Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
757 PM EST Sun Nov 8 2026
Day 2
Valid 12Z Mon Nov 09 2026 - 12Z Tue Nov 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTH TEXAS...

...20Z Update...

Forecast thinking generally remains the same for the Day 2/Monday
ERO, featuring a gradual decline in convection after 18Z as
instability wanes. Prior to 18Z, showers and storms are still
likely to contain heavy rainfall rates, which could lead to flash
flooding concerns lingering from Day 1 into Day 2. The 12Z HRRR and
12Z RRFS/REFS in particular are highlighting the potential for
another focused/convergent line of convection to set up along and
just inland of the Gulf Coast from Brownsville to Corpus Christi
Monday morning, with 2-4"+ of additional rainfall on top of what
has already fallen (and will fall through the remainder of Day 1).
Given the recent positive performance of the HRRR, this scenario is
plausible and would certainly justify a small targeted upgrade to
a SLGT risk. However, in coordination with WFO BRO, opted to hold
off on an upgrade pending additional observational and guidance
trends heading into this evening and overnight. Otherwise, the
existing MRGL risk was largely left unchanged aside from minor
adjustments to fit the latest guidance.

Miller

...Previous Discussion...

Expectation is for the setup to begin slowly breaking down on
Monday with the mid and upper level pattern transitioning from less
of a closed reflection to a more positively tilted upper trough
positioned over the Southern Plains. The low-level flow will remain
more east to northeast across all of South Texas leading to a small
area of convergence within proximity to a decaying surface trough
positioned over the region. Models are consistent in their
interpretation of lingering rainfall for areas south and southeast
of I-10 with the best threat likely over the interior areas to the
west and northwest of Corpus Christi, down through the far South
Texas coastal plain. Models are typically within the range of an
additional 0.5-1" on average with locally higher totals possible in
a narrow corridor along the decaying surface trough. That said,
there's a few ensemble members from the REFS suite, as well as the
HRRR that are more bullish with local totals pushing 2-4"
additional, on top of what will already be a very saturated ground
after what transpires on D1. It's something we'll monitor closely
as this would prompt a short term upgrade until the threat fully
wanes after 18z Monday, an agreement from all models with a sharp
decline in FFG exceedance probabilities for all 1/3/6 hour
thresholds. The previous MRGL risk was maintained as a result, but
will assess in the coming forecast updates to see if a targeted
upgrade is necessary for that area just inland of the South TX
coast.

Kleebauer


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt