Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 300952
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
552 AM EDT Sat Aug 30 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Sunday)...
Issued at 305 AM EDT Sat Aug 30 2014
The Ohio Valley will be placed in deep southwest flow through this
forecast period, between troughing to our NW and ridging off the mid
Atlantic Coast. This will lead to a prolonged period of widespread
shower (and a few storms) chances as deep gulf moisture is funneled
up through the Ohio Valley.
Things will start off quiet this morning with a relative lull in
deep moisture. However, will watch as the next plume lifts northward
out of the Gulf Coast states, combining with moisture over the mid
Mississippi River Valley ahead of a frontal boundary. Scattered to
numerous showers and a few storms are expected to gradually
overspread the area from early afternoon (west) to evening (east).
Today`s activity will mainly be a warm advection/weak isentropic
lift scenario so won`t get too carried away with Pops/coverage.
Expect 60 percent SW to 30 percent NE by early this evening. Highs
today will be dependent on timing of the heavier cloud cover, but
will generally go with highs in the 84-88 range. The west being on
the cooler side.
An impressive surge of moisture looks to arrive overnight and last
through Sunday as an airmass characterized by PWATs in the 2" - 2.1"
range overspreads the area on a 25-35 knot low level jet. With high
confidence in the trajectory this plume will take over the area,
have bumped Pops/Coverage up to 80 percent across the CWA. Won`t go
overboard with thunder coverage on Saturday night as mid level lapse
rates only mirror the moist adiabatic profile through the column,
yielding a tall/skinny look. Therefore, will only mention scattered
t-storms with the widespread rain, but do expect some heavy rainers
will be on the table due to warm rain processes and very moist
atmosphere. Better coverage of t-storms is expected Sunday with
better instability. Overall, it appears central portions of the CWA
could see between 1 to 1.5" of rain through Sunday, locally up to
2". Areas across southern Indiana and near Lake Cumberland can
expect up to 1". Highs on Sunday will be cooler in the low 80s.
.LONG TERM (Sunday night through Friday)...
Issued at 300 AM EDT Sat Aug 30 2014
After storms taper off Sunday evening, looks like we`ll get a brief
pause in precip before additional widely scattered storms develop
Monday afternoon and evening. Coverage will not be as great as for
the weekend, as the focus should be more to our northwest, along a
cold front stretching from Lake Michigan to northern MO. That front
will drift slowly southward through Tuesday, washing out over or
just north of the Ohio River. It`s proximity to us as well as plenty
of moisture should mean at least scattered coverage of storms. Once
again, localized flooding is possible for areas that see training of
Model consensus has a broad ridge across the southern half of the
U.S. for the last half of the work week. For our weather, this
should mean continued above normal temperatures as well as isolated
to scattered storms each afternoon/early evening.
.AVIATION (12Z TAF Update)...
Issued at 551 AM EDT Sat Aug 30 2014
Conditions will start out VFR and pretty quiet across the TAF sites
as we await the next plume of gulf moisture ahead of an approaching
wave. In the meantime, expect scattered to broken mid level clouds
streaming overhead, with light SSE winds. A few light showers will
stretch across the Wabash River Valley.
Will notice an increase in surface winds by mid to late morning, and
a shift to more SSW. Low and mid level clouds will increase during
this time, however should stay above the VFR threshold. Will start
prevailing rain shower and VCTS mention by early to mid afternoon at
SDF/BWG, and by late afternoon at LEX. Conditions will likely
drop to at least low MVFR in any storm, however will nail down
better timing with later issuances.
As we move into the Saturday night period, expect widespread showers
and scattered thunderstorms to overspread the TAF sites. Expect that
prevailing MVFR can be expected, with potential brief periods in IFR
not out of the question. Ceilings will begin to lower after
Midnight, at least into the MVFR range. Widespread showers and a few
storms should prevail well into Sunday as a frontal boundary remains
stalled over the Ohio Valley.