299
FXUS63 KPAH 220427 AAB
AFDPAH

Area Forecast Discussion...UPDATED
National Weather Service Paducah KY
1127 PM CDT Fri Jun 21 2024

.KEY MESSAGES...

- Heat and humidity continue to be the main story through early
  next week. Heat index values around 100 this weekend, will
  peak around 105 by Tuesday.

- A weak cold front may spark a few showers or storms late Saturday
  night through Sunday afternoon.

- A greater chance for showers and storms arrives Tuesday night
  into Wednesday with another cold front. It looks like we
  finally get a brief break from the highs in the 90s and higher
  humidity mid to late next week.

&&

.DISCUSSION...
Issued at 229 PM CDT Fri Jun 21 2024

Surface and upper level high pressure reside across the region
today. The ridge will get suppressed southward by later this
weekend as a shortwave passes across the Great Lakes region and
moves into New England on Sunday. This will help drag a weak
frontal boundary down into our area late Saturday night into
Sunday. Convergence along the boundary doesn`t look especially
great and the main upper level forcing is displaced well
northeast of us. The best wind fields aloft are also to our
east. Initially it looks like a decaying band of showers (maybe
an isolated storm or two) may spread southeast across the area
late Saturday night into Sunday morning. Behind this activity,
there may be some redevelopment during the afternoon as
instability increases. The 12z suite of guidance isn`t overly
impressive with it, and even the notoriously robust FV3 model
struggles to develop much aside from isolated storms over west
Kentucky.

SPC has our eastern half in a marginal risk for severe on Sunday.
Bulk shear may sneak close to 25 kts in our east, so combined with
the instability and moisture present, can`t argue against the
marginal if a few storms can actually fire up. Looks like any storms
would quickly transition southeast of our cwa by early evening.

The upper ridge will build back northeast into the mid Mississippi
Valley early next week, with 850mb temps peaking around 21-22C by
Tuesday. Afterwards, a shortwave dips down across the Ohio Valley
Tuesday night into Wednesday. There appears to be better forcing
with this feature, so the frontal boundary associated with it should
produce more widespread showers and storms compared with the Sunday
system. Wind fields don`t appear especially strong, but another
marginal setup for severe could materialize. The CSU MLP
probabilities generate higher severe probs to our north on Tuesday
and then well east of our area on Wednesday, which seems reasonable
at this point.

Temperatures will remain above normal through Tuesday, with highs
largely in the low to mid 90s, but we may push into the upper 90s on
Tuesday. Humidity levels will be highest on Sunday and Tuesday, when
low to mid 70 dewpoints are possible. More cloud cover on Sunday
should keep temperatures several degrees cooler than Saturday, but
with higher dewpoints present the heat index will be similar if not
a degree or so higher even. Heat Advisory headlines may end up being
needed early next week, especially on Tuesday when heat index
readings may approach or exceed 105.

A somewhat cooler and drier airmass is forecast to move down into
the Ohio Valley late next week. Currently it looks like highs in the
upper 80s on Thursday with dewpoints only in the low to mid 60s.
Beyond that, the ridge may build back in next weekend with a return
of highs in the 90s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1127 PM CDT Fri Jun 21 2024

Conditions appear favorable for at least patchy fog development
through the overnight. Periods of MVFR visibility appear
possible throughout the quad-state region with IFR visibility
likely in the CGI-MDH-MWA-MVN corridor. Rapid improvement is
expected after daybreak with a southeast wind picking up by mid
morning.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...Air Quality Alert until midnight CDT /1 AM EDT/ tonight for
     INZ081-082-085>088.
KY...None.

&&

$$

DISCUSSION...SP
AVIATION...JGG