SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 PM CST Tue Feb 06 2024
Valid 071200Z - 081200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
The risk for severe thunderstorms appears negligible across the
U.S., today through tonight.
...Synopsis...
Downstream of an intensifying cyclone, mid/upper ridging is in the
process of building across the central into eastern mid-latitude
Pacific. To the east of this ridging, a significant short wave
trough is already digging offshore of the Pacific Northwest coast,
and prominent downstream troughing, emerging from the southern
mid-latitude and subtropical eastern Pacific, continues to
accelerate northeastward, inland and through the Southwest.
As the central Pacific cyclone continues to deepen and turn
north-northeastward, toward the Aleutians, models indicate that the
mid/upper ridging will amplify further across the northeastern
Pacific today through tonight. It appears that impulse approaching
the Pacific coast will continue digging through much of this period,
across and inland of the California coast, generally to the west of
the Sierra Nevada. The larger-scale downstream troughing is
forecast to progress across and east of the Rockies, with one
embedded impulse, initially approaching the southern California
coast, accelerating east-northeastward across the Southwestern
international border vicinity through the Texas/Oklahoma Panhandle
vicinity by 12Z Thursday. A preceding impulse, emerging from the
Four Corners region, is forecast to accelerate into the northern
Great Plains and contribute to significant cyclogenesis across the
Dakotas vicinity.
...Great Plains...
By late this afternoon, models indicate an elongated area of
deepening surface low pressure from the southeastern Canadian
Prairies into the southern U.S. Great Plains, with perhaps one
embedded low center beginning to migrate northeast of the Cheyenne
Ridge vicinity. While this will be accompanied by a broad swath of
strengthening southerly low-level flow through the day across the
southern Great Plains toward the Upper Midwest, an initially dry
low-level environment, not only across much of the Great Plains but
also the lower Rio Grande Valley and western Gulf of Mexico, will
preclude substantive boundary-layer moistening. Destabilization
will further be hampered by cloud cover associated with
mid/high-level moisture return off the Pacific, and inhibition
associated with a plume of relatively warm and dry
lower/mid-tropospheric air overspreading the Great Plains.
However, beneath mid-level cooling, and a developing dry slot,
across the high plains, models do suggest that steepening lower/mid
tropospheric lapse rates may become supportive of at least very weak
boundary-layer destabilization by late afternoon. It is possible
that this could become supportive of widely scattered convective
development, which may become capable of producing lightning. Based
on forecast soundings, it remains unclear how sustained any
individual storms may be, but high resolution model output suggests
that potential for weak thunderstorm activity may persist through
this evening, near the possible developing surface low track across
west central Nebraska through south central South Dakota.
...Pacific Coast and Southwest...
The risk for thunderstorms near southern California coastal areas
seems likely to diminish by late this morning, as the supporting
mid-level cold core shifts inland into the lower Colorado Valley.
Beneath the broader mid-level cold pocket overspreading the Four
Corners states during the day, the risk for scattered weak
thunderstorm development will probably increase through afternoon,
as insolation contributes to boundary-layer destabilization.
Convection seems likely to wane quickly after sunset, due to both
radiational surface cooling and the tendency for warming in
mid-levels.
..Kerr/Squitieri.. 02/07/2024
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