PAH issues Area Forecast Discussion (AFD) at Jun 20, 11:00 PM CDT579
FXUS63 KPAH 210400
AFDPAH
Area Forecast Discussion
National Weather Service Paducah KY
1100 PM CDT Fri Jun 20 2025
.KEY MESSAGES...
- A prolonged period of hot and humid conditions, with afternoon
heat indices reaching triple digits, is expected this weekend
through next week. A Heat Advisory remains in effect Saturday
through Tuesday. Moderate to major heat-related health
impacts are expected.
- An isolated mainly heat of the day shower or thunderstorm
cannot be completely ruled out any day over the coming week.
However, better chances will spread south across the area
Thursday and Friday.
&&
.DISCUSSION...
Issued at 246 PM CDT Fri Jun 20 2025
Guidance has not changed much in the upper ridge that will build
over the Quad State through Saturday and then over the Ohio
Valley Sunday through next week. Ensemble data indicates that
Saturday will be the worst day with highly anomalous amounts of
850mb moisture (30 year return interval) underlying highly
anomalous warm mid-level air (10 year return interval). After
Saturday, the ensembles are pinging on high mid-level heights
(30 year return interval through at least Wednesday, but the
underlying mid-level temperatures and low-level moisture are
not so anomalous.
The deterministic guidance has 850mb temperatures over 20
degrees Saturday, but then struggles to climb to that level
again. The bottom-line is that confidence in temperatures
reaching the mid 90s for Sunday and beyond is not that high.
Also, the lower mid-level temperatures could lead to a better
chance of at least some isolated diurnal convection as early as
Saturday. Just looking to the south and southwest today, there
are some widely scattered showers and maybe even a few lightning
strikes. It would not be that great of a stretch to see some of
that activity develop over the Quad State tomorrow.
Once again we stuck with the NBM for temperatures and dewpoints
throughout the forecast. Unfortunately, beginning Sunday, the
NBM MaxT grids are a few degrees warmer than any of its hourly
temperatures. The hourly temperatures are what is used to
calculate the hourly heat indices, which are now more in the
100-105 range Sunday through the work week. NBM dewpoints are
solidly in the middle 70s Saturday, but then drop off to the
lower 70s thereafter. This makes sense with the anomalously
high 850mb moisture only around for Saturday, indicating that
moisture depth could be a problem for the rest of the forecast
period.
No changes were made to the Heat Advisory which should be fine
with at least 100 for most of the area for at least 4 days, and
some locations likely reaching 105 and possibly even 110
Saturday. Unless we get enough convection in the meantime, the
Advisory may need to be extended through Wednesday and possibly
even Thursday. Moderate to major heat-related health impacts are
likely, especially Saturday, and with each successive day adding
to the stress, even if the heat indices are closer to 100 than
105 and greater.
There still is no sign of a larger-scale surface front reaching
the area through Friday, but as the ridge weakens, most
guidance shows better coverage of convection working southward,
bringing 15-25% PoPs across the north Thursday and over most of
the area Friday. With very weak wind fields through the period,
any storms should be pulsy and short-lived. However, the extreme
heat and humidity expected would support some torrential
downpours and maybe an isolated stronger wind gust.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1100 PM CDT Fri Jun 20 2025
No major changes from previous TAF set with VFR conditions
expected. Southerly winds around 5 kts expected overnight with
winds increasing to 7-12 kts and gusts of 15-22 kts on Saturday.
Winds should relax after 00z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from noon Saturday to 7 PM CDT Tuesday for
ILZ075>078-080>094.
MO...Heat Advisory from noon Saturday to 7 PM CDT Tuesday for
MOZ076-086-087-100-107>112-114.
IN...Heat Advisory from noon CDT /1 PM EDT/ Saturday to 7 PM CDT /8
PM EDT/ Tuesday for INZ081-082-085>088.
KY...Heat Advisory from noon Saturday to 7 PM CDT Tuesday for
KYZ001>022.
&&
$$
DISCUSSION...DRS
AVIATION...AD
Source:
PAH issues Area Forecast Discussion (AFD) at Jun 20, 11:00 PM CDT---------------
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