Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 241904
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
303 PM EDT FRI MAY 24 2013
.Short Term (Now - Saturday Night)...
Issued at 303 PM EDT Fri May 24 2013
...Patchy Frost Possible in Eastern Valleys Tonight...
Surface high pressure centered over Lake Michigan has established
control across the Ohio Valley. Meanwhile, northwest flow aloft will
hold between eastern CONUS trough and central CONUS ridge. The main
concern for tonight will be how low temperatures get under good
radiational cooling conditions. Current dewpoints are generally in
the low to mid 40s, however upper 30s dew points lurk just to the
north. Expect dew points to drop some more over the next few hours
as a light advective component from the north and mixing contribute
to overall drier air. This will set the stage for tonight as clear
skies and calm winds allow temperatures to drop. Most locations
should stay in the low to mid 40s, however a few of the coolest
eastern valleys may drop into the upper 30s. There is some concern
for a few patches of frost in these areas so will continue the
Special Weather Statement for the eastern two tiers of counties.
Most spots will not see frost. Also may see some patchy fog in river
valleys toward dawn.
Will keep the forecast dry on Saturday, however will see an increase
in upper level clouds. Will see temperatures recover to the mid 70s
across southwestern portions of the CWA under warmer H85 temps and
less cloud cover, however eastern and central portions of the CWA
will stay in the 65 to 70 degree range. There will be deep enough
moisture aloft for some virga to fall out, however think it will be
too dry in the lowest levels for any precipitation to hit the
Will continue to mention small chances for a measurable rain shower
as we get into Saturday night as deeper moisture from upstream
continues to move into the area. There is some model support for
upstream MCS to dive across our area, which is fitting in this
northwest flow pattern. However, not confident enough in this
scenario at this time. Will continue to monitor trends. Lows on
Saturday night will be milder, generally in the upper 40s and lower
.Long Term (Sunday through Friday)...
Issued at 250 PM EDT Fri May 24 2013
We will begin this period with a warm front oriented northwest to
southeast across the region, flow aloft also from the northwest, and
some weak hard to time vortmaxes coming down in that flow. Despite
the timing, several models are bringing in QPF, with the 4km NAM the
most robust having an MCS come through the region during the day. We
look to have continued chances for showers/storms through at least
Monday, when that warm front will lift north and pull the best
chances away from the region. The temperature forecast through
Monday will depend on timing of these waves, but in general went
with 70s for Sunday and around 80 Monday.
From Tuesday on, a ridge will build aloft, with it becoming centered
over us by Thursday. The result will mean below normal rain chances
and above normal temps. Readings will bump up to the mid 80s Tuesday
but could approach 90 Wednesday through Friday.
.Aviation (18Z TAF Issuance)...
Issued at 1253 PM EDT Fri May 24 2013
High pressure is building into the region and will hold influence
through this forecast cycle. This will keep conditions dry and VFR.
Few - Sct cu should gradually mix out through the afternoon with a
steady NNW wind between 5 and 10 mph. Winds will go nearly calm to
calm tonight. Expect a light easterly wind on Saturday with Few to
Sct upper level clouds beginning to move overhead.