Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jan 16 2024 08:27:33

FOUS30 KWBC 160827
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
326 AM EST Tue Jan 16 2024

Day 1
Valid 12Z Tue Jan 16 2024 - 12Z Wed Jan 17 2024

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

Chenard


Day 2
Valid 12Z Wed Jan 17 2024 - 12Z Thu Jan 18 2024

....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
FAR NORTHWEST CALIFORNIA INTO SOUTHWEST OREGON...

We opted to introduce a small Marginal risk across portions of far
northwest CA and southwest OR with this update. A strong mid level
shortwave will move across western OR between 06z-12z Wednesday
which will result in an uptick in rainfall intensity. After 12z
onshore upslope flow will continue to be directed into this region
to the south of a surface low expected to be positioned off the WA
coast. This is not the strongest core of IVT, but it is persistent
enough to result in up to a 12 hr period where 0.25"-0.5" rainfall
will be possible within the favorable western facing terrain. The
consensus of current guidance would suggest 09z-21z Wed as the
most favored time for these heaver rainfall rates. The 18z
experimental RRFS ensemble supports 20-50% chance of 0.5"/hr
rainfall during that window, with the 00z ECMWF depicting 1"/3hr
rainfall. There remains some model spread with regards to the axis
and magnitude of heaviest rainfall amounts. The GFS remains a bit
lighter, but the 00z ECMWF/NAM/UKMET/HRRR all support some heavier
totals into this region. There are several pieces of guidance that
suggest 2 day rainfall amounts upwards of 4-7" over this area,
which may begin to cause some mainly minor runoff concerns.

Chenard

Day 3

The Day 3 outlook will be updated by 0830Z.


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!7RWI3UCLFtHz3f9_qBlTK1bloAkfHJKAA3MPETy2s8Uk=
MWCj0yos9z0k84GRbTFlsnD6LqveeYzhYjmoxzliXwRkUT8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!7RWI3UCLFtHz3f9_qBlTK1bloAkfHJKAA3MPETy2s8Uk=
MWCj0yos9z0k84GRbTFlsnD6LqveeYzhYjmoxzliGcsBPP4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!7RWI3UCLFtHz3f9_qBlTK1bloAkfHJKAA3MPETy2s8Uk=
MWCj0yos9z0k84GRbTFlsnD6LqveeYzhYjmoxzliqTyNy-0$=20


$$



=3D =3D =3D
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