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