Mesoscale Precipitation Discussion 0036
NWS Weather Prediction Center College Park MD
1239 AM EST Sat Jan 27 2024

Areas affected...Lower Mississippi Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 270532Z - 271100Z

SUMMARY...Training of heavy rain will allow for rainfall rates of
1-2 in/hr across the Lower Mississippi Valley through 11Z. 2-3
inches of rain in 2-3 hours may produce localized flash flooding
given soil moisture values are running well above average from
recent rainfall.

DISCUSSION...Regional radar imagery at 0515Z showed scattered
thunderstorms extending from southwestern MS into central/southern
LA and the northern Gulf of Mexico to the south of southwestern
LA. Southerly flow ahead of an eastward advancing shortwave over
northern TX was helping to transport low level moisture into the
Lower Mississippi Valley, out ahead of a surface low and
associated cold front analyzed in southeastern TX at 05Z. The
majority of convection was elevated and working within 500 to 1500
J/kg MUCAPE as seen on the 05Z SPC mesoanalysis. At the leading
edge of low level moisture return, SW to NE axes of low level
convergence were helping to align convection with the deeper layer
steering flow from the southwest, allowing training of heavy rain
to occur at times.

The shortwave helping to force the convection is expected to
steadily progress toward the east through 12Z, which should keep
the cold front and convection just to its east moving along in a
mostly progressive fashion. However, the prefrontal axes of low
level convergence will allow short term periods of training with
hourly rainfall in the 1-2 inch range and 2-3 inch totals in 2-3
hours.

The SW to NE axis of storms located near and north of Lake
Charles, LA at 0515Z is expected to advance toward the northeast
into northeastern LA and portions of central/northern MS. However,
decreasing instability with northward extent may limit rainfall
rates to the north overnight. A second area of storms that has
become better organized over the past 1-2 hours offshore of the
southwestern LA coast may continue to expand northward, eventually
impacting portions of southeastern LA into southern MS. Greater
access to instability for these southern locations will increase
the probability of higher rainfall rates, with potential impacts
to the I-10 corridor.

Due to heavy rainfall across much of the region over the past few
days, susceptibility to flash flooding will be increased relative
to normal.

Otto

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

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

LAT...LON   34388998 34158937 33548897 31238916 30378935
            29719027 29439134 29379282 29659360 30649351
            32409246 34219102