May 31, 2018 2000 UTC Day 1 Convective Outlook
Updated: Thu May 31 19:57:14 UTC 2018 (20180531 2000Z Day 1 shapefile | 20180531 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180531 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 43,435 2,607,846 Nashville, TN...Clarksville, TN...Bowling Green, KY...Hendersonville, TN...Cape Girardeau, MO...
SLIGHT 239,099 9,081,845 Lexington-Fayette, KY...Springfield, MO...Billings, MT...Murfreesboro, TN...Missoula, MT...
MARGINAL 334,818 40,478,050 Indianapolis, IN...Columbus, OH...Memphis, TN...Charlotte, NC...Cleveland, OH...
Probabilistic Tornado Graphic
20180531 2000 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
5 % 13,120 472,851 Cape Girardeau, MO...Sikeston, MO...Poplar Bluff, MO...Farmington, MO...Jackson, MO...
2 % 102,111 5,121,543 Nashville, TN...Springfield, MO...Clarksville, TN...Jackson, TN...Jonesboro, AR...
Probabilistic Damaging Wind Graphic
20180531 2000 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
30 % 43,729 2,565,741 Clarksville, TN...Bowling Green, KY...Hendersonville, TN...Cape Girardeau, MO...Hopkinsville, KY...
15 % 237,276 8,976,800 Nashville, TN...Lexington-Fayette, KY...Knoxville, TN...Springfield, MO...Billings, MT...
5 % 335,174 41,514,598 Indianapolis, IN...Columbus, OH...Memphis, TN...Charlotte, NC...Cleveland, OH...
Probabilistic Large Hail Graphic
20180531 2000 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
SIG SEVERE 20,754 903,184 Cape Girardeau, MO...Hopkinsville, KY...Paducah, KY...Madisonville, KY...Sikeston, MO...
30 % 20,239 892,216 Cape Girardeau, MO...Hopkinsville, KY...Paducah, KY...Madisonville, KY...Sikeston, MO...
15 % 209,563 5,457,541 Nashville, TN...Springfield, MO...Clarksville, TN...Billings, MT...Missoula, MT...
5 % 144,609 5,576,031 Memphis, TN...Little Rock, AR...Evansville, IN...Murfreesboro, TN...Fort Smith, AR...
   SPC AC 311957

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0257 PM CDT Thu May 31 2018

   Valid 312000Z - 011200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON AND EVENING ACROSS PARTS OF THE MIDDLE MISSISSIPPI  INTO
   THE LOWER OHIO VALLEYS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE NORTHERN ROCKIES AND NORTHERN PLAINS...

   ...SUMMARY...
   Additional strong thunderstorm activity, accompanied by a risk for
   severe wind and hail, is expected across parts of southern Missouri
   and northern Arkansas into the lower Ohio Valley and Tennessee
   Valleys, as well as the northern High Plains and northern Rockies,
   late this afternoon and evening.

   ...20Z Outlook Update...
   Adjustments to categorical and severe probabilistic lines have been
   made in a number of areas.  This is mostly in an attempt to better
   account for latest trends in destabilization, and impacts of
   ongoing/preceding convection.

   Strongest instability (thermodynamic profiles characterized by steep
   mid-level lapse rates and large CAPE) remains present in a corridor
   along/south of a convectively generated or enhanced boundary across
   parts of southern Kentucky into southern Missouri,  where a 40-50 kt
   westerly 500 mb jet streak is contributing to strong vertical shear.
    Perhaps aided mostly by forcing for ascent associated with
   lower/mid tropospheric warm advection, it appears that another
   organized mesoscale convective system could evolve and propagate
   east/southeastward late this afternoon and evening accompanied by a
   risk for potentially damaging wind gusts.  Initial storm development
   may include isolated supercells with primarily a severe hail threat,
   but a tornado or two might not be out of the question.

   For more specific information concerning ongoing or imminent severe
   weather potential, please refer to the latest SPC mesoscale
   discussions and watches.

   ..Kerr.. 05/31/2018

   .PREV DISCUSSION... /ISSUED 1128 AM CDT Thu May 31 2018/

   ...Ozarks into OH Valley...
   Multiple clusters of severe storms are expected to affect this
   region today, with the first currently producing damaging winds over
   southeast IL.  These storms are expected to track eastward across
   southern IN and northern KY through much of the day.  Ref MCD #584
   and WW #136 for more information.

   In the wake of the initial band of storms, visible satellite imagery
   shows rapid clearing across southern MO.  This will result in strong
   heating, steepening low-level lapse rates, and destabilization
   across this region by early afternoon.  12z models are consistent in
   re-development of intense storms over this area as a weak shortwave
   trough moves into the region from KS.  The initial storms will
   potentially be supercellular with the risk of very large hail and a
   tornado or two.  Storms should slowly organize and grow upscale as
   outflows merge, with an eventual bowing complex producing damaging
   winds expected to move across the ENH area through the evening.

   ...Northern Great Basin into Northern Rockies...
   An active thunderstorm day is expected today from northeast NV and
   eastern ID into much of MT.  A large upper trough is moving across
   CA, with large scale lift and strong winds aloft spreading across
   the risk area.  Strong heating is occurring this morning, with
   dewpoints in the 50s over most of this region.  Present indications
   are that scattered fast-moving cells will form over the higher
   terrain throughout this region, and along a cold front moving into
   NV/ID.  Multiple clusters of strong/severe storms may persist
   through the afternoon and evening.  Large hail and damaging wind
   gusts will be the main threats.

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