SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1206 AM CDT Mon Aug 05 2024
Valid 061200Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE TUESDAY
AFTERNOON AND EVENING ACROSS PARTS OF CENTRAL INTO SOUTHEAST
MONTANA...
...SUMMARY...
Strong storms posing at least some risk for severe weather may
impact coastal Georgia and South Carolina, a corridor across the
Ohio Valley into northern Mid Atlantic, parts of the northern
Rockies into adjacent Great Plains, and southern Arizona Tuesday
into Tuesday evening.
...Synopsis...
As northwestern Canadian mid-level ridging elongates eastward,
evolving positively tilted troughing to its south is forecast to dig
toward the western and central Canadian/U.S. border through this
period. This may begin to suppress an initially expansive ridge in
the lower latitudes of the western and central U.S., including a
gradual transition of flow from broadly anticyclonic to cyclonic
across the northern Rockies into northern Great Plains late Tuesday
through Tuesday night.
Downstream, a persistent slow moving mid-level low, initially over
northern Quebec, is forecast to redevelop eastward offshore, to the
south of Greenland, where significant surface cyclogenesis may take
place in response to forcing associated with a vigorous short wave
impulse accelerating east of the Canadian Maritimes. However, models
indicate that large-scale mid-level troughing will linger across the
eastern Canadian provinces and much of the Northeast, reinforced by
another perturbation digging southeast of Hudson/James Bays.
In response to these developments, an initial surface cold front is
forecast to slowly advance southward through the northern Mid
Atlantic, south of the southern Great Lakes into the Ohio Valley,
and perhaps more rapidly through the lower Missouri Valley and Great
Plains.
Farther south, between the Southwestern mid-level high and another
high over the subtropical western Atlantic, the remnant circulation
of what is now Hurricane Debby may only very slowly migrate eastward
across southeastern Georgia coastal areas.
...Coastal Georgia/South Carolina...
Forcing for ascent, boundary-layer buoyancy and low-level shear may
remain conducive to convective development with potential to produce
tornadoes into at least early Tuesday. However, this potential will
be limited by the slow motion of the lingering tropical cyclone, and
may largely become confined offshore of coastal areas later
Tuesday/Tuesday night.
...Ohio Valley into Mid Atlantic...
Westerly mid-level flow is still generally forecast to begin to
weaken Tuesday, and there may be a tendency for the front and/or
preceding outflow to advance south of the stronger lingering flow.
Peak afternoon boundary-layer instability in a narrow corridor
along/ahead of the front may also not be as large as preceding days.
However, it might still become sufficient to support scattered
organizing thunderstorm activity with potential to produce locally
damaging wind gusts Tuesday afternoon and evening.
...Northern Rockies and adjacent Great Plains...
Downstream of the approaching mid-level trough, it appears that
destabilization across the higher terrain of west central and
southern Montana will become supportive of scattered strong
thunderstorm development. Low-level moisture may become sufficient
to support CAPE on the order of 1000+ J/kg, in the presence of
strengthening westerly mid/upper flow (around 40-70+ kt in the
500-300 mb layer). This environment may become conducive to widely
scattered supercells with potential to produce severe hail and
locally strong wind gusts. It also still appears possible that
forcing for ascent, associated with low-level warm advection, could
eventually contribute to an upscale growing cluster accompanied by
increasing potential for severe surface gusts while spreading into
the more strongly heated and deeply mixed lower elevations through
Tuesday evening.
...Southern Arizona...
Models indicate that a strengthening easterly flow (to 20-30 kts) at
mid/upper levels by Tuesday afternoon may aid propagation of
developing thunderstorm activity off the higher terrain of
southeastern Arizona and adjacent portions of Sonora. A very warm
and deeply mixed boundary layer across the lower deserts is forecast
to become moderately unstable with CAPE up to around 2000+ J/kg.
This will support potential for upscale growth along strengthening
convective outflow, accompanied by continuing potential for strong
to severe surface gusts into Tuesday evening.
..Kerr.. 08/05/2024
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