FOUS30 KWBC 142326 CCA
QPFERD

Excessive Rainfall Discussion...CORRECTED
NWS Weather Prediction Center College Park MD
726 PM EDT Tue Apr 14 2026

Day 1
Valid 16Z Tue Apr 14 2026 - 12Z Wed Apr 15 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS THE CENTRAL
L.P. OF MICHIGAN,SOUTHEAST WISCONSIN, AND THE OHIO VALLEY...

... Ohio Valley...

16Z Update: The Slight Risk for Excessive Rainfall was expanded
farther south to include central Illinois to central Indiana.Radar
and surface observations show an outflow boundary lingering across
the region from early morning showers and thunderstorms that may be
a focal point for locally heavy rainfall this afternoon and
evening. The RRFS and ARW model camps in particular are
highlighting this region with QPF maxima in the 2-5 inch range.
High seasonable PWATS and abundant instability also support the
potential for high hourly rainfall rates.

...Wisconsin and Michigan...

16z Update:

The forecast continues to support the risk for flash
flooding as storms are expected to form along a stationary boundary
over Wisconsin and then congeal into a line of storms that
progresses southeastward into Michigan. The low level jet will
transport moisture orthogonal to a stationary boundary across the
region with the training of storms possible. Most of the area
remains at near or above record spring rainfall and soils are
fairly saturated. Cells capable of 1.5-2"/hr rates and localized
totals of 2-3+" suggest the placement of a Slight Risk of Excessive
Rainfall from southern Wisconsin to eastern Michigan.

...Previous Discussion...

A Slight Risk for excessive rainfall remains
in effect for portions of the Great Lakes region. A
shortwave/vorticity center lifting out over the mean ridge in the
Great Lakes region will drive stronger confluence of the low level
jet across Iowa to trigger another round of strong to severe
thunderstorms Tuesday evening. Overall deep layer steering flow and
fairly orthogonal ascent over boundary should help to focus a
similar west to east (WNW to ENE) oriented axis of training
thunderstorms. Upper-level dual jet couplet will further enhance
up-scale growth to a broader complex to maintain through the
overnight period. Most of the area remains at near or above record
spring rainfall and soils are fairly saturated, so with cells
capable of 1.5-2"/hr rates and localized totals of 2-3+" suggest
the placement of a Slight Risk of Excessive Rainfall across
portions of eastern WI and central MI (along and north of I-94).

... Lower Trans-Pecos/Big Bend...

16 Update:

Latest model guidance indicates a higher QPF maxima across the
Lower Trans-Pecos region into the Big Bend as storms fire along the
dry line in presence of a seasonally moist environment. HREF 24
hour QPF neighborhood probabilities are around 50-70% for 2 inches
and 10-20% probabilities for 3 hour QPF exceeding flash flood
guidance. A Marginal Risk was maintained, but this area will be a
focus for locally heavy rainfall.

...Oklahoma and Kansas...

16z Update: Another targeted area for heavy rainfall will be span
south of the Norman area, northeastward into the Tulsa metro and
southern Kansas. Hi-res guidance indicates multiple rounds of
storms could traverse this region as storms fire along the dry line
boundary and south of a stationary front in Kansas. HREF 24 hour
QPF probabilities exceeding 2 inches are fairly high (50-70%) and
20-40% for exceeding 3 inches.

...Previous Discussion...
A steady stream of PW values of 1.25 to
1.5 inches will be advecting northward through the Southern/Central
Plains nearly parallel to the dryline. This will be conducive for
slow storm motion with locally heavy rainfall. Consensus suggests 3
to 4 inches possible within the isolated cells. The Marginal Risk
area is connected to the area of concern over the Great Lakes and
just note the coverage will decrease northward along the dry-line.

Campbell/Wilder


Day 2=20
Valid 12Z Wed Apr 15 2026 - 12Z Thu Apr 16 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR THE GREAT
LAKES AND NORTHERN OHIO VALLEY..

The surface to mid-level environment remains very similar to the
past couple of days with a stark dry line extending from the Pecos
River Valley across the Southern Plains into the Upper Mississippi
Valley. A stationary front will continue to align west to east=20
from Illinois to New York and serve as a mechanism for heavy=20
rainfall potential. The longwave trough will finally be making=20
progress toward the Central Plains and the deep layer moisture axis
and instability shifts slightly eastward.

An upgrade to a Slight Risk for Excessive Rainfall was added across
southern Wisconsin and Michigan. Across the northern Ohio Valley,
northern Illinois, Indiana, and Ohio were included in the risk
area. A persistence forecast worked well here where instability,
plentiful moisture near the surface (PWATS near or exceeding 1.5=20
inches), and a nearby stationary boundary and weak area of low
pressure will help create an environment capable of producing heavy
rainfall. WPC QPF indicates 1-3 inches of rain over the same=20
regions that have have seen rounds of heavy rainfall over the past
couple of days. The flash flood guidance, meanwhile, has lowered to
a half an inch to an inch. Another consideration was the flash
flood sensitivity for urban areas such as Milwaukee, Chicago, and
Detroit. The Slight Risk does extend southward across northern Illinois
and Indiana to account for uncertainty on storm track and the
spread of 2 inch HREF 24 hr QPF neighborhood probability.=20

...Eastern Oklahoma and the Ozarks...

Similar to the past couple of days, afternoon storms are likely to
form and trek from the southwest to northeast ahead of the=20
longwave trough moving into the Central Plains. Eastern Oklahoma
into the Ozarks will be in the right entrance of the jet streak,
which will help provide lift. At the surface, high PWATS and
surface instability will once again prime the atmosphere for hourly
rainfall rates of an inch/hr. QPF guidance does show a maximum of
1-2 inches across the region, but model guidance shows little to=20
no probability for accumulations exceeding 2 inches. Therefore, a=20
Marginal Risk is maintained for the risk area. Additionally, the=20
more flash flood prone Ozark mountain range is relatively dry.=20

...Northeast...

A Marginal Risk for Excessive Rainfall was expanded eastward across
New York State to Connecticut. Moisture transport will increase=20
across the east as the longwave trough shifts eastward into the=20
center of the country. Additionally, weak areas of low pressure=20
will ride along a stationary boundary across the Northeast that=20
will help funnel moisture across the area. Remnants of the storms=20
across the Great Lakes may bring a round of showers and storms in=20
the morning, followed by another round of heavier showers and=20
thunderstorms in the afternoon. Model guidance shows a corridor of
1-1.5 inches rainfall with embedded higher amounts depending on the
model. The relatively lower flash guidance across western=20
Pennsylvania and the more urban footprint of areas such as=20
Connecticut and New England also help confidence of expanding the=20
Marginal eastward.=20

Wilder

Day 3
Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026

The probability of rainfall exceeding flash flooding guidance is
less than 5 percent.

Wilder

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6qXprxWInP10H82QZ3A_xooVfjJN2HoH071NgRtdUcSx= r4T3NS7mDIMxk1Az7UvSBFBrZeFZcKQQtvc0YkOag5imW-s$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6qXprxWInP10H82QZ3A_xooVfjJN2HoH071NgRtdUcSx= r4T3NS7mDIMxk1Az7UvSBFBrZeFZcKQQtvc0YkOaQuV7rU8$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6qXprxWInP10H82QZ3A_xooVfjJN2HoH071NgRtdUcSx= r4T3NS7mDIMxk1Az7UvSBFBrZeFZcKQQtvc0YkOacvSSPBM$=20

=3D =3D =3D
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