Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 232319
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
619 PM EST Thu Nov 23 2017

...Updated Aviation Discussion...

.Short Term...(This evening through Friday night)
Issued at 200 PM EST Thu Nov 23 2017

A very pleasant, though chilly, Thanksgiving Day ongoing at this
time. High pressure over the Commonwealth will move slightly east
into the Appalachians tonight, introducing a subtle southerly wind
which should allow low temperatures to be several degrees warmer
Friday than for this morning. Those winds will pick up more during
the day Friday, allowing high temperatures to rise to near 10
degrees above today, much closer to what the end of November should
see.

Friday night, cloud cover should increase, as a cold front
approaches the region. It`s progged to be near the Ohio River by
daybreak Saturday. The 06Z NAM is similar to the WRF-ARW, with light
QPF down south and the SREF has it closer to the Ohio Valley.
Otherwise, the GFS/GEM/12Z NAM/WRF-NMM all show us dry. Ongoing
forecast has us dry. Cannot rule out some sprinkles, but think the
chance for measurable precip is low. Lows should only fall to the
40s under the cloud cover and southerly winds.

.Long Term...(Saturday through Thursday)
Issued at 200 PM EST Thu Nov 23 2017

The Saturday cool front really won`t change our airmass much,
though highs Sunday should be a little below normal. We recover
quickly though as the surface high pressure behind that front
builds into the Appalachians Monday. Between that and deepening
low pressure across the Northern Plains our southerly flow should
advect in that warm air. By Tuesday we should see 60s for many
locations under breezy south winds.

For the next precip-producing system, I will say it is a good thing
we do not put out Day 8 and 9 forecasts. I remember one such suite
of model runs advertising a wintry mix of precip for today...and it
obviously is much nicer than that out there! Similarly, the models
have been waffling in this extended, with various runs showing
precip from Tuesday (Day 5) through Thursday (Day 7). The GFS
finally has backed off on it precip chances for Tuesday and Tuesday
night, now delaying them to later Wednesday. The 00Z Euro held off
the rain chances to early Thursday, and this is more in line with
long range signal crossing forecasts pegging 11/30 for a crossing in
our region. The GFS solution shows a fairly strong upper low
crossing the TN Valley, which could put part of our area on the
north side of a warm front with some cold rain Wednesday night and
Thursday. The 00Z Euro was not as strong with this feature, and
keeps our area in the warm sector, with a warm front just to our
north. The 12Z Euro coming in now also has a closed low, but is
slower than the GFS. Have coordinated with neighbors for a warmer
forecast than the SuperBlend gave us for Tue/Wed and have kept
pops capped at slight chance range, 20%, for Wed, and 40% for Wed
night/Thu.

&&

.Aviation...(00Z TAF Issuance)
Issued at 619 PM EST Thu Nov 23 2017

Expansive high pressure will help to keep us dry and VFR through
this TAF cycle. Most surface winds should be calm overnight or very
light out of the S. Clear skies will prevail. A steady SSW wind
between 7 and 12 mph will take hold tomorrow, along with a few upper
level clouds.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Short Term...RJS
Long Term...RJS
Aviation...BJS



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