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WPC Met Watch

 
Mesoscale Precipitation Discussion: #0022
(Issued at 1112 AM EST Tue Jan 14 2020 )

MPD Selection
 


Graphic for MPD #0022

Mesoscale Precipitation Discussion 0022
NWS Weather Prediction Center College Park MD
1112 AM EST Tue Jan 14 2020

Areas affected...Central/Northeast LA...Southwest/Central MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 141610Z - 142200Z

SUMMARY...Additional heavy rainfall is expected going through the
afternoon hours, with some areas of flash flooding appearing
likely.

DISCUSSION...A quasi-stationary front focused across the lower MS
and TN Valley region continues to be an active focus for
convection with several clusters of heavy showers and
thunderstorms tending to repeat over the same area. The latest
radar imagery shows the more organized activity focused across
portions of central/northeast LA and through central MS with much
of the convection becoming increasingly aligned in a west/east
fashion.

The convection is being aided by proximity of 500 to 1000 j/kg of
MUCAPE, 30 to 40 kts of effective bulk shear, and 20 to 30 kts of
southwest 850 mb flow into the frontal boundary. There is also
notably favorable 200/300 mb right-entrance region jet dynamics
focused over the region which is fostering deeper layer ascent.

Heavy rainfall is expected to become locally rather focused over
the next few hours from portions of central/northeast LA eastward
across at least west-central MS where a combination of deeper
layer moisture convergence and a strengthening instability
gradient should foster a bit better convective organization and a
likelihood of some training convection given alignment with the
850/300 mb mean flow and proximity of the front.

The latest 12Z HREF suite of guidance along with several morning
runs of the HRRR suggest an axis of as much as 3 to 5 inches of
additional rain locally, with some localized rainfall rates
perhaps reaching 2 inches/hr. This certainly seems plausible given
PWs of 1.6 to 1.7 inches which are at or near record high levels
for mid-January.

Expect some areas of flash flooding to be likely over the next
several hours as the convection continues to redevelop and become
locally focused while also tending to train over the same area.

Orrison

ATTN...WFO...JAN...LCH...LIX...MOB...SHV...

ATTN...RFC...LMRFC...SERFC...WGRFC...

LAT...LON   32728902 32458851 31708882 31428970 31079136
            30859274 30939325 31319355 31779330 32309196
            32629050


Last Updated: 1112 AM EST Tue Jan 14 2020
 

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Page last modified: Wednesday, 13-May-2015 19:29:02 GMT