Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
750 PM EDT Sun Jul 21 2024
Day 3
Valid 12Z Tue Jul 23 2024 - 12Z Wed Jul 24 2024

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF
TEXAS...

21Z Excessive Rainfall Discussion
Few changes needed to on-going EROs given latest deterministic and
ensemble runs from 12Z.

Bann

Previous Excessive Rainfall Discussion

...Southern Plains...

A repeat of heavy convection across TX is forecast as the quasi-
stationary front within deep moisture anomalies remains parked
across much of Central and Eastern TX. Latest ensemble bias
corrected QPF is signaling an additional 2-3" possible within the
I-35 corridor with some scattered heavy rain signals all the way
back into the Central RGV from Del Rio down towards Laredo. Weak
mean storm motions and rates likely pushing 2-3"/hr will allow for
more significant flooding potential over areas that will have been
hit the prior period. In fact, 48-hr QPF could top 6" in spots
within the two successive periods which would allow for significant
issues to arise if it falls across the I-35 corridor. A SLGT risk
was maintained and expanded across the western flank of the risk
area to account for trends in the ensemble QPF footprint and better
instability fields located out towards the RGV. If the previous
period ends up with more significant impacts, this could lead to an
upgrade in the forecast risk over portions of Central TX.


...Southern Rockies and Southwest...

Monsoonal convection will encompass much of the Southwest U.S with
primary coverage in the Great Basin as the mid-level ridge pattern
shifts focus to the west of the Four Corners. Modest moisture
anomalies and relatively formidable instability across much of the
region will allow for scattered thunderstorms with isolated heavy
rain cores that could spell issues if they fall along complex
terrain, burn scars, urban footprints, and slot canyons. A MRGL
risk is in effect across much of the climatologically favored
areas in the Southwestern Monsoon.

...Upper Midwest...

Shortwave trough moving through the Great Lakes will allow for the
initiation of organized convection as it pivots through the region.
Modest instability and moisture anomalies in the confines of the
Lakes will lead to some scattered heavy rain signals as the
disturbance traverses the area. The progressive nature of the
system will limit widespread flash flooding concerns, but a few
isolated heavier cores could pose some issues for more urbanized
areas across Northern and Central WI into the Michigan UP. A low-
end MRGL is in effect for the above area.

Kleebauer
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt