Weather Prediction Center issues Mesoscale Precipitation Discussion #1129 concerning HEAVY RAINFALL...FLASH FLOODING LIKELY532
AWUS01 KWNH 050932
FFGMPD
ILZ000-LAZ000-MOZ000-ARZ000-TXZ000-051530-
Mesoscale Precipitation Discussion 1129
NWS Weather Prediction Center College Park MD
431 AM EST Tue Nov 05 2024
Areas affected...mid-MS Valley into central AR and the Arklatex
Concerning...Heavy rainfall...Flash flooding likely
Valid 050930Z - 051530Z
SUMMARY...Flash flooding is expected to continue from near and
south of the St. Louis metro/mid-MS Valley southwestward into the
Arklatex through 15Z. While rainfall rates will be lowering
overall, occasional pockets of higher rates will maintain areas of
flash flooding, especially atop saturated soils.
DISCUSSION...Regional radar imagery at 09Z showed an elongated
axis of showers and thunderstorms which stretched from the St.
Louis metro into south-central MO, west-central AR and the
Arklatex. This axis was located along a combined cold/stationary
front and outflow boundary which was coincident with the leading
edge of heavy rain. Trends in rainfall intensity have shown a
decrease in higher rainfall rates over the past few hours as
instability has been lowering. 09Z SPC mesoanalysis data showed
MLCAPE values were at or less than 500 J/kg just ahead of the
combo front/outflow boundary from MO into AR, but increased to
1000+ J/kg over TX. However, the southern portion of the
front/outflow was progressing steadily toward the east, to the
south of weak wave located ~40 miles southeast of FSM, limiting
the flash flood threat for these southern locations. To the north,
the front/outflow has been very slow to progress with locations
just south of I-44 in eastern MO to the St. Louis metro containing
repeating and training echoes for the past 2-3 hours.
Water vapor imagery showed the former closed mid-level low over
the southern High Plains has begun to open up and elongate from
SSW to NNE. Just ahead of the elongating upper vorticity max was a
GOES-East DMV sampled 130+ kt jet streak over eastern KS,
providing increased lift via strengthening divergence aloft over
northern AR into MO within the right-entrance region. As the mid
to upper-level trough axis continues to translate east, it is
forecast to acquire more of a neutral tilt with the downstream jet
streak allowing for an extended period of enhanced lift over MO.
Therefore, while instability will continue to gradually lower
until sunrise (~12Z), dynamic forcing will support occasional
pockets of higher rainfall rates within areas of training that
will continue to support pockets of rainfall rates of 1-2 in/hr
within an anomalous moisture axis containing PWATs up to 1.8
inches. This potential will exist from near the Arklatex to the
central and southern MO/IL border, overlapping portions of the
region which have seen heavy rainfall over the past 24 hours.
Overlap of additional rainfall with prior rainfall is expected to
be greatest across MO into northern AR, but at least an isolated
flash flood threat will continue for locations farther south into
northwestern LA and northeastern TX. Additional rainfall totals of
2-3 inches are expected through 15Z.
Otto
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...LSX...LZK...PAH...SGF...SHV...
ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...WGRFC...NWC...
LAT...LON 39058971 38568953 37339024 35379164 33599272
32389359 31859456 31949496 32439503 33479441
35299351 36799266 38379143 39049063
Source:
Weather Prediction Center issues Mesoscale Precipitation Discussion #1129 concerning HEAVY RAINFALL...FLASH FLOODING LIKELY---------------
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