SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1120 AM CDT Wed Jul 21 2021 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON OVER PARTS OF THE MID-ATLANTIC REGION INTO SOUTHERN NEW ENGLAND... ...SUMMARY... Thunderstorms will be capable of producing damaging winds and isolated large hail this afternoon from the Delmarva into southern New England. Other isolated strong storms may occur over parts of Arizona and Montana. ...Mid Atlantic into Southern New England... Water vapor imagery shows an upper trough moving across the northeast states today, with an associated cold front stretching from southern PA into MA. A moist and unstable air mass is present to the south of the front, where most CAM guidance shows the development of scattered afternoon thunderstorms. Confidence of high storm coverage and greatest severe threat is over NJ and vicinity. However, at least isolated intense storms may occur from central VA into southeastern MA. Damaging winds will be the main threat, but a few rotating cells may develop along with a risk of hail. Activity will move offshore by early evening, ending the severe threat. Refer to WW385 for further details. ...MT... Mostly clear skies are present today over western MT, where surface dewpoints in the 50s and relatively cool temperatures aloft will help to destabilize the air mass. Southwesterly mid-level winds are forecast to strengthen later today as well. Widely scattered afternoon thunderstorms are expected over this region, with the potential of gusty/damaging winds and hail in the stronger cells. Coverage of storms is uncertain. If confidence in higher coverage occurs, an upgrade to SLGT risk may be needed at the 20z update. ...AZ... Easterly mid-level winds will help to move storms that form this afternoon over the mountains of southeastern AZ into the lower deserts this evening. A few of these storms may pose a risk of gusty/damaging winds. ..Hart/Karstens.. 07/21/2021 Read more LIVE: spc.noaa.gov
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