Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 200812
Area Forecast Discussion
National Weather Service Louisville KY
312 AM EST Fri Jan 20 2017
.Short Term (Now through Saturday)...
Issued at 303 AM EST Fri Jan 20 2017
A warm front drifting northward across the Ohio Valley will be north
of the region by the beginning of the forecast period. An upper
trof, largely responsible for the overnight rainfall, will pivot to
our northeast by 18Z. So, the rain will continue to diminish this
morning and will end by lunch time. Lingering low moisture will lead
to clouds hanging on into the afternoon. Being situated well within
the warm sector this afternoon, temperatures should swell into the
60s at most locations, as was seen in this air mass upstream
We`ll have dry conditions tonight with temperatures sinking only
into the 50s...10 to 15 degrees warmer than our normal high
temperatures for the date. Some patchy fog will be possible, but at
this time it appears that there will be enough cloudiness in
place, along with a southerly breeze, to keep it in check.
Saturday an upper low will cross the Midwest while an upper ridge
sits off Florida`s east coast. This will put us in broad
southwesterly flow with occasional ripples moving through it. A
pulse of Gulf moisture will head northeast and result in scattered
showers and possibly a few thunderstorms, primarily in the afternoon
when there will be the best instability, steepening lapse rates, and
some isentropic upglide. Severe convection over the Lower
Mississippi Valley and central Gulf Coast may rob us of some of our
potential RH, and available instability this far north is rather
weak. Heavy rain is not expected. Very warm temperatures are
expected, however, with the mercury soaring into the 60s and
possibly touching 70 in a few places.
.Long Term (Saturday Night through Thursday)...
Issued at 311 AM EST Fri Jan 20 2017
A compact stacked surface/upper low traveling through the Red River
Valley Saturday night will roll into Dixie Sunday and on to the mid-
Atlantic Monday. The main activity associated with this feature will
be to our south as showers and storms, some severe, charge from the
lower Mississippi Valley to the SC/GA/FL coasts. Still, scattered
showers and possibly a few thunderstorms can be expected in the
Tennessee and Ohio Valleys as well, especially in southern Kentucky
Sunday afternoon and evening. High temperatures will, once again, be
in the 60s.
Plenty of moisture will still be in place behind the system on
Monday, assisted by NNW flow across the Great Lakes and low level
convergence from Michigan to Kentucky, resulting in scattered light
rain showers. Despite the calendar saying January and northwest
breezes coming in, temperatures should still manage to top out in
the lower 50s.
Shortwave ridging is still expected to give us a break in the
rainfall on Tuesday with mild temperatures continuing. Tuesday
night/Wednesday low pressure advancing from the Midwest to the Great
Lakes will drag a cold front through southern Indiana and central
Kentucky Wednesday. Most of the moisture associated with this system
will be Pacific in origin and will remain well to our north.
Nevertheless, there should still be enough of a Gulf connection for
some scattered shower activity ahead of and along the cold front.
Model runs over the past couple of days have been consistent in
advertising gusty winds on Wednesday.
Wednesday will be our last day in the 50s for a while. Wednesday
night/Thursday we`ll see the beginning of a pattern change as the
western upper trof pushes east and brings much cooler air to the
region for the last few days of January and into early February.
.Aviation (06Z TAF Update)...
Issued at 1215 AM EST Fri Jan 20 2017
Widespread rain will continue across central Kentucky through 8-10z
then become widely scattered before ending southwest to northeast by
12z. IFR to LIFR ceilings are expected to remain in place through 12-
15z then gradually lift into the MVFR range and possibly up to VFR
by afternoon as drier air works into the region. Poor visibilities
can be expected early on in the period with widespread rain but
should improve to VFR by early/mid morning.
Confidence drops off for the evening and Friday night forecast on
the potential for low clouds and/or fog across central Kentucky.
Recent rainfall and plentiful low-level moisture would suggest
fog/stratus but winds just off the surface are forecast to be 15-20
kts. This may preclude widespread low ceilings/visibilities.
Guidance is struggling with this as well, with a wide variety of
solutions. For now, introduced chance of a stratus layer and light
fog by 03-05z, and hopefully forecast confidence will improve with
next set of TAFs.