Jul 8, 2021 0600 UTC Day 2 Convective Outlook
Updated: Thu Jul 8 05:32:24 UTC 2021 (20210708 0600Z Day 2 shapefile | 20210708 0600Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210708 0600 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 94,058 3,440,960 Omaha, NE...Lincoln, NE...Des Moines, IA...Sioux City, IA...St. Joseph, MO...
MARGINAL 143,216 15,908,570 Boston, MA...Kansas City, MO...St. Louis, MO...Providence, RI...Worcester, MA...
Probabilistic Tornado Graphic
20210708 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
5 % 39,827 2,302,642 Omaha, NE...Des Moines, IA...St. Joseph, MO...Council Bluffs, IA...West Des Moines, IA...
2 % 63,045 12,257,234 Boston, MA...Kansas City, MO...Lincoln, NE...Providence, RI...Worcester, MA...
Probabilistic Damaging Wind Graphic
20210708 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
15 % 94,127 3,456,449 Omaha, NE...Lincoln, NE...Des Moines, IA...Sioux City, IA...St. Joseph, MO...
5 % 129,830 6,825,814 Kansas City, MO...St. Louis, MO...Overland Park, KS...Kansas City, KS...Sioux Falls, SD...
Probabilistic Large Hail Graphic
20210708 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 % 94,070 3,457,974 Omaha, NE...Lincoln, NE...Des Moines, IA...Sioux City, IA...St. Joseph, MO...
5 % 129,561 6,754,878 Kansas City, MO...St. Louis, MO...Overland Park, KS...Kansas City, KS...Sioux Falls, SD...
   SPC AC 080532

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1232 AM CDT Thu Jul 08 2021

   Valid 091200Z - 101200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   NEBRASKA...SOUTHWEST IOWA...NORTHERN MISSOURI AND FAR NORTHEAST
   KANSAS...

   ...SUMMARY...
   Severe thunderstorms capable of damaging wind gusts and hail are
   possible Friday afternoon into Friday night across parts of the
   central Plains and Middle Missouri Valley. A tornado or two
   associated with Tropical Storm Elsa also is possible in the vicinity
   of the New England coast through Friday afternoon.

   ...Synopsis...

   A broad area of mid/upper northwesterly flow will extend from the
   northern Rockies through the northern/central Plains to the Midwest
   on Friday. Within this area of northwesterly flow, a series of
   shortwave troughs will migrate southeast across the northern Rockies
   to the central Plains, and from the Upper Midwest toward the Ohio
   Valley/central Appalachians. Tropical Storm Elsa is also forecast to
   continue tracking northeast in the vicinity of the New England
   coast, while a surface cold front advances eastward across the
   Mid-Atlantic and Northeast. Further west, surface low pressure will
   develop over the central Plains, with an attendant cold front
   dropping southward across NE and into KS overnight. A very moist and
   unstable airmass will exist across the central Plains into the
   Mid-MO/Mid-MS Valley vicinity ahead of the surface low and cold
   front. Scattered strong to severe thunderstorms are expected to
   develop over the region during the afternoon into Friday night.

   ...Central Plains to Mid-MS Valley Vicinity...

   A somewhat complicated scenario is expected to evolve on Friday,
   with at least a couple of corridors of severe potential. The timing
   of the shortwave trough ejecting eastward from the northern Rockies
   has slowed some in forecast guidance over the past day.
   Nevertheless, several lead shortwave impulses are indicated, and
   should be sufficient to aid in convective initiation within a
   strongly unstable environment amid increasing vertical shear.
   Surface dewpoints in the mid 60s to low 70s F beneath steep midlevel
   lapse rates will result in MLCAPE values greater than 2000 J/kg
   across much of NE into southwest IA, MO and northeast KS.

   A strong capping inversion is expected across much of KS into parts
   of MO, introducing some uncertainty on the eastern/southern extent
   of severe potential. Additionally, stationary boundary is forecast
   to extend northwest to southeast across IA, and may be reinforced by
   morning convection. This could hinder convective development for
   much of the day by limiting stronger heating/destabilization. If
   early precipitation and cloud cover is limited or clears out quickly
   enough, this boundary could also serve as a focus for intense
   thunderstorm development by late afternoon. If this scenario plays
   out, initial supercell storms could pose a threat for all severe
   hazards before an increasing low level jet during the evening
   support upscale development into a south/southeastward developing
   MCS.

   Further west, convection is expected to develop as increasing ascent
   overspread the northern/central High Plains. High-based storms will
   pose a threat for damaging gusts and large hail. As the cold front
   surges southward during the evening, potential will exist for upward
   development into one or more bowing segments tracking east/southeast
   across NE. 

   Some potential will exist for sig wind/hail across the Slight risk
   area, but given quite a bit of uncertainty in convective evolution,
   will hold off on including 10% SIG probs at this time.

   ...Coastal New England...

   Tropical Storm Elsa is forecast by the National Hurricane Center to
   transition into a post-tropical cyclone on Friday as it shifts
   northeast near the New England coast. A broadening and strengthening
   of the low level wind field is forecast as the system makes this
   post-tropical transition, and strong low level SRH will overspread
   the region. Dew points in the upper 60s F will result in weak 0-3 km
   instability and a tornado or two will be possible through Friday
   afternoon.

   ..Leitman.. 07/08/2021

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

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