SPC AC 040730
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sat Nov 04 2017
Valid 061200Z - 071200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
Thunderstorms may occur along a cold front from parts of southern
New England and the Mid-Atlantic into the Tennessee/Ohio Valleys,
Mid-South, and Ozarks on Monday. Severe thunderstorms appear
...Synopsis and Discussion...
Strong westerly winds at mid/upper levels should remain over much of
the CONUS on Monday with a split flow pattern forecast to continue.
A positively tilted upper trough should progress eastward across
Canada and the northern Rockies through the period. At the surface,
a cold front will move quickly eastward across New England and the
Mid-Atlantic by Monday evening. This front will make slower
southward progress over the OH/TN Valleys and Mid-South as it
becomes increasingly parallel to westerly flow aloft.
Thunderstorms may be ongoing at the start of the period along the
cold front from parts of NY into PA and the eastern OH Valley.
Instability is forecast to remain very weak across southern New
England and the Mid-Atlantic Monday afternoon owing to poor
mid-level lapse rates and only modest diurnal heating. Even though
mid/upper-level flow will be strong across these regions along/ahead
of the cold front, buoyancy should remain too weak to support an
appreciable severe thunderstorm threat.
Farther south across the TN Valley and Mid-South, low-level moisture
should be comparatively greater, with surface dewpoints generally in
the mid to upper 60s to the south of the cold front. Still,
large-scale forcing should remain nebulous across this region
through Monday afternoon, and the potential for additional
thunderstorm formation along the front seems relatively low. A
modestly strengthening southwesterly low-level jet may eventually
encourage some convective development by Monday evening/night. But,
this activity may occur behind the cold front and be mainly
elevated. The potential for organized severe thunderstorms across
the Mid-South/TN Valley and vicinity appears too low/conditional for
any severe probabilities at this time.
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