< Day 2 Outlook
WPC Day 3 Excessive Rainfall Outlook
Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 2006 UTC Mon Oct 22, 2018
Valid: 12 UTC Oct 24, 2018 - 12 UTC Oct 25, 2018
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
410 PM EDT Mon Oct 22 2018
Valid 12Z Wed Oct 24 2018 - 12Z Thu Oct 25 2018
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...
...Southern Plains into the Lower Mississippi Valley...
Synoptic scale lift ahead of long wave troughing tracking from the
Southwest on Day 2 to the Southern Plains on Day 3, combined with
moisture from the remnants of Willa, will pose a threat for heavy
rainfall and possible flash flooding. The anomalous moisture
(around 2 standard deviations above normal) and lift should focus
along an elevated frontal boundary extending from central Texas
into central Louisiana, but the limiting factor here again is
instability which appears to be better south of the boundary near
the coast. Nonetheless, there is model signal for potentially
higher QPF (around 2+ inches) so a localized flash flood threat
cannot be ruled out.
A second area for potentially excessive QPF lies along or just off
the northern Texas Gulf Coast and the Louisiana coast as tropical
moisture and instability interacts with a developing surface low
and quasi-stationary frontal boundary across the northern Gulf.
Much of the guidance continues to keep the heaviest rainfall just
offshore, but small changes in subsequent runs in the placement of
the heavy rainfall axis could place portions of the Texas and
Louisiana coasts at a greater risk for flash flooding than
Given this assessment, a large marginal risk was maintained on the
Day 3 excessive rainfall graphic (valid 12z 10/24 to 12z 10/25)
across central and eastern Texas into much of Louisiana. The only
change from the previous shift was to trim deep south texas out of
the marginal given that the better heavy rainfall threat should be
north and east of this region.
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt