4-8 DAY CONVECTIVE OUTLOOK
REGIONAL 4-8 DAY CONVECTIVE OUTLOOK
SCO/MIDWEST WEATHER SERVICE STEVENS POINT/WHITING WI
944 AM CDT TUE JUN 19 2018
PLEASE NOTE...This product is for guidance purposes primarily, therefore, forecast errors may be large.
OUTLOOK PERIOD: 06/23/18 - 06/28/18.
For this forecast period, many uncertainties exist since model guidance seems varied in the spatial and timing issues of systems across NOAM/CONUS.
First, their is a continued split flow, with the northern branch curving around a huge mid laditude high pressure across much of central and
northwest Canada. The stream flows southeast across Quebec into the Atlantic. The southern stream is forecast to be from southern CA into SC and
out into the Atlantic. As one cutoff low is reabsorbed into the northern stream over Quebec, next upstream closed upper low will move into the
Pacific northwest. Meanwhile, a mid to upper level trough over NE will move east across the region by Tuesday/day 7. This system looks to have at
least some strong to severe storms associated with it. However, given the uncertainties among the models at this juncture, will defer on any
severe probabilities. Scattered thunderstorms maybe possible at times throughout this entire forecast period.
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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