Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 280535
Area Forecast Discussion
National Weather Service Louisville KY
1235 AM EST SAT NOV 28 2015
...Updated Aviation Discussion...
Issued at 727 PM EST Fri Nov 27 2015
Current forecast remains on track this evening. Column is starting
to saturate downward and rain is making it to the surface in areas
along and west of the I-65 corridor. We expect rain to continue to
slowly pick up in intensity in areas west of I-65 by late evening.
Rain will gradually head eastward and make it to the US27/127
corridor around midnight and then toward the I-75 corridor later in
the overnight. For now, only some minor adjustments to the PoP/Wx
grids were made.
Surface cold front remains well out to our west and
will work into western KY late tonight. In the meantime, a
southerly flow will keep temperatures generally mild this evening
and into the overnight. Temperatures will drop into the mid-upper
50s for the overnight period. Current forecast temps have this well
covered at the moment. However, we did make some subtle changes to
the short term T/Td grids to bring them into better alignment with
current conditions and expected trends.
.SHORT TERM (Now through Saturday Night)...
Issued at 323 PM EST Fri Nov 27 2015
Now - Saturday Night...
Rain is beginning to overtake our NW CWA as the deeper plume of
moisture arrives ahead of the slow moving front. Frontal boundary is
currently situated from the Wabash River Valley, down through the MO
Bootheel, and into eastern TX. This will very slowly work toward the
region, and stall over our center CWA through Saturday night. We`ll
stay mild ahead of this frontal feature with small diurnal trends.
Temps in the mid 60s right now will only fall into the mid 50s
The Ohio River Valley is situated under deep southwest flow between
an upper ridge established over the SE CONUS and troughing and a
cutoff low to our NW. This will keep a steady feed of moisture
streaming over our area, parallel to a very slowly moving surface
front through the weekend. The focus for rainfall will be across the
NW half of our CWA through the first part of Saturday, however focus
will shift to mainly the southern and eastern portions of our area
later Saturday. This will occur as the upper flow flattens in
response to the retrograding upper ridge and advancement over the
cutoff low into the northern Plains, helping to slide the frontal
boundary through and shift the orientation/axis of rainfall.
Overall rainfall totals during this time should be between an inch
and an inch and a half within about 50 miles either side of the Ohio
River. Areas across southeast KY should expect between .33" and .75".
Temps should reach the mid and upper 50s in many spots on Saturday,
with our SE climbing to the low 60s. Will start to see a cool off on
Saturday night behind the front in our NW. Look for mid and upper
40s. South of the boundary look for mid 50s.
.LONG TERM (Sunday through Friday)...
Issued at 323 PM EST Fri Nov 27 2015
Sunday - Tuesday Night...
We`ll be sandwiched between and upper ridge to our south and a
slowly moving cutoff low to our NW to end the weekend. This will
keep fairly zonal flow across our region with a stalled frontal
boundary near our southern border. Moisture transport will continue
nearly parallel to this boundary, keeping enough deep moisture in
the area to warrant likely/categorical pops near the front and LLJ.
Main rainfall focus will be across our southern half of the CWA
during this time, although light precipitation will still be
possible even across our north later Sunday as a warm front develops
and lifts north across our region. This will be in response to a
surface low developing over the central Plains as the cutoff low
begins to deepen and eject into the upper Midwest.
A cold front trailing from the aforementioned system will move into
our region later Monday night through Tuesday bringing a final round
of rainfall through Tuesday. Perhaps an elevated rumble of thunder
will be possible across our south with this final push.
Overall rainfall should range between an 1 to 2 inches across the SE
half of the CWA during this time, with a half an inch to 1 inch
across our NW half. Overall totals should range between 2-3 inches
for the whole CWA through the weekend and into the first half of
next week. Highest totals should be near the Bowling Green region.
Temperatures will be mild across our south on warm side of the front
on Sunday. Look for mid and upper 50s, with upper 40s across our
north. Warm sector will get a bit more established over our CWA on
Monday in response to the warm frontal development mentioned above
so will go with 50-60 everywhere. 50s are expected on Tuesday, with
temps falling in the afternoon across our west behind the cold
front. We`ll drop off into the 30s by Tuesday night.
Wednesday - Friday...
We look to dry out for the end of the week as front pushes east and
dry slot controls our region. Will have to watch a southern stream
system on Thursday night/Friday, but will go dry for now as deepest
moisture passes SE. We`ll still be under the upper trough axis and
cloudy through Wednesday. Highs will only be in the 40s to around 50
Wednesday and Thursday, with lows in the low 30s Wednesday night and
.AVIATION (06Z TAF Update)...
Updated at 1230 AM EST Sat Nov 28 2015
Although all TAF sites remain at VFR conditions despite the light
rain falling early this morning, conditions will slowly deteriorate
through the pre-dawn hrs. METARs reveal IFR/LIFR conditions right
behind an approaching cold front. The front will make slow progress
SE over KY over the next 24 hrs. Through around 10-15Z expect VFR
with occasional dips into the MVFR cat. By 10-11Z, BWG/SDF should
go solidly into the low end MVFR cat with LEX following closer to
the 14-15Z. From mid morning through early afternoon expect
conditions to worsen with MVFR occasionally dipping into IFR. Solid
IFR conditions are expected at SDF by 15Z and BWG/LEX by 17-18Z. The
front will finally get through SDF by around 21z and BWG/LEX by 0-
1Z. Behind the front expect at least IFR conditions and probably
dropping to LIFR or lower. Since this is nearing the very end of
the TAF period, will keep things optimistic with IFR for later this
evening. Also with the fropa expect a wind shift from SSW to WNW.
Light rain is expected to continue throughout the entire TAF period.