SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 PM CDT Wed Aug 17 2022
Valid 172000Z - 181200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FROM EAST TX TO THE LOWER MS VALLEY AND NORTH FL...SOUTHERN
AZ...AND THE WESTERN DAKOTAS......
...SUMMARY...
Isolated damaging winds will be possible through this evening from
east Texas across the lower Mississippi Valley to north Florida,
southern Arizona, and the western Dakotas.
...20z Update...
Only minor adjustments have been made to the Marginal risk area
across Florida based on latest convective trends. Otherwise, the
previous outlook remains unchanged and on track. See discussion
below for more forecast details.
..Leitman.. 08/17/2022
.PREV DISCUSSION... /ISSUED 1129 AM CDT Wed Aug 17 2022/
...Lower MS Valley to north FL this afternoon/evening...
A remnant MCV will move east-southeastward from AR to MS/AL this
afternoon, roughly along and just north of an outflow-reinforced
front from the AR/LA border across central MS to southern AL.
Strong surface heating and boundary-layer dewpoints well into the
70s will boost MLCAPE to near 3000 J/kg this afternoon along and
south of the front/outflow, and additional thunderstorm development
is expected by mid afternoon. The surface boundaries that will
focus storm initiation will lie along the southwest fringe of the
20-30 kt midlevel flow, which will support multicell clusters.
Precipitation loading with the strong buoyancy, in combination with
DCAPE near or above 1000 J/kg, will support isolated wind damage
with downbursts this afternoon/evening. Otherwise, isolated strong
storms will also be possible across north FL, primarily with sea
breeze and outflow interactions.
...Southern AZ this afternoon/evening...
To the west of a remnant tropical low over northern Mexico, midlevel
east-northeast flow will strengthen some through this evening over
southern AZ. This will favor convective clusters moving
southwestward from the higher terrain to the lower deserts, where
strong surface heating and boundary-layer dewpoints in the 60s will
contribute to moderate buoyancy and weakening convective inhibition.
Typical steep low-level lapse rates and substantial precipitation
loading will favor hybrid microbursts capable of producing isolated
strong-severe outflow winds.
...Western Dakotas this afternoon/evening...
Some convection is ongoing late this morning over the northern High
Plains, in advance of a weak midlevel trough moving over northeast
MT. The convection is expected to increase some later this
afternoon as it encounters a deeper mixed boundary layer, when there
will be the potential for isolated strong-severe outflow gusts.
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