SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Wed May 29 2024
Valid 292000Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
COLORADO...SOUTHWEST KANSAS...WESTERN OKLAHOMA...FAR NORTHEAST NEW
MEXICO...THE TX PANHANDLE...AND NORTHWEST INTO CENTRAL TEXAS...
...SUMMARY...
Scattered strong storms posing a risk for severe hail and wind still
appear likely across the northern and central High Plains late this
afternoon and evening. Isolated large hail will also remain possible
in southwest Texas.
...Southeast Texas and Louisiana...
Expanded the marginal risk across southeast Louisiana where ongoing
thunderstorms continue amid mid to upper 70s dewpoints and
increasing instability.
Additional thunderstorms are expected to develop across southeast
Texas in the next few hours. See MCD #1067 for additional details.
...Northern High Plains...
Thunderstorms have started to develop across Montana and eastern
Wyoming which will move east and pose a threat for severe wind and
large hail this afternoon/evening. For more information, see MCD
#1064 and #1066.
...Central High Plains...
Increased ascent across a destabilizing airmass across the higher
terrain has led to thunderstorm development early this afternoon. As
the Plains destabilize further and the cap erodes, expect severe
thunderstorms with a threat for large hail and damaging wind gusts.
See MCD #1065 for additional information.
..Bentley.. 05/29/2024
.PREV DISCUSSION... /ISSUED 1125 AM CDT Wed May 29 2024/
...Synopsis...
A mid-level trough will traverse the northern Rockies as an embedded
impulse overspreads the southern High Plains and a second mid-level
trough meanders over the Northeast today. Along the East Coast and
High Plains regions, surface lee troughing will result, that in
tandem with moisture advection, supports the potential for at least
scattered thunderstorm development through the afternoon and evening
hours. Over the High Plains, modest mid-level flow overspreading a
developing low-level jet (especially over the northern High Plains
during the evening hours) will provide enough vertical wind shear to
support strong to potentially severe thunderstorms.
...Northern and Central High Plains...
Diurnal heating ahead of the surface lee trough will assist in
deepening/mixing the boundary layer by afternoon. MLCAPE should
reach 1500-2500 J/kg by afternoon peak heating as 8-9 C/km mid-level
lapse rates overspreads low to mid 50s F. As the mid-level trough
begins to overspread the region and convective temperatures are
reached, convective initiation should occur along the higher
terrain. Deep-layer shear will not be overly strong from the MT/ND
border southward, so mainly multicell clusters (perhaps outflow
dominant) are expected. Given the degree of buoyancy available, at
least a few severe gusts or instances of large hail are possible
with the initial storms. Locally stronger mid-level flow/deep-layer
shear will overspread eastern MT, where a deep boundary layer will
exist. Fast moving, high-based storms may quickly merge their cold
pools, promoting a relatively concentrated threat of strong wind
gusts (some of which may be severe). These storms should track
eastward and merge with the High Plains convection, supporting one
or more MCSs with a severe gust threat into the evening.
...Trans Pecos Region in Texas...
Though deep-layer ascent will be relatively weak, enough lift will
be provided by a subtle passing mid-level impulse, along with strong
diurnal heating and orographic lift over the Davis Mountains, to
support convective initiation ahead of the dryline. 2000+ J/kg
MLCAPE will become commonplace as a 8-9 C/km mid-level lapse rates
plume overspreads the Trans Pecos area, with over 35 kts of
effective bulk shear also likely given modestly curved, elongated
hodographs. Splitting supercells are expected to be the main mode of
convection, accompanied by primarily a large hail threat (some
instances of which may exceed 2 inches in diameter).
...Southeastern Texas...
A remnant MCV continues to meander over eastern TX today, serving as
a source of lift for convective initiation this afternoon as
convective temperatures are reached. Surface dewpoints well over 70
F, overspread by 7 C/km mid-level lapse rates, will boost MLCAPE to
2500 J/kg. The presence of the MCV will also locally boost
deep-layer shear in the absence of other synoptic foci to support
elongated hodographs. Stronger multicells and perhaps a supercell
could pose an isolated severe hail/wind risk through afternoon.
...Portions of the Mid Atlantic...
Scattered thunderstorms (perhaps a few briefly becoming strong) will
be possible this afternoon as a 60+ kt 500 mb jet streak overspreads
the Mid Atlantic. Mid-level lapse rates should remain poor over the
region, with expected 250-500 J/kg of MLCAPE constrained to short
and thin profiles. When also considering modest deep-layer shear,
the severe threat should remain too sparse to support the
introduction of Category 1/Marginal risk probabilities. Nonetheless,
a strong wind gust capable of tree or powerline damage cannot be
completely ruled out.
...Far southern Florida Peninsula...
Surface temperatures exceeding 90 F by afternoon peak heating will
support convective initiation along sea-breeze boundaries,
particularly south and east of Lake Okeechobee. The relatively hot
temperatures will mix the boundary layer, and when considering poor
mid-level lapse rates, 1500-2000 J/kg of the expected MLCAPE should
be constrained to tall and thin profiles. Since deep-layer shear
should also be weak, the severe threat should remain too limited for
the introduction of severe probabilities. Nonetheless, a stronger
and longer lasting storm could produce a severe gust.
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