FOUS30 KWBC 150719
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EDT Wed Oct 15 2025

Day 1
Valid 12Z Wed Oct 15 2025 - 12Z Thu Oct 16 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
COLORADO AND NORTHERN NEW MEXICO...

A large mid/upper wave centered across Nevada at 12Z Wednesday will
migrate eastward during the forecast period, spreading height falls
across the central and southern Rockies. As this occurs, cooling
aloft and surface heating will foster development of a few showers
and thunderstorms across southern Colorado and northern New Mexico
especially during the afternoon and evening hours. Point forecast
soundings across the region depict fast storm motions (30-50 
knots) with any developing convection, although steep lapse rates 
aloft and 0.5-0.75 inch PW both suggest potential for brief heavy
rainfall especially where any backbuilding can materialize. Wet
antecedent conditions and very high streamflows (per the USGS Water
Dashboard) are suggestive of ground conditions that are readily
supportive of excessive runoff due to poor drainage. Additionally,
a few burn scars across the region could support local excessive
runoff at times. Areas of 1-2 inch rainfall totals are possible -
especially in upslope and terrain-favored areas. Isolated flash
flooding is possible in this regime.

Cook


Day 2
Valid 12Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG MUCH OF THE
MONTANA/NORTH DAKOTA BORDER...

Strengthening mid-latitude cyclone will traverse the Northern High
Plains by Thursday afternoon and beyond with a developing closed
mid-level vorticity center propagating over eastern MT to the MT/ND
border. The subsequent evolution will lead to a period of moderate
to heavy rainfall across the above areas with a prominent
deformation axis anticipated to setup along the MT/ND border. At
this juncture, instability will be lacking from a thermodynamic
sense, however the dynamical forcing and prolonged period of
enhancement with the axis of deformation will likely spur a
widespread area of moderate to heavy rainfall capable of low-end
flash flood concerns. These concerns will be suited mainly over 
those urbanized zones and any low-water crossing. Totals area
expected to be a widespread 1-2" of rainfall with some localized
totals >2", likely over western and northwestern ND as the heaviest
rain will hang on there given the proxy of the surface low
progression and positioning of the axis of deformation. A MRGL risk
was maintained with a small expansion south to account for the
latest QPF trends. 

Kleebauer


Day 3
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

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

Kleebauer
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