Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 231516
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1116 AM EDT Tue May 23 2017

...Forecast Update...
Issued at 1114 AM EDT Tue May 23 2017

Light radar returns continue across the far south and southeast CWA
this morning. Some of this is virga, but Lake Cumberland area
webcams indicate sprinkles have reached the ground in a few spots.
There is still plenty of mid-level dry air to overcome across
central KY and southern IN, so primarily dry weather is expected
this afternoon with deeper moisture just off to our southeast. But a
few light showers will be possible south of a line from Bowling
Green to Liberty. Expect broken clouds with sun at times, so highs
into the mid 70s for most still look good. Upper 70s will be
possible, particularly in central KY along and west of I-65. Recent
satellite imagery reveals more breaks in the clouds further west,
where drier air is present in the mid and upper levels in between
two waves.

.Short Term (Now through Tuesday)...
Issued at 245 AM EDT Tue May 23 2017

...Much Cooler and Rainy late Tue night and Wednesday...

Well...copious high level cloudiness is dominating the region with
sfc high pressure underneath. Sfc temps in the 50s with very
pleasant dew points around 50. Srn stream shortwave moving thru
Dixie Alley will track into the Appalachians Mtns bringing threat of
isolated shra acrs Lake Cumberland area this morning. Latest 88D OHX
loop showing sct shra in western TN heading towards srn tier of KY.
Given the southwest flow in place, and pwats around 1.25 inches and
isol tsra across eastern and southern 1/3 CWA seem plausible. Made
several POP/WX tweak changes of keeping shra in this morning acrs
bottom 2 tiers of KY counties this morning.

Deepening upper low diving south out of MN will move to the Show Me
State tonight and near MEM Wed evening. This will set up weak
isentropic upglide this evening. The surface low will lift NE with
PWATs increasing to 1.4 inches. With the deepening low, cannot rule
out a stronger cell developing near the warm frontal boundary
associated with the low, and we may see couple of isol stronger wind
gusts in convection as the low deepens.

GFS is much quicker than NAM with precip overnight and then all the
model data is in decent agreement of widespread shra and isol tsra
Wed morning.  The most immediate concern is the potential late
tonight for minor flooding, especially in areas rain soaked a few
days ago. Model QPF is not more than in the 0.5-1 inch range for any
given 6-hour period. This needs to be monitored.

The 1000-850 thicknesses along with cloud cover and precip should
keep temps down into the 60s Wed. Southwest winds will be the only
thing keeping temps up with even chillier temps ahead on Thu. Normal
highs are in the 81-85 range.

.Long Term (Tuesday Night through Sunday)...
Issued at 250 PM EDT Tue May 23 2017

...Chilly Weather Wed Ngt-Thu...
...Warmer for the Memorial Day Weekend with MCS activity...

Well...sfc and upper low spinning around OH Valley bringing sct shra
copious cloud cover and much cooler temperatures, some 15 degrees
below normal on Thu.  The upper low will move out Thu afternoon bu
nw caa will keep temps in the mid 60s especially east of I 65 and
with areas near OWB and EVV around 70. Would not be surprised to
receive some graupel or very small bb to pea size hail reports
Wednesday night into Thu.

Fri is a brief warmup as shortwave ridging crosses the region with
thicknesses supporting low 80s with sunshine. Clouds will be moving
in late in the day though.

A warm front will lift out of AR/OK and move to near SDF-IND-CVG by
Sat morning. Depending on where this sets up is critical to the
POPs. Upper level disturbances passing along this boundary should
lead to MCS development for the holiday weekend, but should the
boundary be too far north of south will change the rain forecast
significantly.

Memorial Weekend (from 230 pm AFD Mon)

Given some uncertainty, would prefer to keep us out of the likely
range though. The Superblend model agrees with this thinking as
well, so did not make any changes here. Temperature forecast beyond
the cold Wed/Thu values will depend greatly on that frontal location
as well as associated convection. So, this part of the forecast has
a lower confidence.

&&

.Aviation (12Z TAF Update)...
Issued at 648 AM EDT Tue May 23 2017

High pressure over the Ohio Valley will keep winds light and
variable winds in place today.  Skies will generally partly to
mostly cloudy with high cirrus streaming overhead.  Winds look to
turn more to the south this afternoon and evening and we should see
a gradually lowering ceiling.  VFR conditions are expected today and
into the overnight hours.  Rain showers will likely ramp up after
24/05Z at KSDF and KBWG and then after 24/09Z at KLEX.  Winds
tonight and early Wednesday will generally remain light out of the
south.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Update.........EBW
Short Term.....JDG
Long Term......JDG
Aviation.......MJ


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