SPC 1300Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0617 AM CST Mon Jan 11 2021

Valid 111300Z - 121200Z


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

In mid/upper levels, a split-flow pattern is apparent over the
CONUS. The northern stream crosses the northern part of a strongly
positively tilted mean trough that extends from the Great Lakes
across the southern Plains to northern Baja.  Meanwhile the southern
stream jet curves around the trough's base across northwestern/
north-central MX and the Gulf Coast States.  While the mean trough
will remain nearly in place through the period, its geometry will
adjust in response to two associated shortwaves:
1.  A leading perturbation now manifest as a compact cyclone over
eastern OK, northeast TX and parts of AR.  This feature will
eject/accelerate east-northeastward into a broader confluent-flow
regime, crossing the southern Appalachians overnight as a weakening,
positively tilted, open wave.
2.  Trailing vorticity lobes -- initially over the Four Corners area
and between LAS-EED -- that should phase with each other and form a
pronounced trough from west TX across southern NM and northwestern
MX by 12Z tomorrow.

At the surface, 11Z analysis depicted a low, associated with the
leading mid/upper perturbation, near the mouth of the Mississippi
River, with cold front southwestward over the west-central Gulf and
warm front southeastward toward western Cuba.  In keeping with the
forecast trend of the wave aloft, the low should remain weak as it
moves east-northeastward across the FL Panhandle and southern GA
through the period, into cooler boundary-layer air.  Marginal
elevated buoyancy may brush the coastline of the western/central FL
Panhandle today, and lightning cannot be ruled out.  However, with
more-favorable thermodynamic support remaining over the Gulf, and
lift at all scales weakening with time, the potential appears too
brief, isolated and conditional for a 10%/general thunderstorm
outlook over land.

..Edwards/Mosier.. 01/11/2021

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