NWS Paducah Area Forecast Discussion on May 8, 2024

by United States National Weather Service, a branch of the United States National Oceanic and Atmospheric Administration

264 
FXUS63 KPAH 080741
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
241 AM CDT Wed May 8 2024

.KEY MESSAGES...

- Ongoing active storms with severe potential will persist until
  about or just shy of daybreak, with all severe hazards in
  play. 

- A warm front's return by mid to late morning carries the next
  risk of severe storms, also an all hazards in play threat as 
  storm chances heighten again.

- Once warm sectored, an approaching cold front late this
  afternoon will fire a widespread and significant risk of a
  severe weather outbreak this afternoon and evening. Large
  hail, violent tornadoes, and damaging winds are all expected
  with this outbreak. In particular, Southeast Missouri,
  Southwest Illinois, and Western Kentucky have been upgraded 
  to a Moderate Risk for severe storms.

- A Flood Watch is in effect for portions of the area as the
  steering flow suggests training of locally heavy rainfall
  could produce upwards to 3" or more in some locations.

- After this powerful storm system's passage is fully completed,
  then cooler and drier air moves in for the end of the week and
  weekend with highs in the 70s and refreshingly lower 
  humidity.

&&

.DISCUSSION...
Issued at 230 AM CDT Wed May 8 2024

Ongoing active strong-severe storms required a Watch extension
for western Ky til daybreak. Overall, trends are weakening,
however, given its over-achieving persistence, SPC determined a
headline extension was warranted as RAP models peak MLCAPEs of 
2-3K Joules across its approaching corridor, with bulk shear 
upwards of 50 kts...meaning there is still atmospheric support 
for the line to punch with supercell potential as helicities run
to about 200 m2/s2 in the lower 3KM. That said, if current 
trendings hold, the headline could be cancelled in about half 
its time.

After, all eyes turn to the much advertised daytime threat for 
a widespread and significant severe outbreak as the 90 kt upper jet
core is incoming with the mean long wave's dynamical energy input.
Bulk shear exceeds 50 kts, and mean lapse rates increase to 8C,
promoting large scale ascent of the warm/juicy unstable air 
mass with highs in the low-mid 80s and dew points into the lower
70s. Helicity values are progged to be up into the 200-300 
m2/s2 range both along the warm front and more or less hold as 
the cold front approaches. Speaking of, the CAMs all suggest a 
return/lift of the warm front outputs mid-late morning 
convection overspread, and then within the warm sector as the 
cold front approaches late this afternoon...the big show is 
still an all go for the afternoon/evening time frame. In 
particular, SEMO/SWIL/WKY has been upgraded to a MDT risk for 
all hazards severe, including large-giant hail and significant 
tornadoes. Lastly, the hyper-souping PW's and steering winds 
that will promote training cells overtop already wetted grounds 
has prompted us to issue a Flood Watch for western Ky, where WPC
has bumped us into a MDT risk of excessive/FFG rainfall. 
Collaborative efforts are still ongoing as to if/how far west we
may need to extend that, but generally, upwards to 3" areal 
average totals potential in western Ky trails to 2" along the MS
river and lessens west of there.

The cold front's passage is made tonight, and the severe threat
ends as it does so. Severe storms may be self sustaining into 
the night until then, and convective pops linger within the
broader trof even into Thursday morning, in our far east.
Afterward, the air mass modification to a cooler/drier more
spring-like feel, with Thursday's transition onset completing by
Friday, when upper 60s-lower 70s highs and dew points in the 40s
are established. Generally speaking, highs in the 70s and dew
points in the 40s hold thru the weekend before returning closer
to seasonal norms early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 230 AM CDT Wed May 8 2024

A line of storms offers restricted CIGS/VSBYS as it rolls across
the terminals during the pre dawn hours. KMVN has some patchy
dense fog on the cold side of the boundary. After a daybreak
lull, a warm front returns and heightens storm chances again,
which will offer additional deterioration to restricted
categories. Increasing lapse rates suggest these hold into/thru
the afternoon, when storm chances again heighten as the most 
violent of the storm evolutions comes to fruition with the cold
front's approach. Increasingly gusty non thunderstorm winds 
will peak upwards to 25-30 kts this afternoon. 

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...Flood Watch through Thursday morning for KYZ001>022.

&&

$$