SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1159 PM CDT Wed Sep 08 2021 Valid 091200Z - 101200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms appears negligible across the U.S. today through tonight. ...Synopsis... A prominent, broad mid-level high, currently centered over the eastern Great Basin, appears likely to maintain considerable strength through this period. However, the center of highest heights may begin to shrink while shifting east southeastward across the southern Rockies by early Friday, as a mid-level short wave trough translates toward the Oregon/northern California coast, ahead/to the southeast of a stronger impulse migrating within the westerlies across the northeastern Pacific. It appears that a downstream short wave trough, progressing east of the Canadian Rockies, will flatten ridging extending to the north of the high, across the Canadian Prairies and adjacent Canadian/U.S. border area. To the south of this feature, very warm lower/mid tropospheric air is forecast to spread east of the Rockies through much of the Great Plains, in the wake of initially amplified mid-level troughing progressing east of the Mississippi Valley. Considerable lower/mid tropospheric drying is ongoing beneath westerly to northwesterly flow to the west of the Eastern mid-level trough axis, through the lower Great Lakes, Ohio Valley and into the lower Mississippi Valley and southern Great Plains. By 12Z this morning, a lead surface cold front probably will extend from New England and northern Mid Atlantic coastal areas into north central/northwestern Gulf coastal areas and the lower Rio Grande Valley. It still appears that the primary surface cyclone will continue to migrate northeastward across northern Quebec today through tonight. Models are more unclear concerning possible secondary frontal wave development near the northern Mid Atlantic into New England coast, as Hurricane Larry accelerates northward and northeastward, to the east and northeast of the Bermuda vicinity. However, there is better consensus concerning the remnants of Tropical Storm Mindy, likely preceding the front across and east of southeastern Georgia coast near or shortly after 12Z this morning. ...Southeast... Based on the latest forecast track and anticipated intensity trends concerning Mindy, there could be some lingering supercell structures in the waters offshore of the far southern South Carolina and adjacent Georgia coastal areas this morning. However, low probabilities for tornadoes over inland areas probably will diminish by or shortly after 12Z. ..Kerr/Squitieri.. 09/09/2021 Read more LIVE: spc.noaa.gov
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