4-8 DAY CONVECTIVE OUTLOOK
REGIONAL 4-8 DAY CONVECTIVE OUTLOOK
SCO/MIDWEST WEATHER SERVICE STEVENS POINT/WHITING WI
956 AM CDT WED JUN 27 2018
PLEASE NOTE...This product is for guidance purposes primarily, therefore, forecast errors may be large.
OUTLOOK PERIOD: 06/30/18 - 07/05/18.
Primaly belt of westerlies remains in a highly amplified fashion as stout mid laditude anticyclone establishes itself across much of the
southern two thirds of the CONUS throughout much of this forecast period. As this occurs, a broad mid to upper level trough is forecast
to dig into the Pacific northwest states. This type of pattern will mean light and varied flow across much of the nation since the jet will
be shoved well north across Canada. That said, a relatively weak enlongated mid level shortwave and associated surface cold front will
sluggishly move east across the region on Sunday/day 4, and Monday/day 5. These features will likely generate some scattered
thunderstorms in association with modest instability and effective shear of 30-40 knots. This appear sufficient for some loosely organized
strong-severe storms posing a large hail and strong damaging wind gusts. The only caveats at this time are 1) storm coverage, and
2) effects from prior convective activity. For these reasons, will defer introduction of severe probabilities for now.
Beyond Monday/day 5, model guidance becomes more varied suggesting lower confidence in determining any severe weather potential.
OUTLOOK GRAPHICAL DISPLAYS
Inportant, please read:
The severe criteria for the 4-8 day severe outlook differs from that used in our other severe weather products.
Here, a slight risk would equate to 10% probabilities, and a moderate risk would equate to 20% probabilities.
Note: Each day is from 1200Z to 1200Z the next day.
Whenever the wording on the composite graphic (above), shows the text "SEVERE THUNDERSTORMS POSSIBLE...
BUT PREDICTABILITY IS TOO LOW", this indicates severe storms maybe possible based on some model scenarios.
However, the location or occurrence of severe storms are in doubt due to:
1) large differences in the deterministic model guidance,
2) large spread in the ensemble guidance, and/or,
3) minimal run-to-run continuity.
If it appears that little to no potential exists for severe convection of any kind throughout the entire 4-8 day
forecast period, the composite graphic above will have the following wording,
"NO ORGANIZED SEVERE STORMS EXPECTED" on it.
Risk areas will be shown in the graphics above only when a categorical slight risk (10% or greater
probabilities) exists within our coverage region.
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