May 19, 2017 2000 UTC Day 1 Convective Outlook
Updated: Fri May 19 19:59:24 UTC 2017 (20170519 2000Z Day 1 shapefile | 20170519 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170519 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 48,447 7,656,120 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
SLIGHT 187,555 18,079,591 Columbus, OH...Oklahoma City, OK...Kansas City, MO...Tulsa, OK...Wichita, KS...
MARGINAL 314,076 70,197,624 New York, NY...Philadelphia, PA...Indianapolis, IN...Austin, TX...Baltimore, MD...
Probabilistic Tornado Graphic
20170519 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 % 103,289 10,924,845 Dallas, TX...Fort Worth, TX...Arlington, TX...Wichita, KS...Plano, TX...
2 % 126,064 13,281,045 Columbus, OH...Oklahoma City, OK...Kansas City, MO...Tulsa, OK...Cincinnati, OH...
Probabilistic Damaging Wind Graphic
20170519 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 % 39,597 7,286,270 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
15 % 195,922 18,622,259 Columbus, OH...Oklahoma City, OK...Kansas City, MO...Tulsa, OK...Wichita, KS...
5 % 316,717 70,450,789 New York, NY...Philadelphia, PA...Indianapolis, IN...Austin, TX...Baltimore, MD...
Probabilistic Large Hail Graphic
20170519 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
30 % 48,252 7,638,839 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
15 % 156,004 11,538,351 Oklahoma City, OK...Kansas City, MO...Tulsa, OK...Wichita, KS...Overland Park, KS...
5 % 345,042 76,715,366 New York, NY...Philadelphia, PA...Indianapolis, IN...Columbus, OH...Austin, TX...
   SPC AC 191959

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0259 PM CDT Fri May 19 2017

   Valid 192000Z - 201200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   NORTH TEXAS AND SOUTHERN OKLAHOMA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
   SOUTHERN PLAINS TO THE MID MISSISSIPPI VALLEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE OHIO VALLEY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   TEXAS TO SOUTHERN NEW ENGLAND...

   ...SUMMARY...
   Severe thunderstorms are possible this afternoon into tonight across
   parts of the central and southern Plains through portions of the
   Ozark Plateau and middle Mississippi Valley.  Particularly across
   parts of northern Texas into southeastern Oklahoma, some of these
   may be accompanied by large hail, damaging wind gusts and a couple
   of tornadoes.

   ...Portions of the southern Plains...
   No significant changes are made to the ongoing risk areas. A
   somewhat nebulous convective evolution lends some uncertainty
   regarding the severe potential this afternoon and evening.
   Nonetheless, surface heating and dew points in the upper 60s/lower
   70s are maintaining moderate surface-based buoyancy across portions
   of north Texas into southeast Oklahoma. Across this area, large hail
   (with an isolated report over 2 inches in diameter), damaging winds,
   and a couple tornadoes remain possible. Farther north into central
   Oklahoma, while air mass recovery has been stunted by convection to
   the south, storms developing over northwest Texas will potentially
   push east/northeast and pose a threat of large hail.

   ...Portions of the Ohio Valley...
   The Slight Risk is expanded farther east, as a stationary front
   focuses convection along/ahead of a larger-scale complex progressing
   east. Mixed-layer CAPE around 500-1500 J/kg and sufficient westerly
   flow aloft will support a few damaging wind gusts. A tornado may be
   possible as well in the vicinity of the front, where storm-relative
   helicity may be slightly enhanced.

   ..Picca.. 05/19/2017

   .PREV DISCUSSION... /ISSUED 1115 AM CDT Fri May 19 2017/

   ...Synopsis...
   Within the southern branch of split westerlies emanating from the
   mid-latitude Pacific, models continue to indicate that large-scale
   troughing will gradually redevelop northeastward out of the
   Intermountain West and Rockies into the Plains, with an embedded
   closed low migrating out of the Colorado Rockies into the central
   Plains.  At the same time, a significant upper trough within the
   northern branch appears likely to dig across the Canadian Maritimes
   and New England.  In between, mid/upper ridging is forecast to build
   north and east of the middle Mississippi Valley through the Great
   Lakes and Mid Atlantic region.

   In lower-levels, a significant surface cold front associated with
   the northern branch trough has advanced into the Northeast, Ohio and
   middle Mississippi Valleys, and central/southern Plains.  While this
   front is stalling across the central Plains into the Ohio Valley, it
   is expected to advance across the remainder of New England and
   northern Mid Atlantic Coastal areas by late tonight.  Across the
   Plains, in response to forcing associated with the southern branch
   impulse, modest surface frontal cyclogenesis appears possible later
   today into tonight, from parts of western Oklahoma through the
   middle/lower Missouri Valley.

   ...Central and southern Plains into middle Mississippi Valley...
   The ongoing southward frontal surge across the Texas Panhandle and
   south Plains, the presence of significant outflow from prior
   convection across the Ozark Plateau into the Red River area,
   southward into northwest Texas, and the presence of considerable
   ongoing storm development above/to the cool side of this outflow
   across northwest Texas into Oklahoma, all are adding uncertainty to
   severe weather potential for today into tonight.

   Ongoing storms across northwest Texas appear to be supported by warm
   advection on the northern periphery of a plume of warmer and more
   strongly capping elevated mixed layer air.  Little further
   northeastward advection of this air mass may occur, and this may
   remain the focus for the primary thunderstorm development through
   the remainder of this period, as a short wave impulse pivots
   northeast of the southern Rockies.

   The eventual upscale growth of a large mesoscale convective system
   appears possible this afternoon and evening across northern Texas
   into southeastern Oklahoma.  In the presence of thermodynamic
   profiles characterized by steep mid-level lapse rates and moderately
   large CAPE, large hail and damaging wind gusts are expected.  Deep
   layer and low-level shear may remain sufficient to support a risk
   for tornadoes, particularly with any initial discrete supercell
   development, and possible continuing supercell development near or
   just ahead of the evolving convective system.

   Farther north, into the central Plains, potential for significant
   destabilization is becoming more unclear, but the developing frontal
   wave may provide another focus for strong/severe storm development
   late this afternoon and evening.  If sufficient destabilization can
   occur, deep layer wind fields and shear probably will become
   supportive of organized storm development, including supercells.

   ...Ohio Valley into Mid Atlantic and New England...
   Low severe probabilities have been extended northward into parts of
   southern New England, where the pre-frontal environment now appears
   at least conditionally supportive of storms capable of producing
   severe wind/hail.

   Farther south and west, into the Mid Atlantic and Ohio Valley, more
   uncertainty exists concerning severe storm potential, in the
   presence of rising mid-level heights beneath the building upper
   ridge.  However, it appears at least possible that forcing
   associated with a remnant convectively enhanced impulse, could
   support and enhance thunderstorm development near the stalling front
   across the middle Ohio Valley region this afternoon.

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