Mar 3, 2019 1300 UTC Day 1 Convective Outlook
Updated: Sun Mar 3 12:52:48 UTC 2019 (20190303 1300Z Day 1 shapefile | 20190303 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20190303 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 41,660 2,776,379 Montgomery, AL...Columbus, GA...Macon, GA...Albany, GA...Dothan, AL...
SLIGHT 107,123 14,475,459 Atlanta, GA...Mobile, AL...Tallahassee, FL...Metairie, LA...Savannah, GA...
MARGINAL 60,732 8,754,604 Jacksonville, FL...New Orleans, LA...Birmingham, AL...Baton Rouge, LA...Jackson, MS...
Probabilistic Tornado Graphic
20190303 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 31,226 2,184,673 Montgomery, AL...Columbus, GA...Macon, GA...Albany, GA...Dothan, AL...
10 % 31,344 2,206,918 Montgomery, AL...Columbus, GA...Macon, GA...Albany, GA...Dothan, AL...
5 % 104,250 14,593,764 New Orleans, LA...Atlanta, GA...Mobile, AL...Metairie, LA...Savannah, GA...
2 % 43,552 4,944,930 Birmingham, AL...Baton Rouge, LA...Jackson, MS...Tallahassee, FL...Wilmington, NC...
Probabilistic Damaging Wind Graphic
20190303 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 % 41,582 2,774,800 Montgomery, AL...Columbus, GA...Macon, GA...Albany, GA...Dothan, AL...
15 % 107,122 14,693,331 New Orleans, LA...Atlanta, GA...Mobile, AL...Tallahassee, FL...Metairie, LA...
5 % 60,798 8,549,451 Jacksonville, FL...Birmingham, AL...Baton Rouge, LA...Jackson, MS...Gainesville, FL...
Probabilistic Large Hail Graphic
20190303 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
5 % 118,340 16,469,080 New Orleans, LA...Atlanta, GA...Birmingham, AL...Baton Rouge, LA...Montgomery, AL...
   SPC AC 031252

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0652 AM CST Sun Mar 03 2019

   Valid 031300Z - 041200Z


   Severe thunderstorms with damaging gusts and tornadoes are expected
   over parts of the Southeast today.

   The CONUS portion of the large-scale, upper-air pattern will become
   more cyclonic through the period as:
   1.  A series of shortwaves orbit the southern semicircle of a
   northern-stream cyclone, which is forecast to move slowly eastward
   over northern ON to James Bay;
   2.  A well-defied southern-stream shortwave trough -- now apparent
   in moisture-channel imagery from the KS/MO border region
   southwestward across OK to northwest TX -- moves eastward across the
   central/southern Appalachians and offshore from the Atlantic Coast
   by the end of the period.

   At the surface, 11Z analysis showed a broad area of low pressure
   over the westernmost portions of the Carolinas, attached to an
   inland, quasistationary baroclinic zone extending southwestward
   across north-central GA, central AL, southwestern MS, and extreme
   southeast TX.  Farther west, this was a cold front denoting a
   southward surge of arctic air, merging with another frontal zone
   over deep south TX.  The southern front, demarcating the northern
   rim of the maritime/tropical air from the Gulf, extended from there
   east-northeastward to a weak low along the central coast of LA,
   across the western Fl Panhandle to near SAV, then offshore from SC. 
   This boundary -- initially quasistationary as well, will move inland
   across portions of southeastern MS, southern/central AL and GA,
   effectively merging with the inland boundary.

   A better-defined/frontal-wave low should form in the blending
   frontal zone by midday near the MEI-BHM corridor, in response to the
   approaching mid/upper perturbation.  This low will ripple
   northeastward along the front to northwestern SC by 00Z,
   accelerating offshore from the NC Outer Banks around 06Z.  By that
   time, the trailing cold front should be located over southeastern
   NC, south-central GA, the eastern FL Panhandle or coastal bend
   region, and the north-central/west-central Gulf.

   Clusters of elevated, initially non-severe thunderstorms are ongoing
   across parts of the southern AR/northern LA/western MS region, in a
   regime of elevated low-level warm advection and moisture transport
   stimulated by the approaching shortwave trough.  Additional
   convection is forecast to form farther south into the lower Delta
   region over the next few hours, ultimately merging with the
   initially elevated clusters.  The combined activity should evolve
   into a southwest/northeast-oriented, quasi-linear convective system
   (QLCS), moving east-northeastward across the outlook area along or
   shortly ahead of the cold front.  This complex should move into an
   inland/northward-penetrating sector of surface-based effective-
   inflow parcels that are progressively higher in theta-e, and
   resultant MLCAPE, from north to south.

   As that occurs, severe potential will steadily ramp up through
   mid/late morning and into the afternoon.  Bowing segments and LEWP
   formations are expected, with damaging winds constituting the bulk
   of reports, but a few tornadoes also are possible.  Tornado-event
   density, and risk of significant tornadoes, still is somewhat
   unclear -- being strongly dependent on existence/number of preceding
   supercells that can develop in the weakly forced, but also weakly
   capped, warm sector.  Despite modal concerns, a significant-tornado
   probability area will be maintained, given the favorable environment
   (more below).  QLCS-embedded tornadoes, which tend to be briefer and
   smaller than their supercellular counterparts -- yet still damaging
   and potentially harmful -- also may form, given that the activity
   will encounter supportive low-level shear in the inflow region.

   The most favorable parameter space for tornadic potential, as well
   as the most concentrated damaging-wind risk, still appears to be
   within the enhanced-risk area, where strong deep shear, large
   low-level hodographs, and at least low-end surface-based buoyancy
   will juxtapose.  Forecast soundings show rapid prefrontal
   destabilization from midday into mid-afternoon, because of a
   combination of boundary-layer theta-e advection and diabatic heating
   that will be restrained, but not completely shut down, by cloud
   cover.  This will result in MLCAPE 500-1200 J/kg spreading inland
   ahead of the main convective band, with minimal MLCINH in support of
   any pre-QLCS discrete cells that can take root along prefrontal
   confluence/convergence lines.  Winds in and near the 50-70-kt LLJ,
   combined with directional turning in the boundary layer, will yield
   effective SRH 250-400 J/kg in the same areas.  This regime will
   shift east-northeastward over portions of AL and GA and perhaps SC
   before weakening this evening, supporting extended wind/tornado
   probabilities into SC compared to the previous outlook.

   ..Edwards/Leitman.. 03/03/2019