Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 030539
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1239 AM EST WED FEB 3 2016

...Updated Aviation Discussion...

...Mesoscale Forecast Update...
Issued at 1155 PM EST Tue Tue Feb 2 2016

Widespread light to moderate rain with embedded steaks of heavy
rain will continue to move eastward across southern Indiana and
central Kentucky into the pre-dawn hours. The rain should move east
of the I-65 corridor during the 2am-3am time frame, and the last of
the showers should exit the Blue Grass shortly after sunrise.

Kentucky Mesonet sites have consistently been showing gusts of 40-45
mph (not associated with strong convection) so we`ll keep the Wind
Advisory going.

There have been a few instances of minor flooding so far. Heavy rain
will continue to be a possibility, and FFG numbers are low in the
east, especially the Lake Cumberland region. Additional Flood
Advisories may be needed. We`ve been reviewing river stages and
forecast rainfall, and it appears that major streams across the
district are in good shape.

The actual cold front is well back to the west from an occlusion
over northern Illinois SSW to the Arklatex. It will likely come
through the LMK CWA during the daylight hours this morning, so the
pre-dawn hours will continue to be quite warm in the lower and
middle 60s.

...Mesoscale Forecast Update...
Issued at 936 PM EST Tue Feb 2 2016

Let the rest of the Tornado Watch go. Environment is worked over
from first rounds of heavy rainfall, and no surface based
instability is left ahead of the front. Will still need to monitor
hydro through the overnight as surges of moderate to briefly heavy
rainfall will continue to traverse SSW to NNE over the region.
Overall axis of heavy rainfall will shift east, helping to limit
longer training potential. Overall, expect showers and storms to end
along and west of a line from Louisville to Bowling Green around 2
AM EST. Further east, the showers and storms look to exit our CWA
around 4 AM EST. Will let the Wind Advisory continue to ride as some
gusts over 40 mph may still occur in and around any thunderstorms. Ov

...Mesoscale Forecast Update...
Issued at 755 PM EST Tue Feb 2 2016

A ragged line of elevated showers and scattered thunderstorms is now
moving through central KY up through SE Indiana. These showers are
associated with a PWAT maximum around 1.4 to 1.5 inches and have
shown briefly high rainfall rates between 1 to 3 inches per hour.
Overall, these brief pockets of heavy rainfall should be short
lived, but may be intense enough to produce short-lived flash
flooding threat. Will need to continue monitoring hydro through the
late evening hours as there will be another round of showers and
storms to follow.

Latest radar/satellite/lightning data has shown some intensification
of the secondary line of storms over western KY/SW Indiana over the
past hour. This line is in a slightly better environment where a
meager axis of instability still exists, although overall is still
pretty unimpressive. Meanwhile, better forcing is beginning to arrive
as the more SW to NE aligned right entrance region of the upper jet
moves into the region. Have seen evidence of an intensifying low
level jet on regional VAD wind profiles, as a result.

Given the fact that there will still be some potential for a meager
instability axis to arrive in our SW and S CWA as the evening
progresses combined with the stronger forcing arriving, can`t
completely let the guard down yet. That being said, this area will
already be somewhat stabilized by the ongoing showers and storms and
will need to overcome at least some stability near the surface.
Therefore, think any damaging wind threat would be isolated and
mainly confined to our southwest and far southern CWA.

...Mesoscale Forecast Update...
Issued at 730 PM EST Tue Feb 2 2016

Large area of light to moderate rain looks like it will continue to
move eastward across the forecast area. A more prominent line of
thunderstorms is closer to the front and marching eastward across
western KY and southwest IN. There is a narrow window of instability
ahead of this line, but the chance for tornadoes getting into our
eastern forecast area looks pretty slim.  Thus will be canceling
part of the watch box with an update.  The threat is still fairly
small in our southwest forecast area, especially given that PAH is
not seeing any upstream reports of severe weather.  Still will allow
this line a few more hours to mature and possibly develop some
bowing segments.

...Mesoscale Forecast Update...
Issued at 530 PM EST Tue Feb 2 2016

A QLCS has formed over portions of western TN and west-central KY
early this evening, along the eastern edge of the surface-based
instability gradient.  Overall thinking is that this activity will
continue to struggle as it moves northeast, as mid/upper 50s
dewpoint inflow into this system is likely not lending to any
surface-based parcels. Can`t rule out some isolated warnings with
this line, but don`t expect anything major from this activity.

Guidance continues to suggest storms will fill in along the cold
front across western KY and TN over the next few hours.  This
process is already occurring, but thus far there are no warnings for
this activity.  Given this initial QLCS moving through now, we have
some doubts as to how severe this second line will become as it
moves through.  Not ready to downplay the threat too much yet, but
something we are monitoring.  The flood threat has become a bit more
of a concern though, especially across south-central KY where a few
rounds of storms are possible and where the heaviest snow fell.

.SHORT TERM (Now through Wednesday Night)...
Issued at 320 PM EST Tue Feb 2 2016

...Windy This Afternoon and Evening...
...Strong to Severe Thunderstorms Possible this Evening into
Tonight...

