Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 231049
AFDLMK

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

...Updated Aviation Discussion...

.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 Tue night 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 especially in
areas around Salem, IN.

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 surprises 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 with next precip as close as Dubois
County, IN.

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. Upper
level disturbances passing along this boundary should lead to MCS
development for the holiday weekend, but should the boundary stay
far enough north of us, any associated convection would be over the
north half of the region.

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 Issuance)
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...
IN...None.
KY...None.
&&

$$

Short Term........JDG
Long Term.........JDG
Aviation..........MJ


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