NOAA Storm Prediction Center

Convective Outlooks

Convective Outlooks
The convective outlooks serve as guidance to the local NWS forecast offices and are used by emergency managers, private sector meteorologists, media, and other weather customers concerned with public safety. Three separate risk areas (slight, moderate, and high) are used to describe the expected coverage and intensity for the categorical severe weather threat on days 1-3 along with severe weather probabilities for the potential threat.

Day 1 Outlook Day 2 Outlook Day 3 Outlook Days 4-8 Outlook

Day 1 Outlook Convective Tornado
Hail Wind
Categorical Day1 2000Z Outlook
  
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 Forecast Discussion


000
ACUS01 KWNS 041952
SWODY1
SPC AC 041951

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0151 PM CST Sat Dec 04 2021

Valid 042000Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible across a wide area from north
Texas and southern Oklahoma, through parts of the mid South.

...20Z Update...
Forecast outlined in the previous discussion (appended below) still
remains valid. Highest thunderstorm coverage still appears to be
over the Arklatex vicinity after 06Z. Steep mid-level lapse rates
will be in place, fostering modest elevated instability and the
potential for a few storms capable of marginal hail. Limited
large-scale forcing for ascent and relatively warm mid-level
temperatures cast some doubt to overall storm coverage, with current
forecast coverage still expected to remain below thresholds for
severe probabilities.

..Mosier.. 12/04/2021

.PREV DISCUSSION... /ISSUED 1031 AM CST Sat Dec 04 2021/

...Synopsis...
In the mid levels, a split flow regime with moderate to strong
northwesterly flow was observed across the northern third of the
CONUS. Several vorticity maxima and their associated jet streaks
within the mostly zonal flow field will move east with time today,
supporting several areas of wintry precipitation from the Pacific
Northwest/northern Rockies into the Northeast. Within the weaker
southern branch of the mid-level westerlies, an upper low over the
Southwest will linger through the forecast period while a weak
shortwave trough moves east along the Gulf Coast. At the surface, a
stalled front and weak low from eastern Oklahoma and north Texas
into Alabama will support increased ascent and moistening through
the forecast period.

...Southern Plains and portions of the Southeast...
As low-level moisture and weak ascent increase through the period,
Isolated thunderstorms may develop through the forecast period
across several areas. Weak isentropic ascent along the front through
the Gulf coast and central Alabama may support a few thunderstorms
as diurnal warming and moistening contribute to a weakly unstable
(MUcape around 500 J/kg) environment.

The greatest focus for warm and moist ascent appears likely across
portions of north Texas and eastern Oklahoma into southern Arkansas
late in the period, as a low-level jet and upstream shortwave trough
support isolated thunderstorm development overnight. Continued
low-level warm advection should result in low 60s F surface
dewpoints reaching into southern Arkansas by 06z. Cooling
temperatures aloft ahead of the southern branch shortwave should
favor modest lapse rates around 6.5 C/km aiding in weak to moderate
destabilization. With MUCAPE around 500-100 J/kg, and weak mid-level
flow, a few pule type storms with small hail may develop. However,
forecast coverage is expected to remain below thresholds for severe
probabilities.

$$