SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CST Wed Mar 08 2023
Valid 091200Z - 101200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THURSDAY
AFTERNOON INTO EVENING ACROSS PARTS OF SOUTHERN ARKANSAS AND
NORTHERN MISSISSIPPI INTO ADJACENT PORTIONS OF ALABAMA...AND PERHAPS
THURSDAY EVENING ACROSS PARTS OF TEXAS...
...SUMMARY...
Strong thunderstorms may impact a corridor from southern Arkansas
into northern Alabama Thursday afternoon and evening, and perhaps
portions of central Texas Thursday night. A couple of these may be
accompanied by at least some severe weather potential, mainly in the
form of hail.
...Synopsis...
Within the large-scale flow across the eastern Pacific into the
western Atlantic, models indicate that blocking will remain
prominent in the higher latitudes. This likely will include one
lingering mid-level high near the Aleutians and another over the
northeastern Canadian Arctic. In between, general larger-scale
mid-level troughing will persist, with a number of notable
progressive short wave perturbations. This is forecast to include
one trough and embedded low pivoting into the northern U.S. Pacific
coast. While downstream short wave ridging builds across the
eastern Great Basin into the central Great Plains by late Thursday
night, a trough to the east appears likely to advance east-northeast
of the lower Missouri Valley into the upper Great Lakes/lower Ohio
Valley vicinity.
In lower latitudes, models indicate that broad mid-level ridging
will persist across much of the southern tier of the U.S., although
the lead short wave trough may contribute to some suppression of
mid-level heights near/north of the Red River and Ark-La-Tex into
the eastern Gulf Coast states.
Cold/potentially cold surface ridging, still entrenched across most
areas to the east of the Rockies early Thursday, will tend to
suppress substantive surface cyclogenesis as the lead mid-level
trough migrates east of the Rockies. However, an area of low
pressure may begin to form late Thursday evening into early Friday,
along the primary low-level baroclinic zone across parts of the Mid
South into lower Ohio Valley. In its wake, the shallow leading edge
of the cold surface-based air (initially extending from the Edwards
Plateau of Texas into the lower Mississippi Valley at 12Z Thursday)
probably will shift southward toward the northwestern/north central
Gulf coastal plain.
...Southern Great Plains/lower Mississippi Valley vicinity...
Inhibition associated with the remnants of a plume of elevated
mixed-layer air, and warm layers with weak lapse rates farther
aloft, may continue to confine thunderstorm development to where
weak destabilization (associated with moisture return) above/to the
cool side of the surface front is maintained. It appears that the
most substantive instability, perhaps including CAPE on the order of
500-1000 J/kg, will generally be focused in a narrow corridor near
and to the immediate north of the front.
Along this corridor, a combination of forcing for ascent associated
with low-level warm advection and the gradual suppression of
mid-level heights may support intensifying thunderstorm development
by Thursday afternoon across parts of southeastern Arkansas into
northern Mississippi. Given the stable surface-based layer, rather
modest CAPE, and weak to modest low-level flow, the potential for
damaging wind gusts remains uncertain. However, if convection is
able to consolidate and organize in the presence of sufficiently
strong cloud-bearing layer shear, a few strong surface gusts might
not be out of the question before activity weakens while continuing
east-southeastward through parts of northern/central Alabama
Thursday evening. Otherwise, the strong deep-layer shear probably
will contribute to the potential for at least marginally severe hail
in the stronger and, mainly, more discrete storms.
Meanwhile, across northeastern into central Texas, and southwestward
toward the Edward Plateau/adjacent Rio Grande Valley vicinity,
convective potential is more unclear through the period, due to
stronger mid/upper inhibition and weaker (or at least more
uncertain) mid/upper support. However, isolated to widely scattered
strong storms posing some risk for severe hail may not be out of the
question, particularly Thursday evening.
...Northern California...
Forecast soundings suggest that weak conditional instability may
develop by late Thursday night along the western slopes of the
northern Sierra Nevada, perhaps supporting convection capable of
occasionally producing lightning prior to 12Z Friday.
..Kerr.. 03/08/2023
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