May 27, 2018 0600 UTC Day 1 Convective Outlook
Updated: Sun May 27 05:59:21 UTC 2018 (20180527 1200Z Day 1 shapefile | 20180527 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180527 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 152,026 16,002,623 Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...Orlando, FL...
MARGINAL 252,751 5,131,254 Jacksonville, FL...Amarillo, TX...Tallahassee, FL...Gainesville, FL...Fargo, ND...
Probabilistic Tornado Graphic
20180527 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
5 % 38,073 15,244,535 Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...Orlando, FL...
2 % 72,154 3,467,420 Jacksonville, FL...Tallahassee, FL...Gainesville, FL...Daytona Beach, FL...Valdosta, GA...
Probabilistic Damaging Wind Graphic
20180527 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 % 113,715 750,555 Rapid City, SD...Casper, WY...Garden City, KS...Gillette, WY...Liberal, KS...
5 % 253,227 19,922,517 Jacksonville, FL...Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...
Probabilistic Large Hail Graphic
20180527 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 % 114,458 757,445 Rapid City, SD...Casper, WY...Garden City, KS...Gillette, WY...Liberal, KS...
5 % 225,853 2,006,657 Amarillo, TX...Fargo, ND...Duluth, MN...Bismarck, ND...Cheyenne, WY...
   SPC AC 270559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Sun May 27 2018

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE HIGH
   PLAINS REGION AS WELL AS OVER THE FLORIDA PENINSULA...

   ...SUMMARY...
   Severe storms are possible later today into this evening primarily
   from the northern through southern High Plains. A modest threat for
   a few tornadoes will also exist across the Florida Peninsula.

   ...Synopsis...

   Cutoff upper low circulation situated over the Great Basin will
   advance very slowly east today with downstream ridge shifting east
   through the Plains and MS Valley region. At the surface a
   northern-stream low-amplitude shortwave trough moving through
   southern Manitoba will provide the impetus for a cold front to
   continue south into the northern Plains and upper MS Valley. Farther
   south a dryline will become established over the central through
   southern High Plains. Subtropical Storm Alberto is forecast by the
   National Hurricane center to continue north through the eastern
   Gulf. 

   ...High Plains region and central Rockies...

   Post-frontal upslope flow will persist across WY where some low
   clouds may linger into early afternoon. Farther east into the High
   Plains dewpoints generally in the 50s and steep lapse rates will
   support moderate to strong instability as the boundary layer warms
   during the afternoon with MLCAPE from 1500-2500 J/kg likely. Several
   vorticity maxima moving through the upper low circulation will lift
   north through the Rockies and into portions of the High Plains.
   Multiple areas of thunderstorm initiation are likely, including
   within upslope regime over the higher terrain of WY as well as
   farther south along dryline across the central through southern High
   Plains, where the best wind profiles for a few high based supercells
   will exist. Otherwise, multicell storms will be the dominant mode.
   Storms may remain more discrete with southward extent into the
   plains before weakening during the evening, but some upscale growth
   into lines/clusters may occur from WY into western NE and the
   western Dakotas where storms may persist into the overnight. Large
   hail and damaging wind are expected to be the main threats.  

   ...FL through southeast GA...

   Subtropical storm Alberto is forecast by the NHC to advance north
   and northwest through the eastern Gulf. Satellite imagery shows
   middle to upper-level dry air entraining into the west and southern
   portions of the storm, and this should increase the chance of
   diabatic heating in between the outer convective bands today. A
   broad low-level jet east of the center will augment 0-2 km
   hodographs over the southern two thirds of the FL Peninsula during
   peak heating, supporting a threat for mini supercells capable of a
   few tornadoes later today. At least a marginal risk for a couple of
   tornadoes will extend farther north into southeast GA by late
   afternoon or evening.

   ..Dial/Marsh.. 05/27/2018

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