AWUS01 KWNH 080936
FFGMPD
ARZ000-OKZ000-081500-

Mesoscale Precipitation Discussion 0618
NWS Weather Prediction Center College Park MD
535 AM EDT Tue Jul 08 2025

Areas affected...eastern OK into western AR

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

Valid 080933Z - 081500Z

SUMMARY...Isolated flash flooding will be possible from parts of
eastern OK into western AR through the morning hours. Hourly
rainfall of 2 to 3+ inches and isolated totals in excess of 5
inches will be possible through 16Z.

DISCUSSION...GOES East infrared and area radar imagery showed the
early stages of a few showers/thunderstorms forming over eastern
OK as of 09Z. Water vapor imagery showed a mid-level shortwave
advancing across northeastern OK, moving into an airmass that was
partially capped but anomalously moist and weakly unstable (PWs
near 2 inches and MLCAPE of 500 to just over 1000 J/kg via 08Z SPC
mesoanalysis data). In addition, the flow aloft was diffluent
between the sub-tropical jet to the north and a strong upper ridge
centered over far northwestern Mexico.

Over the past few hours, 925-850 mb VAD winds and RAP data showed
a minor increase in low level moisture transport into the region
from the SW, which should help to further reduce weak low level
convective inhibition noted on RAP analysis soundings over eastern
OK. A continued increase in the coverage and intensity of
showers/thunderstorms is expected over the next 1-3 hours over
eastern OK and portions of western AR as the shortwave trough
continues to advance and low level CIN continues to erode.
Steering flow for storm motions is fairly weak (~10 kt) and some
brief training will be possible with cell motions generally moving
from west to east. Due to the high moisture environment, rainfall
rates of 2 to 3 inches (perhaps higher) will be possible along
with 30 minute rainfall of 1-2 inches. While recent HRRR/RRFS runs
have not been matching current radar trends, older HRRR and 00Z
HREF members were doing better and indicate the potential for
locally high rainfall totals (40 percent HREF probs for 3+ inches
and 30 percent HREF probs for 5+ inches through 18Z).

Given relatively low rainfall anomalies across the region over the
past 2 weeks, FFG values are on the high side for the region with
3 to 5 inches per 3 hours. Therefore, any instances of flash
flooding are expected to remain isolated and more likely across
any urban areas and/or typical flood prone regions of the Ouachita
Mountains into the Ozark Plateau.

Otto

ATTN...WFO...LZK...OUN...SHV...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 36499467 36279360 35819293 35199260 34419279
34019385 34049540 34989657 35919588

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AWUS01 KWNH 131121
FFGMPD
ARZ000-TXZ000-OKZ000-131620-

Mesoscale Precipitation Discussion 0667
NWS Weather Prediction Center College Park MD
720 AM EDT Sun Jul 13 2025

Areas affected...Southeast OK into Southwest AR

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

Valid 131120Z - 131620Z

SUMMARY...Scattered flash flooding remains possible this morning
across portions of southeast Oklahoma and adjacent areas of
southwest Arkansas.

DISCUSSION...Expanding convection to the southeast of a well
defined MCV has increased in coverage and intensity early this
morning. The environmental ingredients in place seem supportive of
this activity persisting into the morning hours. Instability is
marginal (MUCAPE between 500-1000 J/KG), but we do have enough of
an upstream instability pool off to the southwest to likely
sustain this convection. PWs are over 2", and likely have a good
amount of warm rain processes occurring increasing rainfall
efficiency with this activity. Deep layer mean flow is off to the
northeast at ~20 kts, however upwind propagation vectors are
pretty weak and pointed south. This supports some of the southward
backbuilding of convection we have been seeing this morning. The
latest SPC mesoanalysis also depicts a corridor of deep moisture
convergence over this area, with both the 925mb and 850mb moisture
transport axis pointed into the region.

While not necessarily the strongest signal, model guidance does
have some signs of this convective cluster. Both the latest HREF
and REFS have modest 3" neighborhood probabilities, and the 10z
HRRR and 08z RRFS runs now show a better training signal. None of
the guidance show too much more upscale development of the
activity, and by mid to late morning these type of nocturnal
events often tend to weaken. Thus generally expecting the scale of
activity to remain similar over the next few hours, with
backbuilding on the south and southwest flank of the northeast
moving area of convection. Where this backbuilding persists an
isolated to scattered flash flood risk will continue. Hourly
rainfall locally over 2", and total amounts upwards of 3-5" seem
probable in spots. By mid to late morning we should start to see a
bit less organization as low to mid level moisture convergence
should weaken. But we will continue to monitor convective trends.

Chenard

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 35329434 35209395 34689367 34179404 33799488
33689571 33609593 33919623 34149642 34469664
34599681 34819656 35189587 35259483

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