Aug 12, 2021 0600 UTC Day 2 Convective Outlook
Updated: Thu Aug 12 05:48:10 UTC 2021 (20210812 0600Z Day 2 shapefile | 20210812 0600Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210812 0600 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 17,738 349,490 Greeley, CO...Cheyenne, WY...Evans, CO...Scottsbluff, NE...Sterling, CO...
MARGINAL 391,439 75,685,410 New York, NY...Philadelphia, PA...Columbus, OH...Memphis, TN...Baltimore, MD...
Probabilistic Tornado Graphic
20210812 0600 UTC Day 2 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 2 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
2 % 14,576 379,837 Greeley, CO...Cheyenne, WY...Evans, CO...Windsor, CO...Scottsbluff, NE...
Probabilistic Damaging Wind Graphic
20210812 0600 UTC Day 2 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 2 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 409,575 76,059,371 New York, NY...Philadelphia, PA...Columbus, OH...Memphis, TN...Baltimore, MD...
Probabilistic Large Hail Graphic
20210812 0600 UTC Day 2 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 2 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 17,738 349,490 Greeley, CO...Cheyenne, WY...Evans, CO...Scottsbluff, NE...Sterling, CO...
5 % 23,953 714,325 Fort Collins, CO...Longmont, CO...Loveland, CO...Brighton, CO...Laramie, WY...
   SPC AC 120548

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1248 AM CDT Thu Aug 12 2021

   Valid 131200Z - 141200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE NORTHEAST STATES INTO THE OHIO...TENNESSEE AND LOWER
   MISSISSIPPI VALLEYS...

   ...SUMMARY...
   A few strong to severe storms with locally strong to damaging wind
   gusts will be possible from a portion of the Northeast States into
   the Ohio, Tennessee and lower Mississippi Valleys Friday.

   ...Northeast States through the Ohio, Tennessee and lower
   Mississippi Valleys...

   A broad upper trough will persist over the Great Lakes region. By
   12Z Friday a cold front should extend from the lower Great Lakes
   through northern or central IL then westward into KS. A moist
   boundary layer will reside in the pre-frontal warm sector. However,
   there will likely be areas of ongoing thunderstorms and widespread
   convective debris over portions of this region. There also remains
   uncertainty where the convective boundaries and MCVs associated any
   ongoing activity will situated, but current indications are that the
   outflow boundaries will likely result in the more unstable portion
   of the warm sector evolving well south of the synoptic front. The
   atmosphere should become moderately unstable during the afternoon,
   and additional thunderstorms will redevelop primarily along residual
   outflow boundaries. Vertical shear in the warm sector will remain
   weak and supportive of multicells, but storms may evolve into lines
   and clusters and become capable of producing isolated strong to
   severe gusts through early evening.

   ...Central High Plains...

   A post-frontal upslope flow regime will evolve Friday, resulting in
   a corridor of upper 50s to 60F dewpoints advecting northwestward
   into northeast CO and southeast WY beneath steeper mid-level lapse
   rates. The atmosphere may become at least marginally unstable in
   this region with 500-1000 J/kg MLCAPE possible. Isolated storms may
   develop over the higher terrain and spread southeast. Weak to modest
   0-6 km shear of 25-35 kt will support multicell storms. The stronger
   updrafts could produce a few instances of marginally severe hail.

   ..Dial.. 08/12/2021

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z