National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
ACUS01 KWNS 151956
SWODY1
SPC AC 151955

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Mon Apr 15 2024

Valid 152000Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL GREAT PLAINS AND CENTRAL TO EASTERN VIRGINIA AND EASTERN
MARYLAND...

...SUMMARY...
Scattered severe thunderstorms are likely across parts of the Great
Plains, beginning mainly this evening and continuing overnight.
Several tornadoes, large to very large hail, and damaging wind gusts
all appear possible.  Strong tornadoes may occur this evening across
parts of Kansas and Nebraska.  Scattered severe gusts are likely
this afternoon into the evening across portions of Virginia.

...Synopsis...
Few forecast changes are needed based on latest observations and
recent short-range guidance. Northward moisture return continues
amid steady surface pressure falls across northeast CO with
convective initiation anticipated in the coming hours across several
regions within the coming hours (see MCDs 440, 441, and 442 for
additional, region-specific details).

...VA/MD...
The Enhanced risk has been modified slightly to better reflect the
corridor of strong/severe wind potential. Latest visible imagery
shows deepening cumulus along a surface pressure trough with
temperatures warming well into the mid/upper 80s. Low-level lapse
rates have increased up to 9 C/km along/ahead of this boundary, as
well as downstream of ongoing convection. These low-level
thermodynamic conditions will support a damaging wind threat with
the strongest cells in the coming hours.

...KS/NE...
Richer moisture is noted advecting northward across central KS into
south-central NE in the form of a shallow cumulus field. Further
convective deepening within this field is anticipated amid continued
heating/destabilization and increasing ascent with the approach of
the primary synoptic wave. Latest WoFS guidance suggests CI may
begin as early as the 22-00 UTC time frame, which is supported by
these observations.

..Moore.. 04/15/2024

.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Apr 15 2024/

...Synopsis...
Water-vapor imagery this morning shows a large, closed upper cyclone
over UT with this feature ejecting over the southern/central Plains
tonight.  A strong mid/upper-level jet will overspread much of the
southern/central Plains while a cyclone deepens over the High Plains
today.  Southerly low-level flow will facilitate moisture return
northward concurrent with a warm front advancing northward across
the central Great Plains.  A dryline is forecast to mix eastward
across the southern/central High Plains through peak afternoon
heating, before retreating westward this evening across parts of the
TX/OK Panhandles and western KS.

...Northern/Central Plains (Kansas/Nebraska/South Dakota)...
No appreciable change in thinking from the previous forecast in the
overall severe scenario for later today/tonight.  Capping will
likely inhibit storm initiation over the northern/central Plains
through at least late afternoon.  However, strong southerly
low-level flow will advect increasingly rich moisture northward with
upper 50s to low 60s surface dewpoints by early this evening across
the warm sector.  Prior to storm initiation, 2000-3000 J/kg MLCAPE
is forecast concurrent with strengthening mid/upper-level flow.

Once convective initiation occurs (early evening), rapid supercell
development is expected as a LLJ intensifies.  Large to very large
hail (around 2-3 inches in diameter) will be a threat with any
supercells that can form along/near the warm front, or southward
along the length of the dryline into western KS.  Enlarged
hodographs during the evening will occur through midnight while some
additional increase in low-level moisture acts to counter increasing
CINH due to cooling surface temperatures.  If a few discrete
supercells can maintain a feed of effective near-surface inflow
parcels, the tornado risk will likely become focused with those
storms.  Given the strength of shear/buoyancy combination, strong
tornadoes appear possible this evening/tonight across portions of
KS/NE.  As additional storms develop, an evolving cluster growing
upscale will potentially yield severe gusts, most likely from
north-central KS into central NE overnight.

...Southern Plains (Oklahoma/Texas)...
A lower coverage of storms is expected to develop farther south
along the dryline over parts of the southern Great Plains late this
afternoon into tonight.  Ample mid to high-level clouds will tend to
limit daytime heating to some extent along the length of the
dryline.  However, model guidance shows sufficient agreement in
depicting storm development across parts of northwest TX by late
this afternoon.  Supercells appear likely with this activity given
strong (50-60 kt) deep-layer shear and large buoyancy.  Isolated
large to very large hail will probably be the main threat with this
convection as it moves towards north-central TX. But, occasional
severe/damaging winds and perhaps a couple of tornadoes may also
occur through the early evening.  Most guidance indicates any
supercells which develop will weaken with eastward extent as they
encounter increasing MLCIN, and become increasingly displaced from
the better large-scale ascent with the upper trough/low ejecting
over the central Plains.  A highly conditional severe threat remains
apparent across OK late this afternoon and evening, with a favorable
parameter space to support supercells capable of producing all
severe hazards.  But, much of OK may have a relative minimum in
convective activity until late tonight as a Pacific cold front
overtakes the dryline.

...Lower OH Valley into the Mid-Atlantic states...
Morning surface mesoanalysis places a residual frontal zone draped
over central IN/OH with a low-level moisture reservoir (low 60s deg
F surface dewpoints) extending from the confluence of the MS/OH
rivers northeastward into the lower Wabash Valley.  Atop this
moisture, a plume of steep 700-500 mb lapse rates (8.0 to 8.3 deg
C/km) sampled at the Lincoln, IL and Wilmington, OH raob sites, will
overspread the OH Valley eastward into VA today.  The richer
low-level moisture will likely remain west of the Appalachians
across the lower OH Valley where 1500-2500 J/kg MLCAPE is forecast.
Widely scattered thunderstorms are forecast to develop by mid
afternoon within the moist axis along/south of a stalled front over
the OH Valley.  Effective shear 25-35 kt will support a mix of
supercells and organized line segments capable of hail and wind.

Farther east, steep lapse rates from the surface to 500 mb are
depicted in forecast soundings by early to mid afternoon (8 deg
C/km).  Although PW will be lower across the Mid-Atlantic region, a
more deeply mixed boundary layer is forecast with strong westerly
mid-level flow (40 kt).  Initial cellular storms will likely develop
over the higher terrain with subsequent development across northern
VA.  A band of storms posing a risk for severe gusts (60-70 mph) and
resultant wind damage is forecast.  Given the lapse rate profile
coupled with ample mid- to high-level flow and a linear mode, have
increased wind probabilities and an upgrade to level 3 categorical
outlook this update.  The overall severe threat should gradually
diminish through late evening with the loss of diurnal heating.

$$