198
AWUS01 KWNH 010050
FFGMPD
NJZ000-DEZ000-MDZ000-VAZ000-NCZ000-010650-

Mesoscale Precipitation Discussion 0527
NWS Weather Prediction Center College Park MD
850 PM EDT Sun Jun 30 2024

Areas affected...Far Southern NJ...Delmarva...Southern
MD...Central to Southeast VA...North-Central to Northeast NC

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

Valid 010050Z - 010650Z

SUMMARY...Renewed rounds of very heavy showers and thunderstorms
are expected heading into the evening hours. Given the rains
locally earlier in the day, and the additional high rainfall rate
potential along with urban impact considerations, areas of
additional flash flooding are likely going through the evening
hours.

DISCUSSION...A cold front continues to gradually settle southeast
into the Mid-Atlantic coastal plain as a very moist and unstable
airmass remains pooled out ahead of it across the coastal plain
from southern NJ and the Delmarva Peninsula down through much of
central to southeast VA and north-central to northeast NC.

Despite locally multiple rounds of convection that have already
occurred, there continues to be as much as 1500 to 2500+ J/kg of
MLCAPE in place which is being aided by surface dewpoints in the
mid to upper 70s. A deeply tropical airmass is entrenched ahead of
the approaching cold front, with PWs across the Mid-Atlantic
coastal plain of locally as high as 2.25 to 2.5 inches.

Additional areas of convection are expected going through the
evening hours as multiple small-scale outflow boundary collisions
and generally convergent boundary layer flow persists ahead of the
upstream cold front. The airmass should remain very moist and
sufficiently unstable to support convection capable of still
producing rainfall rates upwards of 2 inches/hour. And there is
also still as much as 30 to 40 kts of effective bulk shear to
support stronger and more organized updrafts that will help favor
convective sustenance going well through the evening hours.

Additional rainfall totals based on the 18Z HREF and the
experimental 12Z NSSL-MPAS guidance may reach 2 to 4 inches with
isolated heavier amounts through 06Z, and this is also reflective
of some cell-training and cell-merger concerns that should still
persist this evening.

Given these additional rains falling on top of areas that were hit
locally earlier today, and with concerns for additional urban
impacts including the I-64 corridor from near Richmond down
through the Norfolk/VA Beach vicinity, more areas of flash
flooding are likely to occur.

Orrison

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

ATTN...WFO...AKQ...LWX...MHX...PHI...RAH...RNK...

ATTN...RFC...MARFC...SERFC...NWC...

LAT...LON   39707511 39657444 39307442 38687489 38097514
            37117569 36537560 35787599 35407767 35457885
            35917947 36547916 37097852 37767778 38277718
            38877656 39507587