Jun 17, 2018 1730 UTC Day 2 Convective Outlook
Updated: Sun Jun 17 17:19:19 UTC 2018 (20180617 1730Z Day 2 shapefile | 20180617 1730Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180617 1730 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 41,623 2,705,938 Albany, NY...Schenectady, NY...Troy, NY...Concord, NH...Burlington, VT...
MARGINAL 224,148 32,453,177 Chicago, IL...Milwaukee, WI...Boston, MA...Omaha, NE...Lincoln, NE...
Probabilistic Graphic
20180617 1730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 41,606 2,705,521 Albany, NY...Schenectady, NY...Troy, NY...Concord, NH...Burlington, VT...
5 % 224,162 32,453,594 Chicago, IL...Milwaukee, WI...Boston, MA...Omaha, NE...Lincoln, NE...
   SPC AC 171719

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1219 PM CDT Sun Jun 17 2018

   Valid 181200Z - 191200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE NORTHEAST...

   ...SUMMARY...
   Several strong to locally severe thunderstorms will be possible
   Monday over the Northeast with damaging gusts the primary hazard.

   ...Synopsis...
   Upper-level low pressure over the Great Basin will move northeast
   while slowly weakening on Monday while a mid-level high remains over
   the Southeast.  A surface cold front will move through a large part
   of the Northeast after dark while the westward portion of this
   boundary extends through the central High Plains.  A surface trough
   over the western Gulf of Mexico will move northwest in the vicinity
   of the TX coast on Monday.  

   ...New England...
   A very moist troposphere is forecast by model guidance before a cold
   front sweeps through the area overnight.  Almost saturated
   tropospheric profiles and poor mid level lapse rates will limit
   updraft intensity.  However, ample boundary layer heating with
   temperatures rising into the 80s and lower 90s will steepen
   low-level lapse rates.  U.S.-based suite of operational guidance
   (global, convection allowing, and ensemble data) and the Canadian
   show prefrontal storm development during the afternoon.  In
   contrast, the ECMWF, and the UKMET to a lesser extent, are largely
   showing only convection near the front yielding uncertainty.  MLCAPE
   is generally only forecast to range from 250 J/kg north to 1250 J/kg
   south.  However, increasing 700-500 mb flow overspreading the region
   during the afternoon/early evening will result in moderate storm
   motions with strong multicells and transient supercell structures. 
   Damaging gusts capable of tree damage are seemingly the greatest
   hazard.  Isolated strong gusts 40-55 mph are possible with the
   scattered thunderstorms and a couple of localized pockets of gusts
   55-60 mph are possible with the most intense downdrafts.  This
   activity will likely weaken during the evening as surface
   temperatures gradually cool.

   ...Central Plains and Midwest...
   Moderate/strong instability will develop Monday afternoon in the
   vicinity of the front, as widespread dew points in the upper
   60s/lower 70s will be in place.  Guidance is consistent in depicting
   a weak mid-level impulse lifting northeast across the central
   Plains, which may contribute to afternoon thunderstorm development. 
   Deep-layer shear will not be particularly strong (ranging from 20-35
   kts), but supportive of some degree of storm organization.  Damaging
   winds will be the primary severe risk.

   ...Northeast CO/southeast WY...
   Isolated/widely scattered thunderstorms are expected to develop over
   the higher terrain Monday afternoon, aided by low-level upslope
   flow.  Stronger mid-level flow east of the Great Basin upper low
   will result in vertical shear averaging 35-45 kt, and steep
   mid-level lapse rates above lower-mid 50s boundary layer dew points
   should result in surface-based instability of around 1000 J/kg. 
   Isolated supercells will be capable of large hail through early
   evening.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:      5%     - Marginal

   ..Smith.. 06/17/2018

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