Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 230714
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
314 AM EDT Thu Oct 23 2014
.SHORT TERM (Now through Friday)...
Issued at 240 AM EDT Thu Oct 23 2014
The synoptic pattern early this morning features weak shortwave
ridging across the Ohio Valley. However, a shortwave trough will
push in from the northwest tonight into Friday, bringing an increase
in cloud cover and a small chance for a few sprinkles.
Clouds continue to persist early this morning across portions of the
Northern Bluegrass. However, there have been large breaks occurring
in these clouds across portions of southern Ohio, which will
continue to push southwest into KY. The clouds have kept
temperatures up thus far overnight, which will likely inhibit
widespread frost formation across portions of the Northern
Bluegrass. Elsewhere, temperatures have fallen into the 30s and
lower 40s. These readings will continue to drop a few more degrees
over the coming hours, thus some frost formation still appears
likely, especially in sheltered areas.
The region will see abundant sunshine today as surface ridging
remains fixed over the Ohio Valley. With the surface high parked
over the region, turbulent mixing will be limited. Thus, despite
850mb temps rising to near 10C, surface temperatures will only top
out in the low to perhaps middle 60s.
For tonight, the aforementioned shortwave trough will approach the
region. This will make for an increase in cloud cover from west to
east through the overnight hours into Friday. This shortwave trough
has limited deep moisture, and will be fighting a rather dry
near-surface airmass. Therefore, do not expect anything more than
increased cloudiness and perhaps some virga/a few sprinkles out of
this system late tonight into Friday. Lows tonight will dip into
the lower 40s, with highs on Friday recovering back into the middle
.LONG TERM (Friday Night through Wednesday)...
Issued at 308 AM EDT Thu Oct 23 2014
Weak high pressure at the surface Friday night will give way to a
cold front moving through the area Saturday. The front will be
weakening and only some shallow low level moisture will be
associated with it, so while we`ll see an increase in cloudiness it
appears the front will be free of measurable precipitation. Lows
Friday night and Saturday night should mostly be in the 40s. Highs
on Saturday ahead of the front may be able to rise into the 70s,
though that will depend in part on just how much cloudiness there
is. The numbers that are in the forecast right now may be a little
Sunday through Monday night high pressure over the southeastern U.S.
will keep us dry. Sunday will be cool with temps in the 60s as the
high is just about overhead. On Monday, though, we`ll be in return
flow behind the high and ahead of an approaching cold front.
Southerly breezes should help to propel us well into the 70s.
That cold front will draw closer on Tuesday but will remain to our
west, with another day in the 70s in store for southern Indiana and
central Kentucky. Unsurprisingly, the models have trended this
front slower, and it looks like the daylight hours Tuesday may be
dry, especially east and southeast of Louisville.
The front will then sweep through Tuesday night and Wednesday.
Leaned more on the GFS for this forecast since it has begun to show
some consistency over the past couple of runs. The EC has varied
quite a bit from run to run, and the operational run doesn`t look
much like the ensemble mean. Given that, it looks like we should
have a band of showers, and maybe a few rumbles of thunder, pass
through the entire region Tuesday night, with possible redevelopment
over Kentucky on Wednesday. Given all this, we have reduced PoPs
Tuesday, kept chance PoPs Tuesday night, and increased PoPs on
No frosts or freezes are expected through the 30th.
.AVIATION (06Z TAF Update)...
Updated at 1257 AM EDT Thu Oct 23 2014
The near-term TAF concern continues to be the persistent MVFR
stratus deck near KLEX. Given northeast flow at this cloud level,
expect this deck to persist at KLEX for at least the next few
hours. There may be some breaks at times, but will continue a
broken MVFR deck there into the mid-morning hours.
Some shallow ground fog is possible at KBWG this morning. However,
guidance has come in a bit more optimistic, and depressions are
still at 4 degrees, so will limit any vsby restrictions to just a
TEMPO group with this issuance.
Otherwise, today will feature just some passing high clouds at all
sites with VFR conditions persisting. Winds will be light and
variable as a surface ridge crosses the region.
KY...FROST ADVISORY until 9 AM EDT /8 AM CDT/ this morning FOR
IN...FROST ADVISORY until 9 AM EDT /8 AM CDT/ this morning FOR