Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Louisville Kentucky
714 PM EDT Sat Aug 29 2015
..updated aviation discussion...
Short term (now through Sunday night)...
issued at 303 PM EDT Sat Aug 29 2015
The atmosphere has become moderately unstable this afternoon,
characterized by ml cape value mostly in the 1000-1500 j/kg range.
The instability combined with a slow moving vorticity maximum currently over
the MO bootheel should be enough to sustain scattered (30-40%
coverage)mostly east of I-65 through the late afternoon/early
evening. Still lacking any convincing deep layer flow so continue to
expect scattered shower/storm activity to be disorganized. Will
continue to highlight the threat of brief heavy rainfall and perhaps
gusty winds up to 40 miles per hour with a few strong storms this afternoon,
given dcape values in the 1000-1200 j/kg range across south central
Kentucky. Did want to mention that it looks like a narrow corridor along
and either side of the Ohio River will stay relatively dry through
this evening as it lies in a narrow precipitable water minimum evident on
mesoanalyisis and water vapor.
Expect coverage to diminish around sunset with the loss of peak
heating, however will keep an isolated chance in overnight as the
moist airmass remains in place and the upper disturbance will be
hanging around. Otherwise, expect mostly cloudy skies with lows
mostly in the upper 60s to around 70.
Sunday will be a repeat of today, with similar (scattered) shower
and storm coverage by afternoon and evening. While this evening main
coverage should be east of I-65. Sunday's coverage should be more
confined to south central Kentucky and west of I-65. Isolated coverage
will then shift to east of I-65 Sunday night. Again...nothing severe
is expected with weak flow aloft although brief heavy rain and gusty
winds are possible with the strongest storms.
Highs on Sunday are expected to range in the low and middle 80s with
lows Sunday night ranging between 65 and 70.
Long term (monday through saturday)...
issued at 300 PM EDT Sat Aug 29 2015
Weak surface high pressure looks to sit to our east for the first
half of the work week...whereas an upper level low should sit to our
west. Not expecting any strong forcing features during this period
and with precipitable waters just a little above normal...will
maintain lower end rain chances each day. High temperatures should
be a little above normal...amend given the more moisture in the air
lows also should be above.
Later in the week...the forecast still depends on what happens with
the remains of Erika. The overall pattern would indicate ridging
over our area...and consequently warmer temperatures.
However...models show an upper low pushing into that ridge from the
south...perhaps merging with the low to our west early in the week.
The system from the south would pull in some deeper moisture with
Erika...so will have to watch how far north that gets. That
said...will go with isolated probability of precipitation for the end of the week...and a
little higher across our south for Saturday. For temperatures will
basically maintain persistent with the early week forecast.
Aviation (00z taf update)...
issued at 714 PM EDT Sat Aug 29 2015
Other than a stray evening shower, tonight should be dry with cirrus
spilling northward ahead of a Gulf Coast low. Will include some
light fog at bwg and Lex, but will keep it MVFR with the cirrus
Sunday will be a Carbon copy of Saturday with scattered afternoon