Oct 30, 2021 1300 UTC Day 1 Convective Outlook
Updated: Sat Oct 30 12:31:05 UTC 2021 (20211030 1300Z Day 1 shapefile | 20211030 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20211030 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20211030 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20211030 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20211030 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 301231

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0731 AM CDT Sat Oct 30 2021

   Valid 301300Z - 311200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Organized severe thunderstorms are not forecast across the
   contiguous United States today or tonight.

   ...Synopsis/Discussion...
   The mid/upper-level pattern over the CONUS will be dominated by
   three substantial perturbations this period:
   1.  A major synoptic-scale cyclone now over the Appalachians
   forecast to continue filling while pivoting northeastward to NY and
   Lake Ontario by 12Z tomorrow.  The associated swath of elevated
   low-level warm advection and related destabilization above the
   boundary layer will support 200-800 J/kg MUCAPE and thunderstorm
   potential from this afternoon into tonight across roughly the
   eastern 3/4 of New England.  Relatively stable air should remain in
   the boundary layer, with the surface occlusion triple point
   remaining just offshore, south through east of ACK.  A few strong
   gusts may penetrate to the surface, especially over coastal
   southeastern MA and the nearby islands, but severe potential appears
   too minimal for an unconditional outlook. 
   2.  A northern-stream synoptic trough moving eastward over central
   Canada and the adjoining northern Plains/Upper Midwest, with the
   underlying air mass too dry for thunderstorms; and 
   3.  A compact cyclone now evident in moisture-channel imagery west
   of Cape Mendocino, CA.  This circulation will move slowly
   northeastward across the northwest tip of CA and over coastal OR
   through the period.  Downstream, strongly difluent flow aloft and
   several small shots of DCVA, along with marginal midlevel moisture,
   will continue to support sporadic thunder over portions of far
   northern CA to central OR today, and perhaps parts of the northern
   Great Basin region the last few hours of the period.

   ..Edwards/Mosier.. 10/30/2021

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z