SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0737 AM CDT Sun Aug 29 2021 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH THIS EVENING ACROSS LOWER MI...AND THROUGH TONIGHT ACROSS THE NORTH CENTRAL GULF COAST... ...SUMMARY... A few tornadoes are possible through tonight across the north central Gulf coast, mainly east and northeast of the eye of major Hurricane Ida. Occasional damaging winds will also be possible this afternoon across parts of Lower Michigan. ...North central Gulf coast with Hurricane Ida... Hurricane Ida has continued to strengthen rapidly overnight and is now an intense Category 4 hurricane that will make landfall by late morning near Port Fourchon LA (see the latest NHC advisories for details). The stronger low-midlevel wind field with Ida is concentrated in a relatively narrow inner core, but some expansion of the stronger winds is still expected near and after landfall today. The resultant increase in low-level vertical shear/hodograph curvature will contribute to the threat for supercells with occasional tornadoes in the outer northeastern and eastern convective bands. The tornado threat inland of the coast will be modulated largely by the degree of low-level moisture and pockets of surface heating, with the more favored areas maintaining at least mid 70s dewpoints and temperatures close to 80 F. ...Lower MI area this afternoon/evening... A midlevel shortwave trough and associated surface cold front across MN/WI this morning will move eastward to Lower MI this afternoon/evening. Surface heating/moistening in the wake of early morning convection will result in destabilization this afternoon across Lower MI, where MLCAPE will increase to near 2000 J/kg. The midlevel west-southwesterly flow and effective bulk shear near 30 kt or greater will be confined to northern Lower MI, with weakening flow with southward extent. Pre-storm DCAPE is expected to be near 1000 J/kg, which combined with the modestly enhanced midlevel flow will support multicell clusters/line segments both along and ahead of the front that will be capable of producing damaging gusts. ..Thompson/Broyles.. 08/29/2021 Read more LIVE: spc.noaa.gov
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