Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 PM EST Tue Dec 06 2022

Day 1
Valid 16Z Tue Dec 06 2022 - 12Z Wed Dec 07 2022

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

Bann




Day 2
Valid 12Z Wed Dec 07 2022 - 12Z Thu Dec 08 2022

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
EASTERN OKLAHOMA INTO NORTHERN ARKANSAS AND SOUTHERN MISSOURI...

...North Texas and Eastern Oklahoma eastward into the western
Tennessee Valley...
Models still suggest the potential for locally heavy to excessive
rainfall from eastern Oklahoma into northern Arkansas and southern
Missouri on Wednesday as a southern stream trough pivots across
the Southwest U.S. on Wednesday and across the High Plains
Wednesday night.  As this occurs, the downstream upper level
ridging underneath the broad/deep low centered over north-central
Canada will result in upper level confluence and an eventual jet
streak across the Central Plains and Upper Midwest on Day 2.
Increasing southern-stream forcing coupled with the frontogenetic,
entrance-region upper jet forcing from the northern stream will
make for a favorable environment for deep layer lift across the
outlook areas. Both the GEFS and SREF showed a relatively quick
bout of robust low-mid layer moisture transport, with 8500-700 mb
moisture flux anomalies topping out between +3-3.5. PW values and
a stripe of 1.5-1.7" PWs traversing the outlook areas Wednesday
and Wednesday night.

The progressive nature of the favorable forcing
(forward-propagating Corfidi or MBE vectors), along with the
relative lack of deep-layer instability (MUCAPEs generally less
than 750 J/Kg) will be the primary inhibitors to the flash flood
risk. In addition, per the latest NASA SPoRT analysis, 0-100cm
soil moisture percentiles are running between 10-30% of normal
across much of the outlook area. Nevertheless, per earlier
collaboration with WFOs in the Plains and given the anomalous
degree of deep-layer forcing and moisture, consistent with the 00Z
and 12Z GEFS-based first-guess fields, maintained the targeted
Slight Risk area and surrounding Marginal Risk areas with few
changes.

Hurley/Bann


Day 3
Valid 12Z Thu Dec 08 2022 - 12Z Fri Dec 09 2022

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

Bann




Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt