Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 141918
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
318 PM EDT FRI JUN 14 2013
.SHORT TERM (Tonight through Saturday night)...
Issued at 315 PM EDT Fri Jun 14 2013
Tranquil weather will prevail through Saturday evening as dry high
pressure over the upper peninsula of Michigan makes its way
southeast to the Carolina coast. Favorable radiational cooling
conditions tonight as the surface ridge axis crosses Kentucky, and
with dewpoints in the mid 50s, that will allow temperatures to dip
into the 50s over much of the area. The most notable exception will
be in the urban heat island of the Louisville Metro, where lows will
be in the lower 60s. There will be a brief window for some valley
fog in southern Kentucky, but do not expect it to be significant
enough to include in the grids or forecast.
The surface ridge axis will be to our east on Saturday, opening the
door for southerly return flow. Increasing heights aloft will allow
temps to rebound to above normal. H8 temps around 15C will support
highs in the mid to upper 80s.
Could turn a little more unsettled on Saturday night as an upper
impulse currently over south-central Texas rides up and around the
ridge. This feature will help to spark an MCS over the Mississippi
Valley, and as this rolls eastward, a 20-30 POP is warranted over
southern Indiana as we approach daybreak on Sunday. Otherwise the
light S-SW flow and increasing moisture will keep temps up, with
mins ranging from the mid 60s in the rural areas to around 70 near
.LONG TERM (Sunday through Friday)...
Issued at 300 PM EDT Fri Jun 14 2013
Sunday through Tuesday...
Zonal flow will be in control over the majority of the CONUS at the
start of the forecast period. At the surface, a cool front will
extend from a surface low over the Great Lakes through the mid
Mississippi River Valley. The front will become nearly parallel to
the upper level flow as it approaches the Ohio Valley, which will
help to stall it out through the beginning of the week. This will
lead to an extended period of weather where scattered to numerous
showers and storms will be possible.
Sunday morning will likely start out dry, however will likely see an
increase in convective activity through the afternoon and evening
hours, especially across the northern CWA as convergence ahead of
the front initiates convection. Convection should last into the
evening hours, before coverage diminishes overnight. Cannot rule out
a few stronger storms on Sunday afternoon/evening across the
northern CWA as modest instability combines with 30-40 knots of 0-6
Km shear. Monday will bring better chances for more widespread
showers and storms as the front sinks closer to the Ohio River, and
there is some model support for a supporting shortwave diving
through the Ohio Valley. Will continue with likely pops for this
time period and also continue to monitor potential for a few
Temperatures will be in the mid to upper 80s on Sunday, with slightly
cooler temps on Monday in the low to mid 80s. Will stay on the warm
side of the boundary both days, but the added convective debris on
Monday will contribute to the slightly lower temperatures.
By Tuesday evening, the passing eastern CONUS through should help to
drag the cold front through the area with high pressure building in
behind it. Will leave the highest pops across the southern CWA for
Tuesday. Highs on Tuesday will range in the lower 80s.
Tuesday Night - Friday...
Will leave the middle and end of next week dry as surface high
pressure builds in behind the front and northwest flow aloft takes
hold. Future forecasts may warrant low precipitation chances,
however they will be due to local heating effects or any subtle
shortwave response embedded in the NW flow that may not be
discernible this far out. Otherwise, there does not appear to be a
significant focus for shower and t-storm development. Temperatures
through the rest of the week should gradually warm from the lower
80s on Wednesday to the mid and upper 80s by Friday.
.AVIATION (18Z TAF Update)...
Issued at 1250 PM EDT Fri Jun 14 2013
Quiet weather expected through the valid TAF period as dry high
pressure makes its way southeast from Lake Superior to the Carolina
coast. Expect VFR conditions and light winds, with a gradual veering
from north around to southeast or south by late morning Saturday.
Only real concern is that favorable radiational cooling conditions
tonight will allow for some brief MVFR visibilities in BWG and LEX
around daybreak Saturday. However, operational impacts will be
mitigated as we should remain well above fuel-alternate thresholds.