SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Thu Jun 08 2023
Valid 082000Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FOR PARTS OF SOUTH CENTRAL AND SOUTHEAST TX...
...SUMMARY...
The most likely corridor for large hail and isolated damaging winds
will be across a portion of southeast Texas into early evening.
...South central/southeast TX through this evening...
Convection is ongoing from just east of San Antonio to
north/northeast of College Station. The somewhat stronger vertical
shear and potential for more organized/supercell storms with large
hail will remain from the San Antonio cluster southeastward, in
association with a remnant MCV. Farther northeast, weaker vertical
shear suggests more pulse-type storms into southeast TX, where
isolated wind damage and large hail may occur for the next few
hours.
...ND area this afternoon through tonight...
Convection is forming this afternoon along a wind shift/front across
west central ND. Flow is weak over this area near the midlevel
ridge, but moderate-strong buoyancy (MLCAPE near or above 2000 J/kg)
and midlevel lapse rates near 7 C/km will support the threat for
occasional strong-severe gusts and isolated large hail with
multicell clusters that will spread slowly east/southeastward
through tonight.
...South GA and vicinity the remainder of the afternoon...
Storm coverage is expected to remain rather isolated, given weak
forcing for ascent and relatively dry midlevel air. However, a few
storms remain possible along a weak front from southern SC across
south GA and far north FL. Moderate buoyancy and rather weak
vertical shear will primarily support multicell storms with a
marginal wind threat. Slightly stronger vertical shear is present
near the front across southern SC, where isolated large hail may
also occur.
..Thompson.. 06/08/2023
.PREV DISCUSSION... /ISSUED 1129 AM CDT Thu Jun 08 2023/
...Southeast TX...
An MCV over central TX will track southeast off the Upper TX Gulf
Coast this evening. Nearly full insolation will occur ahead of the
MCV coincident with upper 60s to low 70s surface dew points which
persist north of an MCS that tracked across Deep South TX earlier
this morning. This should yield a pocket of moderately large
buoyancy with MLCAPE reaching 2000-3000 J/kg at peak heating.
Consensus of CAM guidance suggests isolated thunderstorms should
develop ahead of the MCV, with the 12Z WRF-NSSL indicative of at
least scattered coverage which would typically be expected with an
MCV. Guidance generally indicates slight mid-level warming in
forecast soundings which may explain the tendency for more isolated
coverage in most CAMs. A belt of enhanced mid-level northwesterlies
from 30-40 kt should be relegated to south-central TX and the
Middle/Lower TX Gulf Coast. A relatively confined overlap of
favorable CAPE/shear space should occur in a portion of southeast
TX. With minimal 0-3 km SRH, updraft rotation should be limited to
the mid-levels. Main threat will be large hail along with isolated
damaging winds until convection moves offshore this evening.
...South GA/SC and north FL...
A slowly southward-sagging surface cold front will serve as a focus
for at least isolated thunderstorms later this afternoon across
parts of the Southeast. West-southwesterly low-level flow will
persist ahead of the front similar to yesterday, but mid-level
westerlies will be stronger today owing to a jet arcing across the
southern Appalachians and the NC/SC border area. This should
compensate for weak mid-level lapse rates and may yield small to
marginally severe hail over the Lower Savannah Valley. Otherwise,
with nearly full insolation, steep low-level lapse rates will
support potential for a primary threat of strong to marginally
severe microbursts.
...Lower Mid-Atlantic Coast...
Isolated, marginally severe hail and locally strong gusts should
persist through the mid-afternoon until lower-topped, frontal-forced
thunderstorms move offshore. A pocket of steeper 850-600 mb lapse
rates in conjunction with an elongated hodograph in the upper
portion of the buoyancy profile will support small to marginally
severe hail production. This may enhance downdraft potential over
the Delmarva peninsula where boundary-layer heating is relatively
greater and yield locally strong surface gusts despite weak
low-level flow. For additional information, please see MCD 952.
...Northern Great Plains...
An upper ridge persists across the central Great Plains
northwestward into eastern MT. With 60-64 F boundary-layer dew
points, an arc of moderately large buoyancy with 2000-3000 J/kg of
MLCAPE will develop from parts of eastern MT to the eastern Dakotas.
Deep-layer shear will be rather weak, especially within the axis of
the mid-level ridge, suggesting that slow-moving, pulse storms will
dominate. 15-25 kt effective bulk shear may develop across parts of
central to eastern ND where light low-level southeasterlies persist
beneath modest mid to upper-level west-northwesterlies. In this
regime, sporadic occurrences of isolated severe wind gusts and large
hail should peak in the late afternoon to early evening, before
waning after sunset.
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