FOUS30 KWBC 110827
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
427 AM EDT Wed Mar 11 2026

Day 1
Valid 12Z Wed Mar 11 2026 - 12Z Thu Mar 12 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
SOUTHERN US...

As the closed low moves across the central and eastern Texas
today...an axis of training convection should persist from the
eastern part of Texas into the lower Mississippi Valley. With very
strong synoptic forcing and increasing moisture transport we 
should see convection expand in coverage and intensity over eastern
Texas by mid- to late-morning. During the development phase cell
training/backbuilding is probable over east TX, and while 
convection should grow upscale and forward propagate during the 
afternoon, some west to east training is possible near the 
southward dropping cold front. The inherited Slight risk was 
expanded off to the south and east once again to account for model
trends into parts of Mississippi and western Alabama. 

Only minor nudges were needed to the Marginal risk area across the
Ohio Valley and into western New York where rainfall rate driven 
localized flash flooding is possible. Areal averaged rainfall is 
only 0.5"-1.5", but given the 500-1000 j/kg and convective nature 
of rainfall, the possibility of localized swaths of rainfall 
exceeding 2 inches persists. This should be enough to at least 
locally exceed FFG across this region. Over western NY, snow melt 
and locally heavy rain may combine to result in areas of excessive runoff.

Chenard/Bann


Day 2 
Valid 12Z Thu Mar 12 2026 - 12Z Fri Mar 13 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE PACIFIC NORTHWEST...

Coastal Areas of Washington into Northwest Oregon...

Only change was to nudge the Marginal risk back to the west just a
bit given the placement of heavier snowfall in the Cascades. 
Despite that change...much of the shift made by the previous shift
was retained in this outlook.

On-shore flow of deep moisture into parts of coastal Washington 
and northern Oregon persists into the Day 2 period...with occasional
moderate to locally heavy rainfall continuing along the coastal 
ranges. An additional 1 to 3 inches of rainfall in 24 hours is
possible...which could result in isolated flooding ot run off 
problems in areas of poor drainage.

Bann


Day 3 
Valid 12Z Fri Mar 13 2026 - 12Z Sat Mar 14 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE PACIFIC NORTHWEST...

The on-shore flow which has been anchored along coastal portions 
of Washington and northern Oregon will finally start to shift its 
focus southward a bit from Friday into early Saturday morning. The 
axis of a precipitable water plume with values of 0.75 to 1.00 
inches will gradually be shifting southward into Oregon which 
allows precipitation rates to weaken farther north. With the rain 
moving into an area with drier antecedent condition...maintained a 
Marginal Risk area.

Bann
$$
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 * Origin: Capitol City Online (618:250/10)