Mesoscale Precipitation Discussion 0721
NWS Weather Prediction Center College Park MD
1249 AM EDT Thu Jul 17 2025

Areas affected...Southeast NEB...Northeast KS...Northwest MO...

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

Valid 170450Z - 171000Z

SUMMARY...Elevated training convection within 850-700mb WAA
confluent stream.  Incidents of training/repeating likely to
result in enhanced totals of 2-3" and possible localized flash
flooding.

DISCUSSION...Regional RADAR mosaic and 10.3um EIR GOES-E loop
shows a weakly anticyclonic arc of increasing thunderstorm
activity along the central KS/NEB border extending into northwest
MO along/north of stronger surface/boundary layer rooted
convection.  CIRA LPW animation shows sfc to 700mb layers with
confluent enhancement of moisture across the axis added from the
northern stream along the trailing edge of the strong exiting
northern stream strung across the Upper MS River Valley.  This
aligns with strong 850mb flux from the south across KS before
veering southwesterly into the 700mb layer.  Low level flow has
strengthened and further veered along/ahead of strong
'ridge-riding' shortwave emerging out of Colorado.  The connection
of streams have provided solid WAA and 925-700 frontogenesis
across western KS through the activating arc.

Convection is utilizing the edge of slightly steepened lapse rates
and the northern gradient of MUCAPE that tightly packs from
500-1500 J/kg in the area of WAA ascent.  Combine with the deeply
confluent moisture streams, provides solid moisture flux and ample
deep layer moisture of 1.75-2". So even though cells are elevated,
moist lower levels will not result in much sub-cloud evaporation
keeping rainfall efficiency relatively high.  Limited capping,
resulted in large area of over-turning, so individual updrafts are
competing to broaden/merge with other ascent parcels.  This is
resulting in broader area of 1.5"/hr rates though spots up to
2"/hr becoming likely.  Deep layer steering from 700-400mb is
generally parallel to the boundary and the 500-1000mb thickness
ridge is south enough that propagation vectors are also aligning
favorably for spots of training/repeating to occur.

Spots of 2-3" are likely to occur with perhaps an isolated small
areal coverage of 4" not withstanding.  Moderate rainfall from
prior day or so, locally reduced FFG values across the NEB/KS into
NW MO where 1hr values are 1-1.75"/hr and 1.5-2.5"/3hrs.  As such,
an incident or two of flash flooding will be possible before
instability is exhausted and cells start propagating southward
into higher FFG/drier soil conditions.

Gallina

ATTN...WFO...EAX...GID...OAX...TOP...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   40599569 40459382 40269278 39749239 39379287
            39429525 39409714 39179922 39659952 40289806
            40549692