Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 200142
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
942 PM EDT Fri Sep 19 2014
Issued 940 PM EDT Fri Sep 19 2014
Only made minor changes to hourly forecast grids based on current
conditions. Of note...some of the 18Z models are indicating an area
of isld showers may develop along the Ohio River due to weak
isentropic lift after sunrise. Will not add POPs at this time, but
it may be worth considering if 0Z runs indicate the same. Otherwise
expect a mostly clear night with some strato-cu developing late.
Low temps will be in the mid 50s to lower 60s.
.SHORT TERM (Now through Saturday Night)...
Issued at 300 PM EDT Fri Sep 19 2014
Surface ridging currently centered over New England extends
southwest along the Ohio River through Missouri. This ridge has
brought quite dry easterly winds to the Commonwealth and pristine,
almost cloud-free skies that will likely continue at least through
the evening hours.
Winds will veer to the south tonight and to the south southwest
Saturday as return flow sets up as this ridge axis sags southwards
into the Tennessee Valley. Skies will initially stay clear this
evening, but forecast soundings hint at a possibility of some
strato-cu developing and advecting north during the early morning
hours tomorrow. Despite south winds Saturday, deep moisture will not
really arrive until late afternoon or during the evening.
Temperatures early tomorrow will only fall into the upper 50s to the
lower 60s. Expect a warm day Saturday under partly cloudy skies with
highs reaching the lower 80s. Indeed, Saturday will be our warmest
day in well over a week.
A quick moving disturbance moving along the U.S - Canadian border
will amplify a bit as it cross the western Great Lakes Sunday
morning. By late Sunday, this feature will move across western New
England. Both the NAM and the GFS bring its associated cold front
south of the Ohio River during the late morning hours Sunday.
Scattered showers and storms may develop to our north late Saturday.
However, this boundary will be crossing the Ohio during the morning
hours, with little surface-based instability present. Scattered
convection over southern Indiana very early Sunday will likely be
weakening. The NAM especially hints at a possible re-development of
convection along our southern counties during the afternoon hours
right before the cold front clears the state. Think that the best
chances of any substantial precipitation will be north across
central and possibly southern Indiana, and to our south along our
Ky/Tn border. Highs Sunday will range from the lower 80s south to
the mid 70s north.
.LONG TERM (Sunday through Friday)...
Issued at 249 PM EDT Fri Sep 19 2014
Sunday - Sunday Night...
The only rain chances in the long term will occur on Sunday as a
trough swings through the Great Lakes region, and the trailing cold
front slides through our CWA. Will continue to mention scattered
coverage of showers and a few storms along and ahead of this front
during the day. Deep moisture ahead of the front isn`t impressive
enough to warrant higher coverage. There has been a considerable
trend toward faster timing over the past 24 hours, so will actually
go dry for the Sunday night timeframe. Temperatures will be a bit
tricky on Sunday due to the frontal passage, however most spots
should find their way to the upper 70s to around 80.
Monday - Friday...
Surface high pressure will settle into the region on Monday behind
the departing front. Meanwhile, the departing upper trough axis will
push east. This will bring a cool down along with some developing
stratocu. Highs will only top out in the upper 60s and low 70s.
Monday night will bring lows into the 45-50 range.
We`ll be under the influence of an expansive upper level ridge and
surface high pressure Tuesday through Friday. Dry conditions will
persist with temperatures slowly trending back toward the 80 degree
mark by Thursday and Friday. After Tuesday night in the upper 40s to
around 50, overnight lows will mainly range in the mid 50s for the
remainder of the week.
.AVIATION (00Z TAF Update)...
Issued at 720 PM EDT Fri Sep 19 2014
VFR conditions are expected this TAF period as we enter return flow
on the back side of departing high pressure. A few things of note
to watch though. First of all, models keep hinting at the
development of a strato-cu deck over TN late tonight that may advect
into our area from the south. If this happens, a cig between 3-4
kft may become established at the TAF sites during the early morning
hours. Have remained optimistic with a sct deck at this time
though. Also, a LLJ of around 30 kts is progged to develop late
tonight which may cause borderline LLWS. Felt that this threat was
too minimal to include in the TAFs at this time.
Sfc winds should remain ESE through the night decreasing to around
or below 5 kts after sunset. Winds will veer more SSW for tomorrow
afternoon increasing to 8-12 kts.