SPC AC 131945
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 PM CDT Mon Oct 13 2025
Valid 132000Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS CENTRAL AND SOUTHEAST AZ...AND LATE TONIGHT OVER
SOUTH-CENTRAL COASTAL CA...
...SUMMARY...
Isolated, marginally severe hail and wind may occur this afternoon
and evening over parts of central and southeastern Arizona. Locally
damaging winds appear possible late tonight along parts of
south-central coastal California.
...20Z Update...
...AZ...
Southwesterly flow aloft will persist throughout the
afternoon/evening and overnight. This flow, coupled with modest
mid-level moisture and buoyancy will promote a continued threat for
isolated strong thunderstorms, a few of which may be capable of hail
and/or gusty winds. MCD #2144 was recently issued to address this
isolated severe potential.
...Coastal Central/Southern CA...
The deep upper low currently just off the northern CA coast will
continue to progress southward tonight, ending the period just off
the central CA coast. A strong mid-level jet max will rotate around
this low as it progresses southward, spreading eastward into
southern CA late tonight/early tomorrow. A strong frontal band is
anticipated along the leading edge of the ascent associated with
this speed max. Current guidance places this band near the coast
around 05Z/06Z before then moving inland over the next few hours.
Thermodynamic profiles indicate predominantly shallow convection
within and ahead of this frontal band, although a few lightning
flash are possible (most likely within the frontal band itself).
Additionally, the combination of modest buoyancy and strong
deep-layer vertical shear could result in rotation within any more
persistent updrafts, with an attendant threat for damaging gusts
and/or a brief tornado. Even so, the modest and shallow buoyancy
should keep updrafts transient, and any rotation within those
updrafts short lived, keeping the overall severe potential low.
..Mosier.. 10/13/2025
.PREV DISCUSSION... /ISSUED 1045 AM CDT Mon Oct 13 2025/
...AZ...
An upper low currently centered along the OR coast will dig
southward through the forecast period. This will maintain deep
southwesterly flow throughout the Southwest US and Great Basin.
Considerable mid-level moisture and marginal CAPE values will
promote a risk of scattered thunderstorms across these areas through
tonight. While an isolated strong storm will be possible over a
broad region, parts of the central and southeast AZ appear to have
the best combination of daytime heating, orographic ascent, and
vertical shear to promote a risk of a few strong/severe storms
capable of hail and gusty winds.
...Coastal CA...
A strong mid-level jet max will rotate inland tonight into parts of
south-central coastal CA, along with an associated surface cold
front. Forecast soundings along/ahead of the front show sufficient
CAPE and vertical shear for a risk of a few low-topped but strong
storms capable of damaging wind gusts or perhaps a tornado. The
main concerns will be after midnight.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
SPC AC 131708
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1208 PM CDT Mon Oct 13 2025
Valid 141200Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
NEW MEXICO...AND COASTAL SOUTHERN CALIFORNIA...
...SUMMARY...
Thunderstorms with marginally severe wind gusts and hail will be
possible on Tuesday across parts New Mexico from late afternoon into
the evening. An isolated tornado and wind-damage threat will be
possible Tuesday morning through midday along the coast in southern
California.
...Synopsis...
A deep upper low will fill as it moves from central CA into NV on
Tuesday. A midlevel speed max will move into southern CA early in
the day, nosing northeastward into southern UT into Wednesday. Cold
temperatures aloft will exist on the north side of the jet, which
will favor scattered daytime convection due to heating.
Ahead of this system, and west of a southern Plains ridge, southerly
winds will maintain a plume of moisture across much of NM and into
CO. As this area will be well east of the upper low, temperatures
aloft will remain relatively warm.
...Coastal Southern CA...
A band of rain and thunderstorms is likely to be ongoing Tuesday
morning along a cold front, extending well offshore. This arcing
line of convection will be supported by very cold temperatures aloft
north of the midlevel speed max, with SBCAPE values of a couple
hundred J/kg. Although low-topped, sufficient buoyancy in the
low-levels combined with veering winds with height and organization
along a boundary may result in isolated severe weather, with
damaging gusts and perhaps a brief/weak tornado. This convection
will likely be strongest from morning to midday, eventually
weakening across southern parts of the Marginal Risk area as that
portion of the front interacts with warmer temperatures aloft.
...NM...
Instability will gradually increase through late afternoon within
the theta-e plume with persistent southerly flow. It appears the
primary risk will occur late in the day/evening, as full
destabilization is persisted into the night due to the established
moist plume. Subtle height falls may occur late, and several CAMs
suggest nocturnal development with storms racing northward across
central portions of NM. Given robust shear profiles, a few storms
could contain marginal hail or gusty winds.
..Jewell.. 10/13/2025
WUUS02 PTSDY2
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
SPC AC 132131
Day 3 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0431 PM CDT Mon Oct 13 2025
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE CENTRAL HIGH PLAINS AND SOUTHERN ROCKIES...
...SUMMARY...
Isolated severe storms are possible on Wednesday across parts of the
southern Rockies, and over the central High Plains. Areas of hail
will be the primary risk, with sporadic strong gusts possible.
...Synopsis and Discussion...
An upper low over UT will pivot northeastward toward the northern
Rockies, with a belt of strong mid and high level flow moving across
the Rockies and into the central and northern High Plains by
Thursday morning. Low pressure will develop over eastern CO and WY
during the afternoon, and will move into the Dakotas overnight.
Surface moisture return will be limited due to a large area of high
pressure over the Great Lakes, with poor trajectories extending
south into the northern Gulf of America. However, cooling aloft with
the upper trough and an existing plume of midlevel moisture will aid
destabilization. By late afternoon, MUCAPE of 500-1000 J/kg is
forecast over central NM, and from northeast CO into western NE.
Early day precip may hamper destabilization in parts of the southern
Rockies, but a few storms could produce marginal hail.
Farther north into CO/WY/NE, isolated severe storms producing hail
appear more likely as instability is more likely to be at or above
1000 J/kg, along with long hodographs. Further, an increasing
southerly low-level jet may aid storm longevity into the evening
into western SD.
..Jewell.. 10/13/2025
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
|
