Mar 28, 2020 1630 UTC Day 1 Convective Outlook
Updated: Sat Mar 28 16:38:18 UTC 2020 (20200328 1630Z Day 1 shapefile | 20200328 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20200328 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 26,324 4,048,610 Aurora, IL...Naperville, IL...Joliet, IL...Springfield, IL...Peoria, IL...
ENHANCED 72,730 14,451,922 Chicago, IL...St. Louis, MO...Rockford, IL...Cedar Rapids, IA...Elgin, IL...
SLIGHT 274,568 30,558,897 Indianapolis, IN...Columbus, OH...Memphis, TN...Milwaukee, WI...Nashville, TN...
MARGINAL 191,785 26,570,271 Detroit, MI...Cleveland, OH...Pittsburgh, PA...Akron, OH...Grand Rapids, MI...
Probabilistic Tornado Graphic
20200328 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
SIG SEVERE 62,228 10,047,108 Aurora, IL...Naperville, IL...Joliet, IL...Cedar Rapids, IA...Springfield, IL...
15 % 26,553 4,090,510 Aurora, IL...Naperville, IL...Joliet, IL...Springfield, IL...Peoria, IL...
10 % 71,774 14,414,202 Chicago, IL...Indianapolis, IN...St. Louis, MO...Rockford, IL...Cedar Rapids, IA...
5 % 129,928 16,632,490 Memphis, TN...Nashville, TN...Cincinnati, OH...Louisville, KY...Lexington-Fayette, KY...
2 % 194,351 19,212,587 Columbus, OH...Pittsburgh, PA...Toledo, OH...Akron, OH...Shreveport, LA...
Probabilistic Damaging Wind Graphic
20200328 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 % 349,477 44,321,917 Chicago, IL...Indianapolis, IN...Columbus, OH...Memphis, TN...Nashville, TN...
5 % 134,898 16,853,100 Cleveland, OH...Pittsburgh, PA...Toledo, OH...Akron, OH...Jackson, MS...
Probabilistic Large Hail Graphic
20200328 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
SIG SEVERE 52,330 11,905,861 Chicago, IL...Aurora, IL...Rockford, IL...Naperville, IL...Joliet, IL...
30 % 86,962 16,770,202 Chicago, IL...St. Louis, MO...Aurora, IL...Rockford, IL...Naperville, IL...
15 % 251,458 30,274,701 Indianapolis, IN...Columbus, OH...Memphis, TN...Milwaukee, WI...Nashville, TN...
5 % 226,341 28,530,187 Detroit, MI...Cleveland, OH...Pittsburgh, PA...Akron, OH...Grand Rapids, MI...
   SPC AC 281638

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1138 AM CDT Sat Mar 28 2020

   Valid 281630Z - 291200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF FAR EASTERN IOWA AND INTO PARTS OF CENTRAL AND NORTHERN
   ILLINOIS...

   ...SUMMARY...
   A severe-weather outbreak is expected for portions of the Midwest
   this afternoon and evening.  A few long-tracked, significant
   tornadoes are possible, along with large, damaging hail and severe
   gusts.

   ...Synopsis...
   A deepening mid-/upper-level low -- now moving east-northeastward
   across Nebraska/Kansas -- will advance to western Iowa by early
   evening, and will be accompanied by an 80 to 100 kt southwesterly
   mid-level jet.  The jet streak will cross the Ozarks and lower
   Missouri/mid Mississippi Valleys this afternoon, and then into the
   Ohio and Tennessee Valleys overnight, atop lower-level southerlies
   in the 40 to 60 kt range.  This veering/increasing of flow with
   height will yield a very favorably-sheared environment over a broad
   area.

   At the surface, a deepening low is analyzed over northeastern
   Kansas, and will move northeastward across the mid Missouri Valley
   this afternoon, and then across Iowa this evening and into Wisconsin
   overnight.  A trailing cold front is currently crossing eastern
   Kansas/eastern Oklahoma and eastern/southeastern Texas, and will
   reach the mid and lower Mississippi Valley vicinity by early
   evening.  A warm front currently extends eastward from the low
   across northern Missouri into central Illinois/central Indiana, and
   will lift northward with time across northern Missouri, Iowa,
   Illinois, and Indiana as the parent low moves northeastward,
   allowing warm/moist/destabilizing air to spread across these areas
   through early evening.  By the end of the period, the low will have
   occluded over Wisconsin, with the cold front approaching the west
   slopes of the Appalachians and the warm front extending
   east-southeastward from the Great lakes region to the mid-Atlantic
   area.

   ...Mid Mississippi Valley/Midwest region...
   A significant outbreak of severe weather remains apparent from parts
   of eastern Iowa and eastern Missouri, eastward into the Midwest/Ohio
   Valley.  

   Widespread clouds, and ongoing showers/thunderstorms, persist across
   much of the risk area at this time -- along and ahead of the cold
   front from southern Missouri to eastern Texas and near/north of the
   warm front from Iowa eastward to Pennsylvania -- which continues to
   complicate the forecast in terms of finer-scale details.  Generally,
   severe risk across the region is expected to occur within two
   regimes:

   1.  A gradual increase in coverage/intensity of the ongoing storms
   near the cold and warm fronts, as modest, local
   heating/destabilization combine with a steady increase in the flow
   field aloft, and

   2.  New storm development -- initially expected from northeastern
   Missouri into southeastern Iowa in the 19 to 21z time frame -- as
   ongoing convection and cloud cover shifts eastward/northeastward
   allowing surface heating/desabilization to occur beneath steepening
   mid-level lapse rates and increasingly strong flow aloft.  

   Broadly speaking, storms increasing from Arkansas and southeastern
   Missouri, and eastward across Illinois and Indiana will continue to
   pose an initial risk for hail and possibly locally strong wind
   gusts.  With time, as both the kinematic and thermodynamic
   environment improve, more intense/rotating storms will gradually
   evolve, posing greater severe potential.  Greatest tornado risk will
   likely occur with northward extent, nearer the warm front, though
   some potential will expand across areas as far south as parts of
   Tennessee and northern Mississippi this evening as severe storms
   spread eastward.

   Greatest risk for long-track/significant tornadoes, along with
   potential for very large/destructive hail and damaging wind gusts,
   still appears to exist from portions of northeastern Missouri and
   arcing northwestward into Iowa, and then eastward across Illinois
   and into Indiana.  This risk will largely exist with new/intense
   storm development this afternoon in the wake of the initial
   convection -- but also potentially evolving with a few intensifying
   storms within the initial/ongoing band of convection -- along/near
   the warm front into Indiana.  As the storms intensify rapidly this
   afternoon in response to the rapidly evolving environment, expect
   peak tornado risk to occur through late afternoon and into early
   evening, spreading from eastern Iowa/northeast Missouri across the
   remainder of the MDT and ENH risk areas.  Given existing
   uncertainties due to ongoing precipitation/cloud cover, and
   anticipated/rapid changes in the environment as the warm front lifts
   northward and clouds thin/clear from the west, confidence remains
   too low to delineate a potentially concentrated area of greatest
   risk, which would otherwise support high risk upgrade.  As the
   situation evolves, a possible upgrade remains possible for the 20Z
   outlook update, given the larger-scale pattern/environment which
   continues to appear favorable for several significant tornadoes.

   ..Goss/Bentley.. 03/28/2020

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