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Storm Prediction Center Forecast


RSS Mesoscale Discussions from Storm Prediction Center

SPC - No watches are valid as of Thu Aug 17 13:10:01 UTC 2017

No watches are valid as of Thu Aug 17 13:10:01 UTC 2017.


SPC - No MDs are in effect as of Thu Aug 17 13:10:01 UTC 2017

No Mesoscale Discussions are in effect as of Thu Aug 17 13:10:01 UTC 2017.


SPC Aug 17, 2017 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0739 AM CDT Thu Aug 17 2017

Valid 171300Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF
MI/OH/IN...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PART OF THE
SOUTHERN HIGH PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS GREAT LAKES TO
OH VALLEY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL SD TO
SOUTHERN HIGH PLAINS...

...SUMMARY...
A couple tornadic storms and scattered damaging winds are possible
across parts of Michigan, Indiana, and Ohio from about 2 to 9 p.m.
EDT. A small severe storm cluster may also develop over the Raton
Mesa and adjacent portions of the southern High Plains in the early
evening.

...MI/IN/OH...
Primary changes this outlook are to expand tornado and wind
probabilities to account for a broader region of potentially
rotating storms. 

998 mb cyclone near the Twin Cities should track towards eastern
Lake Superior through early Friday. Warm front extending southeast
of this wave across central WI to southern Lower MI will gradually
advance north today. Rich boundary-layer moisture characterized by 
lowest 100-mb mean mixing ratios around 16 g/kg is pervasive within
the warm sector. In spite of broken clouds and poor mid-level lapse
rates, this moist air mass coupled with modest surface heating
should result in MLCAPE from 500-1250 J/kg by early afternoon. As
mid-level height falls overspread this buoyancy plume, scattered
storms will develop. 

Wind profiles favor mostly discrete cells and small clusters. Backed
low-level flow is anticipated near the front where instability
should be weakest, with lesser but still adequate low to deep-layer
shear for updraft rotation in the warm sector. The poor lapse rates
aloft should temper updraft acceleration and supercell structures
may remain transient. Still, the setup might support potential for a
couple tornadic storms, with widely scattered damaging winds and
marginally severe hail. Multicells and an associated locally
damaging wind threat should be increasingly predominant with
southern extent in the Lower OH Valley.

...Central SD to southern High Plains...
Modified moisture return flow will ensue as a lee trough/dryline
sharpens by late afternoon. Robust diabatic heating will yield steep
tropospheric lapse rates. Isolated to widely scattered high-based
storms should form late afternoon/early evening with localized
severe hail/wind possible. A greater predictability corridor for
isolated severe will be near the Raton Mesa. Here, a belt of
moderate mid-level westerlies may foster a supercell and/or small
cluster progressing east for a few hours this evening before waning
as MLCIN increases.

..Grams/Dial.. 08/17/2017

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