725 
FXUS63 KLMK 060533
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1233 AM EST Wed Feb 6 2019

...Updated Aviation Discussion...

.Forecast Update...
Issued at 734 PM EST Tue Feb 5 2019

Several issues to deal with here this evening. The first is that 
patchy dense fog is setting up along and north of the warm front 
this evening. The front is currently located along a Hardinsburg, to 
Bardstown, to Lexington line and will very slowly lift north into 
southern Indiana toward Midnight. As this occurs, expect conditions 
to improve along the I-64 corridor, but dense fog could persist 
across more of the southern Indiana counties well into the 
overnight. Would contemplate a Dense Fog Advisory north of the Ohio 
River into tonight, however think that the boundary lifting north 
combined with increasing showers should help clean out some of the 
fog potential. Therefore, have elected to go with a Special Weather 
Statement for now due to the relative short nature of the expected 
fog. Will monitor and issue a Dense Fog Advisory if need be. 

Forecast looks on track for the overnight as increased showers are 
expected with low level jetting ramping up in response to the exit 
region of an upper impulse nosing into the area. Temps should slowly 
rise with the warm front lifting north, and expect most everyone to 
be in the low 60s by dawn on Wednesday.

Did want to mention that there does seem to be a notable severe 
threat along with increasing coverage of showers and a few storms 
later into Wednesday. Looks like our south will be able to realize 
surface conditions of something like 70/65, resulting in the 
potential for some CAPE in the 100-500 J/KG range. This combined 
with a good shear profile could lend itself to an organized stronger 
storm threat anywhere a stronger updraft is able to become 
established. Think the best chances would be across central and 
southern KY into the afternoon and evening. SPC Marginal Risk is 
worth noting and may end up being a higher risk if some instability 
is realized tomorrow.

&&

.Short Term...(This evening through Wednesday)
Issued at 325 PM EST Tue Feb 5 2019

=====================
Near Term
=====================

Afternoon surface analysis reveals a quasi-stationary boundary 
draped across central KY.  The boundary roughly extends from near 
Covington southwest to near Bowling Green.  Data courtesy of the 
Kentucky Mesonet reveals a strong gradient of temperature across the 
state.  Across far northwest KY, temperatures out west of Owensboro 
were in the lower 40s.  However, down in the Bowling Green area and 
points eastward down the Cumberland Parkway, temperatures were in 
the upper 60s with a few 70 degree readings along the KY/TN border. 

A small area of precipitation was located over southern Indiana and 
far north-central KY this afternoon.  This activity stretch from 
near Jasper, IN southeast through the Louisville Metro area.  This 
activity should continue to head east-northeast and remain generally 
north of the I-64 corridor through the remainder of the afternoon. 
Elsewhere, mainly south of the Western KY and Bluegrass Parkways, 
some clearing has taken place and partly cloudy skies are expected 
to continue.  Temperatures will likely warm a little more south of 
the parkways with highs of 65-72 expected.  North of the WK/BG 
Parkways, temperatures will continue to inch up slowly through the 
lower 50s and probably reach the mid-upper 50s later this evening. 
The coldest temps will be found across southern Indiana where highs 
this afternoon will only top out in the lower 40s.

=====================
Tonight
=====================

Latest short term guidance continues to show that the quasi-
stationary boundary will drift northward tonight and stall out 
across southern Indiana late tonight.  As this occurs, our winds 
will shift around to the southeast and then to the south which will 
transport increasing moisture into the region.  We're likely to see 
clouds push back into the region and lower overnight.  A few 
perturbations will move through the region bringing scattered rain 
showers to the region.  The best chances for rain overnight look to 
be north of a line from Bowling Green to Lexington.  There could be 
a few rumbles of thunder overnight, but organized thunderstorm 
development is not expected. In addition to the rain, low clouds and 
patchy fog will be an issue overnight. Most locations in the fog 
would probably drop down into the 1-2SM range.

As far as temperatures go, the lows of the overnight period would be 
very early with a slight rise in temperatures overnight.  In 
general, lows across southern IN would likely be at midnight with 
readings in the mid-upper 40s, across KY, lows in the upper 50s to 
the lower 60s look likely based on the consensus short term blends.

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

By sunrise Wednesday, a weak wave of low pressure is forecast to 
move northeast along the frontal boundary.  The latest high 
resolution models suggest a band of moderate to heavy rainfall 
pushing through the region Wednesday morning and into the afternoon 
hours.  This rain will be convective in nature, largely driven by 
persistent low-level warm advection with some added elevated 
instability.  Overall model proximity soundings show a weakly stable 
boundary layer in place throughout the day.  Given the anticipated 
widespread cloud cover, not really thinking that we'll see much in 
the way of destabilization.  Some pockets of elevated instability 
will likely be realized and we could see some isolated thunderstorms 
moving through the region.  Overall severe threat looks very low at 
this point.  Main threats for Wednesday would be heavy rainfall and 
gusty winds.   Total rainfall amounts for tomorrow look to average 
around an inch north of the Western KY and Bluegrass Parkways. South 
of the parkways a quarter to three quarters of an inch are expected. 

