FXUS63 KLMK 191724

Area Forecast Discussion
National Weather Service Louisville KY
124 PM EDT Tue Jun 19 2018

...Updated Aviation Discussion...

.Forecast Update...
Issued at 1119 AM EDT Tue Jun 19 2018

Morning satellite and observations reveal mostly sunny skies again
across the region. Temperatures had already warmed up into the
lower 80s. Not much change expected in the ongoing forecast for the
rest of the day. Diurnal Cu field should develop in the next hour
or so and we should see a few scattered showers/storms develop after
lunchtime. Highs on the day will top out again in the upper 80s to
the lower 90s. With dewpoints in the 70s, it will feel like it's 95-
100 out there again this afternoon.

Aforementioned convective development is expected again this
afternoon. However, latest CAMs runs showing less convection this
afternoon than in previous days. Most models suggest that southern
IN and then into NE KY would have the best chances at convection
this afternoon. Nonetheless, we're going to keep iso-sct convective
chances going through the afternoon hours. Torrential rainfall,
gusty winds, and frequent lightning would be the main threats.


.Short Term...(This afternoon through Wednesday)
Issued at 259 AM EDT Mon Jun 18 2018

The lower Ohio Valley will remain under the influence of upper level
ridging today. However, this ridge will begin to break down and
flatten out tonight. A frontal boundary currently up across northern
IN will sink slowly southward today and tonight.

Today will be another hot and humid day with high temperatures
topping out in the upper 80s to lower 90s. Today may be a degree or
two cooler than yesterday with more cloud cover. However, peak heat
index values are still forecast to be in the 95-100 degree range.
Lows tonight will again be on the warm side in the lower to mid 70s.

Isolated to scattered storms are expected to develop once again with
the heat of the afternoon. Portions of southern IN and north central
KY will see a bit higher coverage of storms near the slow moving
front. However, will keep the forecast coverage mainly 40% or less
at this time.

.Long Term...(Wednesday night through Monday)
Issued at 330 AM EDT Tue Jun 19 2018

...Tropical Humidity to Persist Through the Period...

While a brief respite from intense heat is expected later this week,
the tropical humidity that has accompanied it over the past several
days will not be departing.

An upper level low over the Pacific northwest early this morning
will attempt to weaken the broad upper level ridge that has been
responsible for the hot, humid airmass over much of the central and
eastern part of the country this week. While the clouds associated
with this disturbance will help reduce daytime heating, the surface
pressure pattern will only briefly cut off the Gulf moisture already
in place over most of the eastern U.S., so overnight lows should
remain above normal, with the upper 60s as low as most locations can
expect to see for overnight lows through the period.

Hit and miss thunderstorms will continue to pop up Wednesday in the
tropical airmass. As the upper low tracks into through the Missouri
Valley Thursday and Friday, rain coverage will increase across the
area, with heavy downpours possible from any storm that develops.
This, along with the slow movement of the storms in the weak flow
aloft ahead of the upper low, could pose problems for runoff, with
localized flooding being a greater threat than hail or strong winds
from any of the storms this week. The axis of the heaviest
widespread rain through the period currently looks to be north of
the Ohio River, though this could change with any diversion of the
track of the upper low.

For now, the best that can be said about this forecast is that even
though dry weather is not on the way, we will see a day or two when
at least the high temperatures could be on the "cool" side of
normal by a degree or two.


.Aviation...(18Z TAF Issuance)
Issued at 123 PM EDT Tue Jun 19 2018

Stationary frontal boundary to the north of the region will drop
southward into the northern Ohio Valley this afternoon and evening.
We expect to see another afternoon of hot and humid conditions with
scattered convection developing. Best chances of storms looks to be
from KHNB through KSDF over to KLEX in the 19/18Z through 20/03Z
time frame. For now, have kept some VCTS in at those terminals for
the late afternoon and evening. Any convection that develops is
likely to diminish after sunset with a return to VFR conditions
overnight. Winds will be out of the west today at 5-10kts with a
few gusts to 15-17kts at times. Winds are expected to back to the
southwest overnight.




Short Term...EER
Long Term....JBS
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