Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 050016
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
816 PM EDT Sat Jul 4 2015
Updated at 815 PM EDT Sat Jul 4 2015
Forecast remains on track for this evening and overnight. Currently
the area is shower/storm free as convection is confined south of the
KY border. As upper level wave begins to pivot to the east/northeast
later tonight, showers and storms will once again spread back into
southern KY and the Lake Cumberland region.
Otherwise, plan on partly to mostly cloudy skies thanks to
debris/anvil clouds moving overhead. This should act to limit
widespread fog and also a day of drying for most will certainly help
.SHORT TERM (Now through Sunday Night)...
Issued at 307 PM EDT Sat Jul 4 2015
Scattered showers have developed this afternoon across mainly south
central KY near the stalled frontal boundary. These showers should
diminish early this evening with just isolated coverage expected
through much of the evening hours. Thus, expect that pretty much all
of the forecast area will have only a 20% or less chance for rain
around time for fireworks celebrations tonight. Temperatures will
be in the mid to upper 70s by sunset.
An upper level trough will move through the region tonight and
Sunday, continuing to slowly shift eastward Sunday night. Moisture
will increase again on the eastern side of this trough tonight with
showers and storms developing again. Storm coverage will increase
late tonight into tomorrow across mainly south and east central
Kentucky. The best chances for showers and storms will be around and
just north of the Lake Cumberland area. However, short term and
mesoscale models do differ a bit in how far east the best storm
coverage will be. It could end up that the higher coverage of storms
is just to the east of the forecast area. These showers and storms
will be efficient rain producers with precipitable water values
rising to around 1.8". If training does occur, some minor flooding
will be possible. However, given model differences, confidence in
widespread problems is low, so will hold off on headlines for now.
Rain will move off to the east tomorrow night with dry conditions
expected for much of the night.
There is the potential for some fog tonight if clouds do clear.
Think this would mainly be across southern IN, similar to this
morning. Lows the next two mornings will range from the mid 60s to
around 70. Highs will be tricky tomorrow and depend on rain
coverage. Highest temps will be across southern IN and along the
Ohio River in the mid 80s. Lowest temps will be in east central KY
where highs may top out only in the upper 70s.
.LONG TERM (Monday through Saturday)...
Issued at 305 PM EDT Sat Jul 4 2015
For the start of the work week, we`ll have an upper low exiting the
Ohio Valley leaving us in a brief relatively subsident region within
the overall pattern. This will result in meager precip chances for
Monday...20-30% at best. Tuesday a frontal boundary from a low
pressure system traversing southern Canada will move into the
Midwest becoming draped over the Ohio Valley through Wed
night/Thurs. A wet setup once again looks likely for the middle of
the coming week with multiple upper level shortwaves riding along
the boundary providing several rounds of showers/storms. This setup
has the potential to pose flooding issues given the very wet end of
June/beginning of July that we`ve already experienced. The threat
for severe wx looks uncertain and will depend on boundary location
and available instability. We may have an opportunity to build some
instability Mon/early Tue with low precip chances, some sunshine,
and highs solidly in the 80s area wide. Highs for Wed/Thurs will
drop back into the upper 70s/lower 80s. Low temps through mid week
will range from the mid 60s to lower 70s.
For the latter half of the week, it is unclear whether a southern
ridge will build over the southeast U.S. and into the Ohio Valley
pushing the boundary and active westerly flow north (12Z GFS/GFS
ensembles) or if the southern ridging will stay suppressed resulting
in a continued active, rainy pattern (12Z Euro). It could be a very
wet first couple weeks of July if the Euro soln plays out. Have
trended the forecast toward the GFS/GFS ensembles going a little
drier (20-30% precip chances) for the end of the week. Also, went
with the resultant warmer temps associated with the better ridging.
This would mean high temps back into the upper 80s/lower 90s by
Fri/Sat. However, given the uncertainty of the pattern, forecast
confidence is low beyond Thursday.
.AVIATION (00Z TAF Update)...
Issued at 710 PM EDT Sat Jul 4 2015
Main concern is ceilings/visibilities at BWG overnight into early
Sunday morning as a southern stream weather system approaches. With
ample low level moisture and light winds expected, there`s above
average confidence for IFR conditions to develop around 09z.
Ceilings may hold in the 500 to 1000 ft range through 14z.
Visibilities are more tricky as mid/high clouds streaming overhead
may preclude more dense fog. Maintained current forecast of 2-3 sm
developing during the pre-dawn hours.
At LEX/SDF, slightly drier air and a day of drying as well should
keep dense fog potential less likely. Some patchy light fog possible
at LEX though. For Sunday, plan on easterly flow as wave of low
pressure moves southeast of the area. Few to scattered VFR cumulus