SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Mon Sep 13 2021 Valid 131200Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN MINNESOTA AND FAR NORTHERN IOWA INTO WISCONSIN...AND ACROSS SOUTHERN NEW YORK AND NORTHERN PENNSYLVANIA/NEW JERSEY... ...SUMMARY... Scattered strong to severe storms are possible from southern Minnesota into central Wisconsin this evening and tonight, and tonight across parts of southern New York, northern Pennsylvania and New Jersey. Both hail and damaging winds will be possible. ...SD and ND... Storms are likely relatively early in the day across the central Dakotas along a cold front and as an upper shortwave trough provides lift. Storms may be elevated, but cool temperatures aloft and ample deep-layer shear may support hail. Gusty winds may also develop into eastern SD where MLCAPE will increase during the afternoon. ...MN...IA and WI... Models are not in very good agreement with just how unstable it will become during the day and extending into the evening. However, as a shortwave trough moves across the region this evening and overnight, shear will become increasingly favorable for severe storms. A surface low is expected to move from IA toward Upper MI, and will provide a focus for storms. Storm mode may become mixed, and partially elevated, but indications are that a few severe cells and possibly an MCS may accompany the mobile trough. Either elevated supercells with large hail, or, damaging gusts may occur. ...Western and southern NY...northern PA and NJ... Much of the day will be void of thunderstorms, allowing for strong instability to redevelop across the region. A front will remain nearly stationary from Lake Erie across northern PA and NJ, with mid to upper 60s F dewpoints to the south. Though a shortwave trough will be departing the region early in the day, cool midlevel temperatures will remain in place, resulting in steep midlevel lapse rates. Weak warm advection in the low levels combined with moistening around 700 mb out of the northwest is expected to lead to isolated storms after about 03Z near and just north of the boundary. Large hail will be possible with any of these cells, and a few strong gusts may also occur where storms have access to the stronger instability as inflow. ...Middle and Upper TX Coast... Moisture and instability will increase especially overnight as Tropical Storm Nicholas approaches from the south. Shear will increase coincident with this system, and a brief/weak tornado cannot be ruled out should the better shear and instability eventually overlap tonight. ..Jewell/Bentley.. 09/13/2021 Read more LIVE: spc.noaa.gov
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