JKL issues Area Forecast Discussion (AFD) at Aug 13, 1:19 AM EDT208
FXUS63 KJKL 130519
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
119 AM EDT Tue Aug 13 2024
.KEY MESSAGES...
- Temperatures gradually rise to return to near normal levels
through Thursday.
- Humidity and the possibility of showers and thunderstorms will
climb late in the week.
&&
.UPDATE...
Issued at 1012 PM EDT MON AUG 12 2024
Showers or sprinkles continue to move across portions of IL and IN
as well as western and into central KY ahead of an approaching
disturbance. Mainly high clouds have increased ahead of this
across eastern KY, with some mid clouds also present. Some
convective allowing models including the HRRR have been a bit more
robust in coverage of this activity compared to the previous
forecast. With this in mind, a couple hours of slight chance pops
were included for much of the north for these, with the areal
extent of sprinkle chances expanded a bit further south. Overall,
the probability of measurable precipitation from this is low.
UPDATE Issued at 754 PM EDT MON AUG 12 2024
Hourly grids were freshened up for the next couple of hours based
on recent observations and trends. This led to no substantial
changes at this point.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 429 PM EDT MON AUG 12 2024
The latest upper level map features troughing positioned from
eastern Canada through the eastern Great Lakes and New England.
Ridging is currently centered over Texas, with west northwest flow
aligned from the Midwest through the Ohio and Tennessee valleys.
At the surface, high pressure is sprawled from the northern Plains
through the central and southern Appalachians. A cool start,
combined with some passing thicker high level clouds kept most highs
near, or just on either side of the 80 degree mark.
The models are in very good agreement through the short term. An
embedded short wave trough will traverse the Ohio Valley late
tonight into early Tuesday morning, bringing increasing and
somewhat lowering clouds to most of the Commonwealth. Some of the
model guidance is also showing some light precipitation; however,
given the drier low levels in place and the lack of surface
features, will only be including a period of sprinkles overnight.
The combination of a mostly clear beginning to the night as well
as dew points starting out in the low to mid 50s, should allow
temperatures in the cooler valleys to dip into the mid 50s, while
broader valleys and ridges cool off to the upper 50s to lower
60s. The short wave will exit Tuesday morning, with 500 mb
heights recovering during the day, and mostly sunny skies
prevailing. Temperatures have been running a bit on the cooler-
side of the guidance with this air mass, so have stayed closer to
the 25th percentile of the NBM, with highs in the lower 80s at
most sites. Mostly clear skies and continued lower humidity will
allow for similar lows Tuesday night compared to tonight, despite
the warmer start.
.LONG TERM...(Wednesday through Monday)
Issued at 405 PM EDT MON AUG 12 2024
The period will begin with mid-level heights building across parts
of the Middle and Upper Mississippi River Valleys and trough in the
east toward much of the Ohio Valley. At the surface, we will see
high pressure centered across the Upper Ohio Valley and Great Lakes
regions. This will lead to weak northerly flow at the surface. This
will keep it dry and near normal through at least most of the day
Thursday. The mid-level heights do tend to rise based on most of the
ensemble and deterministic solutions as a ridge attempts to build east.
This will lead to a little warmer weather Thursday, with
afternoon highs in the upper 80s. The mornings will see river
valley fog and temperature splits, with valley locations in the
mid to upper 50s both mornings.
An upper level wave will push into the Upper Mississippi River Valley
by early Friday and quickly deepens a low that tracks into the Great
Lakes. This will all help to send a warm front toward the Ohio Valley
Friday and help to increase the chance of rain to around 50-60
percent on Friday. This overall troughiness sticks around through
the reminder of the period chances of rain into the 40-60 percent
chance range from time to time through Sunday. There are some
differences in the overall evolution of this system in the ensembles
and deterministic solutions that complicate the overall chances
of rain. Particularly with how quickly it moves the cold front
east through this weekend. Therefore stuck close the NBM for now
to handle these differences and trends overtime. Right now, when
looking at the ensembles the greatest chance (around 30 percent)
of seeing over a half an inch in a 24 hour period will be Friday
into Saturday night and this seem reasonable based on the overall
trends in the other guidance, better forcing signals, and
increasing moisture, with PWATs closer to 1.75 inches. Given the
increasing cloud cover and chance of rain through the weekend
afternoon highs will be running a bit cooler in the low to mid
80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 118 AM EDT TUE AUG 13 2024
VFR conditions are expected under extensive mid- and high-level
cloud cover associated with a passing disturbance, decreasing in
coverage between 12z and 18z Tuesday as the disturbance exits
east. Some sprinkles or brief light rain could fall from these
clouds between now and about 12Z. Winds are still expected to
average around 5 KT or less, generally from a north to northeast
direction.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GEOGERIAN
LONG TERM...DJ
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 13, 1:19 AM EDT---------------
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