Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 240517
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
117 AM EDT Thu Apr 24 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Thursday Night)...
Issued at 300 PM EDT Wed Apr 23 2014
Sfc high pressure will remain in control of the region tonight with
upper level clouds on the increase as a disturbance passes to our
north. Low temperatures should bottom out in the low to mid 40s
across the region.
For Thursday, upper level ridging will push east into the region
helping temps warm well into the 70s. Temps may approach 80 by the
KY/TN border under mostly sunny skies. SE-S sfc winds will increase
to 10-15 mph with some gusts near 20 mph possible Thurs afternoon.
Thurs night a low pressure system will push through the upper
Midwest dragging a cold front through the Ohio Valley. Storms are
expected to erupt along this front to our west Thurs afternoon and
move east into our region late Thurs evening. Although generally
speaking storm strength and coverage should be on the decline as
storms move into our region, think that some strong storms may be
possible west of I-65 with gusty winds up to 40 mph possible. As
convection progresses eastward Thurs night, rumbles of thunder will
still be common but any strong storms should diminish. Convection
should exit the area during the pre-dawn hours Friday morning. Low
temps should stay mild in the low to mid 50s Thurs night.
.LONG TERM (Friday through Wednesday)...
Issued at 320 PM EDT Wed Apr 23 2014
Cold frontal boundary will be exiting our eastern CWA at daybreak
Friday. Expect gradually clearing skies and a steady west wind with
temperatures reaching the low to mid 70s. A few models are holding
onto some QPF along the I-75 corridor for a few hours on Friday
morning, displaying a slower trend. However, will keep the forecast
dry for now until a more clear and slower trend can be established
since we have had dry going for a few days now.
Friday Night - Sunday...
Shallow northwest flow aloft will gradually transition to a
progressive upper ridge over the weekend. Will watch as a moisture
starved cold front approaches the Ohio Valley Friday night and
stalls out Saturday. Will continue to leave the forecast dry across
our north as deep moisture is limited and the best forcing with the
wave embedded in the NW flow aloft passes to our north. The
progressive upper ridge builds in Saturday night into Sunday,
leading to a warmer and continued dry trend to end the weekend.
Temperatures Saturday may end up being tricky depending on where the
frontal boundary actually stalls and then washes out. Regardless,
lower 70s is a reasonable bet across our north with upper 70s
touching 80 across our south. Sunday should be warmer, at least
across our south, if not the whole CWA, however will keep the
gradient in to account for uncertainty in frontal position. Lows 70s
north to around 80 south. Lows will be around 50 Friday night, and
slightly milder in the low and mid 50s Saturday night.
Sunday Night - Wednesday...
Confidence lowers significantly as we start the new work week as
models struggle with the individual details surrounding the
evolution of a complex upper pattern. What can be said with some
confidence is that we will enter a much wetter and cooler setup
heading into mid week as a closed upper low wobbles slowly eastward
against blocking flow downstream. The best chances for showers or
storms will begin to increase by Sunday evening as a reinforced warm
front pushes up through the area from the southeast. This is a
slightly slower trend likely due to the downstream blocking feature.
Generally speaking, it appears the Ohio Valley will be caught in a
baroclinic zone between the closed upper low to our west and gyres
of energy rotating around a closed upper low over the northern
Atlantic. A look at the 500 mb heights reveals one of the more
impressive cols i`ve seen for Monday night Tuesday. At this point,
the Ohio Valley looks to be on the southern side of the col, with
plenty of moisture transport ahead of the main low to our west on
deep southwest flow. Will call for likely chances of showers and
storms during this time. Being on the warm side of the boundary, we
should be able to still see low and even mid 70s, however diurnal
trends may get smaller and smaller each day as we head into mid
Upper low looks to wobble somewhere over eastern CONUS into midweek,
with the center closer to the Ohio Valley. By Wednesday, highs in
the 50s and lows back into the 30s are not out of the question,
along with continued scattered to numerous shower chances.
.AVIATION (06Z TAF Update)...
Issued at 115 AM EDT Thu Apr 24 2014
VFR conditions are expected through this TAF period. High pressure
currently in control will shift east today as a low pressure system
approaches from the west. Currently light easterly winds will become
southeasterly around daybreak and increase to around 10-12 knots
with a few gusts to around 18 knots or so in the afternoon. Clouds
will increase through the day and lower tonight as a front and
associated precipitation nears. Showers and scattered thunderstorms
will enter the picture for the last 6 hours or so of the SDF TAF, so
will introduce VCSH at this time. Precip at BWG and LEX will occur
at or after this valid TAF period.