Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 281721
Area Forecast Discussion
National Weather Service Louisville KY
1221 PM EST SAT NOV 28 2015
...Updated Aviation Discussion...
Issued at 1017 AM EST Sat Nov 28 2015
Current forecast remains generally on track this morning. Well
talked about cold front continues to slowly sag southward toward the
Ohio River. Several bands of showers continue to move out of
western KY and into the I-65 corridor. Echoes out toward the I-75
corridor are now starting to reach the ground as the atmosphere
slowly saturates. Temperatures this morning exhibited a gradient
with upper 40s across our southern IN counties north of the front
with upper 50s to lower 60s across central and southern KY.
For the rest of the morning and into the afternoon hours, we expect
cloudy skies and periods of rain to continue to move across the
region. Axis of best precipitation will generally be across
central/southern KY south of the Ohio River. Rain shower activity
across southern Indiana will be less widespread. Temperatures will
generally remain in the mid-upper 50s across southern/central KY
with temperatures dropping slowly into the lower-mid 40s across
Only some minor tweaks were required for the short term grids in
T/Td/PoP/Wx which results in very minor changes to the onging
.SHORT TERM (Now through Sunday)...
Issued at 255 AM EST Sat Nov 28 2015
A weakening cold front will sink slowly southward across Kentucky
during the weekend, continuing to act as a focus for rain. We can
lower the PoPs some in southern Indiana tonight and Sunday as the
plume of rich 1.5-1.75 PWAT air streams mainly over the
Commonwealth. Weekend rainfall amounts in southern Indiana should be
in the 0.6-0.8 inch range, and in Kentucky around an inch.
This evening, models are showing deep saturation and a sharp
inversion just a few hundred feet off the surface. MOS is suggesting
fog across northern central Kentucky, in an area of nearly calm
surface winds associated with the weak, broad frontal zone. Will put
some patchy fog in the grids to account for this possibility.
Temperatures will be very tricky to figure out today given the
clouds, unevenly distributed rain, and sagging front. Will go for
lower and middle 50s north of the Ohio River to middle 60s in
Lows tonight will mostly be in the 40s, though southern Kentucky
will probably not drop further than the lower 50s. Depending on how
low the temperature at Bowling Green gets before midnight tonight,
and in any heavier patches of rain today, the daily record warm
minimum of 54 degrees set in 1934 may be in jeopardy.
Cool air coming in behind the front will restrict highs to the 50s
on Sunday...maybe even just upper 40s in southern Indiana and the
northern Blue Grass.
.LONG TERM (Sunday night through Friday)...
Issued at 308 AM EST Sat Nov 28 2015
The upper low that has been over the Intermountain West will finally
begin to head east at the start of the long term, crossing the
Midwest Tuesday and the Great Lakes Wednesday. It`s corresponding
surface low will move slightly ahead of the upper low Monday and
Monday night, pulling a warm front north through the Tennessee and
Ohio Valleys, followed by its attendant cold front swinging through
the region Tuesday as the system becomes stacked over the Lakes. As
a result, showers will continue to be in the forecast Monday-
Tuesday. Strong winds aloft will accompany the cold fropa Tuesday,
and models are beginning to show a little bit of instability just
ahead of the front. However the instability still looks weak enough
to leave thunder out of the forecast for now. The Lake Cumberland
region and the southern Blue Grass stand the best shot at a rumble
Winds will be somewhat gusty on Tuesday as the front moves through,
and gustier still on Wednesday in a tight gradient between the low
to our north and high pressure over the Plains.
That high, of Pacific origin, will provide us with dry weather for
the second half of the work week. Morning bus stop temperatures
really won`t be too bad for December, right around freezing. Highs
will be around 50...which is just about normal.
.AVIATION (18Z TAF Update)...
Updated at 1220 PM EST Sat Nov 28 2015
Light rain has now overspread the TAF sites and will persist
through much of the forecast cycle as a frontal boundary stalls
in the region. Surface cold front is now just W of the SDF/BWG
sites, with noticeable drops in ceilings as it approaches. Will
start BWG off low MVFR with a drop into IFR by 2 PM CST. LIFR
ceilings near minimums are expected then through the evening and
SDF will start off IFR, with a drop into LIFR and near minimums just
before midnight. Rain will taper off to drizzle during this time,
but expect the low ceilings/vis to persist through mid morning on
Sunday before a return to low MVFR.
LEX will start off MVFR with a drop into IFR between 1 and 3 PM EST.
Ceilings will continue to drop, likely to near or just above
minimums by sunset. Low ceilings are then expected to hold through
this cycle, although rain will quit shortly after Midnight.
Winds will be SW ahead of the front with a change to variable and
then light NW thereafter. Visibilities will vary between 2-5 SM
during mostly light rain.