Valid 061200Z – 071200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
Isolated thunderstorms are possible from the Pacific Northwest into
Idaho on Monday.
A surface low is expected to be over the western Upper MI/western
Lake Superior vicinity early Monday morning, with an attendant cold
front extending southwestward to another low in central KS. The
primary surface low is forecast to progress eastward across
northeastern Ontario into southern Quebec, just ahead of its parent
shortwave trough. Northern portion of the front will make steady
eastward progress with the surface low. However, the southern
portion of the front is expected to stall across KS and MO amid
persistent low-level moisture return. Low-level convergence will be
sustained along this boundary throughout much of the day, with
dewpoints south of the boundary approaching 60 deg F. Even so, warm
mid-level temperatures are expected to be in place, preventing deep
convection and limiting thunderstorm chances.
Farther west, a pair of shortwave troughs are expected to progress
across the Pacific Northwest. The lead wave is expected to move
through the region Monday morning, while the second wave approaches
early Tuesday morning. Despite relatively cool surface temperatures
and limited low-level moisture, cold mid-level temperatures will
help support modest buoyancy from coastal WA/OR into southern ID.
Consequently, isolated thunderstorms are possible along the coast
throughout much of the period, with a few flashes also possible from
eastern OR into southern ID during the afternoon.