FOUS30 KWBC 111551
QPFERD
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1151 AM EDT Sun Aug 11 2024
Day 1
Valid 16Z Sun Aug 11 2024 - 12Z Mon Aug 12 2024
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR CENTRAL UTAH
THROUGH NORTHWESTERN ARIZONA, PORTIONS OF THE OZARKS AND CENTRAL
PLAINS, AND FOR THE COASTAL CAROLINAS...
...16Z Update Summary...
Some minor adjustments were made to the SLGT risk areas across the
Plains and Ozarks with very little change to the other SLGT risk
areas out west and across the Carolinas. More details for each
setup can be found in the correlating sub-headings below....
Kleebauer
...Central Utah through Northwestern Arizona...
16Z Update: Not much change within the suite of CAMs and global
deterministic so far this morning with the HREF blended mean QPF
relatively unchanged compared to the recent 00/06z runs. Shortwave
is analyzed across Central NV this morning with eastward movement
that will eventually help ignite the enhanced convective concerns
across parts of the Great Basin. General totals of 0.5-1" will be
common as far an areal average, but pockets of 1-2+" will be
plausible given the increasing PWATs and elevated theta-E's
advecting northward through Northwest AZ into Southern UT. SBCAPE
between 2000-3000 J/kg will be situated within the current SLGT
risk forecast implying a very suitable instability axis that will
aid in the heavier convective cores this afternoon and evening.
Considering variables at hand, there was little need to deviate
from the previous forecast, so continuity was maintained.=20
Kleebauer
..Previous Discussion..
Monsoonal moisture will continue to draw northward across the Four
Corners region today. The jet stream and an upper level jet streak
will be set up across northern Utah today. PWATs increasing above
0.75 inches will boost portions of southern Utah to 2.5 sigma above
normal. With moisture and forcing in place, expect a renewed round
of afternoon convection across this area. With previous days'
storms having soaked the soils in some areas, the flash flooding
threat will be higher today as compared to previous days across
Utah and portions of northwestern Arizona. The Slight risk area was
expanded southward with this update to include much of the Grand
Canyon and points north, including Glen Canyon.
...Portions of the Ozarks and Central Plains...
A pretty stout MCS is currently within the final stages of its
life-cycle this morning after dropping a barrage of rainfall across
Central OK with totals across the OKC metro and surrounding locales
coming in between 4-7" based on recent obs. There's been some
warming within the cloud tops in recent IR satellite scans meaning
the complex will be decaying gradually as move into the afternoon
hours. There was thought in removing the current SLGT risk over
Central OK, but with rain ongoing and Flash Flood Warnings in
effect, maintained continuity across the region to account for the
current rainfall. Expect that area to be removed in the next 01z
update as the rainfall expected this period is focused through this
morning with a quieter night anticipated.=20
Further north and northeast will be another story as the next
complex will develop late this evening as a the leading edge of a
30-50kt LLJ will nose into the Four State area (MO/KS/AR/OK) a
shortwave bisecting the region as it ejects out of KS. The setup is
driven by a strong focus of elevated instability with MUCAPE
between 1000-2000 J/kg across the above region within an axis of +1
to +2 deviation PWATs positioned across Central Plains to the
western half of the Mid-Mississippi Valley. There's some
uncertainty on the exact placement of the highest QPF axis with
guidance jockeying on how the mid-level evolution will come to
fruition which plays a significant role in the timing of initiation
of convection, as well as the magnitude of convection that does
develop over the area. The strongest probabilities for heavy precip
are located over Southeast KS into Southeast MO for the second
round of heavy precip within the current SLGT risk forecast. There
was enough consensus to pull away from the Kansas City area,
although another potential complex of thunderstorms will be passing
to the north, putting the metro in a "squeeze" of sorts when it
comes to relevant QPF maxima. In any case, the forecast SLGT was
maintained for the threat with the best potential likely lying
within urbanized areas given the antecedent conditions surrounding
the forecasted zone of impact. The highest probabilities for flash
flooding concerns lies near Tulsa thanks to the ongoing situation
with the MCS with some guidance also bring in the southern flank of
the second round overhead towards the very end of the forecast
period. A tricky forecast overall, but the low-end SLGT risk
remains.=20
Kleebauer
...Coastal Carolinas...
