Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 251041

Area Forecast Discussion
National Weather Service Louisville KY
641 AM EDT Tue Apr 25 2017

...Updated Aviation Discussion...

.Short Term...(Today through Wednesday)
Issued at 250 AM EDT Tue Apr 25 2017

Weak ridging aloft and at the surface extends from the lower Ohio
Valley through the Gulf Coast while a deep closed low spins near the
SC/NC coast. Subsidence has worked onto the blanket of strato-cu
from last evening giving way to mostly clear skies. Light winds
and residual moisture in the lowest levels have resulted in
patchy fog across south-central Kentucky, but this should quickly
burn off soon after sunrise. Readings were generally in the 50s
to around 60 degrees.

For today, a very pleasant spring day is in store for the lower Ohio
Valley as high pressure remains in control. Look for partly to
mostly sunny skies with light and variable winds. Temperatures
should warm well into the 70s, topping out in the mid to upper 70s.
We`ll have comfortable humidity levels as well. Plan on pleasant and
dry conditions this evening and tonight with temperatures bottoming
out in the upper 50s to 60 again.

On Wednesday, energy ejecting out of the southwest US will spawn a
surface low pressure system across the central Plains. In response,
southerly flow will develop locally, helping to bring warmer
temperatures into the area. Winds will become breezy and look for
highs to reach the mid 80s.

.Long Term...(Wednesday night through Monday)
Issued at 255 AM EDT Tue Apr 25 2017

Overall the extended forecast looks to be unsettled with several
weather systems to monitor. The big picture is for above normal
temperatures with a wetter than normal period.

An upper trough axis will move through the Plains late Wednesday and
into the Ohio Valley during the day on Thursday.  A cold front will
approach the region early Thursday morning. A weakening line of
showers and elevated thunderstorms looks to approach central
Kentucky and southern Indiana during the early morning hours then
advance eastward toward the Bluegrass region through noon. No severe
weather Thursday morning is expected as the system lacks sufficient
instability, however convection may upscale and become stronger
Thursday afternoon along/east of I-75. Look for more seasonable
temperatures Thursday with highs in the 70s.

That front drops south of the area and stalls out across Tennessee
and the southern Appalachians Thursday night. However, more energy
coming into the central Plains will lift that boundary back to the
north as a warm front Friday and Friday night. There is some timing
differences with perturbations coming in from the west. The latest
Euro has an impulse sweeping through during the day Friday while the
GFS and GEM hold any precipitation north of the area during the day.
Leaned toward the model consensus of 30-40 percent chances Friday,
mainly in the afternoon hours.

That front eventually does surge north Friday night where more
widespread showers and elevated thunderstorms are expected. Trended
precipitation chances higher into the 60 to 80 percent range, with
the highest chances across north-central Kentucky and southern

Models continue to advertise that any showers and elevated storms
Saturday morning will lift north of the Ohio River during the day,
giving way to a warm and more humid day. Given the unstable and warm
air mass, can`t rule out isolated showers or storms during the day,
but overall the better forcing for ascent will be north of the area.
Temperatures could warm well into the 80s, perhaps in the mid to
upper 80s if clouds clear out in the afternoon. Add in dewpoints in
the 60s to near 70 in places, and it could end up being a very warm
and humid afternoon/evening.

The GFS/GEM/Euro are in good agreement showing widespread convection
Saturday night across Missouri and Arkansas which will slowly
advance eastward toward our area Sunday. Will carry high
precipitation chances again Sunday as that front sweeps through. If
timing holds the same, the environment does support the potential
for strong to severe storms across the entire area Sunday afternoon
and evening - another period to monitor closely.

That front sweeps through Sunday night and then a brief period of
cooler and drier air looks likely early next week before the pattern
returns to more unsettled weather the first week of May.


.Aviation...(12Z TAF Issuance)
Issued at 645 AM EDT Tue Apr 25 2017

Some light fog was present at BWG this morning.  IFR was observed
earlier but vsbys are now improving. By mid morning, all TAF sites
should be VFR.  Light SSE winds will continue through the TAF period
as well.




Short Term...ZT
Long Term...ZT
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