Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLMK 271929
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
329 PM EDT Wed Aug 27 2014

.SHORT TERM (Now through Thursday Night)...
Issued at 315 PM EDT Wed Aug 27 2014

A healthy cu field has developed in a moist, unstable atmosphere
this afternoon.  An upper level ridge was over the region with a
weak sfc boundary located near the Ohio River.  Instability along
with the boundary has created enough lift for a few showers over
southern Indiana as of 245pm.  Expect isld-scattered showers and
some t-storms to continue to develop through the evening hours over
southern Indiana and central Kentucky.  Soundings indicate
plentiful CAPE but meager wind fields so any storms that develop
should be limited in strength.  However dry low levels and steep low
level lapse rates may be enough to force a few windier showers and
storms with wind gusts up to around 40 mph.  Convection should
decline after sunset with the loss of day time heating.

The front should continue to make slow progress southward tonight
with patchy light fog developing during the pre-dawn hours.  Low
temps tonight should hold in the upper 60s and lower 70s.

For Thursday, the weak sfc front will drift into south central
Kentucky providing the best focus for afternoon showers and storms
there.  These storms will be similar to today in strength and
coverage peaking during the late afternoon/evening hours.  It is a
bit unclear if storms will diminish completely Thurs evening or
continue on throughout the overnight night hours Thurs as a
shortwave moves into the region possibly prolonging convective
activity.  For now will remain conservative and diminish POPs by
midnight Thurs night with the next chance for rain on Friday (see
long term discussion).

Temps Thurs should be slightly cooler than today in the 84-92 degree
range with the coolest temps north of the front.  Low temps should
range from the mid 60s to low 70s Thurs night.

.LONG TERM (Friday through Wednesday)...
Issued at 323 PM EDT Wed Aug 27 2014

The tenacious upper ridge across the SE CONUS will have shifted off
the FL/GA coast by the start of this forecast period with meridional
flow dominating. Southerly flow will advect in copious amounts of
moisture by this upcoming holiday weekend with PWATs looking to
reach toward and exceed the 2 inch mark. Previously advertised upper
low swinging through the central Plains late this week will phase
into the mean flow as it takes a northeasterly turn toward the Great
Lakes. Its remnants will bring height falls to the region over the
weekend and with the upper ridge no longer in the picture, zonal
flow will return by the start of the new week but with
shortwaves/perturbations traversing through overhead. This all
equates to another unsettled period with precip chances nearly every
day. This isn`t to say that everyone will see rain each day, but
just that chances exist, especially over the weekend.

The frontal boundary mentioned above (in the short-term section)
will be lifting north across the forecast area on Friday, setting
the stage for WAA and serving as a focus for convection. Have gone
with slight chance on Friday as the day will be the start for warm,
moist air advecting in but won`t have been quite enough to drive too
much convection other than pop-ups that will been diurnally driven
and isolated, such as what has been seen thus far this week. PoPs
will be much higher for Saturday and Sunday with convection
potentially more organized, given the greater synoptic push. As
alluded to already, PoPs continue into the new week with a secondary
focus for convection Monday into Tuesday as another frontal boundary
dives down from the NW. Depending on the speed of the front, could
begin to see some drying out by the middle of next week with
potentially a reprieve from the typical summer heat and humidity
that has enveloped the region lately.

Highs on Friday look to be the warmest of the long-term as they
reach near to slightly above normal - upper 80s to low 90s with
dewpoints in the upper 60s to around 70. We`ll then see the full
spectrum of 80s for the remainder of the period with variations due
to precip and cloud cover. Lows will range from the mid 60s to low
70s with the warmest overnight period looking to be Saturday night
as cloud cover moderates temperatures and WAA in full swing.

&&

.AVIATION (18Z TAF Update)...
Issued at 135 PM EDT Wed Aug 27 2014

An upper ridge is expected to remain over the area with a weak sfc
boundary dropping south through the region tonight.  Isld-sct storms
may develop late this afternoon and evening along the front.
However, will indicate only VCSH for this afternoon/evening attm
because confidence is low in convective development near the
terminals.  Will watch trends this afternoon and update TAFs if
needed.  Any convection chances will end by around midnight with
loss of day time heating.  The next forecast challenge with then be
fog.  Although a sfc boundary will be in the area, wind fields
around it look to be very weak or even calm overnight.  With 70s
dewpts and perhaps a late day shower or storm at the TAF sites,
think that they will see at least some light br at SDF/LEX and IFR
br at BWG.  Vsbys could go lower than that according to some MOS
guidance but will remain on the conservative side for now.  Any br
will diminish shortly after sunrise tomorrow with scattered
afternoon cu developing.  Winds will remain light easterly or calm
through the TAF period.

&&

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

$$

Short Term........AMS
Long Term.........lg
Aviation..........AMS




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.