631
FXUS63 KPAH 041145
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
645 AM CDT Fri Apr 4 2025

.KEY MESSAGES...

- Multiple rounds of additional thunderstorms will result in
  historically high rainfall amounts, totaling over one foot in
  places. Significant flooding problems will intensify and
  become more widespread through Sunday.

- Severe storms with the potential for strong long-track
  tornadoes, very large hail, and damaging winds will be
  possible late this afternoon through tonight. The greatest
  potential for severe storms will be over southeast Missouri,
  and adjacent portions of west Kentucky and southern Illinois
  this evening.

- The severe weather threat will continue into Saturday, mainly
  over west Kentucky. Damaging winds, large hail, and tornadoes
  will all be possible.

- Cool/cold and mostly dry conditions are expected for the first
  half of next week.

- A few showers and thunderstorms will be  possible Wednesday
  and Thursday, as the Quad State warms back up to normal or
  above.

&&

.DISCUSSION...
Issued at 357 AM CDT Fri Apr 4 2025

After 2 days of severe storms and/or heavy rainfall/flooding,
the culminating event of this extended active period is about
here. Tonight will see the severe storm and flash flooding risks
climb to extreme levels. A moderate risk of severe storms with
a 15% chance of strong tornadoes is in place over southern
portions of southeast Missouri mainly for this evening into the
early overnight hours. An enhanced risk extends into the
Purchase Area of Kentucky and into much of southern Illinois.
These areas have a 10% chance of strong tornadoes. In addition,
very large hail in excess of 2" in diameter will be possible in
those enhanced and moderate risk areas. Elsewhere all manner of
severe weather will also be possible, but it is not expected to
be as intense or widespread.

The cold front will lift northwest across the area this
afternoon and evening, and that will push the focus for heavy
rainfall to our northwest border regions by the end of the day.
It does not look like there will be much of a cap, so some
showers and storms will still be possible in the warm sector
this afternoon into the evening. Given the expected moderate to
strong instability south of the front, severe storms with all
manner of severe threats will be possible.

Around 00Z, a 55-60kt low-level jet is expected to overspread
southeast Missouri where the front is expected to be. Very moist
and unstable air is expected, resulting in at least moderate
surface-based instability. The increased low-level shear
resulting from the low-level jet will create an environment
supportive of supercells with a high end tornado and hail
threat. This activity will spread northeast along the front into
southern Illinois and possibly far west Kentucky through the
evening.

Widespread showers and storms will gradually shift southeast
across the Quad State overnight into Saturday morning. Some
modest severe threat will continue along the leading edge of the
convection, although the environment overnight into Saturday
will not be supportive of higher-end severe storms. The severe
threat could intensify Saturday if there is sufficient warming
ahead of the convection. There is considerable uncertainty in
how fast the convection will push the active frontal/outflow
boundary south of the Quad State, but once it does, the severe
threat will finally come to an end.

No changes were made to the Flood Watch this morning.
Significant flooding has been reported in Clinton and Mayfield
Kentucky overnight, and that is likely to extend farther east
across west Kentucky early this morning. The flash flood
situation will likely worsen as convection continues to stream
over those areas this morning. As the front lifts north of those
areas, the more widespread convection and heavy rain should
shift north and bring a much needed break for waters to attempt
to recede this afternoon.

The focus for heavy rainfall will shift to far northwest
portions of the region this afternoon and early this evening.
These areas have not received "much" rainfall, generally 2
inches or less since Wednesday, so hopefully, they will be able
to handle it with only relatively minor flooding impacts this
afternoon. However, as storms intensify in these areas this
evening and then shift back slowly to the southeast through the
overnight hours, the flash flooding threat will be maximized,
especially where the heaviest rains have fallen in west
Kentucky. Even after the front/outflow boundary passes south of
the area, widespread moderate to heavy rainfall will continue
through Saturday and Saturday night before ending from the west
early Sunday.

Rainfall amounts since Wednesday range from around 2 inches to
over 8 inches, and another 4 to 8 inches is forecast through
early Sunday. Some locations in west Kentucky are likely to see
12-15 inches of rainfall before it is all done. Catastrophic
flash flooding of homes and businesses is likely to develop.
Bridges and culverts could be washed out impacting travel for
the long haul. Some light showers could linger through Sunday
as the upper trough moves by, but the impactful rains should be
done by Sunday morning.

A clipper system will swing through the Great Lakes Monday and
that could bring a few showers to the Evansville Tri State
Monday afternoon. The associated cold front will bring much
cooler air to the region for Monday night through Tuesday night.
Well below normal temperatures are forecast, and portions of the
region could see a light freeze for a few hours early Monday and
Tuesday. A couple of disturbances in northwest flow aloft could
induce some warm advection forcing and result in a chance of
showers and a few thunderstorms Wednesday through next Friday.
Temperatures will climb back to normal Wednesday and then above
normal for Thursday and Friday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 645 AM CDT Fri Apr 4 2025

IFR and lower ceilings will be the rule through much of the day.
Some improvement, even to VFR, will be possible as a warm front
lifts north through the region. Widespread showers and
thunderstorms will precede the warm front, with more isolated
convection south of it. Showers and thunderstorms are expected
to push back south and east across the region tonight along with
a return to lower conditions.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch through Sunday morning for ILZ075>078-080>094.
MO...Flood Watch through Sunday morning for MOZ076-086-087-100-
     107>112-114.
IN...Flood Watch through Sunday morning for INZ081-082-085>088.
KY...Flood Watch through Sunday morning for KYZ001>022.

&&

$$

DISCUSSION...DRS
AVIATION...DRS