759
AWUS01 KWNH 152132
FFGMPD
MOZ000-MNZ000-IAZ000-KSZ000-NEZ000-SDZ000-160300-

Mesoscale Precipitation Discussion 0443
NWS Weather Prediction Center College Park MD
531 PM EDT Sat Jun 15 2024

Areas affected...far northeast KS, eastern NE, western IA, far
southeast SD

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

Valid 152130Z - 160300Z

Summary...Showers and thunderstorms will increase along a
northward advancing warm front through the evening. Rainfall rates
within developing convection could reach 2"/hr at times, which
through short-term training could produce 2-3" of rain with
locally higher amounts. Flash flooding is possible.

Discussion...The GOES-E IR imagery this afternoon indicates
expansion of rapidly cooling cloud tops associated with deepening
convection from central KS through eastern NE. These thunderstorms
are developing immediately ahead of a warm front which is slowly
lifting northward, with significant additional ascent provided via
an impressive shortwave ejecting out of KS noted on the GOES-E WV
imagery, and within the RRQ of a modest jet streak pivoting into
IA. This deep layer lift is occurring into intensifying
thermodynamics as the atmosphere recovers from this mornings
outflow boundary as reflected by increasing mid-level lapse rates
noted by the SPC 3-hr lapse rate change, with PWs reaching 1.5 to
1.8 inches overlapping a ribbon of MLCAPE as high as 3000 J/kg
according to the SPC RAP analysis.

As the warm front gradually lifts north and the shortwave pivots
into the region, ascent is forecast to intensify into the evening
while thermodynamics become even more impressive noted by PWs
progged to reach 2 inches, which would be a daily record for the
area, combined with the strong MLCAPE. Together these should
result in a rapid expansion of convective development, especially
where low-level convergence and isentropic ascent merge in the
vicinity of the warm front. Additionally, the isentropic lift atop
the warm front should rapidly intensify as the 850mb LLJ surges to
around 40 kts, reaching nearly double the mean 0-6km wind to
produce intense moisture convergence into eastern NE and western
IA this evening. This surging LLJ will also drive a veering of the
propagation vectors to become increasingly aligned to the right of
the mean wind, indicating a higher training potential in the next
few hours. With HREF neighborhood probabilities indicating a
40-50% chance of 1"/hr rates (and 10-20% for 2"/hr), where
training or multiple rounds of heavy rain occur, total rainfall
will likely reach 2-3", and there is a low potential (5-10%) for
isolated amounts reaching 5".

FFG across this region is generally 1.5-2"/3 hrs, although 0-40cm
soil moisture from NASA SPoRT is generally around normal. This
could have at least a somewhat moderating effect on the flash
flood potential, but the HREF 3-hr FFG exceedance probabilities
still reach 20-30%. This suggests an increasing flash flood
potential into the evening, with the greatest risk likely beneath
any training to enhance the duration of these rain rates.

Weiss

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...FSD...GID...LBF...OAX...TOP...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON   43769653 43659545 42849479 41459451 39759528
            39249622 39129731 39359796 40049853 42149825
            43429740