Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 180727
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
327 AM EDT Fri Apr 18 2014
.SHORT TERM (Now through Saturday)...
Issued at 325 AM EDT Fri Apr 18 2014
Weakening surface cold front is pushing toward the Wabash River
early this morning. Area 88-D`s are showing a few returns, but
observations show nothing hitting the ground. The front will slowly
move eastward later today. In the meantime, mostly cloudy skies
will continue across the region as a thick veil of mid-high level
cloudiness remains across the region. The clouds have kept
temperatures warmer than in previous mornings with NWS observation
points and Kentucky Mesonet stations showing readings generally in
the lower to middle 40s. The data suggests that we are still seeing
a little big of a ridge/valley split again...but not as dramatic as
in the last few nights. We expect temperatures to fall a few more
degrees before sunrise with minimums dropping into the mid-upper 30s
in the cool spots with lower 40s elsewhere.
For today, the latest model guidance continues to trend drier with
the front crossing the region today. The underlying cause of the
drier solutions is the rapidly developing upper cut-off low
developing across northern Gulf. This feature will tend to keep all
the moisture well to our south. Have trimmed back PoPs a bit more,
especially across the north. Still think a stray shower may
transverse our southern counties, but overall most areas will remain
dry today. Clouds will keep temperatures down slightly with highs
topping out in the upper 60s to around 70.
For tonight and Saturday, upper level cut off low across the SE US
will continue to slowly work eastward. Drier influx of air will
push in tonight and into Saturday which will bring increasingly
clear skies tonight and mostly sunny conditions for Saturday. Lows
tonight will cool into the lower to middle 40s with highs on
Saturday warming into the 70-75 degree range.
.LONG TERM (Saturday Night through Thursday)...
Issued at 302 AM EDT Fri Apr 18 2014
The synoptic pattern at the start of the long term period will
feature split flow across the Ohio Valley. However, this will
transition to more of a western trough/eastern ridge upper-level
regime towards the end of the long term period, meaning warmer
temperatures are likely through the long term period.
Easter Sunday is shaping out to be a very pleasant day across the
region, perfect for hunting eggs and enjoying the outdoors.
Temperatures will rise into the middle and upper 70s (perhaps
flirting with 80 in a few locations) under mostly sunny skies.
Winds will be rather light as well, as a surface ridge slides
through the Ohio Valley.
A weak PV anomaly and associated surface cold front will slide
toward the region Monday into Tuesday. Have taken a bit of a model
blend to handle this system. Think the ECMWF is a bit too
aggressive with the precip arrival on Monday, as it tries to develop
some convection well ahead of the surface front within the warm
conveyor belt. Given the general lack of low-level moisture with
this system due to high pressure over the northern Gulf, and the
indication of a weak cap in the forecast soundings, think the
majority of Monday will likely stay dry. So, will side with the GFS
and lean toward a later arrival to the precipitation, and only keep
slight chance/chance wording in for Monday. Coverage looks to
increase a bit overnight Monday into early Tuesday as the cold front
and trough swing through. Think the GFS is too aggressive in this
timeframe with QPF given the general lack of deep moisture and
forcing for ascent, so have sided more toward the ECMWF for QPF
The showers and isolated thunderstorms will push east by late
Tuesday afternoon, allowing things to dry out through at least
Thursday. Temperatures Tuesday behind the front will be slightly
cooler, in the low to middle 70s, but should moderate back into the
upper 70s by Thursday.
The ECWMF tries to bring the next system into the Ohio Valley
Thursday night into Friday. However, with the upper-level flow
undergoing amplification, think the ECMWF is likely too quick with
this feature. With this reasoning, have kept Thursday night dry and
limited pops to 20% on Friday.
.AVIATION (06Z TAF Update)...
Issued at 113 AM EDT Fri Apr 18 2014
A weak surface front will approach the region this morning. With
the lack of any significant forcing, this front will just be
accompanied by mid-high level cloudiness. VFR conditions are
expected to prevail through the period with generally light and
variable winds. We will likely see a bit of cu develop during the
day tomorrow with bases around 5kft AGL. Clearing skies are
expected toward the end of the period.