Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 171908
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
308 PM EDT Wed Sep 17 2014
.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
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 (18Z TAF Update)...
Issued at 1245 PM EDT Wed Sep 17 2014
Morning fog/stratus finally lifting at BWG, leaving us with a VFR
afternoon. Just enough low-level moisture that we will see a
strato-cu ceiling at times, but no restrictions to flight category.
The challenge will be fog potential around daybreak Thursday.
Similar setup to this morning, but we will be a bit more on the
periphery of the surface high. Still, winds will be nearly calm and
temps are expected to cross over the dewpoints, so IFR fog seems a
pretty good bet in BWG. Will carry borderline IFR/LIFR conditions
for a couple of hours. SDF and LEX should remain unrestricted, with
light winds generally out of the NE.