Quantitative Precipitation Forecast
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FOUS30 KWBC 171459

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1058 AM EDT Sat Mar 17 2018

VALID 15Z Sat Mar 17 2018 - 12Z Sun Mar 18 2018

20 SW LHB GRK 15 SSW SEP 20 SE MWL 10 SE RBD 15 SW 3T1
35 SSW SHV 30 N JAS 25 SE LFK 15 NE CLL 20 SW LHB.

1500 UTC update

Changes to the previous excessive rainfall potential outlook were
to add a marginal risk area over northeast portions of TX to cover
the spread in the latest hi res guidance for potentially locally
heavy rainfall amounts.  As mentioned in the previous discussion
below---believe convection that does form late this afternoon
ahead of southern stream shortwave energy moving into central TX
will be progressive.  However---hourly rainfall from the hi res
guidance---including the latest hrrr runs is showing hourly
amounts in the 1-2+" range with totals for this period over 3" in
the NAM conest and hrrr exp .  There is some spread in the
latitude of the heaviest potential---leading to low confidence in
detail placement---but we do favor the overall farther southward
solutions of the hi res guidance with respect to where any
potential runoff issues may occur.


Initial discussion

...Discussion for Texas...

Scattered strong thunderstorms are expected in central and
northeast Texas this afternoon/evening (see Storm Prediction
Center Day 1 Convective Outlook). Given the season and the hi-res
model signal, as well as the marginal precipitable water
environment, this event will likely include severe storm modes,
relatively quick cell motions, and a progressive mid level
shortwave which should prove detrimental to residence time of
heavy rain over any given spot. Very local cell mergers or
training along outflows could yield a low-end flash flood threat,
but not enough to raise the neighborhood probability of excessive
rainfall to 5 percent.



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