Jun 7, 2018 0600 UTC Day 1 Convective Outlook
Updated: Thu Jun 7 05:42:02 UTC 2018 (20180607 1200Z Day 1 shapefile | 20180607 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180607 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 227,496 1,288,155 Billings, MT...Rapid City, SD...Great Falls, MT...Bozeman, MT...Butte, MT...
MARGINAL 571,312 17,685,844 Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...Wichita, KS...
Probabilistic Tornado Graphic
20180607 1200 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
2 % 99,641 512,383 Billings, MT...Gillette, WY...Sheridan, WY...Scottsbluff, NE...Spearfish, SD...
Probabilistic Damaging Wind Graphic
20180607 1200 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
15 % 226,829 1,284,389 Billings, MT...Rapid City, SD...Great Falls, MT...Bozeman, MT...Butte, MT...
5 % 575,726 17,735,254 Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...Wichita, KS...
Probabilistic Large Hail Graphic
20180607 1200 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
15 % 227,552 1,283,339 Billings, MT...Rapid City, SD...Great Falls, MT...Bozeman, MT...Butte, MT...
5 % 575,766 17,770,036 Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...Wichita, KS...
   SPC AC 070542

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1242 AM CDT Thu Jun 07 2018

   Valid 071200Z - 081200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
   MONTANA INTO THE CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Severe thunderstorms are expected mainly across the central through
   northern High Plains and into central Montana this afternoon and
   evening. Hail and wind will be the main threats. Sporadic severe
   storms are also possible across much of the Great Plains, along with
   corridors of heavy rain.

   ...Synopsis...
   An upper high will remain centered over TX with a mean ridge
   extending northward into the Canadian Prairies. A southern-stream
   shortwave trough will however move from the Great Basin toward the
   northern Rockies, with modest southwesterly flow aloft and lift
   moving into MT and WY. At the surface, a low pressure trough will
   extend from eastern MT across WY and into the central and southern
   High Plains during the afternoon, with southerly low-level winds
   maintaining a moist and unstable air mass across much of the Plains.

   ...MT into the central High Plains...
   Southeasterly surface winds will maintain 50s to perhaps 60 F
   dewpoints across the eastern half of MT during the day, with lift
   maximized near the surface trough during the afternoon. Storms
   should form at that time over central MT, as well as farther
   southeast across WY and into the central High Plains. Large hail is
   likely with the initial cellular activity, with perhaps a few
   slow-moving supercells capable of isolated very large hail. Storms
   may form into clusters, with a damaging wind threat as well,
   although meager shear profiles suggest storms may not become very
   well organized for any widespread severe threat.

   ...Much of the Plains...
   An unstable air mass is likely to remain in place from near I-90 in
   SD southward into TX. Given the numerous storms ongoing as of
   Wednesday evening, predictability is low for potential MCS corridors
   during the day, which will depend heavily on the early-day
   convective coverage. Damaging wind and isolated hail will be
   possible, and a Slight Risk could be needed across parts of the
   Marginal Risk area. Possible corridors of severe risk include KS
   into OK, as well as across IA into NE where a backbuilding MCS is
   forecast by some models.

   ..Jewell/Dean.. 06/07/2018

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