Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Sat Jul 08 2017 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EXTREME EASTERN NEW YORK INTO NEW ENGLAND... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN VIRGINIA INTO NORTH CAROLINA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOUISIANA INTO ALABAMA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN ARIZONA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN NEW YORK INTO NEW ENGLAND... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL PLAINS ACROSS THE LOWER MISSISSIPPI VALLEY INTO THE CAROLINAS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF FLORIDA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... A few severe thunderstorms are expected from the central Plains to the Carolinas and Mid-Atlantic States, and across New England. Localized damaging wind gusts are most likely, with large hail most probable over the Plains. Isolated storms producing strong-to-severe wind gusts are possible across southern Arizona as well. ...Extreme eastern New York into New England... Water vapor imagery shows a short wave trough lifting northeastward across the lower Great Lakes toward New England. This feature is enhancing large-scale ascent with scattered thunderstorms occurring from northern/eastern New York into western Maine. Visible imagery shows a corridor of limited clouds from southeast New York into Massachusetts and southern parts of New Hampshire and Maine which will promote stronger diabatic heating this afternoon. Although 12Z soundings exhibit weak mid-level lapse rates across the region, surface dew points in the mid/upper 60s and steepening low-level lapse rates will contribute to some destabilization with SBCAPE reaching 1000-1500 J/kg. Thunderstorms are expected to continue developing this afternoon ahead of an advancing cold front. Moderate westerly flow aloft coupled with 35-40 kt deep layer shear will support organized storm structures including potential for short bowing line segments. Stronger storms will be capable of producing strong-to-severe wind gusts into the evening hours. ...Southern Virginia into North Carolina... Strong heating is occurring across this area with surface temperatures approaching 90 degrees. 12Z sounding at GSO indicated the moisture over the Piedmont was relatively shallow suggesting that current surface dew points in the lower 70s over this area may mix out this afternoon as steep low-level lapse rates develop. Storms are expected to develop within a weakly capped environment over the higher terrain and spread eastward along the southern edge of stronger westerly winds in the mid-levels. Deep layer shear of 20-30 kt will be sufficient to support organized multi-cell storm structures including short line segments. Stronger storms will be capable of producing damaging wind gusts through the evening hours. ...Louisiana into Alabama... 12Z soundings at SHV, JAN, and BMX indicate ample low-level moisture with pronounced drying above the PBL that is contributing to large values of DCAPE greater than 1300 J/kg. Strong heating is occurring over central parts of Louisiana, Mississippi and Alabama to the south of ongoing convection, with a well-defined outflow boundary evident in visible imagery moving southward into central Louisiana and Mississippi. Storms are expected to continue developing and intensify this afternoon within an environment favorable for wet microbursts with potential to produce locally damaging wind gusts. ...Southern Arizona... 12Z soundings at PHX and TUS exhibit very deep mixed layers with precipitable water values around 1.2 inches and layers of stronger easterly component winds in the low-to-mid levels. Intense diabatic heating will support development of thunderstorms over the mountains of southeast and east central Arizona this afternoon and evening, with potential for cells to propagate westward toward the lower deserts. The deep mixed layer and dry sub-cloud environment will promote generation of strong-to-severe wind gusts later this afternoon and evening. ...Central Plains... In the presence of moderately strong north/northwesterly flow aloft, storms appear most likely to develop across parts of Nebraska this afternoon in vicinity of a surface low and weak front with storms also potentially spreading into portions of western and central Kansas. Modest amounts of buoyancy and deep-layer shear could yield isolated severe storms capable of severe hail and wind mainly late this afternoon into evening. ..Weiss/Mosier.. 07/08/2017Read more
from SPC Forecast Products http://ift.tt/wWCv9s
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