Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 221657
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1257 PM EDT Tue Apr 22 2014
...Updated Aviation Discussion...
Issued at 920 AM EDT Tue Apr 22 2014
Updated the forecast to move rain showers out of the Lake Cumberland
region faster this morning. This is the end of the rain shower
activity for the day. The cold front was just south of the Ohio
River as of 13Z. The front will continue to move SE through the
region this morning shifting winds to the NW. Winds will pick up to
10-15 mph with gusts up to 20-25 mph this afternoon. Cooler air
filtering in behind the front should limit high temps to the upper
60s and lower 70s despite mostly sunny skies expected this afternoon.
Issued at 650 AM EDT Tue Apr 22 2014
Forecast has been updated to clean up the pre-1st period wording, as
showers along and ahead of the cold front continue to have a tough
time holding together. Scattered showers look like a good call
across south-central Kentucky until the mid-morning fropa, while
isolated may be generous for areas north of the Parkways.
.SHORT TERM (Now through Wednesday)...
Issued at 255 AM EDT Tue Apr 22 2014
Cold front continues to make steady progress across Illinois and
Indiana, with scattered showers ahead of it. Expect fropa just
before daybreak in the Hoosier National Forest, a bit after sunrise
near the I-65 corridor, and around mid-morning from the Bluegrass
region to Lake Cumberland. Will carry the dreaded 50 POP, or
certainly no more than 60 ahead of the front, even though coverage
at any given time will be no more than scattered.
Precip chances come to a quick end after fropa, but low strato-cu
will linger behind the front for a few hours as low-level moisture
remains trapped. Cold air advection notwithstanding, temps will
recover to near 70 this afternoon with some clearing, and the
benefit of an unseasonably mild start. NW winds could be a bit on
the gusty side as high pressure builds from the Great Lakes.
Biggest question tonight is how effectively the winds decouple, and
how cold we get as a result. Surface ridge axis makes it roughly to
I-65, but the high center should remain over eastern WI or Lake
Michigan, far enough north to keep our temps from crashing. Coldest
temps will be mid/upper 30s over the Bluegrass, with just enough of
a north breeze to limit frost formation. Will still carry mention of
patchy frost over the Bluegrass, mainly in the sheltered valleys.
Wednesday temps will run solidly below normal as the low-level
thermal trof takes its sweet time moving out. Went near or just
above the milder GFS MOS, which is in line with the raw model
.LONG TERM (Wednesday Night through Monday)...
Issued at 245 AM EDT Tue Apr 22 2014
Surface high pressure will be sliding to our east Wednesday night,
with southerly winds ramping up Thursday. A ridge axis aloft will
move across the area, so expect a dry Wednesday night and Thursday.
Southerly winds and ridging aloft will allow temperatures Thursday
afternoon to reach the upper 70s to low 80s. Clouds will increase
during the day as a PV anomaly and associated surface cold front
approach from the west. Should start to see showers and scattered
thunderstorms enter our western counties Thursday evening and sweep
across the forecast area overnight. The precip should be east of our
area by daybreak Friday.
Friday through Saturday will generally be dry. Cannot rule out an
isolated shower or storm Saturday afternoon with another front
sweeping through the area. However, moisture convergence and forcing
is slated to stay to our north, so will keep things dry for now.
Temperatures will cool down into the middle 70s for Friday and upper
60s to lower 70s for Saturday, as the front sags southward.
The frontal boundary will become quasi-stationary somewhere across
the Ohio or Tennessee Valley Saturday night through Monday, with a
few PV anomalies passing across the area during this time frame. The
exact location of this stalled frontal boundary remains a mystery
given the spread amongst guidance, but some signals indicate it
being oriented west-east across roughly central Kentucky. This will
lead to an unsettled period for the entire forecast area,
particularly Sunday through at least Monday with on-and-off
scattered showers and thunderstorms. With clouds and precip across
the area, temperatures will generally top out in the middle to upper
60s Sunday and Monday. Could be some lower to middle 70s across
southern Kentucky, but that will depend on the location of the front.
.AVIATION (18Z TAF Update)...
Issued at 1250 PM EDT Tue Apr 22 2014
The cold front was through BWG/SDF as of 1630Z and passing through
LEX. Expect winds to veer to the NW at LEX within the next hour.
Just behind this front, expect MVFR cigs to continue until 19-21Z
before moving southeast of the area and scattering out. VFR
conditions will then be the rule for the rest of the TAF period as
sfc high pressure settles into the area for tonight and tomorrow.
Expect clear skies overnight with north winds under 7 kts. For
tomorrow some upper level clouds will begin to work into the region
with winds shifting to the NE and remaining under 7kts.