FOUS30 KWBC 021518
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1018 AM EST Sun Nov 2 2025

Day 1
Valid 12Z Sun Nov 02 2025 - 12Z Mon Nov 03 2025

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

Several model solutions are fairly aggressive in depicting heavy
rainfall along coastal areas of North Carolina tonight into early
tomorrow (Monday). Cooling aloft (from eastward movement of a deep
mid/upper trough currently over Middle Tennessee) and
warming/moistening (from advection over the Gulf Stream) may 
result in enough surface-based instability for deep convection 
along coastal areas and the Outer Banks. Concerns about the 
magnitude of instability and sensitivity of ground conditions (with
marshy ground areas and only modest streamflow signals via USGS 
Water Dashboard) lend considerable doubt regarding inland flash 
flood potential. A small Marginal area might be needed in later 
and/or special outlook updates if inland convective signals become 
more pronounced later this evening.

Cook/Churchill


Day 2
Valid 12Z Mon Nov 03 2025 - 12Z Tue Nov 04 2025

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

Churchill


Day 3
Valid 12Z Tue Nov 04 2025 - 12Z Wed Nov 05 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHWESTERN CALIFORNIA AND FAR SOUTHWESTERN OREGON...

The next strong landfalling atmospheric river (IVT > 750 kg/ms)
looks to impact coastal portions of northern CA/far southwestern OR
come Tuesday afternoon, likely peaking in strength in the evening
to overnight period. Initial low-level flow earlier in the day
looks more ideally directed perpendicular to the coast/mountains,
but by the time higher IVT sets in veering to the SW-SSW may
mitigate the effectiveness of the topographic lift (with otherwise
limited instability as MUCAPE of less than 250 J/kg is forecast).
Even still, this is a relatively warm system (with the cold core
staying offshore until beyond Day 3) and PWATs of 1.2-1.4" are in
the vicinity of the 90th percentile climatologically. Rainfall 
totals of 2-4" are generally expected (and may locally exceed 4",
and much of that could occur in a 6-12 hour period. The inherited
Marginal Risk is sufficient (in-line with the latest GEFS-driven
machine learning first guess field) and has been maintained (with
only minor adjustments based on the latest models QPF footprint).
Any flash flood impacts are most likely where relatively high
rainfall rates (0.25"+/hr) coincide with sensitive burn scars. 

Churchill
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