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Day 2 Outlook >
WPC Day 1 Excessive Rainfall Outlook Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 0046 UTC Wed Feb 19, 2025
Valid: 01 UTC Feb 19, 2025 - 12 UTC Feb 19, 2025
Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
757 PM EST Tue Feb 18 2025
Day 1
Valid 01Z Wed Feb 19 2025 - 12Z Wed Feb 19 2025
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF
THE WESTERN AND CENTRAL GULF COAST...
...01Z Outlook Update...
Made minor tweaks to the Day 1 Marginal Risk area, based on the
current mesoanalysis and latest trends in the high res guidance.
Based on the instability trends from the current mesoanalysis and
latest RAP output, along with the 18Z HREF exceedance
probabilities (including >1"/hr rainfall rates), have trimmed the
western and northwestern areas a bit across portions of eastern TX
and western-northern LA. Thermodynamic parameters and more intense rainfall
rates this evening and overnight will favor an isolated risk for
flash flooding from the Upper TX Coast eastward through southern LA
(southern half), southern MS, and southern AL.
Hurley
...Discussion...
Strengthening southwesterly return flow from the Gulf ahead of an
amplifying upper-level shortwave and an associated surface cold
front are expected to draw deeper moisture into portions of the
central Gulf Coast with PWs climbing to 1.5"+. This moisture,
along with increasing lift (via right-entrance region of 120+ kt
subtropical jet streak) and marginal instability (MU CAPE rising to
near 500 J/kg right along the immediate coast) are likely to be
sufficient for a relatively short period of heavy rainfall rates
(concentrated between 00-09z, and lasting for around 3 hours total
at any one locality). While the potential for training storms looks
relatively low (with instability largely lacking prior to the
arrival of the progressive storms along the front), chances for any
isolated flash flooding appear maximized in the vicinity of Lake
Charles (with the best instability resulting in highest odds for
1-2"/hr rainfall rates, and localized totals of 2-4" over a 3-hr
period). Elsewhere (and particularly farther north from the
immediate coastline) rates will likely struggle to surpass 1"/hr
with a lack of instability, though in some places these brief
downpours may be enough to cause localized excessive rainfall
(particularly into portions of east-central TX and west-central LA
where antecedent conditions are wetter, especially compared to
relatively dry antecedent conditions in south-central LA).
Churchill
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
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