Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 172300
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
700 PM EDT Wed Sep 17 2014

...Updated Aviation Discussion...

.SHORT TERM (Now through Thursday Night)...
Issued at 255 PM EDT Wed Sep 17 2014

Weakening NW flow aloft, and surface high pressure to our north and
east will dominate our weather pattern through Thursday night. Dry
weather and cooler than normal temperatures will persist, with early
morning fog potential as the main forecast challenge.

Modifying high pressure over the Ohio Valley will be reinforced a
bit from the north, as a stronger surface high migrates east across
the upper Great Lakes. Still don`t expect a very tight pressure
gradient, so winds will remain quite light, and this will make for
favorable radiational cooling conditions tonight. Min temps in the
lower/mid 50s will just cross over current dewpoints, especially at
BWG. Therefore, fog development is a concern, and we will include at
least patchy fog over much of the forecast area, and bump up to
areas of fog in the typical fog-prone locations.

Once any fog burns off Thursday morning, expect even more sunshine
than today, with temperatures moderating but still solidly below
normal. Followed raw model consensus with highs generally in the mid
70s.

Thursday night will again be favorable for radiational cooling.
However, less concerned with fog as there doesn`t appear to be as
much low-level moisture. Also looking for an easterly low-level jet
to pick up to 15-20 kt, which creates a much better chance of
lifting anything into a stratus deck.

.LONG TERM (Friday through Wednesday)...
Issued at 307 PM EDT Wed Sep 17 2014

Friday - Saturday Night...

Expect a pretty benign upper air pattern for most of the weekend,
with the western edge of a surface high anchored over New England
controlling our weather. This will result in dry conditions with
highs in the 75-80 range on Friday. Temperatures will warm a few
degrees to th 80-84 range on Saturday. Friday night lows will be
milder and generally in the 55-60 range.

Sunday - Early Monday Morning...

By Sunday, a trough and its associated surface low will slide across
the Great Lakes, with a trailing cold front approaching from the NW.
This feature should be enough to fire off scattered thunderstorms on
Sunday as it sinks slowly SE. At this point, the best energy looks
to stay north of the CWA so potential for stronger storms seems low.

Models have come into a bit better agreement with precipitation
exiting our SE CWA by early Monday morning. Temperatures on Sunday
look to top out around 80, with lows Monday night in the upper 50s
to around 60.

Monday - Wednesday...

Another dry and cooler period looks to return next week as expansive
surface high pressure and upper level ridging build in behind the
front. Expect dry conditions with highs settling back in the low
70s. Some spots may struggle to get out of the 60s on Tuesday and
Wednesday. Lows will find their way back down to at least the upper
40s and low 50s.

&&

.AVIATION (00Z TAF Update)...
Issued at 700 PM EDT Wed Sep 17 2014

An upper level disturbance moving from the Missouri bootheel into
the Tennessee Valley is expected to develop and spread mid level
clouds into central Kentucky tonight.  These clouds may help to keep
fog development from getting out of hand.  Still, will have to
include a few hours of MVFR BR at BWG and LEX Thursday morning to
cover the possibility of patchy fog.

After light and variable winds tonight, we`ll have northeast breezes
around 6 knots on Thursday thanks to high pressure over Ontario.

&&

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

$$

Short Term........RAS
Long Term.........BJS
Aviation..........13



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