AWUS01 KWNH 200411
FFGMPD
TXZ000-NMZ000-201010-

Mesoscale Precipitation Discussion 1107
NWS Weather Prediction Center College Park MD
1210 AM EDT Sun Oct 20 2024

Areas affected...Eastern NM

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

Valid 200410Z - 201010Z

SUMMARY...Heavy showers and thunderstorms are expected to continue
to impact portions of eastern NM overnight. Additional areas of
flash flooding are likely.

DISCUSSION...The latest GOES-E IR satellite imagery shows a very
divergent flow regime aloft over eastern NM with an expansive
canopy of persistent cold convective tops associated with an
elongated band of heavy showers and thunderstorms. All of this is
occurring downstream of a rather strong upper-level low that is
nearly stationary over central AZ.

MLCAPE values over eastern AZ remain on the order of 500 to 1000
J/kg out ahead of a quasi-stationary front, but the front is
helping to focus a strong north/south axis moisture convergence
which is being facilitated by a southeast low-level jet of 40 to
50 kts that is persisting across the southern High Plains.

This enhanced moisture convergence/transport working in tandem
with the available instability and deep layer ascent downwind of
the upper low has resulted in some very well-organized convection
including a few occasional supercell structures this evening that
have been resulting in locally extreme rainfall rates.

In fact, Roswell, NM (KROW) picked up 0.73" of rain in just a
7-minute period between 0148Z and 0155Z. The persistence of this
extreme rainfall rate led to Roswell seeing 2.70" of rain in one
hour from 0151Z to 0251Z. This has led to locally catastrophic
flash flooding impacts, with a Flash Flood Emergency for the city
of Roswell.

The instability trends over eastern NM are somewhat negative with
3-hour differentials in the MLCAPE of -200 to -400 J/kg. This
suggests that the rainfall rates will likely tend to come down a
bit in the hours ahead, however, the persistence of deep layer
ascent/upper-level jet forcing and the low-level jet yielding
enhanced moisture flux convergence should tend to compensate and
help keep rainfall rates still capable of reaching 1.5" to
2.0"/hour with the stronger cells.

Some gradual eastward advance of the overall convective rainfall
axis is expected overnight, but some additional rainfall amounts
of 3 to 4 inches will be possible locally where any of these cells
continue to train or backbuild over the same area. As a result,
additional areas of flash flooding will be likely.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6Erj1W2ZbGyiBF-FSnt-SrG-9xoMutAVM4HNJIbSKgsAMN7kdXXu-NmMmIk8dTvWHuXU=
eb0UGL4mjNc6pCwboFNLaog$  for graphic product...

ATTN...WFO...ABQ...AMA...EPZ...LUB...MAF...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON   36490328 36060290 35190289 34000322 33170377=20
            32780425 32640496 33090539 33520542 34670525=20
            35840496 36450415=20

=3D =3D =3D
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