4-8 DAY CONVECTIVE OUTLOOK
REGIONAL 4-8 DAY CONVECTIVE OUTLOOK
SCO/MIDWEST WEATHER SERVICE STEVENS POINT/WHITING WI
924 AM CDT WED AUG 29 2018
PLEASE NOTE...This product is for guidance purposes primarily, therefore, forecast errors may be large.
OUTLOOK PERIOD: 09/01/18 - 09/05/18.
Primary belt of westerlies for this forecast period looks to gradually shift north of the Canadian border as western Atlantic mid level anticyclone begans
retrogressing westward into the mid Atlantic states, and continues moving into the OH valley area by the end of the period. As this occurs, a strong mid -
to upper level closed low moves into the Pacific northwest states. As a result, it appears that intense heat may spread northward with time as deeper
GOM/Atlantic moisture is channeled northward by the mid level high. While there is some chance for thunderstorms during the afternoon and evenings
due to strong surface heating and convergence, organized storms appear unlikely due to weak wind fields aloft. Some of the models do hint at a piece
of energy moving across southern Canada by the ladder part of this forecast period, which could produce a bit more active weather to parts of the
region. For now, will go with low predictabilities.
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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