Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 011751

Area Forecast Discussion
National Weather Service Louisville KY
1251 PM EST TUE DEC 1 2015

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1207 PM EST Tue Dec 1 2015

Current water vapor imagery continues to show a steady plume of
moisture streaming across the southern CONUS up through the Ohio
River Valley and into New England. This is occuring ahead of the
broad SW upper flow ahead of a strong closed low over the upper
Midwest. Water vapor is a bit misleading though as a significant dry
slot has worked in between 850-450 mb. The dry slot and passage of
the frontal boundary has shut off measurable rain across all but our
far east CWA, however enough 1000-850 mb moisture is remaining to
allow for some patchy drizzle to linger for a few more hours. This
is confirmed by current radar and obs. So, have added mention to the
grids, with dry conditions gradually working east through the
afternoon. Forecast remains on track otherwise, with temps staying
steady or beginning to fall from where they are currently.

Issued at 905 AM EST Tue Dec 1 2015

Quick mid-morning update. Rain showers continue to push northeast
over the east half of central KY at this time. The surface cold
front has been identifiable on radar by a thin line of enhanced
showers in the middle of the rain area. At 900 am EST, this front is
entering Fayette County, so Lexington will see winds shift from
south to west shortly. After showers end, clouds will continue but
partial clearing is expected over our western forecast area later
this afternoon. No significant changes to temps at this time...will
take another look at these late this morning.

Issued at 625 AM EST Tue Dec 1 2015

The rain is pretty much on track this morning with the heaviest rain
falling east of I-65 as of 625am. The cold front was sitting roughly
along a New Castle to Boston to Scottsville, KY line and will
continue to make good progress eastward through the morning hours
taking the rain with it. Louisville/Bowling Green metros should be
dry by around Noon with Lexington metro dry by mid afternoon.

.SHORT TERM (Now through Wednesday)...
Issued at 300 AM EST Tue Dec 1 2015

A cold front was entering west central KY as of 230 am this morning.
The final round of steady light to moderate rain was pushing NE just
ahead of the front into our region mainly along and west of I-65.
Expect this area of rain to continue through the pre-dawn hrs
finally moving out around sunrise.  An additional 0.5 to 1 inch of
rainfall can be expected with this round of steady rain.  This
amount of rainfall combined with the fact that most areas saw a
break in the rainfall a few hrs ago should result in little if any
minor flooding issues this morning.  The Lake Cumberland region may
see one more enhanced area of rainfall after sunrise so will still
keep a close eye on that region for any minor flooding issues.  The
moderate steady rains should be done before the rush hour traffic
hits in the metro areas so that will be good for travelers this
morning.  Also, most of the fog in the area should diminish by
around sunrise also.

The cold front will push through the area this morning with the end
of the rainfall lagging behind it by an hr or two.  So most
locations along and west of I-65 will be dry by early afternoon.
East of I-65, precip should end by late afternoon or early evening.

Expect high temps to be reached early in the day with highs ranging
from the lower 50s to lower 60s.  Temps will fall throughout the
day behind the fropa into the lower 50s/upper 40s.

For tonight, expect a mainly dry night with variable sky cover. Some
areas will see only partly cloudy skies before thick low level
clouds arrive with an upper trough.  The variable cloud cover will
provide a temp challenge.  Will forecast lows in the lower 30s/mid
40s with a good gradient across central KY that may need to be
adjusted.  Also patchy fog may form in some areas tonight.

Wed will be chilly and breezy with highs in the mid 40s/lower 50s
and low clouds hanging around.  A vorticity max swinging through the
base of the upper level trough combined with a thick moisture layer
in low levels should be enough to produce some sprinkles late Wed
afternoon/early evening.  After 0Z, soundings indicate that the
moisture layer will be deep enough to produce ice crystals leading
to some flurries mixing in with the sprinkles and maybe just some
flurries later in the evening.

.LONG TERM (Wednesday Night through Monday)...
Issued at 315 AM EST Tue Dec 1 2015

Wed night - Sunday...

After some light sprinkles or flurries early Wed night, the rest of
the overnight period should be dry with lows dipping into the lower

A dry period is in store for the rest of the week and into early
next week as we enter a blocking pattern aloft and maintain high
pressure at the sfc.  Expect mostly clear to partly cloudy skies Thu-
Sun.  Thu will be the coldest day in the long term with highs in the
mid to upper 40s. Highs will moderate into the lower 50s by the
weekend.  Lows will generally be in the upper 20s to lower 30s Thu-


Long range models don`t have a real good handle on how the upper
level pattern will evolve next week.  There seems to be an upper low
progged to push across south central U.S. some time early next week
but models vary great on track/timing/precip.  Thus, will only keep
a very low POP going Monday/Mon night.  Will continue forecast temps
slightly above normal Mon as well.  However, this forecast is low
confidence at this point given the model spread.


.AVIATION (18Z TAF Update)...
Updated at 1240 PM EST Tue Dec 1 2015

Main precip shield will move east of LEX in next hour or so, with
low clouds and patchy drizzle left behind. As a result, cigs at LEX
should rise a bit into MVFR category, while cigs remain MVFR at SDF
and BWG well into the afternoon. By this evening or later evening,
low cigs should break resulting in VFR conditions for awhile at SDF
and LEX and possibly BWG, while high clouds remain.

Cig/vsby forecast for late tonight/Wednesday morning is a bit
tricky. Assuming low clouds clear out, then residual boundary layer
moisture will result in areas of fog which will lower vsbys into
MVFR category at SDF and IFR at BWG and LEX. If low clouds were to
remain or reform instead, then cigs might become IFR again but vsbys
may stay a bit higher. Either way, conditions should deteriorate and
feel that fog/vsbys will be the main contributor to IFR/MVFR
conditions at the 3 TAF sites.

Southwest boundary layer flow becomes established later Wednesday
morning, so this will scour out fog and raise any cigs. Model cross
sections do show potential for cigs around or just above MVFR
category but will keep as VFR for now.


.LMK Watches/Warnings/Advisories...


Short Term.....AMS
Long Term......AMS
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