Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 251646
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1246 PM EDT SUN SEP 25 2016

...Updated Aviation Discussion...

.SHORT TERM (Now through Monday)...
Issued at 247 AM EDT Sun Sep 25 2016

Strong upper level ridging continued across the lower Ohio Valley
early this morning while high pressure remained across the Great
Lakes region. An area of low pressure was analyzed over North Dakota
with a strong cold front stretching south through the central Plain
states. Locally, it was quite mild with readings mainly in the
mid/upper 60s to low 70s, along with patchy fog across the favored
valley locations.

For today, expect one more hot day with readings forecast to top out
in the upper 80s to low 90s, more or less the same as the past few
days. Winds are expected to be mainly light and out of the
east/northeast.

The aforementioned cold front will approach the region late tonight
and likely be along or just west of the I-65 corridor by daybreak
Monday. Forecast models remain very consistent showing a band or two
of showers and perhaps some thunderstorms quickly moving through
southern Indiana and central Kentucky Monday morning and into the
portions of the afternoon. By the evening commute Monday, the front
is expected to be east of the I-75 corridor and most of the shower
activity out of the area. Rainfall amounts are forecast to be around
0.10 of an inch or less.

The morning frontal passage along with showers/storms and afternoon
cold air advection will keep Monday`s highs in the 70s to around 80,
coolest across southwest Indiana. Plan on breezy west to northwest
winds increasing in the afternoon as the dry air really pours into
the region. Clouds will scour out by sunset giving way to mostly
clear skies for the evening.

.LONG TERM (Monday Night through Saturday)...
Issued at 249 AM EDT Sun Sep 25 2016

The long term period will feature seasonably cool temperatures but
questions remain whether the week will be dry. Forecast confidence
drops considerably mid-week onward.

An anomalously deep upper trough is forecast to move into the Great
Lakes region, close off, and then stall over the Appalachians
throughout the week. At the surface, high pressure will be mainly
positioned across the Upper Midwest.

The air mass will be seasonably cool with 850 mb temperatures
forecast to be between 5 and 10C Monday night through Friday. This
translates to daily highs in the 70s and morning lows in the upper
40s to low 50s. Deeper mixing during the afternoon will bring down
some higher winds compared to what we`ve seen recently, with gusts
15-25 mph possible. Dry weather is expected Monday night through
Tuesday night.

The chances for precipitation Wednesday onward depend greatly on the
evolution of the closed low that may form and stall over the
Appalachians. The GFS and Canadian solutions suggest the bulk of its
influence will remain east of the area, but the ECMWF continues to
advertise a western scenario which would bring more clouds and
showers to the lower Ohio and TN Valleys. Forecast models typically
handle these closed low scenarios poorly beyond days 3 or 4, so
overall confidence is below average. WPC`s analysis favors a blend
of the non-ECMWF solutions and notes that the ECMWF has had the
poorest continuity and most changeable appearance over the past few
days.

For now, will still feature a mainly dry forecast for the area
but if the next model cycle continues to show this idea of a closed
low nearby, precipitation chances may need to be introduced for
parts of the area Wednesday or Thursday onward. Temperatures also
would need to be dropped as more clouds and showers would greatly
limit daytime heating and some of the raw gridded guidance shows
highs easily stuck in the 60s.

&&

.AVIATION (18Z TAF Update)...
Issued at 1245 PM EDT Sun Sep 25 2016

VFR conditions with light winds will prevail through the day and
evening as high pressure holds on for one more day. A cold front
will approach the region tonight and move through Monday morning
into the early afternoon. Scattered showers and a few thunderstorms
will accompany the front passing through. Ceilings will lower to
near MVFR range as it moves through tomorrow. Winds will shift to
northwesterly with the front tomorrow morning and could become a bit
gusty at times. BWG may see some light fog tomorrow morning.
However, do not think it will be as dense as this morning due to
stronger winds not far off the surface ahead of the front.

&&

.LMK Watches/Warnings/Advisories...
KY...NONE.
IN...NONE.
&&

$$

Short Term........ZT
Long Term.........ZT
Aviation..........EER



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