Highs on Wednesday will be quite warm with readings in the 60-65 
degree range across southern Indiana.  Across Kentucky, highs of 65-
70 will be seen.  If we get any filtered sunshine, highs in the 
lower 70s would be attainable across far southern/southeast KY.

.Long Term...(Wednesday night through Tuesday)
Issued at 355 PM EST Tue Feb 05 2019 

...Heavy Rainfall Expected Through Thursday Night...

Waves of moderate to heavy rains will increase the risk for flooding 
Wednesday evening through Thursday night. Minor flooding is likely, 
and isolated flash flooding will be possible Thursday evening. 
Longer duration river flooding concerns will linger into next week. 

The synoptic scale pattern over the next few days will be quite 
favorable for heavy rainfall across the lower Ohio Valley. Upper 
troughing swinging from the Intermountain West to the Upper Midwest 
will maintain an uninterrupted supply of Pacific moisture aloft. 
Meanwhile, strengthening low level SW flow and substantial moisture 
transport into a quasi-stationary sfc boundary will also help 
produce waves of moderate to heavy rainfall Wednesday night through 
Thursday night. 

Minor model differences exist in the exact placement of the heaviest 
rainfall axis Wednesday night. But the heaviest rain is likely to 
fall just south of the sfc boundary, which is forecast to be just 
north of the Ohio River. PWATs are forecast to reach 1.4+ inches 
across central and southern KY Wednesday evening into Wednesday 
night as well. So through Wed night at least, have focused somewhat 
higher QPF along and south of the Ohio River. 

However, the sfc boundary will surge northward on Thursday, taking 
the heaviest rain axis into southern and central Indiana. This is in 
response to substantial deepening of the sfc cyclone from Missouri 
into the Great Lakes. Our southern Indiana counties could get dumped 
on during this transition, while our southeastern forecast area 
could dry out. A 55-60 kt SW develops over the western half of KY, 
and portions of central KY could actually dry out and achieve record 
high temperatures in the mid 70s. Sfc gusts in excess of 30 mph are 
also likely during this time frame. 

Any lull will be short-lived, with the sfc cold front crashing 
through from west to east Thu afternoon and evening. Strong linear 
forcing will help produce a convective band of showers, possibly 
with scattered thunder/lightning. Regardless of lightning activity, 
additional heavy rainfall rates may start to result in isolated 
flash flooding given prior rains. There's also a non-zero severe 
threat, with 50+ kt winds just off the sfc. Isolated damaging winds 
would be the main threat here. But the screaming message is the 
potential for flooding continuing into Friday. Longer duration river 
flooding concerns will linger into next week. 

As for sensible weather beyond Thursday night, temperatures will 
plummet some 40-50 degrees by Friday morning behind the cold front. 
Expect cold, breezy, dry conditions on Friday with wind chills 
starting in the teens. High pressure building across the region 
should keep things dry through Saturday night. Highs Fri and Sat 
afternoon should be mainly in the 30s. 

The flow aloft again becomes WSW to SW after Sunday, as an active 
series of waves aloft continue to eject out of the southwestern U.S. 
One wave brings moisture back into our area by Sun afternoon, 
bringing more rain. There is a slight chance the rain could start 
briefly as a wintry mix based on current model guidance, but this is 
predominantly a liquid event. Additional waves could bring 
additional showers Tue and/or Wed. Although the timing of these 
waves is certainly in jeopardy at this time range and model guidance 
does diverge from each other to some extent, additional rains, 
perhaps significant, will only add to or prolong any river and areal 
flooding that occurs from rains this week.

&&

.Aviation...(06Z TAF Issuance)
Updated at 1233 AM EST Wed Feb 6 2019

A nearly stationary front will remain in the vicinity of the TAF 
sites through tonight. A wave will move eastward along the front 
through central Kentucky this morning, and another will approach 
from the west tonight. As a result, low clouds and widespread 
showers will prevail throughout the forecast period. Ceilings will 
be variable and tricky, but should be below fuel alternate for much 
of the time.

Winds will also be tricky with the oscillating surface boundary and 
waves of low pressure moving through. The most significant winds 
will be at BWG this afternoon, just south of the boundary, where 
southwest winds could gust to around 20 kt.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch from this evening through late Thursday night for 
     INZ076>079-083-084-089>092.

KY...Flood Watch from this evening through late Thursday night for 
     KYZ023>043-045>049-053>057-061>067-070-071.

&&

$$

Update...BJS
Short Term...MJ
Long Term....EBW
Aviation...13