FOUS30 KWBC 281515
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1115 AM EDT Sat Mar 28 2026

Day 1
Valid 16Z Sat Mar 28 2026 - 12Z Sun Mar 29 2026

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

...16Z Update...

No changes were needed with the blank outlook for the rest of today
and tonight. In coordination with MFL/Miami, FL forecast office,
there was agreement that the flooding threat in south Florida
remains sub-Marginal. The CAMs are in good agreement that any
convection that forms today will develop west of the urban I-95 
corridor, then track southwest across relatively rural areas around
Lake Okeechobee and into the Everglades and the Naples/Marco 
Island area. This should preclude any flooding concerns, especially
given the ongoing drought and below average soil moisture levels 
broadly across south Florida.

Wegman

...Previous Discussion...

We will keep an eye on south FL, where convection is likely this
afternoon into tonight. However, at this time the flash flood risk
looks low. Initial convective development along the east coast of
FL should move off to the southwest, limiting rainfall rate
duration. Additional development this evening into tonight near and
post frontal passage should generally stay transient in nature,
with a downward trend in CAPE also expected overnight.

The 00z HREF and REFS neighborhood probabilities of exceeding 3"
are over 50%, but generally focused over inland areas of south
FL...and 5" exceedance probabilities from the HREF are zero. For a
Marginal risk we would like to see the higher 3" probabilities
focused across the coastal urban areas and/or significantly higher
5" probabilities. Thus will continue with no risk area.

Chenard


Day 2
Valid 12Z Sun Mar 29 2026 - 12Z Mon Mar 30 2026

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

Additional showers and thunderstorms are expected across southeast
FL, with a stream of activity potentially focused near the urban
corridor. However, most model instability forecasts are below 1000
j/kg, and thus currently not expecting rainfall rates to be high
enough for flash flooding, but we will continue to monitor.

Chenard


Day 3
Valid 12Z Mon Mar 30 2026 - 12Z Tue Mar 31 2026

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

There is a non-zero risk for minor urban and small stream flooding
across portions of MI, northwest PA and western NY Monday into
Monday night. There is a notable increase in instability, with
values exceeding 1000 j/kg. This is anomalous for the time of
year, especially over portions of MI where the ECMWF EFI for CAPE
is over 0.9. Combine this CAPE with above average PWs and strong
moisture transport and we would expect there to be a potential for
heavy rainfall rates. At the moment, not really seeing enough of a
consistent model QPF signal to justify introducing a risk area, but
we will have to continue to monitor trends, especially as we move
more into the high res model timeframe.

Chenard
$$
--- SBBSecho 3.28-Linux
 * Origin: Capitol City Online (618:250/10)