Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/20/21

Area Forecast Discussion

National Weather Service Louisville KY

 933 PM EDT Sat Jun 19 2021

.Forecast Update...
Issued 930 PM EDT Sat Jun 19 2021

Muggy conditions ongoing for the Ohio Valley region, with a pool of
low 70s dewpoints along and west of I-65 and readings more around 70
for the rest of the state, per the Kentucky Mesonet. Atmosphere
appears still capped over our region, but SPC mesoanalysis shows
some instability peaking just to our north, over central IN. Some
subsidence is occurring here now though, thanks to the stronger
cells that are over the MO/IL border area tonight. Still cannot rule
out a very isolated storm popping up overnight, but trimmed those
chances even farther north, to a roughly Paoli, IN to Bedford, KY
line.

Issued 555 PM EDT Sat Jun 19 2021

Warm air above an inversion at 900 mb has kept most of the region
capped through the afternoon. AMDAR sounding from 19Z sounding
showing this well, and RAP forecast soundings agree for SDF. Over
near HNB the RAP shows a weaker cap, with convective temperatures of
89-90. Current reading there is in upper 80s, so its not out of the
question that we could get an isolated storm to pops out of the
cumulus field that has popped up near there. Rest of the region
should be harder to see development given extensive cloud cover
streaming northward from TC Claudette. Did go in and change the
point and click forecast to lower pops to slight chance along and
north of I-64.

&&

.Short Term...(This evening through Sunday)
Issued at 245 PM EDT Sat Jun 19 2021

Widespread mid and high clouds from both TS Claudette and a couple
rounds of showers and thunderstorms have kept temperatures in the
70s over southern Indiana and some of far north central Kentucky
this afternoon, keeping convective redevelopment in check. Winds
aloft weaken significantly tonight and little if any thunderstorm
development is expected. The best chance for something to pop would
be isolated development along and north of the I-64 corridor. Low
temperatures tonight should generally be in the 65-70 degree range
with a light SSW breeze.

Tomorrow an upper level impulse is expected to move from Missouri to
Indiana by afternoon. However, sounding progs are showing warm
temperatures in the 850-700mb layer and 700mb charts show
temperatures warming to around 11-12C by afternoon. Atmospheric
cross-sections show some subsidence on the northwest side of former
Claudette as the tropical remnants move into the southern
Appalachians.  The front to our northwest will remain well to our
northwest. Will allow for an isolated thunderstorm in southern
Indiana, but otherwise keep things dry.

Sunday will be hot and muggy with afternoon highs in the upper 80s
and lower 90s on 10-15 mph southwest winds. Afternoon heat index
readings will peak in the 90s.

.Long Term...(Sunday night through Saturday)
Issued at 257 PM EDT Sat Jun 19 2021

...Strong Storms and Heavy Rain Possible Monday...

Long term forecast likely begins dry Sunday evening, but a strong
cold front will be in the process of pushing southeast across the
Midwest. A tightening pressure gradient and warm SW flow will result
in a warm night with lows ranging through the 70s. Deep convection
is likely to initiate along the cold front late in the day Sunday
and surge southeast in a linear mode Sunday night. Weakening storms
could pose a gusty wind threat in our southern Indiana counties by
09-12z Monday.

Monday afternoon and evening, an amplifying upper level trough swings
eastward over the mid-Mississippi Valley. Plenty of mid-level PVA
over the warm sector and sfc cold front will result in plenty of
lift for renewed development. Sfc cold front could be near the Ohio
River as early as 15z Monday, so portions of central and eastern KY
may see the strongest destabilization prior to fropa. There is a
modest increase in WSW flow aloft, but deep-layer shear is generally
25-30 kts in the warm sector with stronger shear lagging the cold
front slightly. Given the linear forcing and largely unidirectional
wind profile, the main concern is damaging winds. A very moist
airmass will support torrential rainfall rates and a marginal risk
for flash flooding as well. Highs Monday will be in the mid 80s to
around 90.

Showers and storms exit off to the east late Monday night/early
Tuesday, and temperatures drop into the mid 50s to lower 60s by
daybreak Tuesday. Upper trough axis remains overhead Tue with cool,
northerly low-level flow and sfc high pressure building in from the
west. Afternoon highs likely only top out in the low to mid 70s for
most, perhaps upper 70s near Bowling Green. Tue night looks cool
with light winds and lows in the low to mid 50s.

Upper level ridging builds over the southern Plains Wed and Thu with
heights rising from the SW. Expect warmer temps Wednesday afternoon,
but still really comfortable with highs in the upper 70s/lower 80s
and dewpoints in the 50s. Mid/upper 80s highs look more likely
Thursday, and the atmosphere does begin to moisten ahead of the next
low pressure system. Expect increasing shower and storm chances late
in the week and heading into next weekend.

&&

.Aviation...(00Z TAF Issuance)
Issued at 715 PM EDT Sat Jun 19 2021

Expect a steady south to southwest wind most of this period as we
remain nestled in between high pressure to our east and low pressure
over the Midwest. Some warm air above the surface should keep storm
threats out of the region for this period. Cannot rule out some
brief stratus overnight/early Sunday, but forecast soundings show
this should remain above 3kft...so no aviation concerns there.


&&

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

$$

Update...RJS
Short Term...13
Long Term...EBW
Aviation...RJS