Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Mon Aug 14 2017 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN NM AND NORTHWEST TEXAS NORTHWARD INTO SOUTHERN SD... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHEAST... ...SUMMARY... Thunderstorms, some potentially severe, are expected to develop across portions of the central and southern High Plains Tuesday. A few strong storms may also develop across portions of the Northeast Tuesday afternoon. ...Synopsis... A progressive flow pattern over the Lower 48 states will feature a shortwave trough moving across the Lower Great Lakes through the Northeast. Another shortwave trough, evident on water-vapor imagery Monday over northern CA/NV, is forecast to move from the eastern Great Basin into the north-central High Plains. A cold front over the central High Plains will accelerate southeast into central NE/KS by early Wednesday. ...Western portion of the central Plains and into the southern High Plains... An area of surface low pressure over the central High Plains will aid in maintaining southerly low-level flow across the discussion area. A relatively moist boundary layer will heat/destabilize considerably during the day beneath a plume of steep 700-500 mb lapse rates. Convective inhibition is expected to initially erode during the afternoon near a front located over the north-central High Plains and over the higher terrain. A corridor of 1500-2500 J/kg MLCAPE is forecast from northwest TX northward into southwest NE. Despite veering winds with height, modest flow aloft will limit vertical shear (25-35 kt effective shear). Strong to severe multicell clusters will gradually evolve towards evening as a southerly LLJ over KS strengthens to 40-kt by 06Z Wednesday. Severe gusts and large hail will be the primary risks with the stronger storms. A lingering risk for strong storms may persist well into the evening but a diminishing spatial extent of severe/intensity is expected. ...NY Adirondacks and northern New England... A shortwave trough located over MN/WI will deamplify and eject across the Lower Great Lakes by 18z Tuesday, partly in response to a strengthening upper trough over QC that will dig toward the international border by 16/12z. Strong boundary-layer heating is expected ahead of a cold front over southern ON/QC early in the day and strong heating is also expected across northern New England. As a result, buoyancy should increase across this region which will likely support isolated robust thunderstorm development. While frontal convection will primarily stay north of the international border through late afternoon, a few storms should evolve across northern New England into upstate NY. Isolated strong gusts capable of isolated pockets of wind damage and marginal hail may be noted with the more organized convection. ...Coastal VA along the Southeast coastal plain and central Gulf Coast... Diurnally driven scattered thunderstorms are forecast to develop within a very moisture rich airmass located near and south of a decaying frontal zone. Middle to upper 70s degrees F dewpoints over much of the area will contribute to moderate destabilization despite weak mid-level lapse rates. Several clusters of storms will likely evolve within this broad region. A couple of strong gusts/localized pockets of vegetation damage cannot be ruled out. This activity will weaken by early evening. ..Smith.. 08/14/2017Read more
from SPC Forecast Products http://ift.tt/ws9HZn
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