Convective Outlook
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1206 PM CDT Mon Jul 22 2019 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTH CAROLINA ACROSS CENTRAL AND EASTERN NORTH CAROLINA AND EXTREME SOUTHEAST VIRGINIA... ...SUMMARY... Numerous thunderstorms with a few damaging wind gusts are possible Tuesday mainly across the central and eastern Carolinas. ...Synopsis... An upper high will be centered over the Four Corners states, with a ridge extending north across WY and MT. Northern portions of this ridge will break down Tuesday night as a shortwave trough moves across ID and MT, and this feature will also support thunderstorms through evening. To the east, a deep upper trough will approach the Appalachians with cooling aloft and substantial southerly winds. A cold front will slowly move across eastern VA and the Carolinas, where a moist and unstable air mass will support numerous daytime thunderstorms, some producing strong wind gusts. ...Eastern NC/SC and extreme southeast VA... A very moist air mass with mid 70s F dewpoints will exist ahead of the cold front, and heating will lead to MUCAPE in excess of 2000 J/kg prior to frontal passage. Substantial lift along the front will lead to early afternoon development, with numerous storms expected from southeast VA across the Carolinas. Storms may be cellular at first, but deep-layer shear and mean winds will be oriented parallel to the front. The result should be merging outflows, with linear structures advancing east throughout the day. Shear will be weak, but numerous storms with substantial outflow will create opportunities for marginally severe but locally damaging wind gusts. ...Southwest into central MT... Batches of storms are likely to develop near the ID/MT border during the afternoon with the upper disturbance which will eventually flatten the ridge. A steep lapse rate environment will exist, with generally weak winds below 700 mb. This may support small hail and gusty winds, but severe weather is generally not anticipated as storms continue into central MT through evening. ...MAXIMUM RISK BY HAZARD... Tornado: Read moreUpdated 22 July 2019 | 12:07 pm
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1135 AM CDT Mon Jul 22 2019 Valid 221630Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST/MID-ATLANTIC STATES AND TENNESSEE VALLEY... ...SUMMARY... Scattered damaging winds are possible across portions of the Mid-Atlantic States into southern New England, as well as the Tennessee Valley, this afternoon to early evening. ...Mid-Atlantic States to southern New England... Additional amplification of the large-scale trough over the eastern CONUS will contribute to a slight cooling of mid-level temperatures and strengthening southwesterly winds aloft coincident with a slow-southeastward-moving front across the central Appalachians toward parts of the Mid-Atlantic region. The coverage of yesterday's storms across most of this region has impacted thermodynamic profiles, with surface temperatures/dewpoints running at least several degrees lower than this time (late morning/midday) yesterday. As noted in the prior Outlook discussion, 12Z soundings from Sterling, Wallops, Upton, Pittsburgh, and Wilmington OH all sampled mean mixing ratios about 2-3 g/kg lower compared to 12Z yesterday and have weaker mid-level lapse rates. That said, moisture will steadily recover and ample insolation is noted at midday across the Mid-Atlantic in the lee of the Appalachians, with MLCAPE to 1500-2000 J/kg possible (highest near the coast). As compared to yesterday, somewhat stronger wind profiles between 2-6km AGL will also be a factor for individual storm longevity/organized storms. Multicells will be common and the possibility exists for a few transient supercells from far southern New York/northern New Jersey into southern New England. Damaging winds will be the most common risk through the afternoon into early evening. ...Mid-South and Tennessee Valley... A moist air mass (70-75F surface dewpoints) remains ahead of a southeastward-moving cold front. As morning cloud cover thins, increasing cumuliform/thunderstorm development are expected this afternoon, particularly downstream of a pair of residual MCVs. Wet microbursts yielding localized wind damage will be the main risk. While weak vertical shear will tend to limit overall organization and risk magnitude, a somewhat more focused/organized severe risk may exist this afternoon into early evening across western/middle Tennessee and nearby southern Kentucky and perhaps northern portions of Mississippi/Alabama. Enhanced winds are noted with the MCV near the Mississippi River, with 30-40 kt west-southwesterly winds between 4-6 km in recent (16Z) Paducah, KY WFO-88D VWP data. ...Central/southern Rockies and adjacent High Plains... Isolated thunderstorms will develop this afternoon and remain largely confined to the higher terrain of Wyoming/Colorado/New Mexico, although a few storms could drift into the immediately adjacent High Plains. A belt of modest mid-level north/northwesterly flow aloft will persist around the Four Corners/southern Rockies upper ridge, yielding some threat for marginally severe hail/wind. ...Southeast/south-central Arizona... On the southern periphery of the south-central Rockies-centered upper ridge, 15-20 kt mid-level easterlies may help loosely organize scattered thunderstorms that develop over the higher terrain during the late afternoon and move toward the desert floor. Hot/deeply mixed boundary layer will support vigorous downdrafts and the possibility of severe-caliber winds and blowing dust late this afternoon/early evening. ..Guyer/Nauslar.. 07/22/2019Read more
Updated 22 July 2019 | 11:56 am