Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 192330
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
730 PM EDT Sun Apr 19 2015
...Updated Aviation Discussion...
.SHORT TERM (Now through Monday Night)...
Issued at 325 PM EDT Sun Apr 19 2015
Warm front is lifting north through Kentucky this afternoon, with
the transition underway from the steady rain that we had this
morning to a more convective regime. Upper wave will lift NE across
the Ohio Valley, with a surface low over southern Illinois lifting up
the Wabash Valley. Should have well over 50 percent coverage of
T-storms as we head into the evening, then shutting down quickly
once the upper wave is to our north and east. Will carry high POPs
for an early evening period, with lower POPs to follow.
Could have a few strong storms through early evening. Just enough
deep-layer shear and mid-level wind to support marginally severe
wind and hail. Much of the region dodged the heavy rain potential
with this morning`s precip shield, but some totals near 1 inch have
been observed west of I-65. Any of the stronger thunderstorms this
afternoon/evening, especially in these areas, could cause flooding
Will remain quite unsettled overnight into Monday as a series of
disturbances will swing through a broad full-latitude trof. Main
limiting factor in POPs is whether the next rounds of showers and
storms will be tonight or Monday. Cold front swings through during
the day, with POPs tapering quickly behind it. very little diurnal
recovery expected in temps, and southern Indiana may realize daytime
highs in the morning. Monday night appears dry with temps actually
slightly below normal as a much cooler and drier air mass spills in.
.LONG TERM (Tuesday through Sunday)...
Issued at 300 PM EDT Sun Apr 19 2015
Overall mid-level pattern in extended forecast period looks to be
somewhat amplified and blocky across North America. Ohio Valley
should be under general west or northwest mid-level flow most of the
period between a closed low over the Great Lakes which will progress
into southeast Canada and northern New England, and ridging well to
our west. Within this pattern, a few embedded weak shortwaves should
ride east or southeast toward the Ohio and Tennessee Valleys. This
could produce a couple episodes of showers, but no particularly
heavy or persistent rain is expected at this time in the extended.
In the dailies, Tuesday will start off mostly clear but models agree
that the approach of one such shortwave will cause clouds to
increase in the afternoon, with a chance of showers and perhaps a
few thunderstorms by late afternoon into evening over south-central
IN and north-central KY. This wave will move ESE Tuesday night over
our area with some showers.
From Wednesday onward, model forecast agreement and confidence
becomes a bit more tenuous, as would be expected in the forecast
synoptic pattern. On Wednesday, a weak frontal boundary will move
through, which could spark scattered showers, mainly over central
KY. Thereafter, another impulse or two could bring a chance of
showers about Friday night and/or Saturday, but again, nothing too
heavy or long-lasting is expected based on current projections.
Normal high temperatures right now are in the upper 60s to lower
70s, with lows in the mid to upper 40s. Forecast max temperatures
for mid this week through next weekend generally will average at or
below normal in most areas, with perhaps only lower to mid 60s late
week into next weekend. Low temperatures will be cool, especially
late week and next weekend with around 40 to the mid 40s, and even
some upper 30s in cooler valleys.
.AVIATION (00Z TAF Update)...
Updated at 725 PM EDT Sun Apr 19 2015
A low pressure system will continue to bring rounds of
showers/storms tonight ahead of a cold front. Another batch of
convection is progged to move east through the area this evening
before midnight. Current radar indicates this second batch will be
more stratiform rain with embedded t-storms so won`t put any
prevailing restrictions on the TAF sites to start out, but tempos
and amendments may be needed throughout the evening as we continue
to track storms across the Ohio Valley.
We should see a break in convection around midnight through 8-10Z
before the next round of storms arrives just ahead of the cold
front. We should see a window brief window between 8Z to 13Z of
showers/storms before the front passes right around or just after
sunrise. In the wake of the front, expect residual showers to stick
around for the rest of Monday in low clouds.
As far as flight restrictions, IFR/MVFR restrictions will be
possible at any time in convection. At least MVFR restrictions seem
likely overnight and through the day tomorrow because of low cigs.
Cigs will begin to improve tomorrow evening.
Winds will pick up overnight and become gusty along and behind the
cold front. Wind gusts of 20-30 kts will be common tomorrow morning
with gusts declining to the 15-25 kt range for Monday afternoon.