Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KLMK 201730

Area Forecast Discussion
National Weather Service Louisville KY
1230 PM EST Tue Nov 20 2018

.Short Term...(This evening through Wednesday)
Issued at 315 AM EST Tue Nov 20 2018

Broad upper trof will win out for most of the day, resulting in
dreary and somewhat raw conditions across the Ohio Valley in spite
of a strong sfc high building from the Plains. Could start the day
with a few sprinkles over the northern part of the Bluegrass region.
Otherwise, a low stratus deck holds on well into the afternoon
before heights start to rise and moisture begins to scour out
towards sunset. Not expecting much recovery in temps with most
locations just barely cracking 40.

Unseasonably cool weather continues tonight as the sfc ridge lays
out more west-to-east across the Tennessee Valley. Even with partial
cloud cover and light SW winds to keep temps from bottoming out, Wed
morning lows will be closer to winter normals.


.Long Term...(Wednesday night through Tuesday)
Issued at 317 AM EST Tue Nov 20 2018

Wednesday - Friday Morning - Very nice Thanksgiving weather

Tomorrow, an upper level ridge will continue to advance towards the
CWA. The axis of the incoming ridge will still be near the Rockies.
This will give turkey eaters plenty of nice weather to look forward
to through their Thanksgiving holiday. High surface pressure
centered over the Mississippi River Valley will keep skies mostly

Wednesday, temperatures will range from the mid 40s to near 50 in
the southwest central part of Kentucky. Thursday, temperatures are
nearly the same, but the southwest central part of Kentucky will
likely hit the mid 50s. Wednesday night lows will be near 30, and
Thursday night lows will range from the upper 20s to mid 30s.

Friday Afternoon - Saturday

By Friday afternoon, the axis of the upper ridge will have passed
the CWA. The ridge will be followed closely by an upper trough with
an embedded shortwave and a north to south oriented front. Out ahead
of this line stretching north to south, rain showers will move from
west to east. Expect rain chances to increase across the CWA from
the southwest to the northeast starting Friday afternoon. By Friday
night, the whole CWA will see high chances for rain. Saturday
morning, the rain will be on its way out, and by Saturday evening,
the rain should be out of the CWA.

Saturday Night - Sunday

An intense upper trough diving down to the Four Corners region with
a strong surface low in front will start advancing east towards the
CWA, but until it arrives, skies will remain mostly cloudy and dry.

Sunday Night - Tuesday

The massive system arrives in the CWA. The upper and surface low
will stack as the system moves through the Ohio River Valley. Ahead
of this system, low level moisture will flow north and wrap around
the low. This appears to be mostly rain, but with cooler
temperatures behind the front, the back side of this system could
bring some frozen p-types. As we get closer to this event, the
forecast should become more focused. Monday night into Tuesday
morning, precipitation should come to an end. Tuesday should be dry
with partly sunny skies.


.Aviation...(18Z TAF Issuance)
Updated at 1230 PM EST Tue Nov 20 2018

Low ceilings are the main challenge with this TAF package. Knowing
how stubborn low clouds in RH trapped under an inversion can hang
around much longer than models suggest, went very pessimistic in the
TAFs with the MVFR cigs blanketing much of the region into this
evening. Satellite trends will be monitored for future AMDs.

Another question is the possibility of fog early Wednesday morning.
It looks like dew point depressions will stay up in the 2-4 degree
range, and in some locations northwest breezes will stay up around 5-
7 knots. So, kept fog out of the TAFs for now. BWG would stand the
best chance at seeing any local fog development.




Short Term...RAS
Long Term...KDW
Aviation...13 is the U.S. government's official web portal to all federal, state and local government web resources and services.