SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0155 PM CST Tue Jan 26 2021

Valid 262000Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO TONIGHT ACROSS PARTS OF THE FLORIDA
PANHANDLE...SOUTHERN GEORGIA...SOUTHERN SOUTH CAROLINA...

...SUMMARY...
A couple of strong thunderstorms could still impact a narrow
corridor across the Florida Panhandle and parts of southern Georgia
into southern South Carolina late this afternoon into tonight,
accompanied by some risk for severe weather.

...20Z Outlook Update...

...Southeast...
Thunderstorms through this afternoon have been mostly confined to
the vicinity of a narrow plume of higher precipitable water
returning around the northern periphery of the subtropical ridge. 
Pre-frontal destabilization over land, aided by daytime heating, has
been generally weak, but in the presence of strong deep-layer shear.
 While low severe weather probabilities are being maintained along
this corridor into early evening, the Rapid Refresh, supported by
area VWP data, suggests that low-level flow is in the process of
weakening.  An appreciable increase in severe weather potential
seems unlikely, and strongest thunderstorms may tend to remain
focused  near the coastal waters south/west of Panama City through
Pensacola, aided by inflow (albeit perhaps slightly elevated above a
stable near surface layer) of higher moisture content/potential
instability.  Otherwise, in advance of the significant short wave
trough accelerating northeast of the southern Rockies tonight,
strengthening lower/mid tropospheric warm advection may support
increasing thunderstorm activity, mostly to the cool side of the
stalling surface frontal zone, across parts of southern Mississippi
through north central Georgia.

...Southeast Arizona into southern Rockies...
While convection capable of producing a flash or two of lightning
might still be possible across southeastern Arizona through 20-22Z,
the relatively compact mid-level cold core appears in the process of
the shifting northeastward into southwestern New Mexico, with
mid-level warming underway in its wake.  As the larger-scale
mid-level thermal trough continues overspreading the higher terrain
of New Mexico this afternoon, forecast soundings suggest that
thermodynamic profiles might become conducive for some convection
capable of producing lightning.  However, eastward into the high
plains, this potential appears likely to become increasingly
negligible.

...Northern California coast...
Some lightning is evident in convection along the occluding surface
front offshore, which might spread into northern California coastal
areas by early evening.  Otherwise, post-frontal cooling aloft may
contribute to isolated thunderstorm activity approaching coastal
areas toward 12Z Wednesday.

..Kerr.. 01/26/2021

.PREV DISCUSSION... /ISSUED 1025 AM CST Tue Jan 26 2021/

...FL/AL/GA/SC...
Deep southwesterly tropospheric flow is present today over much of
the eastern CONUS, with the primary mid level jet extending from TX
into the upper OH Valley.  A surface boundary extends from southern
SC southwestward into parts of southern GA, southeast AL, and the FL
panhandle.  A moist and marginally unstable air mass remains along
and south of the boundary, with a few breaks in the clouds possible
this afternoon.  This will provide sufficient CAPE and forcing for
scattered afternoon thunderstorms across the MRGL risk area.  Flow
fields are strong but veered.  This would suggest that locally
gusty/damaging winds are the main concern, although an isolated
tornado is possible.

Mid level heights will rise slightly this evening in between
systems, before the next upper trough begins to approach AL/FL
panhandle late tonight.  Low level winds will strengthen before dawn
in this area, with the potential for redevelopment of a few
thunderstorms - with some risk of gusty/damaging wind or an isolated
tornado.

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