Jun 19, 2017 1630 UTC Day 1 Convective Outlook
Updated: Mon Jun 19 16:27:18 UTC 2017 (20170619 1630Z Day 1 shapefile | 20170619 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170619 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 56,352 40,500,492 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Newark, NJ...
SLIGHT 121,196 23,780,245 Charlotte, NC...Boston, MA...Raleigh, NC...Greensboro, NC...Durham, NC...
MARGINAL 421,900 58,585,280 Chicago, IL...Houston, TX...San Antonio, TX...Austin, TX...Milwaukee, WI...
Probabilistic Tornado Graphic
20170619 1630 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 % 127,531 49,653,480 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Newark, NJ...
Probabilistic Damaging Wind Graphic
20170619 1630 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 % 56,352 40,500,492 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Newark, NJ...
15 % 121,205 23,783,300 Charlotte, NC...Boston, MA...Raleigh, NC...Greensboro, NC...Durham, NC...
5 % 421,798 58,546,841 Chicago, IL...Houston, TX...San Antonio, TX...Austin, TX...Milwaukee, WI...
Probabilistic Large Hail Graphic
20170619 1630 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
5 % 388,222 92,294,854 New York, NY...Chicago, IL...Houston, TX...Philadelphia, PA...San Antonio, TX...
   SPC AC 191627

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1127 AM CDT Mon Jun 19 2017

   Valid 191630Z - 201200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   EASTERN VA TO SOUTHEASTERN NY AND WESTERN NEW ENGLAND...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED RISK FROM PORTIONS OF THE CAROLINAS TO MAINE...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK FROM PARTS OF NEW ENGLAND TO THE SOUTHEAST STATES AND
   WESTWARD TO TX...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   ND AND WESTERN MN...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   EASTERN IA AND SOUTHERN WI TO WESTERN OH...

   ...SUMMARY...
   Strong to severe thunderstorms are forecast over parts of the
   Northeast into the Mid-Atlantic states this afternoon and evening. 
   Damaging wind gusts will be the primary severe hazard but a tornado
   or two and some hail may also be possible.  Isolated strong to
   severe thunderstorms are possible farther southwestward, across
   parts of the Southeast to Texas through late afternoon

   ...Portions of the Eastern States...
   Little overall change has been made to the ongoing forecast.
   Convection will continue deepening along the eastern fringes of a
   multi-layered cloud band from northern NY to the southern
   Appalachians through the afternoon hours. Convection will most
   notably develop in the short term from the Mid-Atlantic to New
   England in closer proximity to at least 30-meter/12-hour 500-mb
   height falls, with convection subsequently developing southward as
   diurnal heating continues. Numerous bands of convection will
   elongate north-northeastward while shifting east, ahead of a deeper
   baroclinic zone crossing the Great Lakes region. As a diffuse warm
   front advances north across New England, a corridor of 1000-2500
   J/kg of MLCAPE will continue to extend north with time -- primarily
   driven by rich boundary-layer moisture (e.g., 15.5 g/kg mean mixing
   ratio per Brookhaven NY 12Z sounding). Given 25-35 kt of flow around
   1-km above ground per VAD wind profiles over the meridionally
   extensive moist sector/surface dewpoints in the 70s, scattered
   damaging wind gusts will be likely -- enhanced in association with
   line-embedded meso-vortices/small rear inflow jets. Convection will
   spread toward the Atlantic coast through the evening before
   weakening as it moves offshore while also encountering a stable
   marine layer across northeastern parts of New England.

   The greatest concentration of damaging wind is expected across the
   Enhanced Risk area. Across the surrounding Slight Risk area, weaker
   buoyancy across northern New England, and somewhat warmer midlevel
   profiles and a weaker low-level mass response across the NC/SC
   Piedmont will limit the severe risk in those areas.

   ...South of the southern extent of the Slight Risk area from parts
   of the Southeast States to Texas...
   A moist and uncapped boundary layer will continue to destabilize
   where surface heating is the strongest. Low-level ascent along a
   weak surface boundary -- augmented by outflow accompanying a
   persistent convective cluster in central TX -- will support a
   corridor of isolated to scattered thunderstorm potential into the
   early evening hours. Weak deep shear should limit convective
   organization, while a few strong microbursts potentially support
   isolated damaging winds.

   ...Portions of ND into western MN...
   Clusters of convection will increase ahead of a compact midlevel
   impulse advancing southeastward from Saskatchewan. Despite a dearth
   of tropospheric moisture, long mid/high-level hodographs and
   moderate midlevel lapse rates may support a few persistent
   convective elements capable of isolated severe hail/wind.

   ...Portions of eastern IA/southern WI to western OH...
   Cold midlevel conditions above a diurnally warming, though
   relatively dry, boundary layer will support sufficient instability
   for sustained convective clusters to move across the region into
   early evening. Sufficient deep shear and high-level flow may support
   weakly organized convective structures capable of isolated severe
   hail/wind.

   ..Cohen.. 06/19/2017

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