Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
000
FXUS63 KLMK 281136
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
636 AM EST Sun Dec 28 2014

...Updated Aviation Discussion...

...Forecast Update...
Issued at 640 AM EST Sun Dec 28 2014

Fine tuned the pop grids again for the light precip/drizzle showing
up on radar as well as area observations and webcams. Also tweaked
other parameters to observed values.

.SHORT TERM (Now through Monday)...
Issued at 230 AM EST Sun Dec 28 2014

Cold front just now moving through the Louisville metro area. Had a
band of showers just ahead of this front, but southwest flow aloft
will continue to pump moisture in here. Low clouds will linger
through most of the day, and likely will see patches of drizzle if
not some light rain continue. The slight rain chances will continue
this evening across the Lake Cumberland region before we dry out
Monday as the flow aloft becomes more westerly.

Arctic high pressure spilling into the Northern Plains will force
northeasterly winds in our area, keeping temperatures similar to
today, which will be near normal for highs.

.LONG TERM (Monday Night through Saturday)...
Issued at 310 AM EST Sun Dec 28 2014

Canadian high pressure will dominate through the middle portion of
the week, with dry weather and cold temps to ring in 2015. One small
uncertainty is injected by the NAM late Monday night and Tuesday
morning, at which point it tries to generate some light precip over
south-central Kentucky. However, with none of the other models on
board at this time, will discard it as an outlier and keep the
forecast dry. Coldest time period will be Wednesday into Wednesday
night, with temps nearly 10 degrees below normal. Latest extended
GFS MOS is quite cold for Thursday morning, but low-level wind
fields suggest that the surface high will migrate south quickly
enough that we`ll have some light WSW return flow to keep temps from
bottoming out. That said, traditional cold spots will be in the
teens on New Year`s morning, with lower 20s elsewhere.

Forecast confidence decreases late in the week as a system currently
digging down the West Coast will finally start to eject out of the
Desert Southwest. For the first time we`re starting to see consensus
between ECMWF and GFS in going from a closed upper low over the Four
Corners Friday morning to an open wave lifting through the Great
Lakes Saturday afternoon. The devil remains in the details of
sensible weather, specifically when precip will start and what
precip types the thermal profiles support at that time.

ECMWF is quicker to develop precip over the Ohio Valley, with POPs
ramping up quickly Friday morning. This is close to 6 hrs slower
than previous runs but still a good 6 hrs faster than the GFS.
Timing could have a substantial impact as morning precip onset would
mean starting off with a wintry mix, while it would be all rain if
it holds off until afternoon. Will continue the mention of mixed
precip in the zones and in the form of a heads-up in the HWO, but
still not enough confidence to get into any impacts just yet.
Highest POPs still look to be Friday night into Saturday, as it
evolves into a soaking rain event with QPF pushing an inch and a
half.

&&

.AVIATION (12Z TAF Update)...
Issued at 635 AM EST Sun Dec 28 2014

Surface front has cleared all of the terminals this hour, but
moisture lingering behind it will keep lower cigs and light
rain/drizzle in for the near term. SDF is at the MVFR/IFR threshold
this hour and should stay there through the morning hours. Other
sites should see a later rise. Guidance still optimistic on cigs for
tonight, but will hold in the MVFR range for now. Winds will be from
the north today in the wake of the front.

&&

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

$$

Update.........RJS
Short Term.....RJS
Long Term......RAS
Aviation.......RJS





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.