KLMK issues Area Forecast Discussion (AFD) valid 2019-11-27T09:49:00Z    

361

FXUS63 KLMK 270949

AFDLMK



Area Forecast Discussion

National Weather Service Louisville KY

449 AM EST Wed Nov 27 2019



.Forecast Update...

Updated at 445 AM EST Wed Nov 27 2019



A couple of features we're watching this hour.  One is a thin band 

of showers now entering Dubois county. The other is the fairly wide 

clear slot in clouds behind that line.



The showers have been producing some stronger wind gusts from the 

west southwest...in the 40-45 mph range. Behind that line winds have 

died back some. Given the Wind Advisory in place now, not planning 

to issue any special weather statements along this line. Will watch 

for pockets of stronger wind gusts and issue warning products as 

needed. 



The second feature is a bit more concerning. Sunshine later this 

morning will allow for deeper mixing earlier in the day, while we 

still have strong winds aloft. Models have been overdoing the winds 

aloft so far this morning...with NAM and WRFs advertising 70-knots 

at 850 mb. Area VAD wind profiles have peaked in the 50-55 knot 

range, closer to the Euro and RAP solutions. As we get some daylight 

around here, we should mix into the 3-4 kft range in the 10-11 AM 

EST range. At that point, the Euro weakens winds at 850 mb to 40 

knots...whereas the RAP keeps us at 50 knots. Based on upstream obs, 

would not be surprised to see some wind gusts in the 50-60 mph range 

along and north of the I-64 corridor from 9 to Noon EST. Our current 

forecast already is above the high end of guidance for wind gusts. 

Will nudge those winds up a tad and keep a close watch at those wind 

profiles to see if we need to upgrade a part of our forecast area to 

a High Wind Warning.



&&



.Short Term...(Today and tonight)

Updated at 300 AM EST Wed Nov 27 2019



990 mb surface low now over eastern Iowa will continue to deepen 

over the next few hours on its way to southern Wisconsin by 

daybreak. A couple of bands of showers are expected to develop out 

ahead of this low's attendant cold front. Will be watching 

temperature trends ahead of these bands, to see if we could get any 

surface-based instability, but there is a pretty solid inversion 

aloft, helping to keep the strongest winds above the surface for 

now. Satellite does show a nice clear slot that, if current trends 

continue will move that slot over our area during daylight morning 

hours. Sunshine should aid in the mixing of the low levels and allow 

for a very windy morning...with gusts likely in the 40-50 mph range. 



Expect a field of low clouds to develop within that clear slot 

thanks to that heating and trapped low-level moisture. Cloudy skies 

look to stay along and north of the I-64 corridor though, so our 

southern KY counties could keep gusting a little longer. Current 

timing of the Wind Advisory product still looks good, so will just 

re-issue with this forecast package.



By this evening, the gradient will continue to loosen as the surface 

low continues into Ontario. Stratus cloud cover may linger some, as 

time-height sections keep in a narrow low-level moisture field. The 

wind mixing and potential for cloud cover will mean temperatures 

only falling to around freezing, not too far from normal for this 

time of year.



.Long Term...(Thursday through Tuesday)

Issued at 315 AM EST Wed Nov 27 2019



Thanksgiving...The long term begins with upper level ridging 

extending from the Gulf of Mexico northward along the Mississippi 

Valley sandwiched between two potent low pressure systems, one along 

the West Coast and the other situated over the NE US. NNE winds 

flowing around surface high pressure will see a cold start to 

Thanksgiving with lows hovering right around the freezing mark. 

Cloud cover will increase throughout the day due to an increase in 

Gulf moisture transport and weak isentropic lift. Forecast soundings 

show ample dry air in the mid and low levels that will evaporate any 

falling precipitation likely resulting in a pretty display of virga 

during the afternoon. As a result of increased cloudiness and 

northerly winds, max temps will only reach into the low to mid 40s. 



Friday through Sunday...After spinning nearly stationary for 48 

hours, the West Coast low will eject eastward and begin its 

advancement across the Rockies, undergoing lee cyclogenesis before 

entering the Ohio Valley. Rain will make its return by Friday 

afternoon east of I-65 and become more widespread overnight. 

Saturday will be a wet one as we sit in the warm sector ahead of the 

cold front with deep southwesterly flow bringing in copious 

moisture. A warm day can expected Saturday as max temps reach into 

the mid 50s across southern Indiana and northern Kentucky gradually 

increasing to the low 60s across southern Kentucky. Tight gradient 

will also result in breezy conditions Saturday through Sunday with 

gusts ranging between 20 and 30 mph. There is also a slight chance 

of embedded thunderstorms Saturday night, though a stable layer up 

to 850mb should keep any storms elevated. Actual FROPA should occur 

sometime Sunday morning. Models indicate a dry period through Sunday 

late morning into the afternoon hours before wrap around moisture 

brings rain showers back through the area. 



Monday and Tuesday...As the upper trough axis passes overhead, a 

rain/snow mix is possible beginning early Monday morning across 

southern Indiana and parts of northern and through the afternoon 

hours for east central Kentucky as a result of continued wrap around 

moisture from the weekend's exiting system. Monday morning lows will 

bottom out in the low to mid 30s and ease into the low 40s by 

afternoon. Tuesday looks to be cool and dry with decreasing clouds 

as surface high pressure builds in across the area. Morning lows 

will dip into the upper 20s with afternoon highs reaching into the 

mid 40s.



&&



.Aviation...(06Z TAF Issuance)

Issued at 1215 AM EST Wed Nov 27 2019



Rain shield across the terminals this hour...with a narrow break 

coming before a couple of other waves of showers are possible before 

daybreak. Low-level wind shear continues, with south winds at the 

sites now at the surface, but 45-50 knots at 2 kft. Winds at all 

levels will continue picking up as the morning goes on. With 

potential for some clearing by daybreak, 40+ knot gusts are likely 

at each of the I-64 terminals. A broken deck of clouds then should 

develop by late morning/early afternoon that could help weaken the 

wind gusts some. By evening, breezy conditions will continue, but 

the peak gusts will come down.





&&



.LMK WATCHES/WARNINGS/ADVISORIES...

IN...Wind Advisory until 5 PM EST /4 PM CST/ this afternoon for 

     INZ076>079-083-084-089>092.



KY...Wind Advisory until 5 PM EST /4 PM CST/ this afternoon for 

     KYZ023>043-045>049-053>057-061>067-070>078-081-082.



&&



$$



Update...RJS

Short Term...RJS

Long Term...CG

Aviation...RJS