FXUS63 KLMK 180531
Area Forecast Discussion
National Weather Service Louisville KY
1231 AM EST Mon Feb 18 2019
...Updated Aviation Discussion...
Issued at 910 PM EST Sun Feb 17 2019
The evening forecast update includes the addition of drizzle behind
the main area of rain as well as higher POPs in the Lake Cumberland
region. KY Mesonet obs confirm 1-1.6 inches of rain have fallen
today in that area which includes some afternoon thunderstorms and
steady light to moderate rain this evening. Although no road
closures have been reported, calls down to that region reveal
creeks/streams running high. Felt that some minor flooding may be
possible so did issue a Flood Advisory for Monroe/Cumberland/Clinton
counties through 1am CST.
Behind the main rain shield we should see some patchy drizzle
through the overnight hours transitioning over to perhaps some light
snow flurries before sunrise. One thing to watch overnight will be
the p-type. If moisture isn't deep enough for ice crystals we could
end up with a patchy freezing drizzle over southern Indiana and
portions of north central KY Mon morning. Right now though,
forecast soundings support more flurries for Mon morning. Overnight
lows should range through the upper 20s to lower 30s.
.Short Term...(This evening through Monday)
Issued at 305 PM EST Sun Feb 17 2019
A band of showers and isolated storms was streaming across south-
central Kentucky this afternoon near a cold front. The actual sfc
low is now centered near east-central KY, and sfc obs show winds
beginning to veer westerly near and west of I-65. We've seen
light/variable winds today and patches of fog and drizzle with the
low moving across the CWA. This particular storm track has also left
southern Indiana in the low to mid 30s all day, while temperatures
in southern KY are in the upper 40s to around 50.
For the remainder of the afternoon and evening, showers are likely
along and south of a line from Glasgow to Winchester. The rain is
expected to exit the southeastern CWA between 03-06z tonight. Behind
the front, winds will increase to 10-15 mph out of the west.
Temperatures are forecast to fall into the upper 20s to lower 30s by
Sfc ridging building southeast will exert more of an influence on
our weather for Monday. So it's a rare dry day, though the
northeastern CWA could see a few flurries. Stratus will linger
throughout the day, lifting in the afternoon. Afternoon highs will
be limited to the mid 30s to lower 40s.
.Long Term...(Monday night through Sunday)
Issued at 310 PM EST Sun Feb 17 2019
...Heavy Rainfall and Flooding Likely Tuesday Night through Sunday...
After a brief dry period Monday night into Tuesday, rain will return
late Tuesday. Expect several periods of rain, excessive at times,
over the remainder of the week. Multi-day rainfall totals exceeding
6 inches are possible, especially over southern Kentucky, and will
result in flooding.
Southeast CONUS ridging will hang a front up over the Ohio and
Tennessee Valleys for most of the upcoming week. Several
disturbances in the WSW upper flow will move along the periphery of
the ridge, interacting with the stalled front.
The first wave Tuesday night into Wednesday is the most complicated
and concerning. A sfc warm front will focus precip over south-
central Kentucky with a 50-60 kt low-level jet feeding copious
moisture into the region. Look for widespread 2-3 inch rainfall
totals over south-central KY between 00Z Wed-00Z Thu, which will
likely result in areal and river flooding. Will hold off on a Flood
Watch at least one more cycle, but refine the Hydrologic Outlook for
Another layer to the Tue night system is precip type over southern
Indiana and northern Kentucky. Looks cold enough early on to support
up to 1 inch of snow in those areas, but will not hit that very hard
in this issuance given the broader message.
Will most likely see a break in the action late Wed night and part
of Thursday with a bubble high over the Great Lakes. Additional
waves of widespread rain are likely Friday through the weekend, as
the quasi-stationary front wavers repeatedly in response to
disturbances passing to our north. Given the already saturated
ground, plus the mid-week rains, flash flood guidance should be low
enough that any late-week impulse could drop enough rain to result
in localized flooding, and further aggravate any river flooding.
High POPs and heavy rain potential will be in play all the way
through Sunday, at which point we finally see a progressive
disturbance to provide a break in the SW flow aloft.
.Aviation...(06Z TAF Issuance)
Updated at 1231 AM EST Mon Feb 18 2019
Ceilings are mostly in the fuel-alternate range at this hour as
persistent stratus continues to linger behind the departing cold
front. The moisture may even be deep enough for some patchy drizzle,
very light rain, or flurries overnight at HNB/SDF/LEX. Don't expect
these to reduce visibilities below 6sm, but will amend if necessary.
Do expect some improvement of ceilings into the MVFR range above
fuel alternate toward dawn and into the late morning hours, with
improvement back to VFR by mid to late afternoon and more likely
early evening at HNB/LEX. Expect a steady W wind overnight and
through much of the day, with a few gusts possible up around 20 mph
at times. Winds go light and variable this evening as high pressure
continues to build into the area.
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