JKL issues Area Forecast Discussion (AFD) at Apr 16, 7:40 PM EDT
794
FXUS63 KJKL 162340
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
740 PM EDT Wed Apr 16 2025
.KEY MESSAGES...
- Frost development is expected overnight, especially in the
valley locations. A frost advisory is in place through much of
eastern Kentucky as a result from midnight tonight through 9am
EDT Thursday.
- A strong warming trend is expected for the rest of work-week,
continuing through the weekend.
- Shower and thunderstorm chances return to the forecast on
Saturday and linger at times through Wednesday.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 459 PM EDT WED APR 16 2025
Northwest flow is persisting across the Ohio Valley, with high
pressure in place across the state at the surface. This is leading
to good dry air advection, and weak cold air advection having to
compete with abundant sunshine. Even still temperatures have topped
out generally in the low 60s across much of eastern Kentucky this
afternoon. As we head into the overnight and the high pressure
continues to take hold of eastern Kentucky, we will be in an ideal
pattern for strong subsidence and decoupling of the valleys,
especially the deeper eastern valleys as light winds turn more
southerly. Forecasted overnight temperatures actually haven't
changed much since the midnight shift, with mid and upper 30s
possible on the ridges, and lower 30s in the deeper valleys.
Wouldn't be surprised if a some locations drop even cooler than
what's in the forecast, and expect that the evening shift will
continue to make adjustments on the overnight temps as a result.
With temperatures dropping near and below freezing, it's not
unlikely that many of these valley locations will also see frost
development. Last night's midnight shift went ahead and issued an
Frost Advisory for overnight for much of the CWA, which still seems
very much warranted.
Upper level ridging will start to take hold for the day Thursday
across much of the Ohio Valley. Meanwhile, the surface high pressure
system will continue to shift eastward, increasing the return flow
across the Commonwealth. Meanwhile, a strong low pressure system
will be taking shape across the southern Plains and into the Middle
Mississippi Valley. A warm front associated with this system will
lift north through Kentucky during the day Thursday, fueled by the
increased llvl southerly flow and WAA from the Gulf. Yesterday,
models showed some precip along this boundary making it into eastern
Kentucky, however the NBM showed it fizzling out before making it
the CWA and therefore kept us dry. There has been an opposite shift
today, where several of the long range models keep us dry through
Thursday night, but the NBM does show some precip chances along the
warm front as it moves through late Thursday. Either way, with
strong ridging in place, these are low end chances pops with only
light rain expected with little to no impacts. Despite some cloud
cover moving through with the warm front, afternoon temperatures
will still warm into the mid and upper 60s, with a few 70s possible.
Once clouds exit to the northeast Thursday night, skies will once
again clear. However, at this point we will be in the warm sector of
the system, with continued southerly flow and WAA into the region.
Therefore, did include some ridge/valley differences, but only minor
given the lack of subsidence and the stronger wind flow. Compared to
the 30s expected tonight, Thursday night will be in the mid 40s to
low 50s. So even if the valleys did drop some, ultimately it
wouldn't have any actual impacts.
.LONG TERM...(Friday through Wednesday)
Issued at 459 PM EDT WED APR 16 2025
Heading into Friday, the low pressure system will have made it into
the Upper Great Lakes region and parts of Ontario. Several other low
pressure systems will have also developed on the SW to NE flow side
of the upper level ridge still in place, with a frontal boundary
connecting all of them in a line. Latest model trends have this
boundary remaining well NW of the CWA, and even the state, through
the day Friday, which should keep us dry, while also remaining warm
a bit more humidity. Temperatures will soar into the upper 70s and
low 80s by the afternoon.
The whole system continues to shift eastward Friday night, with the
frontal boundary still expected to become elongated and begin to
stall near the Ohio River during the day Saturday. Both the GFS and
NAM continue to keep the boundary located just enough to our north
that the JKL CWA (southeast KY) remains dry throughout the day
Saturday, however the ECMWF drops it slightly farther south,
possibly affecting the very far northern extents of the CWA.
Meanwhile, the NBM continues to take a more pessimistic approach,
with a chance of precip moving in from the NW during the day
Saturday, extending through the top half of the CWA. SPC still has a
Day 4 15-30% severe weather potential across the same area of the
CWA - but will be interested to see how this also trends, especially
if the models continue to keep the better convection to our north.
Meanwhile, one of the spot lows along this line, located in the
southern Plains, will be able to strengthen on the heels of a
deepening upper level trough also located in this region. As it
does, it will become the primary system, shifting northeast towards
the Mid Mississippi Valley by 18Z Sunday. There is still quite a bit
of disagreement in the models with this system, especially when it
comes to the strength, but there is at least general agreement that
this shift will allow the stalled boundary along the Ohio River to
begin lifting north as a warm front, while a cold front forms on the
southern side of the system and begins to shifts eastward. The upper
level flow will also become more SWrly into the Ohio Valley, which
will amplify the amount of moisture moving into the region. At least
slight to chance pops are therefore in place across the CWA until
the actual cold front moves through late Sunday night into Monday.
Being fairly close to the actual low pressure system, it's not
surprising that instability and lift will be increased across the
region, which will also introduce thunder chances to the forecast in
some portions of the CWA at times from Saturday night through
Monday. Right now the NBM has generally high end chance pops as the
front moves through Monday, but based on model agreement during this
time (at least across our CWA), wouldn't be surprised if these pops
increase. Temperatures will also continue to be unseasonably warm as
we remain in the warm sector through this time, with highs topping
out in the upper 70s and low/mid 80s.
High pressure will begin to move back in from the west behind the
frontal boundary Monday night into Tuesday morning. However, upper
level flow will be more zonal behind this departing system, which
will prevent CAA into the region. As such, post-frontal temperatures
really won't swing too much to the colder side. In fact, highs on
both Monday and Tuesday are still going to be 70s in many locations.
The NBM has some pops lingering across the CWA Monday night into
Tuesday, though not sure that the models are currently supporting
this with the latest runs. But given how far out it is the forecast,
expect both the models and the NBM solution to adjust over the
coming days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 740 PM EDT WED APR 16 2025
VFR conditions will prevail through the TAF period. Mainly high
clouds will pass through the JKL area at times tonight and
Thursday morning. Sky cover is expected to thicken and lower more
substantially after 18z Thursday as a weak disturbance
approaches. A few very light showers are possible at SME or LOZ
late in the day, but most locations will likely see only virga.
Winds will be variable at around 5 kts or less tonight before
turning southeasterly during the daylight hours on Thursday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight tonight to 9 AM EDT Thursday for
KYZ044-050>052-058>060-068-069-080-085>088-104-106>120.
&&
$$
SHORT TERM...JMW
LONG TERM...JMW
AVIATION...GEERTSON
Source: JKL issues Area Forecast Discussion (AFD) at Apr 16, 7:40 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202504162340-KJKL-FXUS63-AFDJKL)
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