Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Tue Sep 05 2017 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC/NORTHEAST STATES... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX/LOWER MS VALLEY TO NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible especially this afternoon through early evening across portions of the Northeast and Mid-Atlantic States. Additional strong thunderstorms are possible ahead of a cold front extending to Texas and perhaps across portions of the Southwest and Great Basin. ...Northeast/Mid-Atlantic States to Southern Appalachians... Considerable longwave trough amplification will continue to occur over the eastern half of the CONUS through the period, with upper heights gradually falling as far south as the Gulf Coast States and coastal Southeast. Gradual cooling aloft and a steady strengthening of mid/high-level cyclonic flow will occur roughly coincident with an east/southeastward-advancing front across the Northeast/Mid-Atlantic regions today, while the stronger winds aloft will tend to lag the front in areas farther to the south along with poorer mid-level lapse rates. Although scattered convection and thicker cloud cover precedes the cold front in some areas near/west of the Appalachians spine early this morning, somewhat stronger heating/insolation is expected in the lee of the Appalachians into parts of New England this afternoon. This includes areas from eastern PA and NJ into southeast NY and much of interior New England. Convection should generally increase and intensify this afternoon initially near the mountains, with the aforementioned strengthening winds aloft contributing to well-organized/sustained convection including some initial supercells and evolving line segments. Damaging winds should be the most common severe hazard, although some hail will be possible especially with any supercells and a tornado cannot be ruled out. Storm intensity should gradually wane this evening, although some potential for strong/locally severe thunderstorms could linger into at least late evening across the coastal mid-Atlantic and/or parts of New England. ...Southern Appalachians to Lower MS Valley/ArkLaTex... At least some potential for strong to locally severe thunderstorms are expected mainly this afternoon across the region as convection diurnally increases and intensifies near the south/southeastward-moving cold front. ...Southwest States... Aided by a belt of moderately strong east/southeasterly mid-level winds, a few stronger storms with gusty winds could occur across parts of AZ and/or the Lower CO River Valley into interior southern CA this afternoon into evening. However, the potential for organized/sustained severe weather currently appears low, especially with a trend of a somewhat drier air mass across AZ. ..Guyer/Broyles.. 09/05/2017Read more
from SPC Forecast Products http://ift.tt/rATNzD
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