Scientific Forecaster Discussion
fxus63 klmk 191416
Area forecast discussion
National Weather Service Louisville Kentucky
1016 am EDT Sat Oct 19 2019
issued at 1015 am EDT Sat Oct 19 2019
Updated the sky cover grids to account for a layer of mid-level
clouds that is currently moving through central Kentucky and
southern Indiana. GOES-16 visible satellite shows this layer being
rather progressive so don't expect the cloud cover to impact current
temperature forecast. Also refreshed grids with current
observational data. Updated products forthcoming.
Short term...(today and tonight)
updated at 325 am EDT Sat Oct 19 2019
The axis of an upper ridge runs through Ohio. High surface pressure
centered over Pennsylvania drives the south southeast flow through
the Ohio Valley. To the south, tropical storm Nestor sits in the
Gulf of Mexico near the Florida Panhandle.
Today, Nestor will move northeast over the Florida Panhandle.
Southeast flow towards the Ohio River valley will help to channel
moisture from Nestor over Kentucky and Indiana. Clouds will build in
overhead, and showers over south central Kentucky will be possible
(20%). Highs will make it into the 70s with the south wind and early
sunshine to warm things.
Tonight, a south wind and cloud cover will keep the area warmer than
the last few nights with temperatures only dropping into the 50s.
Long term...(sunday through friday)
updated at 257 am EDT Sat Oct 19 2019
..heavy rain and strong storms possible Monday...
First, Sunday should be dry as we sit between former ts Nestor
moving off the NC/Virginia coast and a gathering storm system over the
plains. It should be a pretty decent day with light winds, partly
cloudy skies, and temperatures rising into the lower and middle 70s.
On Monday strengthening low pressure will lift across Minnesota with
an occluded front across the Great Lakes and cold front reaching
southward to the Gulf Coast. Ahead of the front will be a band of
showers with embedded thunder, and non-thunderstorm winds gusting 30-
The 850mb jet will strengthen to 50-60kt by afternoon with an upper
jet around 160kt from the mid-Mississippi Valley to the Great Lakes.
Soundings suggest any morning storms should be elevated and there
won't be much in the way of instability, though later in the day
there may be a corridor of 300-800 j/kg SBCAPE as storms become
surface based in the afternoon and early evening. Soundings are
showing very deep moisture and modest low level lapse rates so dcape
is low, but with such strong winds aloft we certainly can't rule out
some stronger gusts making it to the surface, possibly in a thin
line of enhanced convection just ahead of the front. 0-1/0-3km srh
are strong enough in some model solutions that we can't rule out a
brief spin-up, especially across southern and eastern portions of
the area. Storm Prediction Center marginal risk area is in good agreement with cips
Dew points are still expected to surge into the lower and middle 60s
on those stiff southerly winds coming right up from the Gulf.
Precipitable water values may reach 1.7" which is very high for this
time of year. However, the progressive nature of this system will
help to limit rainfall totals a bit. Right now it looks like most
folks should see 1 to 1.25" of rain, with locally heavier amounts in
spots where some training can get set up. Wpc has placed a marginal
risk for excessive rainfall over much of central Kentucky and
Behind the system on Tuesday winds will become gusty once again,
though with a lack of cold air temperatures will be in the 50s and
60s. Dry weather will continue through Thursday as high pressure
moves from Texas to the mid-Atlantic.
The next chance of rain will come Friday ahead of an upper trough
crossing from the plains into the Mississippi Valley.
Aviation...(12z taf issuance)
issued at 645 am EDT Sat Oct 19 2019
VFR conditions should last through the period for sdf, hnb, and Lex,
but bwg might not be as lucky. As tropical storm Nestor continues to
move northeast, lowering clouds and low (20%) rain chances will move
north of the Kentucky/Tennessee border. Guidance has MVFR ceilings
moving over bwg as early as 6z. Believe this will be delayed and
reality will be more optimistic than some current guidance. There is
still plenty of time for fine tuning.