Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 131852
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
252 PM EDT Sat Sep 13 2014
.SHORT TERM (Now through Sunday Night)...
Issued at 240 PM EDT Sat Sep 13 2014
The synoptic pattern this afternoon features a low-amplitude trough
across much of the central CONUS. The flow will slowly transition
to more zonal regime through the short term period, as dry
The short term forecast looks mainly to be a temperature forecast,
as surface ridging moves in. Mostly cloudy skies from earlier this
morning continue to mix out, thus think most will see some sunshine
before the sun sets this evening. Therefore, think temperatures
will still rise a few degrees over the next few hours into the
The sprawling ridge of surface high pressure will settle into
IL/IN/OH tonight. Winds over our region will go light, but likely
won`t go completely calm. However, with clear skies and dewpoints
currently dropping into the 40s as a dry airmass advects in, it
looks to be a cool night. Average low temperatures this time of
year are in the upper 50s and lower 60s. Given the favorable
radiational cooling conditions tonight, lows will likely be about 15
degrees below these normal readings, ranging from the mid 40s to the
lower 50s. Some of the typically cooler locations could drop into
the lower 40s.
Sunday will be quite a pleasant day across the Ohio Valley. Large
scale subsidence will make for abundant sunshine, which will help
highs push into the low to mid 70s.
Temperatures will remain cool on Sunday night, but should not be
quite as cool as tonight with the surface ridge shifting a bit
further east. Overnight lows will range from the upper 40s to the
.LONG TERM (Monday through Saturday)...
Issued at 255 PM EDT Sat Sep 13 2014
Monday - Monday Night...
A shortwave trough embedded in the overall zonal flow over the
eastern CONUS will move from the upper Midwest to the lower Great
Lakes on Monday, passing east to New England on Monday Night. A
trailing cold front with little deep moisture to begin with will
wash out over the area by Tuesday morning. Will keep only a slight
chance of a light rain shower or sprinkles mentioned over the
northern two-thirds of the CWA for Monday night as a result.
Southern Indiana would have the best shot at seeing a few hundredths
of rainfall. Otherwise, expect a dry Monday with highs mostly in the
low to mid 70s ahead of the aforementioned system. Lows Monday night
should stay a bit milder with the enhanced cloud cover over the
area. Look for the 55 to 60 degree range.
Tuesday - Friday...
Tuesday through at least Friday will feature Ohio Valley fall
weather at its finest. Drier air arrives Tuesday as winds will
become light northerly as surface high pressure descends south
across Iowa. There is good model agreement advertising a 500mb
trough amplification across the eastern Great Lakes and New England
Wednesday through early Friday. Colder air with this trough will
skirt the Great Lakes and invade New England, bypassing us to the
For us, this 500mb northwesterly flow pattern setting up will bring
an extended period of mostly clear days with generally light winds
beginning on Tuesday. Tuesday will cool a bit from Monday, with
highs only reaching the lower 70s in most spots. Expect slow
moderation in temperatures throughout the next work week with highs
reaching the mid and upper 70s by Friday.
Lows Tuesday night will mainly be in the 52 to 57 range, however
expect Wednesday and Thursday nights to be down around the 50-55
Friday Night - Saturday...
We`ll find ourselves on the west side of the departing surface high
as we enter the weekend, meanwhile upper level ridging will try to
take hold. This will keep a dry forecast in place across the region,
with the warming trend continuing. Milder conditions will be around
Friday night with lows back toward the 55-60 range. Highs on
Saturday are expected to be around the 80 degree mark.
.AVIATION (18Z TAF Update)...
Issued at 1251 PM EDT Sat Sep 13 2014
After an hour or two of lingering MVFR cigs, generally VFR
conditions are expected to prevail through the rest of the TAF
period. Pesky MVFR stratus continues to mix out early this
afternoon as bases have risen to around FL025. Bases will continue
to rise and the clouds will begin to break up through the couple of
hours as drier air works in.
VFR conditions will persist through the overnight hours as generally
clear skies prevail. There may be some light BR at KBWG or KLEX
early Sunday morning, but with the drier air working in, confidence
in this occurring is low so will not include any mention at this