightly better chance tonight at KLEX as
low-level moisture is a bit more established. Therefore, will
introduce a brief period of MVFR vsbys toward dawn. Otherwise, all
sites should remain VFR through the remainder of the TAF period.