U.S Directory

U.S. | Northeast | Greatlakes | Northern plains | Northwest | Southwest | Central plains | West coast | Southern plains | East coast | South East |

ACUS48 KWNS 220836
SPC AC 220834

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0334 AM CDT Sun Jul 22 2018

Valid 251200Z - 301200Z

Models continue to indicate that a significant short wave impulse
will dig across the central Canadian/U.S. border by mid week, before
turning eastward and northeastward across Ontario and the upper
Great Lakes, through Quebec and portions of the Northeast early this
weekend.  In the wake of preceding, increasingly sheared troughing
accelerating across the Atlantic Seaboard, it remains unclear as to
the extent to which associated forcing for ascent may interact with
a residual seasonably moist air mass to the lee of the Appalachians.
A risk for strong/severe thunderstorms does not appear out of the
question Friday afternoon and evening across parts of the northern
Mid Atlantic into New England, but due to large uncertainties,
severe probabilities remain below 15 percent.

Otherwise, the medium-range guidance indicates that upper ridging
will build to the north of the prominent Southwestern subtropical
high, through the Pacific Northwest, northern intermountain region
and Rockies by late next weekend.  A coinciding upper trough
amplification may take place across the middle Mississippi into
lower Ohio Valleys, perhaps accompanied by frontal wave development.
However, appreciable organized severe thunderstorm potential is not
readily apparent at this time.

..Kerr.. 07/22/2018