This is a multi-part message in MIME format...

------------=_1563680449-2024-2784
Content-Type: text/plain

AWUS01 KWNH 210340
FFGMPD
MOZ000-IAZ000-KSZ000-NEZ000-210945-

Mesoscale Precipitation Discussion 0645
NWS Weather Prediction Center College Park MD
1140 PM EDT Sat Jul 20 2019

Areas affected...NW Missouri, SW Iowa, SE Nebraska

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

Valid 210345Z - 210945Z

Summary...An MCS diving through northern Missouri is laying a NW
to SE oriented outflow towards Nebraska. A modest LLJ will
continue to transport moisture into this region, persisting an
environment favorable for heavy rainfall. As storms backbuild
along this outflow, storm motions will become less than 5 kts,
supporting a risk for flash flooding through the early morning.

Discussion...Radar mosaic from KDMX WSR-88D shows a line of
thunderstorms dropping slowly southward into northern Missouri
along the leading edge of an MCS. The outflow associated with this
feature is expanding to the NW into an area of better forcing on
the nose of a SW 850mb LLJ. PWATs on the 00Z U/A soundings from
KTOP and KOAX were 1.90 and 1.96 inches, respectively, both above
the 90th percentile for the date. This moisture will continue to
increase on the LLJ, with PWATs forecast to touch 2 inches
overnight, with up to 2.25 inches possible, 2 to 2.5 standard
deviations above the climo mean. In addition to this moisture,
instability remains quite high as noted by RAP analyzed MUCape of
3000-5000 J/kg, highest into southeastern Nebraska.

In this highly favorable thermodynamic environment, ascent is
being provided by low-level convergence along the outflow,
especially where the 20-25kt LLJ impinges orthogonally along the
boundary to drive stronger isentropic ascent. Additionally, a
nearly stationary front just north of the area will likely begin
to merge/combine with the outflow to produce a hybrid boundary
overnight. At the same time, subtle mid-level forcing lifting from
the SW will further erode the 12C 700mb cap, which combined with
subtle RRQ jet-streak diffluence will drive deep layer ascent for
thunderstorm development.

All of this forcing interacting on the boundary will drive
increasing coverage of thunderstorms to the W/NW, with individual
cells following the mean cloud layer westerly winds to train along
the wavering outflow boundary. RAP Corfidi vectors are forecast to
drop to near zero, suggesting the potential for nearly stationary
motion. FFG across much of the discussion area is 3-4"/3 hours,
but HREF neighborhood probabilities show an increasing likelihood
for 2"/hr rain rates while exceedance probabilities for 6-hr
rainfall above the 5-yr ARI are over 40%. Recent CAMs, including
the last three runs of the HRRR, show many locations receiving
2-3" of rainfall, with some spots possibly exceeding 5". This
suggests that flash flooding will be possible as storms expand and
move slowly overnight.

Weiss

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

ATTN...WFO...DMX...EAX...LSX...OAX...TOP...

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

LAT...LON   41509561 41449490 41259435 41019368 40679291
            40309240 39889220 39439224 39169245 38979281
            38959323 39059384 39249436 39479482 39789538
            39949565 40299603 40619622 40979624 41259613



------------=_1563680449-2024-2784
Content-Type: text/plain; charset="US-ASCII"
Content-Disposition: inline
Content-Transfer-Encoding: 7BIT

= = =
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.
------------=_1563680449-2024-2784--

--- SBBSecho 3.07-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)