Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 240438
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1238 AM EDT Sun May 24 2015
...Updated Aviation Discussion...
.SHORT TERM (Now through Sunday Night)...
Issued at 310 PM EDT Sat May 23 2015
Afternoon satellite imagery showing partly to mostly sunny skies
across the region this afternoon. Quite a bit less high cloud cover
than yesterday has allowed temperatures to warm up into the mid to
upper 70s this afternoon. Still have another hour or two to see
maximum temps be attained. Expect those highs to top out in the
upper 70s to near 80. This evening we`ll see partly cloudy skies
continue with temperatures falling into the upper 60s and lower
70s. Overnight lows should cool into the mid-upper 50s in the east
with mainly upper 50s in areas from I-65 and points westward.
For Sunday/Sunday night, surface ridge will drift a bit further to
th east as a stronger mid-level trough axis pushes into the western
Plains. A deep southerly flow will transport moisture northward
from the Gulf resulting in widespread shower and thunderstorm
activity in the eastern Plains into the Mid-Mississippi valley. Our
region still looks to remain on the eastern edge of this convective
activity. Still can not rule out some isolated showers and storms
tomorrow afternoon in areas well west of I-65. Model soundings do
show a mid a mid-level cap holding through the afternoon, so keeping
PoPs at 20% or less still seems very reasonable at this time. Highs
tomorrow should range from about 80 to 85 in most spots. It will be
a bit more breezy tomorrow with southwesterly winds of 10-15 MPH
with gusts in the 20-25 MPH range at times.
Upper ridge will continue to shift eastward tomorrow night which may
result in slightly higher precipitation chances late Sunday night
and into early Monday. For now, plan on keeping chance PoPs in
place with lows in the mid-upper 60s.
.LONG TERM (Monday through Saturday)...
Issued at 315 PM EDT Sat May 23 2015
The Ohio River Valley will be positioned between upper ridging to
our east and troughing to our west. This places the area in deep SW
flow which will bring an increase in moisture, instability, and
several disturbances passing through the flow. Resultant sensible
weather will feature an active period with rounds of scattered
shower/storm activity nearly every day. High temps look to be at or
above normal (dependent on convection/cloud coverage) with mild
overnight lows given the steady southerly winds and higher Td`s.
Monday - Wednesday...
Scattered to numerous showers and storms should be ongoing west of
I-65 Monday morning as a 30-40 knot LLJ responds underneath the
right entrance region of an upper impulse. Precipitation will only
slowly work eastward through the day, decaying as it does so.
Afternoon convection then potentially develops on the eastern flank
of convective debris due to differential heating in the afternoon.
This coverage will most likely be centered more toward our eastern
CWA if this scenario pans out. Given the morning convection, think
our west will struggle to warm so will go with mid and upper 70s for
highs. Meanwhile, the east should see the low 80s.
Lingering convection should die off in our east after sunset, with a
brief lull in activity through a chunk of the overnight. As we near
dawn, coverage across our west may pick up again as we see another
spike in the LLJ. This coverage looks to be isolated to widely
scattered. Will continue to advertise a mild overnight with lows
Tuesday looks like pretty decent coverage (50-60%) of showers/storms
ahead of a disturbance passing through the deep SW flow. Temps
should again range in the 76 to 81 range, dependent on convection.
The upper trough axis looks to pass Tuesday night with continued
scattered showers/storms ahead of it.
Wednesday sees lingering convection in the east dropping off by
midday, with low chances in the afternoon in a more subsident
Any severe threat continues to look low due to unimpressive
instability and deep layer shear. That being said, a few pockets of
marginal deep layer shear (25-35 knots) and some instability may
interact at times to produce a few more organized clusters. This
would be most likely across our western CWA early and mid week.
Heavy rain may end up being the biggest concern given moist
Thursday - Saturday...
The end of the week and into the weekend looks to be more of an
early summer-like pattern with warmer temperatures and isolated to
widely scattered t-storm chances. This will occur as upper ridge
holds over the SE conus and better flow stays well NW of the area.
Look for temps mostly in the mid 80s during this time, with
diurnally driven convective chances.
.AVIATION (06Z TAF Update)...
Updated at 1235 AM EDT Sun May 24 2015
Plan on VFR conditions through the TAF period as high pressure
drifts off the mid-Atlantic coast, while a weather system remains to
the west over the central Plains. Southerly return flow will
increase later this morning through the afternoon with gusts to
around 20 kts expected at SDF/LEX/BWG. Winds should subside toward
late afternoon or early evening. Expect scattered high clouds
throughout the day, becoming broken after sunset. High confidence
all terminals will remain dry through 06z Monday though
precipitation chances will spread west to east over the region just
beyond the current TAF period.