Jan 22, 2017 1300 UTC Day 1 Convective Outlook
Updated: Sun Jan 22 12:53:18 UTC 2017 (20170122 1300Z Day 1 shapefile | 20170122 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170122 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
HIGH 52,325 4,828,034 Jacksonville, FL...Tallahassee, FL...Savannah, GA...Gainesville, FL...Albany, GA...
MODERATE 44,236 9,345,964 Tampa, FL...St. Petersburg, FL...Columbia, SC...Clearwater, FL...Charleston, SC...
ENHANCED 54,540 8,455,690 Orlando, FL...Columbus, GA...Cape Coral, FL...Fayetteville, NC...Port St. Lucie, FL...
SLIGHT 68,779 19,272,935 Charlotte, NC...Atlanta, GA...Miami, FL...Raleigh, NC...Greensboro, NC...
MARGINAL 58,080 13,692,306 San Jose, CA...San Francisco, CA...Virginia Beach, VA...Oakland, CA...Norfolk, VA...
Probabilistic Tornado Graphic
20170122 1300 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
SIG SEVERE 95,336 13,200,743 Jacksonville, FL...Tampa, FL...St. Petersburg, FL...Orlando, FL...Tallahassee, FL...
30 % 52,311 4,824,800 Jacksonville, FL...Tallahassee, FL...Savannah, GA...Gainesville, FL...Albany, GA...
15 % 44,337 9,370,344 Tampa, FL...St. Petersburg, FL...Columbia, SC...Clearwater, FL...Charleston, SC...
10 % 42,022 5,926,863 Orlando, FL...Columbus, GA...Fayetteville, NC...Wilmington, NC...Lakeland, FL...
5 % 81,803 21,852,295 Charlotte, NC...Atlanta, GA...Miami, FL...Raleigh, NC...Greensboro, NC...
2 % 48,102 6,722,417 Virginia Beach, VA...Norfolk, VA...Birmingham, AL...Chesapeake, VA...Winston-Salem, NC...
Probabilistic Damaging Wind Graphic
20170122 1300 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 % 133,154 20,032,737 Jacksonville, FL...Tampa, FL...St. Petersburg, FL...Orlando, FL...Columbus, GA...
15 % 87,324 21,961,970 Charlotte, NC...Atlanta, GA...Miami, FL...Raleigh, NC...Greensboro, NC...
5 % 57,763 13,517,893 San Jose, CA...San Francisco, CA...Virginia Beach, VA...Oakland, CA...Norfolk, VA...
Probabilistic Large Hail Graphic
20170122 1300 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 % 66,315 5,652,400 Jacksonville, FL...Tallahassee, FL...Savannah, GA...Gainesville, FL...Albany, GA...
15 % 131,079 32,125,422 Charlotte, NC...Atlanta, GA...Miami, FL...Tampa, FL...St. Petersburg, FL...
5 % 38,813 6,902,941 Raleigh, NC...Greensboro, NC...Birmingham, AL...Durham, NC...Winston-Salem, NC...
   SPC AC 221253

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0653 AM CST Sun Jan 22 2017

   Valid 221300Z - 231200Z

   ...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS TODAY ACROSS SOUTH
   GEORGIA...NORTH FLORIDA...AND EXTREME SOUTHEAST ALABAMA...

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   HIGH RISK AREA...FROM CENTRAL FLORIDA TO SOUTH CAROLINA...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE RISK AREA...FROM SOUTH FLORIDA TO SOUTHERN NORTH
   CAROLINA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED RISK AREA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK AREA IN THE SOUTHEAST STATES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS THE
   CENTRAL CALIFORNIA COAST...

   ...SUMMARY...
   A severe thunderstorm and tornado outbreak is expected today across
   north Florida and south Georgia, with the significant severe threat
   also expected to extend southward into central Florida and
   northeastward into South Carolina this evening.

   ***Significant tornado outbreak expected today across north Florida
   and south Georgia***

   ...Synopsis...
   An amplifying mid-upper trough over TX/OK this morning will continue
   eastward to MS/AL by this afternoon.  The initial synoptic cyclone
   near Texarkana will likely be replaced by cyclogenesis today at the
   triple point of the effective warm front across southern AL, and the
   eastward-surging cold front/trough from LA/MS.  This new cyclone
   will deepen and move north-northeastward today across AL/GA in
   association with the strong height falls/ascent within the exit
   region of a 100-130 kt mid-upper jet.  Likewise, very strong
   deep-layer tropospheric flow is expected within the warm sector,
   where boundary layer dewpoints in the 65-70 F range and a lingering
   steep lapse rate plume will support moderate buoyancy.  The net
   result of these factors will be the potential for a significant
   tornado episode today across north FL into south GA.

   ...AL/FL/GA today to the Carolinas this evening/tonight...
   A broken band of severe storms that formed overnight persists this
   morning across south GA.  This convective band was associated with
   low-level warm advection, as well as an ejecting midlevel trough
   that is now over north GA and east TN.  It is not clear if this
   convection will weaken this morning, or if it will persist until new
   thunderstorms begin to form farther to the west across south AL and
   the FL Panhandle.  Regardless the boundary should begin to move
   northward by midday as cyclogenesis proceeds across AL.  Likewise,
   as the synoptic midlevel trough approaches from the west,
   strengthening vertical shear is expected within the unstable warm
   sector.  Observational data confirm the most important aspects of
   the thermodynamic and kinematic profiles, thus confidence is high in
   the unusual combination of ingredients today.  Forecast soundings
   suggest the potential for MLCAPE of 1000-1500 J/kg, with effective
   bulk shear in excess of 70 kt, and effective SRH in excess of
   300-400 m2/s2.  The orientation of deep-layer shear vectors across
   the cold front/trough will favor broken bands of tornadic
   supercells.

   Aside from the ongoing storms across south GA, the severe/tornado
   risk will likely ramp up again later this morning across south AL
   and the FL Panhandle along the residual rain-cooled boundary/warm
   front, and then spread east-northeastward across north FL and GA
   through the day.  Long-tracked, strong tornadoes will be possible
   with fast moving supercells, in addition to damaging winds and large
   hail.  The severe/tornado risk will spread northeastward into the
   Carolinas this evening as the cyclone deepens and moves
   northeastward to the southern Appalachians.  There are some concerns
   regarding the degree of near-surface destabilization with
   northeastward extent into the Carolinas.  However, very strong
   low-level shear would favor maintenance of any supercells that
   mature a bit farther southwest in the warm sector, with the risk for
   tornadoes persisting after dark into SC and perhaps southern NC. 
   Farther south, the band of storms with the cold front will reach
   south FL overnight, with a continued risk for damaging winds and a
   couple of tornadoes.

   ...Central CA coast today...
   Another strong shortwave trough will move inland today over CA.  As
   the left exit region of the mid-upper jet overspreads the coast and
   near-surface flow becomes onshore with frontal passage, weak
   surface-based buoyancy will develop.  There will be some potential
   for low-topped thunderstorms with isolated damaging gusts in this
   regime.

   ..Thompson/Cohen.. 01/22/2017

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