Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 130646

Area Forecast Discussion
National Weather Service Louisville KY
246 AM EDT Thu May 13 2021

.Short Term...(Today and tonight)
Issued at 240 AM EDT Thu May 13 2021

Thursday morning sfc analysis shows an expansive Canadian 1030mb sfc
high centered over Chicago/northern IL, influencing low level NE
flow into our neck of the woods. Quiet wx will continue across the
Ohio Valley as the sfc high slowly sags south and east by this
evening. Hi-res forecast soundings and sky cover guidance agree well
on seeing some afternoon diurnal cu develop as temps reach the mid-
upper 60s (near 10 degrees cooler than climate normals for this time
of year). Clouds should be scattered enough to keep mostly sunny to
partly cloudy wording in forecast products.

Clouds should dissipate by sunset this evening, leading to clear
skies and continued NNE light winds. Friday morning lows will bottom
out in the low 40s, essentially limiting any frost potential.


.Long Term...(Friday through Wednesday)
Issued at 234 AM EDT Thu May 13 2021

Surface high pressure will be directly over the Ohio Valley by
Friday morning. This high will slowly drift off to the east over the
weekend, and as it does so, return flow on the back side of the high
will allow for the return of southerly winds and warmer temperatures
across southern IN and central KY.

By Sunday, an area of low pressure will eject into the Plains. A
surface warm front associated with the low will pass through our
region, but likely stall as it approaches central IL/IN/OH. An
increase in low-level moisture (Td`s) will be noticeable behind the
passage of the warm front, as dewpoints will likely climb and stay
in the 60s through much of next week.

Weak waves riding along the stalled frontal boundary will contribute
to periods of active and wet weather early next week. With higher
dewpoints present, there will be some instability in place to fuel
thunderstorms, particularly at peak heating. In this kind of pattern,
will have to keep an eye on the timing of some of these waves given
the potential for organized convection.

The stalled frontal boundary looks to lift northward into the Great
Lakes region by midweek. Long range guidance begins to amplify
ridging across the eastern half of the U.S. at this point, but
varies on the overall strength and extent of the ridge. Depending on
where the ridge sets up, our pattern could turn relatively quiet and
warm (ridge overhead)... or become quite active (ridge axis to our
east). As a result, confidence in the forecast is quite low from the
midweek timeframe onward.


.Aviation...(06Z TAF Issuance)
Issued at 120 AM EDT Thu May 13 2021

IMPACTS: VFR conditions through the forecast with very
light northeast winds.

DISCUSSION: Clear skies thanks to high pressure settling in over the
Ohio Valley. Winds will remain out of the northeast through the
forecast and range from 4 to 8 kts. No major changes are expected in
the overall forecast and conditions.

CONFIDENCE: High on all forecast elements.




Short Term...CJP
Long Term...DM
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