Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
239 PM EDT Sun Jun 1 2025
Day 3
Valid 12Z Tue Jun 03 2025 - 12Z Wed Jun 04 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PARTS OF THE
CENTRAL UNITED STATES AND OVER SOUTH FLORIDA...

...Texas to the Great Lakes...
The cold front pushing southeast across the central CONUS Tuesday
may become more progressive as the Baja low from Sunday gets even
more sheared into the westerlies, producing a more amplified trough
axis pivoting east into the Plains. Embedded within this flow,
multiple vorticity maxima will rotate E/NE, leading to additionally
enhanced lift, aided significantly the latter half of D3 by
diffluence within the RRQ of a poleward arcing jet streak
downstream of the trough axis. This will result in expansive and
impressive deep layer ascent from the Southern Plains through the
Great Lakes, with return flow out of the Gulf on 30-50 kts at 850mb
drawing impressive thermodynamics northward into the front. This
suggests that convection will be widespread across the area
Tuesday, which is supported by both simulated reflectivity and
24-hr rainfall progs from the global models and ensembles, with
rainfall rates exceeding 1"/hr likely anywhere along the front. The
greatest risk for excessive rainfall will be from northern Texas
through eastern Iowa where deeper warm cloud depths will produce
more efficient rainfall rates, which will likely train SW to NE
along the front. The SLGT risk was tailored to match the highest
probabilities for 3"/24 hrs from the ECENS/GEFS, but some eastward
expansion of the SLGT was also drawn to account for the AI guidance
(AIFS, Graphcast) that is generally east of the deterministic
models.


...South Florida...
A meandering shortwave trough positioned over the Florida
Peninsula will be the impetus for another round of scattered to
widespread showers and thunderstorms Tuesday. With thermodynamics
remaining robust across the region (PWs 1.75 to 2 inches and MUCAPE
above 1000 J/kg), slow moving storms will again have the potential
to produce excessive rain rates above 2"/hr. While there is some
uncertainty into how much convective debris from Monday could limit
coverage, the general consensus among the various ensemble camps
is for another day of heavy rain, especially across South Florida,
where ECENS/GEFS/SREF all suggest at least a low end risk (5-10%)
for 3"/24 hrs. This will fall atop ground that will likely be
sensitive from heavy rain on D2, and the inherited SLGT and MRGL
risks were adjusted only cosmetically from previous.


Weiss

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