Severe Weather Center

Current Severe Weather Discussion Issued by the Storm Prediction Center

   SPC AC 101626

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1126 AM CDT Thu Apr 10 2025

   Valid 101630Z - 111200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE LOWER MISSISSIPPI VALLEY INTO THE SOUTHEAST...

   ...SUMMARY...
   Scattered strong to severe thunderstorms are expected from portions
   of the lower Ohio Valley into the Deep South this afternoon and
   evening. Large hail and damaging winds should be the main threats.

   ...Lower Ohio Valley into the Southeast...
   Large-scale upper troughing is forecast to further amplify today
   over the eastern CONUS, as multiple embedded shortwave troughs
   rotate through its base. A lead shortwave trough will advance
   eastward over the upper OH Valley and central Appalachians through
   the day, while a trailing shortwave trough is expected to move
   southeastward across the mid MS Valley, lower OH Valley, and TN
   Valley through this evening. A weak/diffuse cold front is likewise
   forecast to develop southeastward across these regions through the
   day, providing some focus for thunderstorm development later this
   afternoon and evening.

   12Z soundings across the Southeast indicate shallow/limited
   low-level moisture in place, but also relatively steep mid-level
   lapse rates. Strong daytime heating, gradual low-level moistening
   from the southwest, and cooling mid-level temperatures associated
   with the trailing shortwave trough should all aid in the development
   of around 1000-1500 J/kg of MLCAPE ahead of the front by mid
   afternoon. Weak low-level westerly winds are forecast to gradually
   veer and strengthen with height through the mid/upper levels, which
   will likely foster relatively long/straight hodographs and 40-55+ kt
   of effective bulk shear. This should easily support organized
   updrafts, including the potential for supercells.

   Current expectations are for robust thunderstorm development to
   occur over the lower OH Valley/Mid-South region by 18-20Z. This
   initial activity will likely be supercellular, with an associated
   threat for large hail given steep lapse rates aloft and strong
   deep-layer shear. Additional strong to severe thunderstorms should
   develop through the rest of the afternoon and early evening across a
   larger portion of the lower OH Valley into the TN Valley and
   Southeast. Any convection which can remain at least semi-discrete
   should pose a continued hail threat. Some tendency for upscale
   growth into multiple bowing clusters seems likely by late
   afternoon/early evening. A well-mixed boundary layer should support
   efficient downward momentum transfer and a threat for scattered
   damaging winds, before convection eventually weakens by mid/late
   evening with the loss of daytime heating.

   ..Gleason/Guyer.. 04/10/2025

   CLICK TO GET <a href="/products/outlook/archive/2025/KWNSPTSDY1_202504101630.txt">WUUS01 PTSDY1</a> PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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Current Excessive Rainfall Discussion Issued by the Weather Prediction Center

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1143 AM EDT Thu Apr 10 2025
Day 1
Valid 16Z Thu Apr 10 2025 - 12Z Fri Apr 11 2025

...16Z Update...

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Latest hi-res guidance continues to suggest the potential of
thunderstorms with up to 1 to 1.5"/hour rainfall rates broadly
from the Ohio Valley into the Southeast, particularly for portions
of the Tennessee Valley into the southern Appalachians. However,
storm coverage and progression will likely limit overall totals to
these isolated quick bursts which will keep any flooding concerns
related to some isolated ponding on roadways in urban areas.

Putnam

...Previous Discussion...

...OH Valley and Mid-South...
The latest GOES-E WV suite shows a mid-level trough gradually
amplifying across the Midwest as shortwave energy digs
southeastward from the northern Plains. The model guidance shows a
further amplification of mid-level height falls down across the OH
Valley and Mid-South by later today and tonight which will allow
for a cold front and an attendant area of low pressure to cross
portions of the region. Locally heavy showers and thunderstorms are
expected to develop in the warm sector this afternoon and evening
as a moderately buoyant airmass characterized by MLCAPE values of
1000 to 1500 J/kg sets up and couples with proximity of left-exit
region upper jet dynamics associated with the arrival of a jet
streak. Adding to the convective footprint will be steep mid-level
lapse rates given the amplifying trough overhead, and a sufficient
amount of shear will be in place for some supercell convection.
While moisture is not going to be particularly supportive of heavy
rainfall totals, the convection will be locally well-organized and
capable of producing some hourly rainfall totals of as much as 1 to
1.5 inches. Areas from KY/TN down through northern MS/AL will
generally see scattered pockets of this convection with this
rainfall potential. Given the wet antecedent conditions from the
most recent high-end rainfall/flooding event, it is possible that
these additional rains may result in an isolated concern for some
flash flooding. For now, a Marginal Risk will not be depicted given
some question marks on the overall coverage of convection and
modest rainfall totals, but a non-zero threat of additional
flooding will exist at least on a small-scale and highly localized
basis.

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Orrison


Day 1 threat area: <a href="https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt"<u>www.wpc.ncep.noaa.gov/qpf/94epoints.txt</u></a>