LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1109 PM CST Sat Feb 18 2023
Valid 191200Z - 201200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
The risk for thunderstorms appears negligible across the U.S.
through at least early Monday.
...Synopsis...
Models suggest that the center of a broad, deep low over the
northeastern Canadian Arctic may slowly begin a south/southwestward
shift toward northern Hudson Bay later today through tonight, in
response to a couple of short wave perturbations pivoting around its
western and southern periphery. While the coldest low-level air
emerging from the Arctic is forecast to largely remain confined to
the interior Canadian Provinces, potentially cold/dry boundary-layer
air likely will remain entrenched across much of the interior U.S.,
beneath broad mid-level troughing to the south of the Arctic low,
within a belt of westerlies emanating from the northern mid-latitude
Pacific.
In lower latitudes, there appears unlikely to be much change in the
strength or position of a prominent mid-level high centered over the
southern mid-latitude eastern Pacific (roughly around 140-150 W),
and a prominent subtropical high elongated along an axis from the
southern Mexican Plateau into the Caribbean/Bahamas. While modest
low-level moistening may occur along and south of a weakening
remnant frontal zone across parts of southern Florida and the Texas
coastal plain, forecast soundings indicate that this will be
strongly capped by warm-layers aloft associated with the ridging.
Along a positively tilted trough axis between the highs, a mid-level
low may migrate northeastward toward the southern
California/northern Baja coast. It appears that the colder
mid-level temperatures, potentially supportive of convection capable
of producing lightning, will remain offshore through this period.
Otherwise, it appears that moisture return, within deep-layer south
to southwesterly flow emanating from the subtropical eastern
Pacific, may begin to contribute to at least elevated layers of weak
destabilization across parts of the Southwest into the southern
Great Plains. While some associated convection might briefly become
capable of producing a flash or two of lightning, it currently still
seems probable that the coverage of any such activity will remain
generally less than 10 percent.
..Kerr/Wendt.. 02/19/2023
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