From Mike Powell@618:250/1 to All on Sun Apr 6 09:22:00 2025
FOUS30 KWBC 060825
QPFERD
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Sun Apr 6 2025
Day 1
Valid 12Z Sun Apr 06 2025 - 12Z Mon Apr 07 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN UNITED STATES...
Introduced a Moderate risk mainly across central and parts of
southwest Alabama today. Even though the synoptic-scale forcing
has finally dislodged the focus mechanism for heavy
rainfall...expectation is for storms initially in Mississippi and
far northern Alabama at the start of the period to slow in forward
motion as they pushes across parts of Alabama later today...leading
to some 3 to 5 inch totals with isolated higher totals. Confidence
in these amounts was boosted as more high- resolution CAMS in the
06/00Z model production cycle continued to depict focused, training
bands of convection from central Alabama with a few of them
showing localized amounts exceeding 6-8 inches. Of note was that
the 06/00Z guidance tended to favor higher amounts extending
southward rather than northeastward toward Georgia. The 00Z HREF
neighborhood probabilities tended to show a risk of 1 inch and 2
inch per hour rates at the start of the outlook period gradually
slow down later this morning with occasional upticks/downturns in
the probabilities across into the afternoon. This is still
conditional on when/where cloud cover allows for best instability
to form and on any lingering convective outflows that can serve as
a focus for renewed convection.
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHEAST US ON MONDAY...
Overall...the ongoing forecast remained on track and only some
minor adjustments were needed to account for a few pieces of
guidance which still favored a slower solution and, consequently,
higher rainfall amounts over a somewhat larger territory than in
the previous outlook. Still think that any lingering moderate to
heavy rainfall will continue to shift eastward on Monday as the
large scale flow pattern remains progressive. Current model QPF
generally remained in the 1.5 inch to 2.5 inch range with isolated
higher totals possible from far northern Florida northward into
the eastern portions of the Carolinas. The plume of 1.75+ inch
precipitable water values slowly decreases with time before being
shunted entirely off the Carolina coast Monday evening (and across
the central Florida peninsula late Monday night/early Tuesday
morning. Until that happens...moisture transport of deeper moisture
remains favorable to support a low- end risk of excessive rainfall
(especially in regions of poor drainage),