Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 021038
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
638 AM EDT Thu Oct 2 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Friday)...
Issued at 249 AM EDT Thu Oct 2 2014
Today will be a warm one as we sit in southerly flow between high
pressure along the East Coast and a storm system over the lower
Missouri Valley. With partly cloudy skies and dry ground, readings
will reach into the middle and upper 80s this afternoon. A few spots
could even touch 90. Isolated thunderstorms will be possible west
of Interstate 65 late this afternoon as a weak wave comes northeast
from the lower Mississippi Valley.
Tonight a primary area of low pressure will deepen as it moves from
Iowa into Michigan, with its attendant cold front arriving in the
Wabash Valley by early Friday morning. Showers and thunderstorms
will be widespread ahead of the front, and will sweep into southern
Indiana and central Kentucky from the west. The best chances for
rain for us will be after midnight. Though a few gusty winds can`t
be entirely ruled out as the low level jet kicks up to around 40 or
50 knots, it appears that the storms will be slightly elevated. The
best chance for anything strong to severe will be west of I-65 as a
line of storms, which potentially could be severe off to our west
from Illinois to Texas, moves in. Low temperatures tonight will be
in the 60s.
On Friday the cold front will sweep through the region, accompanied
by widespread showers and embedded thunderstorms. The convection
looks to become more surface based on Friday, but mid-level lapse
rates will be weak and the atmosphere will be well worked-over from
earlier convection, so once again severe weather looks unlikely.
After highs in the 70s on Friday, temperatures will begin to fall by
mid to late afternoon behind the front, especially north through
west of Louisville as much cooler air rushes in. West winds will
likely gust to around 25 mph in the afternoon.
.LONG TERM (Friday Night through Wednesday)...
Issued at 405 AM EDT Thu Oct 2 2014
There should be little doubt left that the change in seasons is upon
us at the start of this extended period. "Blustery" is not a word
that has been used for a while, but it fits well with at least the
start of the weekend.
Any post-frontal showers that persist in the stratocumulus that
follows in behind the cold front moving through Friday will end from
west to east Friday night. The clouds themselves, though, could be a
little more stubborn to leave, especially in the I-75 corridor,
thanks to high relative humidity in the surface to 850 mb range and
upslope flow into the Appalachians. Some lingering low clouds will
likely continue through Saturday morning over all but the southwest
corner of our CWA - around Bowling Green. By midday Saturday,
though, sunshine will prevail. With a tight surface gradient and the
core of the cold air sweeping through the Ohio Valley on Saturday,
though, gusty west-northwest winds and temperatures failing to warm
out of the 50s will counteract any warming from the sun.
By Saturday night, surface winds will drop off as the pressure
gradient weakens, and with mostly clear skies, radiational cooling
will allow temperatures to drop to their lowest levels in months,
with many locations reaching the upper 30s. Fortunately, the
thermal trough will be well past us by early Sunday, or the first
widespread frost of the season would have been likely then. Even
with the core of the colder air exiting, though, some sheltered
locations - especially in southern Indiana, along the Kentucky
River, and east of I-75 - could see a little frost by daybreak
The central and eastern part of the country remain in a long wave
upper level trough for the remainder of the extended. Even so,
surface winds become southwesterly enough to moderate temperatures a
bit into the early part of the work week. The models all hint at
another chance for rain on Monday with a sharpening of the upper
level trough. For now this does not look to be as potent as the
front coming through in the short term of this forecast, and
temperatures are expected to warm back into the 70s for highs, and
into the 50s for lows.
.AVIATION (12Z TAF Update)...
Issued at 638 AM EDT Thu Oct 2 2014
Dry, VFR conditions are expected today as we await an approaching
storm system coming in from the west. That system will spread
showers and thunderstorms into central Kentucky tonight, with the
most widespread coverage occurring after midnight and continuing
into Friday morning. Embedded thunder can be expected as well,
especially at BWG and SDF tonight, and LEX Friday morning. LLWS is a
possibility, but it looks borderline enough at this point to leave
out for now, and can be further evaluated in future forecast