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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Wednesday, March 30, 2022

SPC Mar 30, 2022 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Wed Mar 30 2022 Valid 301200Z - 311200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MISSISSIPPI VALLEY INTO ALABAMA...AND INTO THE FAR WESTERN FLORIDA PANHANDLE... ...SUMMARY... A regional outbreak of severe thunderstorms is expected from the Lower Mississippi Valley into parts of the Ohio and Tennessee Valleys today, and over portions of the central Gulf Coast states later today into tonight. Widespread damaging winds with gusts over 75 mph and several strong tornadoes (EF2+) appear likely. ...Synopsis... A large-scale upper trough will exist over the central U.S. today, with an intense leading wave moving across OK and TX through midday. This feature will then take on a negative tilt as it moves across the lower MS Valley and into the OH Valley after 00Z, providing large-scale lift with rapid height falls. Midlevel wind speeds of 70+ kt will be common across the region, with a compact speed max to 100 kt possible with the ejecting wave. Just off the surface, 850 mb flow will already average 60-70 kt at 12Z Wednesday from eastern TX into AR and LA, and speeds will only increase with time, possibly as high as 85 kt out of the south across TN and KY by 00Z. As a surface low deepens over MO and IL during the day, low-level moisture advection will occur quickly across the warm sector, with upper 60s F dewpoints across LA, southern MS and AL, and mid 60s F as far north as western TN. Two primary severe-weather regimes appear evident today, one in association with the negative-tilt wave as it ejects northeastward, and another farther south late in the period ahead of the trailing cold front as it sweeps east along the Gulf Coast. ...Eastern AR/northern LA northeastward into KY and TN... Storms are likely to be ongoing near a cold front early in the day, roughly from central MO into eastern OK, and near a developing dryline pushing east of I-35 in TX. While instability will be relatively weak at this juncture, shear will be extreme with large looping hodographs. This may favor QLCS structures within any ongoing lines of storms. By midday, the combination of cooling aloft and strong low-level moisture advection will lead to destabilization near the cold front, with a rapid increase in storm coverage and intensity. Most CAMs suggest this will occur around 18Z, focused over northern LA, central and eastern AR, and southeast MO. The bulk of this activity is expected become severe as it quickly crosses the MS River into MS, western TN and KY. Extreme shear is forecast, with effective SRH of 500-800 m2/s2 common as MLCAPE increases to 1000-1500 J/kg over LA/AR/MS and southwest TN. Supercells are likely, with strong tornadoes possible as well as particularly damaging outflow surges. As outflows merge, QLCS tornadoes may occur as well. Although CAPE values will be lower across the OH Valley, strong lift may sustain a severe-wind threat there through about 03Z. ...Parts of eastern LA...much of MS...AL...FL Panhandle... Southern portions of the front/dryline will move much slower compared to farther north, resulting in a longer duration of boundary-layer moistening. A line of convection should become evident by 21Z from southwest MS into parts of southern LA, moving across MS and into north-central AL by about 03Z. The subtle lift, combined with ample low-level moisture beneath an intense low-level jet, will favor tornadic supercells which may peak during the night. Effective SRH will remain high, averaging 400-500 m2/s2, with proper hodograph elongation in the mid and high levels. Given the long duration and slow eastward movement of this line of supercells, and the magnitude of the forecast hodographs, a few intense tornadoes could occur. However, the threat will become limited late in the period due to decreasing instability to the east of about longitude 86W. ..Jewell/Bentley.. 03/30/2022 Read more CHECK UPDATE ZOOM GRAPHIC
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