Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 300941
Area Forecast Discussion
National Weather Service Louisville KY
541 AM EDT FRI SEP 30 2016
Issued at 535 AM EDT Fri Sep 30 2016
Fog has become extensive enough across south central Kentucky to
warrant at least a mention in the 1st period of the forecast. While
there are pockets of dense fog, webcams and observations show they
are localized enough that a Special Weather Statement should cover
it. Expect visibility to actually improve around daybreak in some
places as a band of showers pinwheels into the area from the north.
.SHORT TERM (Now through Saturday)...
Issued at 320 AM EDT Fri Sep 30 2016
Deep upper low currently lifting slowly through central Kentucky,
slinging just enough moisture around onto its north and west side to
bring a decent batch of showers into the I-65 corridor in north
central Kentucky and southern Indiana.
This upper low will keep our weather chilly and unsettled well into
the weekend as it takes its sweet time lifting through Kentucky
today, and then through Indiana tonight and Saturday. Expect rounds
of mainly scattered showers as different impulses pinwheel around
this upper low through the period. Fairly steep lapse rates in the
afternoon will support isolated thunder chances, and with low
wetbulb zero heights, can`t rule out some small hail with any
stronger cells. Overall, clouds and precip will keep temperatures
well below climo.
POPs will be in the chance range on Saturday, with a more pronounced
taper from 50% near the Ohio River to 30% along the Tennessee
border, as the upper low continues its trek north of the area. Hail
is not a concern for Sat with the diminishing influence of the cold
pool aloft, but still worth isolated thunder mention.
.LONG TERM (Saturday Night through Thursday)...
Issued at 255 AM EDT Fri Sep 30 2016
Upper low somewhere near the NW corner of Ohio to start the period,
but will continue to lift NE toward Lake Ontario by Sunday night.
Flow aloft over the Ohio Valley remains cyclonically curved on
Sunday, so will hang onto a decent amount of cloud cover and even
some slight chance POPs. Should be enough breaks to allow temps to
recover to near climo. Still expecting a dry day on Monday, but
confidence is limited by the GFS still holding some trofiness in the
Ohio Valley while pumping up the ridge more to our west and north.
Better confidence in the ridging for Tue/Wed, so look for quiet
weather and above normal temps, with most of the area punching into
the lower 80s on Wednesday. Upper trof will approach the area on
Thursday, and this forecast will include a very low-confidence 20
POP. This precip chance will hinge on how far east the moisture feed
can set up, as the upper low closes over the Upper Midwest. If
anything this pattern could slow down further, given the blocky
nature of upper ridging over the mid-Atlantic/New England while
Matthew spins off the southeast coast.
.AVIATION (06Z TAF Update)...
Issued at 109 AM EDT Fri Sep 30 2016
Closed upper level low will continue to spin over the region through
the upcoming TAF period. Ceilings and visibility overnight will be
the main forecast challenge. KSDF will likely see rain showers
overnight as a batch of showers moves westward into the metro area.
Ceilings will start off VFR but look to drop into the MVFR range
with a possible drop into IFR toward dawn. Ceilings may lift a
little during the morning hours but remain in the MVFR range.
Over at KLEX, rain showers will continue to move away from the
terminal, but low clouds and fog will remain the issue for night.
Plan on going with MVFR cigs/vsbys with a drop to IFR ceilings
around 30/09-11Z. Some improvement will be see after sunrise.
Down at KBWG, rain showers should remain north of the terminal
overnight so low clouds and fog development will be the primary
concern. MVFR conditions will start off the period with a drop into
IFR in the 30/08-12Z time frame with some improvement after sunrise.