=================================
Environment and Forecast Analysis
=================================

Late this afternoon, several lines of SW to NE moving convection
have developed along and ahead of the front.  The most notable line
was over western TN and western KY with a few stronger cells
developing within that line.  These lines of pre-frontal convection
make the severe scenario a bit complicated for this evening.  First
of all, there is the concern that parts of atmosphere over western
KY and into west central KY/southwest IN may have destabilized
enough in a decent wind environment for some of these cells to
become strong to severe as they enter our far western forecast area
(Logan County, KY to Dubois County, IN) so will be watching these
cells in the pre-frontal convection closely over the next few hours.
These pre-frontal lines of showers and storms may also work to eat
up some of our instability, however robbing the atmosphere of fuel
for the main line of convection still set to develop this evening.

Although convection doesn`t look all that impressive along the front
as of 345pm, a shortwave moving NE out of the southern Plains is
still expected to enhance convection during the late
afternoon/evening hours.  The line of convection along the front
should have the best sfc moisture and decent ribbon of sfc based
instability to work with.  Some of the high-res models don`t look
too impressive though with convection along the front.  The pre-
frontal line of convection will likely be enhanced as the shortwave
arrives also.  Whatever does develop along the front should merge
with the initial pre-frontal line of convection west of I-65 and
continue east across our forecast area through the evening and
overnight hours.  A good 60-70 kt LLJ will get going along and east
of I-65 parallel to the mean flow which should yield a good moderate
to heavy rainfall setup for a good portion of our forecast area.

=============
Storm Threats
=============

Damaging winds and isld tornadoes are still a threat mainly west of
I-65.  These would be threats in cellular structures as well as
linear structures.  As the front/convection merge with the pre-
frontal line of convection along or just west of I-65, damaging
winds will still be a threat, the tornado threat will lessen, and
flash flooding will become more of a threat.  With flash flood
guidance between 1.5-2 inches east of I-65 and rainfall amounts
coming up on the latest high-res guidance to 2-3 inches in pockets,
will definitely need to watch minor flooding issues this evening and
through the overnight hours.

=========
Wind Advy
=========

Will keep the current Wind Advy in place through tonight.  The
highest wind gusts (lower 40 mph range) have been observed over
south central KY this afternoon.  While clouds and rain showers over
southern Indiana and north central KY have limited wind gusts so
far, still think a good wind threat of 40-45 mph exists outside of
storms.

==========
Wednesday
=========

Remaining showers should linger over east central KY Wed morning
before ending.  Temps on Wed won`t go much of any where lingering in
the mid 40s to mid 50s across the area.

.LONG TERM (Thursday through Tuesday)...
Issued at 245 PM EST Tue Feb 2 2016

Thursday - Saturday...

Dry conditions are expected Thursday and through the end of the week
as we remain largely under sfc high pressure and a split flow
pattern aloft.  Temps will be the coldest on Thurs with highs in the
upper 30s/lower 40s and lows Thu night in the lower 20s.  Temps will
moderate for Fri/Sat though with highs back in the upper 40s/lower
50s by Sat.

Sunday - Tuesday...

As a ridge axis amplifies just west of the Rockies, a deep trough
will become carved out over the Midwest for the beginning of next
week.  This will lead to colder temps and a more active pattern.
With many embedded disturbances expected in the upper trough, light
rain or snow chances will be possible beginning Sun night and
continuing through Tues.

&&

.AVIATION (06Z TAF Update)...
Updated at 1237 AM EST Wed Feb 3 2016

A widespread area of moderate to briefly heavy rainfall is lifting
to the NNE across the TAF sites, while the overall storm pushes
slowly east. Expect the back edge of rain showers to quickly let up
at SDF/BWG shortly after this cycle goes valid. VFR vis/ceilings
will then prevail as a dry slot works into the region. Surface winds
should only very slowly veer to a SW component between 10 to 15 mph.

LEX is just beginning their period of heaviest rainfall at the start
of this cycle where low MVFR or IFR visibilities will be noted in
moderate to briefly heavy rain. Also. A few gusts around 30 mph are
possible. Ceilings will also likely be in the MVFR range at times.
Expect rain to let up to light showers with a return to VFR around 4
AM EST, then going dry by sunrise.

Expect VFR skies through Wednesday with a steady SW wind between 10
and 15 mph, gusting up around 20-25 mph through the day. Low VFR
ceilings arrive later Wednesday evening, possibly venturing into the
MVFR range. Winds will be out of the west by evening.

&&

.LMK Watches/Warnings/Advisories...
KY...Wind Advisory until 7 AM EST /6 AM CST/ this morning for
     KYZ023>043-045>049-053>057-061>067-070>078-081-082.

IN...Wind Advisory until 7 AM EST /6 AM CST/ this morning for
     INZ076>079-083-084-089>092.

&&

$$

Mesoscale......13
Short Term.....AMS
Long Term......AMS
Aviation.......BJS


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