Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 171356
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
955 AM EDT MON JUN 17 2013
Issued at 940 AM EDT Mon Jun 17 2013
Isolated thunderstorms have popped this morning, and are now just
south of the Bluegrass Parkway. SPC mesoanalysis shows an axis of
higher K-index extending ESE from near Jasper, IN to near Richmond,
KY. Products have been tweaked slightly to go with coverage wording
instead of chances for today, and also to include thunder this
.SHORT TERM (Today through Tuesday)...
Issued at 300 AM EDT Mon Jun 17 2013
500mb flow is currently broadly cyclonic across the upper midwest
and the Northern Ohio Valley. This configuration will continue
through late Tuesday as somewhat displaced south polar vortex
remains over northern Quebec. A series of weak, difficult- to-time
waves embedded in this flow will move through the region through
The axis of greatest PWATs orientated along the Ohio River yesterday
has slipped farther south across southern Missouri and the Tennessee
Despite a lack of any discernible disturbance approaching later this
morning, isolated showers are possible through the morning across
central and eastern Kentucky. Weak to moderate instability is again
forecast for this afternoon, and again feel that isolated to
scattered thunderstorms will develop by mid afternoon. Think they
will stay more unorganized than Sunday`s storms due to very light
winds up to around 850mb. Outside of any afternoon convection,
expect partly cloudy skies and temperatures peaking a few degrees
warmer than yesterday, reaching the mid to perhaps the upper 80s.
A weak disturbance has been consistently forecast by short term
guidance to move southeast across western Kentucky late this evening
or early Tuesday. Some of our earlier forecasts have emphasized the
possibility of widespread convection late Monday or early Tuesday
with this feature. However, am losing confidence in these earlier
projections. Southern Indiana increasingly looks like it will be
missed by any convective development late Monday as it looks to lie
north of the preferred deep moisture over Tennessee. Will reduce
forecast pops to 40 to 50% over central Kentucky from late Monday
through Tuesday morning. Will maintain at least a slight chance for
convection through Tuesday afternoon as well.
Winds will stay quite light through this entire period, with calm
winds this morning becoming southerly at only around 5mph this
.LONG TERM (Tuesday Night through Sunday)...
Issued at 315 AM EDT Mon Jun 17 2013
Tuesday Night through Thursday Night...
Much of the region will continue be influenced by a baggy eastern
CONUS trough at the beginning of the period. May see some
isolated-scattered diurnal convection at the very beginning of the
period Tuesday night...mainly across the south. The upper trough
over the eastern US is forecast to shift eastward as the multi-model
consensus agrees that another mid-level ridge will steadily build
across the central Plains. As the mid-level heights rise, we should
see mainly dry conditions from Wednesday through Thursday night
along with a moderation in temperatures. Highs Wednesday should
average in the lower to middle 80s with readings generally in the
middle 80s for Thursday. Overnight lows during the period will be
in the 60s.
Friday through Sunday...
Rather large heat ridge looks to strengthen to our west during the
period. The multi-model consensus agrees with this synoptic
evolution, but there are minor differences in the direct placement
of the ridge axis. It does appear that the ridge axis will be to
our west and may be just east enough to keep us relatively dry
through much of the period. It does appear that MCS action will
probably be in full swing across the northern Plains and these
systems will rotate around the periphery of the ridge. At this time
range, it is nearly impossible to time or place these features, so
have opted to just to keep a near climatological PoP in for Sunday.
With increasing time, temperatures will continue to moderate through
the period. Highs Friday and Saturday will warm into the 85-90
degree range with highs generally near 90 by Sunday. Overnight lows
will be in the upper 60s to the lower 70s.
.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Mon Jun 17 2013
Light winds and some scattered mid-level cloudiness will continue
through the mid-morning hours today. Wet grounds brought light haze
to SDF and LEX, which will erode by 13z. Isolated light showers with
less than 10% coverage will continue through mid-morning, but
coverage is so sparse that they will not be included in the TAFs.
Scattered thunderstorms will develop, especially across the south by
morning or early afternoon, continuing through the evening hours.
With the unorganized nature of these pop-up storms, will not attempt
to time any potential convection to any TAF site.
Winds will be very light during the day on Monday, perhaps becoming
southerly around 5kt during the afternoon hours. Isolated showers
and nearly calm winds are expected again tonight.