Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 011721
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
121 PM EDT Mon Sep 1 2014

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1153 AM EDT Mon Sep 1 2014

A small cluster of showers with some embedded thunder is progressing
quickly across central Kentucky and will be capable of producing
some locally gusty winds into the 40-50 mph range as it moves into
the Green River Lake region and an area of maximized DCAPE and
surface instability.  Have updated the forecast grids to reflect
this area of precipitation, along with the few other showers that
are scattered around the area.

Issued at 859 AM EDT Mon Sep 1 2014

Widely scattered showers have formed in a corridor of higher surface
dew points and CAPE, and diminished CIN, from Memphis to Detroit.
have upped PoPs for a few hours this morning in the northwest LMK
CWA to account for this.

.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014

A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.

Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.

There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.

.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014

Tuesday Night and Wednesday...

Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.

Wednesday Night - Friday...

The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.

Friday Night - Saturday Night...

The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.

Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.

Sunday...

Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!

&&

.AVIATION (18Z TAF Update)...
Issued at 121 PM EDT Mon Sep 1 2014

Scattered showers and isolated thunderstorms will be possible this
afternoon in the warm, humid, unstable air over central Kentucky.
Any convection will be moving quickly and would affect any one
airfield only very briefly.  For now will stick with VCSH, and
monitor radar closely for any helpful AMDs.

Winds this afternoon will be gusty from the southwest, gusting into
the 22 to 26 knot range.

Tonight winds will settle down though there will still be a
southerly breeze around 5 to 9 knots as we sit in accelerated flow
ahead of an approaching cold front.  Isolated convection will be
possible, but at this time chances appear slight enough to omit from
the TAFs.

Toward morning that cold front will be entering the region, bringing
a band of showers and thunderstorms along with it.  Right now will
time it into SDF around dawn and a little later at LEX/BWG, though
they could end up coming in a little quicker than that.

&&

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

$$

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




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