Jul 8, 2017 1630 UTC Day 1 Convective Outlook
Updated: Sat Jul 8 16:27:29 UTC 2017 (20170708 1630Z Day 1 shapefile | 20170708 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170708 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 161,285 25,148,746 Phoenix, AZ...Charlotte, NC...Boston, MA...Tucson, AZ...Mesa, AZ...
MARGINAL 524,903 51,910,180 Oklahoma City, OK...New Orleans, LA...Atlanta, GA...Tulsa, OK...Wichita, KS...
Probabilistic Tornado Graphic
20170708 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20170708 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
15 % 161,548 24,929,614 Phoenix, AZ...Charlotte, NC...Boston, MA...Tucson, AZ...Mesa, AZ...
5 % 512,993 51,845,093 Oklahoma City, OK...New Orleans, LA...Atlanta, GA...Tulsa, OK...Plano, TX...
Probabilistic Large Hail Graphic
20170708 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 % 617,374 66,322,238 Charlotte, NC...Boston, MA...Oklahoma City, OK...New Orleans, LA...Virginia Beach, VA...
   SPC AC 081627

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1127 AM CDT Sat Jul 08 2017

   Valid 081630Z - 091200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EXTREME
   EASTERN NEW YORK INTO NEW ENGLAND...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
   VIRGINIA INTO NORTH CAROLINA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOUISIANA
   INTO ALABAMA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
   ARIZONA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN NEW
   YORK INTO NEW ENGLAND...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   PLAINS ACROSS THE LOWER MISSISSIPPI VALLEY INTO THE CAROLINAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   FLORIDA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND
   SOUTHERN ARIZONA...

   ...SUMMARY...
   A few severe thunderstorms are expected from the central Plains to
   the Carolinas and Mid-Atlantic States, and across New England.
   Localized damaging wind gusts are most likely, with large hail most
   probable over the Plains. Isolated storms producing strong-to-severe
   wind gusts are possible across southern Arizona as well.

   ...Extreme eastern New York into New England...
   Water vapor imagery shows a short wave trough lifting northeastward
   across the lower Great Lakes toward New England. This feature is
   enhancing large-scale ascent with scattered thunderstorms occurring
   from northern/eastern New York into western Maine.  Visible imagery
   shows a corridor of limited clouds from southeast New York into
   Massachusetts and southern parts of New Hampshire and Maine which
   will promote stronger diabatic heating this afternoon.  Although 12Z
   soundings exhibit weak mid-level lapse rates across the region,
   surface dew points in the mid/upper 60s and steepening low-level
   lapse rates will contribute to some destabilization with SBCAPE
   reaching 1000-1500 J/kg.

   Thunderstorms are expected to continue developing this afternoon
   ahead of an advancing cold front.  Moderate westerly flow aloft
   coupled with 35-40 kt deep layer shear will support organized storm
   structures including potential for short bowing line segments. 
   Stronger storms will be capable of producing strong-to-severe wind
   gusts into the evening hours.

   ...Southern Virginia into North Carolina...
   Strong heating is occurring across this area with surface
   temperatures approaching 90 degrees.  12Z sounding at GSO indicated
   the moisture over the Piedmont was relatively shallow suggesting
   that current surface dew points in the lower 70s over this area may
   mix out this afternoon as steep low-level lapse rates develop. 
   Storms are expected to develop within a weakly capped environment
   over the higher terrain and spread eastward along the southern edge
   of stronger westerly winds in the mid-levels.  Deep layer shear of
   20-30 kt will be sufficient to support organized multi-cell storm
   structures including short line segments.  Stronger storms will be
   capable of producing damaging wind gusts through the evening hours.

   ...Louisiana into Alabama...
   12Z soundings at SHV, JAN, and BMX indicate ample low-level moisture
   with pronounced drying above the PBL that is contributing to large
   values of DCAPE greater than 1300 J/kg.  Strong heating is occurring
   over central parts of Louisiana, Mississippi and Alabama to the
   south of ongoing convection, with a well-defined outflow boundary
   evident in visible imagery moving southward into central Louisiana
   and Mississippi.  Storms are expected to continue developing and
   intensify this afternoon within an environment favorable for wet
   microbursts with potential to produce locally damaging wind gusts.

   ...Southern Arizona...
   12Z soundings at PHX and TUS exhibit very deep mixed layers with
   precipitable water values around 1.2 inches and layers of stronger
   easterly component winds in the low-to-mid levels.  Intense diabatic
   heating will support development of thunderstorms over the mountains
   of southeast and east central Arizona this afternoon and evening,
   with potential for cells to propagate westward toward the lower
   deserts.  The deep mixed layer and dry sub-cloud environment will
   promote generation of strong-to-severe wind gusts later this
   afternoon and evening.

   ...Central Plains...
   In the presence of moderately strong north/northwesterly flow aloft,
   storms appear most likely to develop across parts of Nebraska this
   afternoon in vicinity of a surface low and weak front with storms
   also potentially spreading into portions of western and central
   Kansas.  Modest amounts of buoyancy and deep-layer shear could yield
   isolated severe storms capable of severe hail and wind mainly late
   this afternoon into evening.

   ..Weiss/Mosier.. 07/08/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z