Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 221500
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1100 AM EDT Sun Apr 22 2018

.Forecast Update...
Issued at 1058 AM EDT Sun Apr 22 2018

Made some minor adjustment to timing of showers as 12z guidance
begins to get a better handle on things. Still looks like showers
will creep up slowly from the south this morning and begin to stall
out this afternoon across south central Kentucky. As the upper level
low approaches from the southwest tonight, we`ll begin to see the
showers lift northward and eventually overspread the entire region
by tomorrow morning. Rest of forecast is on track.

&&

.Short Term...(Today through Monday)
Issued at 300 AM EDT Sun Apr 22 2018

Well the smoke has cleared, and a quiet night is in progress with
thickening mid-level clouds and a steady northeast wind. A strong
upper level low was over KS/OK, and water vapor imagery shows
excellent diffluence downstream over the Mississippi Valley. The
upper PV anomaly rotates east over Arkansas and Missouri today,
while a surface low tracks northeast through Mississippi. A cold
front is forecast to reach the MS/AL border by 00z this evening.

Moisture transport and dynamic lift will increase ahead of this
system today, particularly over the southwest third of the CWA. Rain
chances ramp up across southern KY during the mid to late morning
hours. Recent runs of the HRRR/3 km NAM suggest steady rain arriving
in Bowling Green by lunchtime (16z). Areas north of a Jasper, IN to
Fort Knox to Liberty line are likely to stay dry until late this
evening and tonight. Highs today in drier locales should reach the
upper 60s to around 70. In the far southwest where the rain moves in
quicker, highs should be limited to the low to mid 60s.

The system occludes tonight near Memphis, and a healthy 55 kt SE LLJ
is forecast to develop over Middle Tennessee. A corresponding jump
in moisture transport will occur this evening and tonight, with the
strongest magnitude again over the southwest third of the CWA. So
widespread showers are likely, which will then finally spread to the
northeast throughout the Monday morning hours. The deep upper low
continues to rotate north over KY/TN on Monday, with numerous
showers likely. Models are hinting at trying to wrap some drier air
in from the south Monday afternoon, so coverage could be a bit
lower. But based on fairly steep lapse rates and a low freezing
level, showery conditions could also include small hail. Monday
looks breezy, with steady temps near 60.

.Long Term...(Monday night through Saturday)
Issued at 315 AM EDT Sun Apr 22 2018

It will remain fairly wet Monday night into Tuesday with the upper
low sitting right over the forecast area. Rain looks to exit off to
the east Tuesday night as another trough forces the upper low out of
the region. With the Wednesday trough, it looks like we could see
some sprinkles or very light rain. But a lot of the day could be
dry. The GFS has trended much drier and is now closer to the ECMWF
solution. This forecast will hang on to slight chance/low chance
PoPs for Wednesday, with highs still in the 60s.

Another trough/surface cold front could impact the region late in
the week. Significant model differences in timing and location of
precip remain, so will only feature some low PoPs at this time. The
weekend looks dry and pleasant with high pressure building in.

&&

.Aviation...(12Z TAF Issuance)
Issued at 650 AM EDT Sun Apr 22 2018

A broad upper level low now along the Oklahoma/Arkansas border will
spin its way into the Tennessee Valley late tonight. A surface warm
front will develop east of it, allowing for enough forcing for light
rains at BWG by late morning, getting into the MVFR range by early
afternoon. These rains should stay south of the other terminals, but
a strengthening wind field around the system will mean steady 10-15
kt with perhaps stronger gusts. Rain shield will lift north by later
in the period of the other TAF sites, bringing MVFR conditions by
daybreak Monday.


&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...DM
Short Term...EBW
Long Term...EBW
Aviation...RJS



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