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FXUS63 KLMK 161947

Area Forecast Discussion
National Weather Service Louisville KY
347 PM EDT Tue Jul 16 2019

.Short Term...(This evening through Wednesday)
Updated at 330 PM EDT Tue Jul 16 2019

Afternoon satellite imagery reveals mostly sunny skies across much 
of central and eastern KY.  Cloud cover has really been limited to 
our far western counties where scattered convection has been moving 
northeastward.  Temperatures ranged from the upper 80s in the sun 
with 90-91 in the urban heat islands, to the upper 70s under the 
clouds in western KY.

For the rest of the afternoon and evening, we will be watching the 
remnants of tropical cyclone Barry move northeastward through the 
region.  Overall convection looks to come in several waves this 
afternoon.  First wave is pushing through southern IN at the moment. 
Secondary wave is developing from near Evansville, IN southward into 
western TN.  Atmosphere is modestly unstable with MLCAPE values in 
the 1200-1500 J/Kg range.  There is a pocket of elevated effective 
SRH stretching from Owensboro northeastward into our far NW CWA. 
Overall surface flow remains rather unidirectional with some speed 
sheer, but not really seeing much in the way of low-level backed 
flow.  The combo of MLCAPE and effect SRH may pose an isolated 
tornado risk over our far NW CWA over the next few hours.  However, 
KLVX/KVWX Vrot values have been very low (20-25kt) and LCL heights 
are still around 800-1000m.  Thus, probably going to see several 
reports of funnel clouds with the strongest storms.

PWAT gradient was also seen across the region with values around 1.5-
1.7in across the Bluegrass region and then sharply rising to above 2 
inches west of Evansville.  So storms out west of I-65 will be 
capable of producing heavy rainfall.  Flash flood risk is certainly 
there, especially where storms transverse over the same locations 
repeatedly or train over the same swath of land.

Convective coverage should spread eastward into the I-65 corridor 
later this afternoon and into the evening hours.  Just how far east 
we'll see it get is rather questionable.  Much of the high 
resolution guidance keeps best chances of precipitation west of a 
line from about Frankfort to Tompkinsville.  With that said, will 
keep high PoPs out west of I-65 and tapering it to chance PoPs out 

Moving into the overnight hours, convection is likely to diminish in 
coverage and intensity with the loss of heating.  We'll probably see 
some scattered showers and possibly a storm overnight, though the 
best combo of moisture/instability looks to remain to our south. 
Will maintain chance PoPs overnight, but will monitor trends this 
evening and make further modifications as needed.  Lows will remain 
mild with readings in the 70s.

For Wednesday, upper trough axis will shift to the east along with 
the slug of tropical moisture associated with the remnants of Barry. 
Best chances of storms on Wednesday will likely be across the 
northeast half of the forecast area.  Highs will be in the mid-upper 
80s in most areas with a few spots hitting 90 once again.

QPF amounts through the short term period will likely see basin 
averages around an inch, though some isolated amounts of 2-3 inches 
will be possible...especially in areas that see training of storms. 
The isolated nature of the high amounts and relative high FFG values 
across the region should preclude the need for a watch.  That is not 
to say that isolated flash flooding in some areas could occur over 
the next 24 hours.


.Long Term...(Wednesday night through Tuesday)
Updated at 345 PM EDT Tue Jul 16 2019

...Excessive Heat Possible for End of Week through Weekend... 

Heights aloft begin rising Wednesday night behind the departing 
wave. At least scattered showers and storms look to linger east of I-
65 into late Wednesday evening. A period of dry weather is then 
likely for much of the area 06-12z Thursday morning. There is a weak 
NW to SE oriented boundary that drifts east from western KY and 
southern IL Thursday morning. 12z models show moisture pooling with 
sfc dewpoints above 75 F along with a subtle wind shift. Before 
substantial upper ridging can build overhead, this may be enough for 
isolated convection on Thursday, particularly west of I-65 in the 
morning hours. Coverage should remain limited with anticyclonic flow 
aloft and poor mid-level lapse rates. It will remain very humid in 
the wake of the current tropical remnants, however. Heat and 
humidity will be oppressive. Afternoon highs will reach the upper 
80s to mid 90s with maximum heat indices in the upper 90s to mid 

Confidence in medium range guidance is fairly high in its depiction 
of a 593-594 mid-level ridge building over the Lower Ohio Valley 
Friday into Saturday. Afternoon highs should have no trouble 
reaching the low to mid 90s both days with peak heat indices of 100-
110 degrees. Will highlight the heat and humidity in an SPS and the 
HWO for now, but will likely need a Heat Advisory late in the week.

The chances for precip return Sunday into early next week. Upper 
ridge will gradually retrograde westward, and a large northern 
trough drops southeast over the Great Lakes and Northeast US. A sfc 
cold front should drop south through the area in the Monday time 
frame, so bumped up rain chances for early next week.


.Aviation...(18Z TAF Issuance)
Updated at 111 PM EDT Tue Jul 16 2019

Remnants of tropical cyclone barry will lift northeastward through 
the northern Ohio Valley this afternoon and evening.  With this 
feature approaching, we'll see more widespread shower and 
thunderstorm activity.  This activity is likely to affect 
KHNB/KBWG/KSDF through the afternoon and evening.  Some isolated 
showers and storms may develop out in the I-75 corridor near KLEX, 
but more widespread coverage over there will likely not occur until 
around 17/00Z.  Winds will be gusty this afternoon out of the 
southwest with sustained speeds of 10-15 knots and gusts to 25 kts.

For the overnight period, scattered convection will be possible 
overnight so will continue a mention of VCSH in the TAFs.  Winds 
will likely remain elevated overnight with speeds in the 10-12kt 
range.  Model guidance suggests we'll see ceiling build down into 
the MVFR range after 17/10Z.



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