Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 140526
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1226 AM EST Sat Jan 14 2017

.Forecast Update...
Issued at 1220 AM EST Sat Jan 14 2017

Vis really going into the tank over parts of south-central Kentucky
in the last hour based on surface observations and webcams. The
stratus build-down has yet to occur as far east as Lake Cumberland
or into east-central Kentucky, but believe that is just a matter of
time. Therefore, will run a Dense Fog Advisory along and south of
a line from Morgantown to Campbellsville to Stanford. All signs
point to a continuation of the fog well into the morning, so will
carry the advisory through 16Z, and it can be cancelled early if
drizzle/rain actually cleans out the boundary layer before then.

Issued at 900 PM EST Fri Jan 13 2017

Added drizzle to the forecast for the remainder of the evening and
overnight hours. While radar returns along/south of the Ohio River
have diminished or moved on (or soon will), plenty of low level
moisture and saturation and weak lift could bring some patchy to
areas of drizzle to central Kentucky.

Also added patchy to areas of fog to the entire area. Current T/Td
spreads are 1 to 3 degrees and with wind fields expected to be
light, should see visibility reductions to 1 to 2 mile. Am a bit
concerned about dense fog forming across southern Kentucky where
some visbys are down to 1 mile already and guidance hits that area
the hardest with hints of 1/4 mile visbys possible. In coordination
with OHX and JKL, will issue a SPS to cover locally dense fog
through Saturday morning.

Issued at 520 PM EST Fri Jan 13 2017

Updated PoPs to account for current radar trends, increasing PoPs to
over 80 percent in the near term across southern Indiana and
northern Kentucky. South of the KY Parkways, less coverage of
showers is expected, though there could be some drizzle into the mid
evening hours.

Also removed threat for freezing rain across southern and southeast
Indiana as temperatures remain 34 degrees or warmer and with no push
of colder air expected this evening, feel this threat for icing is
north of the forecast area.

&&

.Short Term (Now through Saturday Night)...
Issued at 258 PM EST Fri Jan 13 2017

Average sfc-500 flow around an upper ridge over the Gulf of Mexico
is bringing moisture northward into the mid-Mississippi and Ohio
Valleys. Waves of precipitation will continue to break out along the
periphery of the ridge north of a surface boundary stretching from
the central Appalachians to the Tennessee Valley and Red River
Valley. Weak isentropic lift persisting through the short term will
also support occasional precipitation.

The very great bulk of the precip will be in the form of light rain
and drizzle. As temperatures tumble toward the freezing mark
Saturday night, there is a non-zero but small chance of some light
freezing rain in Indiana north of a Paoli-Madison line.

.Long Term (Sunday through Friday)...
Issued at 307 PM EST Fri Jan 13 2017

Next week the southeast upper high will elongate into more of an
East Coast ridge as a Desert Southwest upper low ejects into the
Plains. Rain chances will continue on Sunday and then diminish
somewhat Sunday night and Monday as that boundary surges north and
puts us squarely into the warm sector. We`ll be back up into the 60s
both Monday and Tuesday.

Low pressure crossing the Great Lakes will drag a cold front through
here on Tuesday, accompanied by widespread showers and some elevated
thunder. Though the main models were in good agreement with this
system earlier this week, there is now some disagreement on whether
or not additional waves of low pressure will develop on the front
and, as a result, just how progressive the front will be.
Nevertheless, the trend does seem to be a more aggressive frontal
passage so will lean in that direction.

It look like the week will end with the possibility of another
system crossing the southeastern U.S. with attendant shower chances.
Temperatures will remain mild.

&&

.Aviation (06Z TAF Update)...
Updated at 1205 AM EST Sat Jan 14 2017

Not much optimism in this forecast period if you`re looking for
anything better than IFR conditions, at least when it comes to
clouds. With the 05Z obs in, SDF has just joined BWG and LEX with
IFR cigs, and except for a few minutes here and there, cigs at all
three terminals should below 010 for the duration of of the forecast
period.

Visibility is not quite as dire, at least for SDF and LEX, where
guidance is generally 4-5SM with occasional drops to 2SM in drizzle.
BWG, however, has already dropped below 1SM and some short term
mesoscale models take it to W0X0F for all intents and purposes.

Winds will be variable under 5kts.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Dense Fog Advisory until 11 AM EST /10 AM CST/ this morning for
     KYZ061>067-070>078-081-082.

&&

$$

Update...ZT/RAS
Short Term.....13
Long Term......13
Aviation.......JBS



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