Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 270718

Area Forecast Discussion
National Weather Service Louisville KY
318 AM EDT WED APR 27 2016

.SHORT TERM (Now through Thursday)...
Issued at 300 AM EDT Wed Apr 27 2016

Stalled frontal boundary resides just north of the region, whereas a
second boundary is just south of the region, the remnant from the
line of storms that moved through the region last evening. In
between we are seeing some weak isentropic lift that is resulting in
some new shower development across central Kentucky. Model QPF
fields seem overdone in areal coverage of this precip, based on
latest radar, but for the daylight morning hours, the higher-res
versions try and provide more focus on a northwest/southeast-
oriented line. Have gone in line with this thinking and placed a
narrow band of high-likely pops from HNB to AAS with pops tapering
off north and south of that line.

Beyond the morning hours, expect a brief lull in coverage, with the
airmass just juicy enough to squeeze out some scattered showers
perhaps thunder. A PV anomaly will then rotate around a larger upper
low centered over southeast Nebraska. Timing this feature with peak
daytime heating, expect a line of storms to develop across western
TN/KY and head northeastward. The main threat with these storms
again will be damaging winds, with this threat mainly limited to
points west of the I-65 corridor. The storms should weaken with loss
of heating as they continue into the rest of the forecast area.

We dry out some for Thursday, with precipitable waters dropping down
to around an inch. The upper low over the Central Plains this
afternoon should be over the upper Midwest Thursday. The distance
from this feature and lack of a trigger should limit coverage of any
storms to isolated to scattered.

As for temperatures, our string of above normal days will continue,
with highs ranging from the mid 70s to low 80s and lows around 60.

.LONG TERM (Thursday night through Tuesday)...
Issued at 300 AM EDT Wed Apr 27 2016

The drying trend should continue at least through Friday, as ridging
moves over the region. Then Friday night, that ridging will start to
push east of us as another storm system comes out of the Plains.
This system should lift a warm front toward the region, which could
bring some light rain showers west of I-65 by daybreak Saturday.
Deterministic model guidance shows this boundary stalling over our
region for the weekend, meaning another couple of days with good
rain chances. A surface low crossing the region during the day
Sunday could mean some stronger storms, and will be something to
watch for, to see if we can get some instability to go along with
the dynamics of this system.

Latest deterministic models pull this low out of the region by
Monday morning, whereas the GEFS mean has it a little slower, a sign
of timing differences within the ensemble members, as spread also is
high. Thus will keep in a lower-end chance for rain into Monday.
After that Tuesday should have even less chance for rain, as a
narrow shortwave ridge moves into the region. Given how small this
feature is and another wave potentially dropping into the Midwest,
cannot pull rain chances altogether.

As for temperatures in this period, Friday should be one more above
normal day, then we should be closer to normal for the weekend and
possibly below for the start of the next work week.


.AVIATION (06Z TAF Update)...
Updated at 121 AM EDT Wed Apr 27 2016

The challenge for this set of TAFs is the timing of rounds of
convection developing today. Leftover boundaries from the convection
yesterday evening and additional disturbances moving through will
lead to a couple of rounds of storms. The first round should develop
early this morning along a boundary draped across central KY. These
showers/storms could impact BWG. Most models have them staying south
of SDF and LEX until later this afternoon. Therefore, the mention of
VCTS in the TAFs has been pushed back until later this afternoon for
these sites. However, should the boundary set up a bit further to
the north SDF may be impacted earlier. In addition, there is another
round of storms that looks to move through during the early evening
hours. Thereafter will mention only showers as uncertainty becomes
higher late in the forecast period.

Guidance indicates some lower ceilings will build into the area this
morning for a few hours and some upstream observations are beginning
to show this. Will keep cigs MVFR for now. Winds will generally be
out of a southerly direction, but could be variable with showers and
thunderstorms passing through the terminals.


.LMK Watches/Warnings/Advisories...


Short Term........RJS
Long Term.........RJS
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