SPC 1200Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1102 PM CST Sun Jan 10 2021

Valid 111200Z - 121200Z


The risk for thunderstorms appears negligible across much of the
nation today through tonight.

Short waves will continue to emerge from a strong, generally zonal
mid-latitude Pacific jet, before progressing into and through
modestly amplified branching downstream westerlies.  To the
southeast of the center of an initially broad and deep cyclone near
Kodiak Island, models indicate that one of these perturbations may
contribute to modest surface cyclogenesis across the northeastern
Pacific.  Coinciding strengthening of southwesterly lower/mid
tropospheric wind fields into the Pacific Northwest is also
forecast, including to 50-80 kts in the 850-700 mb layer,
accompanied by a plume of moisture emanating from the lower
latitudes of the western and central Pacific.  While this may
contribute to the development of very weak CAPE, primarily to the
west of the Cascades, it appears that colder mid-level air with
steeper lapse rates more supportive of convection capable of
producing lightning will generally remain to the northwest of the

Downstream, generally stable conditions will be maintained across
much of the nation.  An influx of moisture off a still modifying
boundary layer over the Gulf of Mexico does appear likely to
overspread much of the Southeast, as a short wave impulse emerges
from larger-scale troughing to the lee of the southern Rockies. 
However, this perturbation will undergo considerable deformation as
it accelerates into increasingly confluent mid-level flow across and
east of the Mississippi Valley.  And associated surface wave
development along a frontal zone across the northeastern Gulf of
Mexico and northern Florida into the western Atlantic is forecast to
remain weak.  Warming temperatures aloft, to the south of the
perturbation, should maintain weak mid-level lapse rates across and
inland of the northeastern Gulf coast.  And models indicate that
boundary-layer moistening will only become supportive of very weak
CAPE across the coastal waters and immediate coastal areas.  While a
categorical risk for thunderstorms is being maintained across this
region, probabilities may be near the minimum 10 percent threshold.

..Kerr.. 01/11/2021

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