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000
FXUS63 KLMK 071748
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1248 PM EST Sat Dec 7 2019
.Short Term...(This evening through Sunday)
Issued at 310 AM EST Sat Dec 7 2019
Sfc high pressure centered over Illinois and Indiana early this
morning will build eastward over Ohio and Pennsylvania later today.
The northern edge of a stratus layer is now south of I-64, with
clear skies across southern IN and northern KY. The clearing line
will only slowly move south this morning, so a mostly cloudy start
for southern KY.
NNE winds will veer easterly during the daytime as the sfc high off
to our north slides to the east. Consensus highs for this afternoon
range from the mid 40s in southern IN to the lower 50s in southern
KY. Due to high pressure off to the east and a strengthening Hudson
Bay low, SW return flow increases early Sunday. A 30-35 kt SW LLJ
develops by 09-12z Sun, which will keep temps steady or rising
during that time. This could result in a tighter temp gradient for
lows tonight. Sheltered areas in the Bluegrass could dip to 30 or
even upper 20s, with some areas in southern KY not dipping below 40.
&&
.Long Term...(Sunday night through Saturday)
Issued at 254 AM EST Sat Dec 7 2019
A strong, +120kt 300mb jet part of a broad upper level trough will
begin ejecting into the southern Plains on Sunday. Models indicate
lee cyclogenesis over the western Central Plains as the trough
advances eastward with very cold Arctic air in Canada being drawn
southward. In our neck of the woods, Sunday should stay dry, though
clouds will gradually increase during the day. Showers begin
developing after midnight Sunday as the region falls into the left
exit region of the strong upper level jet while a strong LLJ advects
GoM moisture northward. Overall setup looks like a classic
isentropic lift event with light to moderate rain showers, so will
continue advertising very high PoPs for the Monday timeframe.
The strong cold front will advance quickly from the Plains into the
Ohio Valley by Monday night. Precipitation won't immediately end
behind the front given the shallow nature of the cold, Arctic air
and lift/dynamics at play, which could result in a transition to
wintry precipitation if moisture lingers long enough. The majority
of guidance moves precipitation out of the region before this
becomes an issue... but it'll be something to watch closely.
After Tuesday, expect cold and dry weather to persist into the end
of the week as an Arctic high dominates the northern US east of the
Rockies. The high should push east of New England by Friday and
return flow around the high becomes southerly over southern Indiana
and central Kentucky, resulting in some moderation to temperatures.
Another system may take aim at the region late Friday into Saturday,
though timing and confidence remain low this far out.
&&
.Aviation...(18Z TAF Issuance)
Issued at 1245 PM EST Sat Dec 7 2019
Satellite shows stratus deck cleared from all TAF sites now, but
stubbornly persisting just 20 miles south of LEX. This will continue
to slowly erode through the remainder of today.
As the surface high currently over NE Ohio continues to drift east,
southerly surface flow will return overnight. This will result in
clouds returning back to the area, but ceilings should remain above
MVFR level until the after 08/18Z, except at HNB, where CIGS AOB 020
are expected by 08/15Z.
Earlier indications of marginal LLWS possibilities overnight due to
a low level jet setting up in the southerly flow have lessened per
short term guidance updates, but still bears watching. For now will
not include in forecasts.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
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