FXUS63 KLMK 151052
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
652 AM EDT Wed Jul 15 2015
...Updated Aviation Discussion...
.SHORT TERM (Now through Thursday)...
Issued at 305 AM EDT Wed Jul 15 2015
Sfc high pressure and upper level ridging will move into the region
today and tomorrow providing relief from the rainfall and heat.
Early this morning, some isolated patches of light fog have
developed. Think we'll continue to see some light patchy fog
develop through sunrise but don't think visibilities will drop too
low given the upper level clouds over much of the area currently and
some low clouds progged to work into the region from the NE during
the pre-dawn hours. Will continue to monitor though.
Portions of southern Indiana and north central KY may have a blanket
of low clouds for a good portion of the morning hours before these
clouds break up and lift. This may limit high temperatures to the
upper 70s and lower 80s in the cloudy areas. Elsewhere over south
central, west central KY, and southwest IN, expect high temps to
range from the low to mid 80s.
Tonight skies will go mostly clear with only a few upper level
clouds expected over the region. Winds will go calm or light and
variable with soundings looking a little more favorable for fog.
Will insert light patchy fog for much of the area late tonight and
let coming shifts decide if more coverage or lower vsbys are
warranted in the forecast. Low temps should range from the lower
60s to around 70.
For Thursday, expect another dry and mostly sunny day with high
temperatures ranging through the 80s.
.LONG TERM (Thursday night through Tuesday)...
Issued at 310 AM EDT Wed Jul 15 2015
Forecast pattern in extended continues to emphasize persistent
mid-level high pressure and ridge over the southern Plains and
southeast U.S. with faster flow and various shortwaves across the
northern Plains and Great Lakes. The Ohio Valley will continue to be
positioned between these major features with west to northwest flow
aloft as the ridging aloft tries to poke into our area late this
week into early next week. As a result, parts of the Ohio Valley and
southern Great Lakes should remain in the axis of active periodic
convective systems (MCSs).
It is difficult at this time range to determine where such mesoscale
systems will set up exactly, but the synoptic setup again suggests
such systems could occur. At this time, it appears the main action
should remain just north of our forecast area over the weekend into
Monday where better forcing and instability will reside. Neverthe-
less, isolated to scattered thunderstorms will still be possible in
parts of our area, i.e.. mainly southern IN into north-central and
east-central KY, with dry weather over southern/western areas where
mid-level capping and less instability will reside. It will not be
out of the question that an MCS could turn enough southeast to
affect mainly our northeastern counties sometime in the Saturday to
Monday time frame. The Canadian GEM would suggest this most, while
the GFS and ECMWF are a little more ridgey keeping more widespread
convection to our north. Will continue to indicate our northern
counties as the best chance of convection, but not the widespread
MCSs we have seen lately.
Deeper into the extended there is some model discrepancy with the
approach from the west of an elongated moisture and instability axis
associated with a cool front. The GFS and ECMWF are most consistent
with this, albeit different in timing (ECMWF faster), while the GEM
appears as an outlier. Thus, an axis of convection may occur in the
late Monday or Tuesday time frame depending on system speed and
mid-level flow characteristics. As always, convection would be
associated with more heavy rain potential.
Friday through Sunday will also feature hot mid-summer temperatures
across much of our area. Highs will be in the lower and mid 90s with
surface dewpoints rising into the upper 60s to perhaps mid 70s at
times (mainly north). This would push afternoon heat indices over
100, especially in western/northern areas. Temperatures should then
recede somewhat late in the period associated with the cool front.
.AVIATION (12Z TAF Update)...
Updated 650 AM EDT Wed Jul 15 2015
Low MVFR/IFR clouds are expected to build south from Indiana and
Ohio into the SDF/LEX TAFs around or just before 12Z. This low
cloud deck should persist for at least 2-4 hours before beginning to
break up and lift by mid to late morning resulting in a return to
VFR conditions. Northerly winds will become light or calm tonight
with light br possible tomorrow morning.
Delivered by Weather Underground Inc. Wed Jul 15 2015 6:52AM EDT