FOUS30 KWBC 120808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Fri Jun 12 2026

Day 1
Valid 12Z Fri Jun 12 2026 - 12Z Sat Jun 13 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE SOUTHERN
ROCKIES THROUGH THE MID-SOUTH, MID-ATLANTIC, AND NORTHEAST AS WELL
AS FOR CENTRAL AND SOUTHWEST FLORIDA...

...South-Central States through Northeast...

An upper trough over Michigan early this morning will shift east
across the Northeast through tonight. Prefrontal activity ahead of
the associated cold front persists over Lake Erie and the lower
Ohio Valley with stronger activity over the Oklahoma/Arkansas
border early this morning. Deep moist convection develops diurnally
today ahead of the cold front east of the Mid-South and a warm
front lifting over the southern Plains. An extensive Marginal Risk
remains from the southern Rockies/Sacramento and Davis Mtns across
Texas/Oklahoma, the Mid-South/Tennessee Valley and over New
England. Some activity is still progged over the Central
Appalachians, so the Marginal Risk was maintained there, though it
is a notably low risk compared to northern New England and the
Tennessee Valley where PW anomalies are over 2 sigma (more like a
peak of 1.5 sigma in the Mid-Atlantic). Most of this activity will
be fairly progressive hence no Slight Risks at this time.

Some trimming of the north side to the Marginal Risk was made,
though timing tonight with surging Gulf moisture limits that
reduction, particularly based on the 06Z HRRR with central
Missouri activity late tonight.

...Central and Southwest Florida...
Anomalous moisture will reside over southwest and central portions
of the Florida Peninsula today, though it should be a little less
in terms of PW compared to Thursday. Convection along the sea
breezes should produce very heavy rainfall that could lead to
flooding concerns for urban areas in Central and Southwest Florida.
A Marginal Risk remains in effect with Tampa Bay removed due to CAM
consensus to the east/south of there.

Jackson
 

Day 2
Valid 12Z Sat Jun 13 2026 - 12Z Sun Jun 14 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CENTRAL PLAINS THROUGH THE MIDDLE MISSISSIPPI VALLEY INTO THE
LOWER OHIO VALLEY...

An upper trough swings down the northern Plains Saturday, pushing a
cold front across the central Plains and Midwest through Saturday
night. Meanwhile, a warm front tracks from Oklahoma through
Illinois ahead of the cold front, creating focus for strong
convergence in a very warm, moist, and unstable air mass. Resultant
heavy thunderstorms look to organize and repeat from the central
Kansas/Oklahoma border through central/southern Illinois and
western Kentucky where the Slight Risk was expanded a bit.
Particular focus for heavy rain remains near the Kansas/Missouri
border where a higher than normal Slight Risk is noted. Scattered
instances of flash flooding can be expected and a targeted Moderate
Risk is possible.

More isolated heavy thunderstorms are also expected over the
eastern New Mexico and west Texas terrain and nearby plains where
the Marginal Risk remains.

The Marginal Risk was removed from most of Michigan based on the
00Z high-res solutions available with little PW anomaly noted.

Jackson
 

Day 3
Valid 12Z Sun Jun 14 2026 - 12Z Mon Jun 15 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
TEXAS AND THE LOWER MISSISSIPPI VALLEY...

...Southern Rockies, Texas to Southeast...

A cold front pushes down the Southern Plains into Texas on Sunday.
This shunts the heavy rain focus south of Saturday and provides a
strong focus for convective development in a rich Gulf-sourced
moisture environment. PW anomalies are 2 to 3 sigma above normal
across Texas (south of the Panhandle) by that afternoon with 2
sigma anomalies expanding east to Alabama by late Sunday night.
Expansion of the Slight Risk to both North Texas and the Houston
metro areas are warranted given the environment as well as the 00Z
consensus of the UKMET and EC-AIFS for the Houston area, and the
RRFS and RDPS for North Texas. Furthermore, a decent signal for
lasting thunderstorm development is over West Texas in the Permian
Basin into the Concho Valley, so a Slight Risk was raised there as well.

Additional terrain driven diurnal activity is expected over the
Southern Rockies/Sacramento and Davis Mtns. This activity should
spread southeast through the evening, so the Marginal Risk was
expanded over the southern High Plains.

A surge of moisture up the southern Appalachians Sunday morning
brings enough of a heavy rain threat for a Marginal Risk expansion
up to the westernmost section of Virgina.

...Hampton Roads and Delmarva...
Southwesterly low level flow from the Carolinas bring 2" PW to the
Mid- Atlantic coast Sunday afternoon ahead of a cold frontal
passage that night. Evening thunderstorms should be heavy and slow
enough to warrant a Marginal Risk.

Jackson
 

Day 4 and Day 5

Valid 12Z Mon Jun 15 2026 - 12Z Wed Jun 17 2026

...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND THE SOUTHEAST...

Overall, not much change from the previous forecast, with the
overnight guidance continuing to present a good signal for highly-
efficient training storms along a slow-moving front settling into the region.

Models continue to show a cold front settling slowly south though
the southern Plains, lower Mississippi Valley, and the Southeast as
shortwave energy gradually amplifies a broad upper trough centered
along the Mississippi Valley on Monday. A deepening pool of
moisture along the front, fed by southerly low level inflow from
the western Gulf, will fuel the potential for highly-efficient
showers and storms. Guidance continues to show PWs increasing to
2.25 inches (2.5 to 3 std dev above normal) along and ahead the
front from south South Texas to southern Alabama on Monday.
Interacting with this moisture is expected to be an area of
enhanced ascent provided by right-entrance region upper jet forcing
positioned along the base of the amplifying trough. In addition to
the deep moisture and large-scale ascent, repeating storms are
expected to raise the potential for heavy amounts and flash
flooding concerns. A Slight Risk was maintained from southeastern
Texas to central and southern Alabama on Day 4.
By Tuesday, the upper trough axis begins to shift to the east,
pushing the front, deeper moisture, and the better chance for heavy
rain farther south and east along the Gulf Coast. For Day 5, a
Slight Risk was drawn from southeatern Lousiana to southwestern Georgia.

While Slight Risks were drawn for both periods, given the potential
for several inches of rain in some locations, an upgrade to a
Moderate Risk may be required in future updates if the signal
persists as the event draws nearer.

Pereira
$$
--- SBBSecho 3.28-Linux
 * Origin: Capitol City Online (618:250/10)