16Z Update: The setup from the last few days will be on repeat once
again with scattered to widespread convection developing across the
Carolinas thanks to lingering buoyancy, elevated moisture tied near
and east of the stationary front, and afternoon destabilization
allowing for a priming of the environment with eventual cell
initiation. The probability fields are basically a carbon copy from
yesterday with neighborhood probs for >3" settled between 45-80%
over a large area with the highest probabilities positioned just
inland from Morehead city down to Wilmington. This area has been
hit incessantly for several days leading to very low FFGs and
continued flooding that will only be exacerbated with any
additional rainfall. Considering the relevant probabilities and
consistent CAMs depiction of scattered heavy thunderstorms this
afternoon and early evening, the SLGT risk remains with little
variance from the previous forecast.
Kleebauer
..Previous Discussion..
Guidance has been gradually shifting south and east/closer to the
coast with the axis of the heaviest rain with the afternoon
convection expected tonight. Thus, the Slight and surrounding
Marginal risk areas have been shrunk to the southeast accordingly.
Nonetheless antecedent conditions along the coast remain very
favorable in the recovery post-Debby. Expect similar coverage of
flash flood warnings as today's storms, but are likely to occur
further east. Given the uncertainty as to where the storms will
form, the Marginal risk still extends into central NC and western
SC for the potential for more widely scattered storms, as well as
across eastern Georgia.
Wegman
Day 2
Valid 12Z Mon Aug 12 2024 - 12Z Tue Aug 13 2024
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE FOUR
CORNERS REGION EAST TO THE MID-MISSISSIPPI VALLEY AS WELL AS FOR
PORTIONS OF THE COASTAL CAROLINAS...
...Four Corners Region to the Mid-Mississippi Valley...
Concern continues to increase with potential heavy rain and
subsequent flash flooding in various areas. For the Four Corners,
no major changes are expected, but with the greatest moisture
having shifted east, convective coverage should be lesser on Monday
as compared to today. Meanwhile, the signal for heavy rain remains
strong from eastern Colorado into western Kansas. Easterly flow
north of an ejecting low will draw plentiful Gulf moisture into the
High Plains of Colorado. Meanwhile, a stalled front to the north
will supply lower level forcing. The result will be an area of
heavy rain caused by training storms moving east along the front,
as moisture flowing northwestward on the warm side of the front
supports backbuilding. There remains some uncertainty both with the
placement of the heaviest rains, and for Kansas, the development of
drought conditions potentially resulting in less flooding. However,
it appears likely a Slight will be needed as plentiful moisture
will support storms capable of rates to 2 inches per hour, which in
areas of training storms should overcome otherwise high FFGs.
Further east into Missouri, lingering storms from tonight will
continue into Monday morning. Then, the stalled out front over the
area will begin to reorient, but pivoting over Missouri. This
should reduce the overall coverage of rainfall over Missouri for
the day, but will keep the area in the crosshairs for heavy=20
rainfall going forward.
...Coastal Carolinas...
Some lingering storms are possible along the coast Monday afternoon as
the front over the area dissipates. With much reduced storm
coverage, the Marginal remains over the area for the potential for
isolated instances of flash flooding. This would likely be the
result of sea breeze interactions.
Wegman
Day 3
Valid 12Z Tue Aug 13 2024 - 12Z Wed Aug 14 2024
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE FOUR
CORNERS REGION TO THE MID-MISSISSIPPI VALLEY, AS WELL AS FOR
EASTERN NORTH CAROLINA...
...Missouri...
A renewed push of Gulf moisture with the LLJ will impact a
persistent front across Missouri today. This will likely result in
an area of training thunderstorms capable of localized flash
flooding. The area is likely to be upgraded to a Slight with future
updates and higher confidence, but given the counter flow out of
the northeast on the dry side of the front over the Midwest, it's
likely that training storms are likely to impact a narrow corridor
over Missouri along the front. There is potential that the St.
Louis metro may be part of the heavy rain corridor.
...Eastern North Carolina...
A bit stronger moisture push off the Atlantic may result in more
widespread showers and storms a bit further inland into North
Carolina. With little to organize the convection however, the flash
flooding threat remains isolated.
Wegman
Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!45Fwd5Z3_8VQg3VuaOSKQ4A6QYOLSWZ5o5dtduymbSPn=
UA7u17ylyv6Cdq2CneN9KHY7Vt2OB873HOaQwzUbK4vO-J8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!45Fwd5Z3_8VQg3VuaOSKQ4A6QYOLSWZ5o5dtduymbSPn=
UA7u17ylyv6Cdq2CneN9KHY7Vt2OB873HOaQwzUbjKEqaqs$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!45Fwd5Z3_8VQg3VuaOSKQ4A6QYOLSWZ5o5dtduymbSPn=
UA7u17ylyv6Cdq2CneN9KHY7Vt2OB873HOaQwzUb2WLRFBI$=20
=3D =3D =3D
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.
--- SBBSecho 3.20-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
|
