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FOUS30 KWBC 071557
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Sun Jul 7 2024

Day 1
Valid 16Z Sun Jul 07 2024 - 12Z Mon Jul 08 2024

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
COASTAL TEXAS...

16Z Update...

...Coastal Texas into Louisiana...

Beryl still has a landfall forecast prior to 12Z Monday on the
middle TX Coast (please see the NHC website for the latest
information). The most outer band is roughly along the entirety of
the TX Coast here at 16Z (only spotty heavy rain with this though) with
the inner core picked up on regional NEXRAD heading toward the
middle TX Coast. Updated timing from recent HRRRs allows some
updates to the Day 1 coverages. The inner core rainfall should
exceed 7" over much of the middle TX Coast by 12Z, warranting the
Moderate Risk from Rockport to Freeport an points north. However,
there is increased confidence on inflow bands to the right of the
track spreading up as far east as Galveston Bay and up through the
Houston metro starting around 08Z. In coordination with WFO HGX,
the Moderate Risk has been expanded through the immediate Houston
metro and now extends from San Antonio Bay to Galveston Bay.

The Marginal Risk still does not extend down all of Padre Island
with the 12Z CAM consensus for heaviest rainfall to be east from
Oso Bay where the Slight Risk begins. On the east side, far outer
bands will cross southwest LA, warranting maintenance of the
Marginal Risk there as well as the Slight Risk from Galveston Bay
to the Sabine River/TX-LA border.


...Southern Plains to the central High Plains and to the Upper
Midwest...

Organized convection/MCS is over central OK and tracking southeast
which is more progressive/farther southeast than most any HREF CAM
guidance had depicted. This should focus the heaviest
redevelopment later today to be farther south over southwest OK
into Northwest TX this afternoon/evening and less so over KS. The
best guidance so far seems to be the 12Z NAMnest if it is
considered 3-4 hours too slow this morning. This served as a guide
to remove the Slight Risk for most of KS and maintain the Slight
Risk for much of OK into Northwest TX where southerly low level
flow looks to maintain 1.75" PW.

Farther north, greater synoptic forcing is present with the upper
trough extending from an upper low over northern MN to the
southwest over the central Dakotas and extending to the central
High Plains. Redevelopment of activity over the central High Plains
this afternoon/evening looks to track south over eastern CO where
the Marginal Risk was expanded. Downstream is a broken swath of
expected heavy rainfall in the moist southwesterly flow ahead of
the trough axis over eastern KS, northern MO, much of IA and into
southwest WI and western IL where the Marginal Risk was expanded a
bit. Even farther north, ahead of the upper low, redevelopment
around western Lake Superior raises an isolated flash flood threat
for the Arrowhead of MN, around through Duluth to northern WI and
far western U.P. of MI where a Marginal Risk was introduced.

...Southeast...

A stalled frontal boundary across the region will be the focus for
convection which will maintain an isolated threat for flash
flooding concerns. PWs will remain above the climatological 90th
percentile, and layered IVT suggest we may see some mid/upper level
moisture connection to Beryl. The intrusion of tropical moisture
may help bolster rainfall efficiency in what will already be a
favorable environment for heavy rainfall rates. A Marginal Risk remains
in effect for a majority of the Southeast region for this period
with a minor expansion over western NC terrain up to the VA border
per recent HRRR runs.

Jackson


Day 2
Valid 12Z Mon Jul 08 2024 - 12Z Tue Jul 09 2024

...THERE IS A MODERATE RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS
OF EASTERN TEXAS...

The National Hurricane Center has Beryl tracking north/northeast
through eastern Texas. The guidance continues to suggest a fairly
compact storm, therefore the QPF swath is expected to be relatively
narrow and oriented N-S along and slightly east of the storm track.
WPC has areal average QPF ranging from 3 to 7 inches with isolated
maximums in the double digits. Given the adjustment to the NHC
storm track and the new WPC QPF, the inherited risk areas were all
shifted as follows. The Moderate Risk spans from Port Lavaca to
east of Galveston Bay and northward into southwest Arkansas. The
Slight Risk spans from San Antonio Bay to west of Vermilion Bay
and northward into central Arkansas. The Marginal Risk spans from
east of Corpus Christi to Atchafalaya Bay and from the Texas
Panhandle to Southern Missouri, tied to the frontal boundary to the
north. Note that the placements of the Excessive Risk areas will
largely be dependent on the NHC track so stay tuned for future
adjustments.

...Southeast...

Convection in proximity to the lingering frontal boundary will
persist across the Southeast; therefore maintained the Marginal
Risk area. Recent rains have increased soil saturation levels and
with additional showers and thunderstorms expected the threat for
isolated flooding concerns will remain elevated for this part of
the country, despite the lower QPF signal in the guidance. Will
gain more insight once we move into the CAM window, and also with
better clarity on the speed of recurvature of Beryl.

Fracasso/Campbell


Day 3
Valid 12Z Tue Jul 09 2024 - 12Z Wed Jul 10 2024

...Mississippi Valley and Midwest...

Beryl is expected to quickly phase with an upper trough and
surface front to the north, which lead to a significant change from
the previous forecast. These features should lead to the potential
for heavy rain causing flash flooding concerns over some areas
from eastern Texas northeastward through Wednesday. At this time,
the higher QPF amounts focus over northwest Arkansas to central
Illinois with the highest over the Ozarks. Areal averages are
expected to be around 2 to 5 inches with local maximums upwards of
8 inches. A Slight Risk extends from northwest Arkansas to central
Illinois. A Marginal Risk stretches from the central Gulf Coast
northward to northern Illinois and southern Michigan. Again, an
future adjustments will likely be dependent on the latest NHC track
for Beryl.

...Southwest...

Some moisture may feed into the Southwest and southern Colorado in
a monsoonal pattern. A Marginal Risk was maintained for most of New
Mexico, southeast Arizona and south-central Colorado for this
period considering sensitivities due to burn scars and areas that
have seen ample rainfall recently.

...Southeast...

Given the abundant moisture over the region and some model are
signaling for locally heavy rainfall, especially for eastern
portions of Florida. General consensus suggests 1 to 2 inches
although local maximums of 3 to 4+ inches will certainly possible.
A Marginal Risk remain in effect for portions of central/northern
Florida and southeast Georgia.

...Northeast...

Interaction of moisture ahead of Beryl and a front settling over
the Mid-Atlantic/southern New England may favor heavy rainfall
potential over this region. Some focus of the convective rain
ahead of the front(s) and sufficient instability for heavy rain
rates in the northern Mid-Atlantic to Northeast favor of a
Marginal Risk.

Campbell

Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt