FOUS30 KWBC 150800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Sat Feb 15 2025

Day 1
Valid 12Z Sat Feb 15 2025 - 12Z Sun Feb 16 2025

...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE
LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS...

Confidence remains high that repeating rounds of heavy rainfall
will produce very heavy accumulations, resulting in numerous to
widespread flash flooding across portions of the lower Mississippi,
Ohio, and Tennessee Valleys today into the overnight. The greatest
threat for life-threatening flash flooding remains centered over
parts of western Tennessee and Kentucky.

The 00Z models showed a slight southern shift, but overall remained
consistent, indicating widespread amounts of 3-6 inches extending
from northeastern Arkansas to eastern Kentucky, with locally
heavier amounts, especially across portions of western Tennessee
and Kentucky.

Increasing southwesterly flow ahead of an amplifying shortwave
trough moving across the southern Plains will support an
environment anomalous for mid-February, with PWs climbing to
around 1.5 inches along a 60+ kt low level jet extending across the
lower Mississippi Valley into the Tennessee and Ohio valleys. This
strong jet aligned nearly along a slow-moving front, extending
east from the Mississippi through the Ohio Valley, will support
training, redeveloping storms along the boundary beginning later
this morning. Storms will continue to train through the afternoon,
with some intensification expected during the late
afternoon/evening ahead of a low moving into Arkansas, which is
forecast deepen in response to the sharpening mid-level shortwave
and increasing divergence along the right-entrance region of the
upper jet. These storms are expected to train across western
Tennessee and Kentucky ahead of the advancing low, adding
additional heavy amounts to the region. Guidance shows a convective
line beginning advance steadily east during the overnight, but not
before several inches of rain will have likely fallen across parts
of the region.

Given the model consistency and the likelihood for heavy, highly-
impactful amounts, a High Risk was maintained across portions of
western Tennessee and Kentucky and into the far southeastern
extent of Missouri and northeastern Arkansas. A slight southern
adjustment was made to the area, reflecting a small shift in the
model QPF and where the HREF shows the highest neighborhood
probabilities for 5 inches or more. But overall, the area remains
similar to the previous Day 2. A similar southward adjustment was
made to the Moderate Risk as well. Further to the south, trimmed
back the Slight Risk east of Louisiana into the Southeast, where
guidance indicates the progressive nature of the convection
developing across the region tonight will help limit amounts and
the potential for widespread flash flooding.

Pereira


Day 2
Valid 12Z Sun Feb 16 2025 - 12Z Mon Feb 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN PORTIONS OF THE MID-ATLANTIC...

A Marginal Risk was maintained across portions of the Mid-Atlantic,
mainly as a reflection of the potential for brief, heavy rains
advancing along the cold front moving across the region early in
the period. While these storms are expected to be progressive,
with widespread additional heavy totals not expected, moist soils
further saturated by rain in the previous period may encourage
isolated flash flooding responses, especially across portions of
southwestern to central Virginia.

Pereira

Day 3
Valid 12Z Mon Feb 17 2025 - 12Z Tue Feb 18 2025

The probability of rainfall exceeding flash flood guidance is less
than five percent.

Pereira
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