SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0905 AM CDT Wed Jul 14 2021 Valid 141300Z - 151200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF IOWA...SOUTHEAST MINNESOTA...NORTHWEST ILLINOIS...AND SOUTHERN WISCONSIN.... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON OVER PARTS OF NEW ENGLAND... CORRECTED FOR STATE REFERENCE IN NORTHEAST STATES SECTION ...SUMMARY... Damaging winds, along with some hail threat, are expected with thunderstorms across the upper Midwest later this afternoon and evening. Isolated damaging winds are also possible across parts of the Northeast. ...IA/WI and Vicinity... A large and well-organized MCS is moving into northwest IA this morning. Strong thunderstorms have been occurring along the leading edge of this system through the night, but intensities have generally remained below severe limits. These storms may intensify later this morning as they organize into a bowing line and move into northeast IA and eventually into WI. The risk of damaging winds with this activity should increase throughout the day - and be greatest over parts of WI by late afternoon. Please refer to MCD #1279 for further details on this scenario. In the wake of these morning and early afternoon storms, overnight model guidance is in agreement that the potential for re-development of convection across IA/MN is relatively high. These late-afternoon storms will be most likely along and north of the trailing outflow boundary from the morning activity across central/northern IA. Forecast soundings suggest that vertical shear profiles will be quite strong in this area, with a greater change for discrete supercells and related risks of hail, damaging winds, and isolated tornadoes. These storms will track eastward across roughly the same corridor as the morning storms, further justifying the ongoing ENH risk area. ... Northeast States... A mid-level shortwave trough currently over western NY will track eastward into New England later today. This boundary layer in this area is relatively moist with dewpoints in the mid-upper 60s. Morning visible satellite imagery shows considerable breaks in the clouds, which should allow afternoon CAPE values to reach 1500 J/kg. Sufficient flow and relatively cool temperatures aloft will promote a few strong storms capable of hail and gusty winds. Will maintain the ongoing small SLGT risk area centered over western MA, where guidance is a bit more bullish on storm coverage and intensity. Locally damaging winds are the primary concern. ...Northeast CO... Water vapor imagery shows considerable deep moisture across parts of UT/CO, along with a remnant MCV over western CO. Broken clouds will lead to pockets of daytime heating and scattered thunderstorm development this afternoon over the mountains. Activity will spread eastward into the foothills and plains by late afternoon, where weak upslope flow and greater CAPE will foster convective intensification. A few strong storms are expected to form over northeast CO, with a risk of hail and gusty winds. ...NV/UT... Strong heating will occur once again this afternoon over parts of eastern NV and western UT, leading to a deeply-mixed and marginally unstable environment. Most overnight model guidance indicates scattered thunderstorm development over eastern NV by late afternoon, spreading into southwest UT during the evening. This area will be on the southern fringe of stronger northwest flow aloft, with sufficient steering flow to maintain a few strong storms capable of gusty/damaging wind gusts. ..Hart/Marsh.. 07/14/2021 Read more LIVE: spc.noaa.gov
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