Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Jun 6 2026
Day 1
Valid 01Z Sun Jun 07 2026 - 12Z Sun Jun 07 2026
...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS, OHIO VALLEY, AND CENTRAL GULF COAST...
01Z Update...
Adjustments were made based on current radar trends, recent runs of
the HRRR, and the latest HREF/REFS guidance. With the exception of
the upper Texas Coast, Slight Risks from the previous issuance were
left in place. Both model guidance and observation trends indicate
at least some potential for additional heavy rain and flooding
concerns in these areas through the remainder of the evening into
the overnight.
One area of potentially greater concern extends across portions of
Central into North Texas. Supported by sustained low level inflow
and deepening moisture, backbuilding along the southwestern flank
of the ongoing line of convection may produce heavy amounts, with
both the HRRR and HREF showing the potential for localized amounts
in excess of 3 inches along an axis extending northeastward from
the northern Hill Country toward the DFW Metro.
Another area of greater concern is along the AR-TX border, where
north-south training is expected to continue, resulting in
heavy amounts. Here too the HRRR and the hi-res ensemble guidance
show the potential for localized amounts over 3 inches.
Pereira
Previous Discussion...
...Southern Plains...
A plume of deep tropical moisture will surge northward across the
Southern Plains Saturday. The low level jet advecting this moisture
north will run into an area of enhanced lift due to a nearby
lingering upper-low, which will be lifting northeast to rejoin the
jet. The result will be a series of rounds of storms moving north-
northeast across portions of north/northwest Texas, Oklahoma, and
western Arkansas. Highly efficient warm rain processes will
dominate due to the presence of such abundant amounts of moisture,
with PWATs close to 2 inches. For eastern Oklahoma/western
Arkansas, rainfall is already ongoing and will persist for much of
the day in the form of training lines of storms. To the west,
another round of storms is expected to develop with daytime heating
along the eastern periphery of the upper-low, with the expectation
that repeated rounds of storm development and storm
clustering/merging cold pools may eventually lead to a more
organized convective system that will progress slowly to the east-
southeast through the evening and overnight hours. An internal
higher- end Slight covers from southwest of the Metroplex through
it, and continuing into much of eastern Oklahoma and western
Arkansas for the combination of two areas of persistent heavy rain.
The latest convection allowing guidance (CAMs) show peak rain
rates reaching upwards of 2-3 inches per hour with locally heavy
totals into the 5-6+ inch range, more than sufficient for at least
scattered instances of flash flooding despite some locally drier
antecedent conditions.
...Ohio Valley...
A very-slow moving cold front drifting south across the
Midwest/Ohio Valley on Saturday will be the animus for multiple
rounds of storms which will track east-southeast within the Slight
Risk area roughly from central Indiana east to the central
Appalachians. The front will form the leading nose of a plume of
deep Gulf moisture tracking northward up the Mississippi Valley.
The front will "shear" the moisture eastward in a narrow corridor,
along which the storms will form and move. There is some
uncertainty as to how persistent an ongoing complex of storms
moving into central Ohio will be as they progress east-
southeastward through the afternoon. However, even if storms do not
maintain quite the same strength/organization as they move into
the Mountains of western Pennsylvania and West Virginia, these
areas have lower FFG thresholds and the risk for scattered flash
flooding will remain a concern. Uplift along the western face of
the Appalachians may also locally enhance rainfall rates. Another
round of storms is expected along the boundary further west within
the Slight Risk over central Indiana where the CAMS/HREF suggest
heavier totals into the 3-5 inch range are possible. Additional
storms are also forecast to develop further west along the boundary
stretching through central Illinois and along the Iowa/Missouri
border. However, these storms are forecast to remain more
scattered/less organized with generally lower rain totals in the
CAMS, keeping the flash flood threat more isolated compared to
further east.
...Central Gulf Coast...
No changes were needed to the Slight Risk area from New Orleans
east to Pensacola. A strong front is in place across the eastern
Gulf, characterized by very dry air to its east, rather than any
significant temperature gradient. The dry air is 2 sigma below
normal over portions of central Florida...under 1 inch PWATs.
Meanwhile to the west from Louisiana through Texas, an abnormally
moist air mass will be streaming north to the west of the high
pressure area characterized by the dry air. Over much of Louisiana,
PWATs will be over 2.25 inches or 3 sigma above normal. The front
makes up the gradient between these extremely contrasting air
masses. Through the day, the front will push east as the moist air
mass gradually gains ground. However, the front will be the forcing
along which numerous showers and thunderstorms pushing north out
of the Gulf will form along. The front will be slow to move,
allowing repeating rounds of storms to impact the central Gulf
Coast. FFGs are high, about 4 inches/hour, but the repeating rounds
of storms should rather quickly bring those numbers down, allowing
for scattered instances of flash flooding to develop where the
rains are most persistent by late afternoon, particularly for urban
areas. HREF probabilities for rainfall exceeding 5 inches are also
moderate to high (45-70%), with low end probabilities (~15%) of
exceeding 8 inches. Storms are also expected west along and just to
the north of the I-10 corridor between the Slight Risks covering
southeastern and far southwestern Louisiana. However, more
persistent forcing/greater storm coverage to the east and lower
FFGs to the west suggest there will be a relatively more isolated
threat in between. Similar to the Upper Texas Coast, nightfall
should see a decrease in shower and storm activity, ending the
flooding threat.
Putnam/Wegman
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
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