Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 030059
Area Forecast Discussion
National Weather Service Louisville KY
859 PM EDT FRI OCT 2 2015
Issued at 859 PM EDT Fri Oct 02 2015
Updated the forecast this evening to account for the latest radar
trends. Main slug of precipitation associated with a PV anomaly
rounding the upper-level low off to our south continues to push
northwest this evening. Precipitation behind this feature has
become more showery. Hi-res guidance continues to suggest that some
low-level dry air will work in overnight, which may help to cut off
measurable precipitation for a few hours overnight into early
Saturday morning in the wake of this upper-level feature. However,
additional rains will push in from the east likely around sunrise
Saturday and trek through the rest of the region through the
.SHORT TERM (Now through Saturday Night)...
Issued at 315 PM EDT Fri Oct 2 2015
Now through Saturday Night...
The upper low will continue to spin over the Gulf Coast through the
short term, sending surges of deep moisture westward across our CWA.
This will result in two main batches of rain, with periods of
isolated coverage in between. As far as temperatures are concerned,
we`ll stay well below normal for highs as steady NE surface flow
combines with heavy cloud cover.
...First Batch of Rain...
A band of widespread light rain is lifting NW across the CWA, and
will continue to do so through the remainder of the afternoon into
the evening. Most spots should see between a quarter and a half inch
of rain with this round, although many spots north of I-64 may see
less than a quarter inch. The most widespread rain will fall between
now and 8 PM, then tapering off from east to west through the
remainder of the early evening. Will leave a slight chance in
overnight, however do expect a relative lull in precip before the
next wave arrives later Saturday morning.
Temps will stay in the 50s the rest of this afternoon and evening,
dropping into the upper 40s and low 50s tonight.
Second Batch of Rain...
A good fetch of Atlantic moisture moves in from the east on
Saturday, combining with mid level deformation north of the parent
upper low. These ingredients will pivot from a N-S orientation along
the I-75 corridor to a NW-SE orientation through the afternoon and
evening, weakening as it does so.
As we near the dawn hours of Saturday, expect precipitation coverage
to begin increasing along the I-75 corridor. Coverage and intensity
should then increase through the day, with numerous to categorical
chances along and east of I-65. Further west, we`ll see scattered to
numerous light rain showers. Areas along and east of I-75 could see
prolonged periods of moderate rain where rainfall totals might
exceed an inch in spots, however the bulk of the precipitation will
fall east of our CWA border.
The axis of rain will diminish through the evening with only iso-sct
coverage across our far south after Midnight. Highs Saturday are
expected to be cooler than today, with a continued steady NE wind.
These temps combined with the wind and rain will make for a raw day.
Look for highs only topping out in the low and mid 50s.
.LONG TERM (Sunday through Friday)...
Issued at 245 PM EDT Fri Oct 02 2015
The synoptic pattern at the start of the long term period will
feature two closed mid/upper-level lows, one across the Southeast
and another across the western CONUS. The low across the Southeast
will be the main near-term focus, before upper-level ridging builds
in for much of the upcoming workweek.
Joaquin has begun its northward jog to the north, a trend which will
continue for the next couple of days before it turns more northeast
and heads out to sea. This trajectory will allow for the cutoff low
across the southeast to meander to the east through the weekend. As
this occurs, the better fetch of Atlantic moisture will be pushed to
the SSE of the region, which will allow for decreasing pops through
the day on Sunday. Will continue with slight chance-chance pops in
the southeast, but coverage should not be great. Clouds will likely
hang tough through the day across the southeast CWA, so expect a
pretty large range from northwest (mid 70s) to southeast (mid 60s)
in temperatures on Sunday.
The remainder of the long term period looks mainly dry as the upper
low pushes off the coast allowing heights to build over the Ohio
Valley. A warming trend will commence through the workweek, with
highs likely nearing 80 by Thursday of next week. A cold front
associated with the aforementioned west coast low will approach
towards the end of the long term period, but precipitation chances
look to mainly hold off until Friday.
.AVIATION (00Z TAF Update)...
Issued at 709 PM EDT Fri Oct 02 2015
The main surge of deep moisture off the western Atlantic continues
to push northwest of KLEX/KBWG, affecting KSDF as of this writing.
In its wake, scattered light showers will linger through about
midnight before precipitation becomes rather isolated overnight.
Cigs remain a challenging forecast overnight, but obs upstream (to
the northeast) show the potential for some improvement in cigs
overnight. Some hi-res guidance even suggests a period of VFR
conditions will be possible overnight. Will not trend that
optimistically given all the low-level moisture in place, but will
trend all sites to at least break out of IFR cigs and into MVFR
conditions for a time overnight. Additional showers and fuel-
alternate MVFR/IFR conditions will once again be possible at all
sites tomorrow, especially KLEX. Winds through the period will
remain out of the ENE at 8-15 knots with a few higher gusts.