Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 011908
Area Forecast Discussion
National Weather Service Louisville KY
308 PM EDT SUN MAY 1 2016
.SHORT TERM (Now through Tuesday Night)...
Issued at 305 PM EDT Sun May 1 2016
...Severe Storms Ongoing this Afternoon...
The synoptic pattern early this afternoon features broad southwest
flow across the Ohio Valley. A dampening trough was moving through
portions of the Midwest, interacting with a surface front located
across portions west-central KY northeast into portions of southern
Strong to severe thunderstorms have developed along residual outflow
boundaries and along the surface front this afternoon. Dewpoints in
the low to mid 60s coupled with temperatures rising into the low 80s
has resulted in MLCAPE values in excess of 1500 J/kg. Deep layer
shear around 50 knots is contributing to long, straight hodographs
which will favor supercells (possibly splitting) and a few multicell
clusters. Main threat will be hail with wet bulb zeros around 9-10k
feet, but given dry air around 700mb some dry air entrainment into
downdrafts may lead to localized damaging winds as well.
Convection should wind down in coverage tonight as instability wanes
and the front pushes east/southeast. However, this front will stall
just to the south of the region tonight. Yet another PV anomaly
will eject out of the Southwest and will ride up along the front
Monday afternoon into Monday evening, which will result in renewed
showers and a few thunderstorms mainly across the southeastern half
of the LMK CWA. It appears much of the region will be on the cool
side of the boundary, so severe weather is not anticipated. Highs
will be cooler on the north side of the boundary with temperatures
in the 60s to lower 70s.
The trough will deepen across the eastern CONUS on Tuesday,
spreading its trough axis through the region Tuesday afternoon.
There won`t be much low-level moisture to work with, but think lift
will be sufficient to squeeze out a few very light showers Tuesday
afternoon. Temperatures will be even cooler in the northwesterly
flow, with temperatures only expected to make it into the mid 60s.
.LONG TERM (Wednesday through Saturday)...
Issued at 249 PM EDT Sun May 1 2016
A deep upper trof is still expected to dig into the eastern half of
the United States for the second half of the work week, followed by
ridging building in from the Plains for most of the weekend.
A surface cold front will come in from the north Wednesday, pushing
off to the south and east Wednesday night. There is some wind energy
with this system but very little instability as we only get into the
60s for highs that afternoon. Precipitable numbers aren`t all that
great either. So, at this time it just looks like showery weather
with maybe a few rumbles of thunder. A few CAA showers may also
linger behind the front in the Blue Grass on Thursday.
Canadian high pressure dropping to the southeast along with rising
heights aloft will lead to pleasant weather for late this week and
into the weekend. Can`t rule out a few showers generally along and
east of I-75 closer to the upper trof, but coverage should be low.
The upper trof will bring downright chilly temperatures with lows
Thursday morning and Friday morning well down into the 40s. Folks in
the Blue Grass may see readings not get out of the 50s on Thursday.
A warming trend will then ensue as the Plains ridging moves in, with
afternoon temperatures back up near 80 by Sunday.
.AVIATION (18Z TAF Update)...
Updated at 1241 PM EDT Sun May 1 2016
Confidence is growing that a cluster of thunderstorms will develop
just west of SDF over the next hour or two and move east into LEX
later this afternoon. Have timed this window out with a TEMPO
group, but will go prevailing once the storms begin to develop.
Expect IFR vsbys, gusty and variable winds, along with possibly some
hail with these storms. Confidence in convective coverage is not as
high at BWG, but still think a storm or two may impact the terminal
this afternoon. Outside of any storms, cigs should continue to mix
out to VFR with winds turning more to the WSW at 5-10 knots.
Convection will clear out tonight leaving VFR conditions. There may
be some low stratus development especially at LEX, but not high
enough confidence to include at this time. Additional showers will
move in from the southwest late in the period at BWG and into the
planning period at SDF.