WPC Met Watch |
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Mesoscale Precipitation Discussion: #0439 (2019) |
(Issued at 1252 PM EDT Mon Jun 17 2019
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MPD Selection |
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Mesoscale Precipitation Discussion 0439...Corrected
NWS Weather Prediction Center College Park MD
1252 PM EDT Mon Jun 17 2019
Corrected for typo in header
Areas affected...portions of MO into southern IL/IN
Concerning...Heavy rainfall...Flash flooding possible
Valid 171647Z - 172245Z
Summary...Scattered thunderstorms are expected to increase in
coverage across portions of Missouri into the lower OH Valley this
afternoon. High rainfall rates and storm mergers are expected to
produce areas of 2-4 inches of rain through 23Z which may cause
flash flooding.
Discussion...Water vapor imagery at 1630Z showed a closed low
centered over southwestern MO along with a smaller scale vorticity
max ejecting ENE across east-central MO. Regional radar imagery
showed a mostly stratiform region of rainfall over central to
southwest MO beneath the upper low with embedded heavier elements
containing radar estimated rain rates of 1-2 in/hr (eastern Camden
County) while storms were more discrete and scattered in nature
along the MO/IL border, out ahead of the smaller scale ejecting
vorticity max moving into eastern MO.
The environment across the region contained precipitable water
values between 1.5 and 1.8 inches with tall/skinny CAPE between
500-1000 J/kg as seen on the 12Z RAOB from SGF and nearby RAP
analysis soundings near STL. Daytime heating coupled with breaks
in cloud cover noted on visible satellite imagery near and south
of a quasi-stationary front should allow further increases in
MLCAPE to develop by mid-afternoon. With little CIN noted on
nearby 12Z observed soundings, convective coverage is expected to
rapidly increase over the next 1-2 hours from the Mississippi
River into southern IL/IN. Storm motions are expected to be fairly
slow, especially across MO into central IL where 850-300 mb and
0-6 km mean winds are 10 kt or less. A lack of greater speed sheer
may cause cells to be somewhat short lived over any given location
but the environment is supportive of rainfall rates between 1-2
in/hr, with locally higher rates possible. Development of
convection farther east across eastern IL into IN is not expected
to be as widespread until later in the afternoon as better upper
forcing arrives as the mid-level low in MO continues to shear ENE
along with smaller scale impulses ahead of the main center.
However, FFG values across much of southern IL into southern IN
are low, and inch or less of rain in one hour, which would easily
be met given the moisture/instability in place.
Otto
ATTN...WFO...EAX...ILX...IND...LMK...LSX...LZK...PAH...SGF...
TSA...
ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...
LAT...LON 39708648 39288548 38648581 37798893 37439074
36649200 36479331 36879399 37359419 38209404
38809336 39369214 39599110 39578822
Last Updated: 1252 PM EDT Mon Jun 17 2019
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