Aug 19, 2014 1300 UTC Day 1 Convective Outlook
Updated: Tue Aug 19 12:16:10 UTC 2014 (20140819 1300Z Day 1 shapefile | 20140819 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140819 1300 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 107,114 21,217,329 Detroit, MI...Indianapolis, IN...St. Louis, MO...Toledo, OH...Cincinnati, OH...
Probabilistic Tornado Graphic
20140819 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.
Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20140819 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.
Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 105,616 20,932,877 Detroit, MI...Indianapolis, IN...St. Louis, MO...Toledo, OH...Cincinnati, OH...
5 % 397,412 29,162,984 Columbus, OH...Memphis, TN...Nashville, TN...Lexington-Fayette, KY...Montgomery, AL...
Probabilistic Large Hail Graphic
20140819 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.
Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 105,101 20,740,509 Detroit, MI...Indianapolis, IN...St. Louis, MO...Toledo, OH...Cincinnati, OH...
5 % 354,552 22,906,175 Columbus, OH...Nashville, TN...Omaha, NE...Lexington-Fayette, KY...Grand Rapids, MI...
   SPC AC 191216

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0716 AM CDT TUE AUG 19 2014

   VALID 191300Z - 201200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SOUTHEAST LOWER MI
   SOUTHWESTWARD ACROSS THE MIDWEST TO EASTERN MO...

   ...SUMMARY...
   STRONG TO SEVERE STORMS WITH HAIL AND POTENTIALLY DAMAGING WINDS
   WILL BE POSSIBLE FROM LOWER MICHIGAN SOUTHWEST TO ILLINOIS AND
   INDIANA AND NORTHWEST OHIO. OTHER STRONG TO ISOLATED SEVERE STORMS
   MAY DEVELOP FROM UTAH AND WYOMING EAST INTO THE CENTRAL PLAINS WITH
   A THREAT FOR GUSTY WINDS AND HAIL. OTHER STORMS POSING A THREAT FOR
   ISOLATED DAMAGING WINDS APPEAR POSSIBLE OVER SOUTHERN PARTS OF
   ALABAMA AND GEORGIA...AS WELL AS NORTHERN FLORIDA.

   ...SYNOPSIS...
   A NUMBER OF MID/UPPER LEVEL DISTURBANCES EXIST ACROSS THE CONUS
   TODAY AND WILL DRIVE DEEP CONVECTION AMIDST WEAK TO MODEST MID-LEVEL
   FLOW. ONE MID-LEVEL CYCLONE TRACKING SOUTH ALONG THE WEST COAST WILL
   ACT TO  DISLODGE A DOWNSTREAM IMPULSE ACROSS THE GREAT BASIN. THE
   SMALLER-SCALE DISTURBANCE AND ASSOCIATED BELT OF 30-40KT MID-LEVEL
   FLOW WILL SPREAD NORTHEAST FROM UT TO WY AND NORTHERN CO THROUGH
   THIS EVENING...BREAKING DOWN THE MID/UPPER RIDGE OVER THESE AREAS.
   MEANWHILE...THE SLOW-MOVING SHORTWAVE TROUGH TRACKING EAST ALONG THE
   U.S./CANADA BORDER WILL MOVE FROM THE UPPER MS VALLEY TO THE GREAT
   LAKES TODAY. A WEAK LOW-LEVEL BAROCLINIC ZONE ASSOCIATED WITH THIS
   DISTURBANCE EXTENDS FROM A SURFACE LOW NEAR LAKE SUPERIOR SOUTH AND
   WEST TO THE MID MO RIVER VALLEY BEFORE BECOMING MORE DIFFUSE WITH
   WESTWARD EXTENT ACROSS THE CENTRAL HIGH PLAINS. LASTLY...A NUMBER OF
   CONVECTIVELY INDUCED/SUSTAINED MID-LEVEL CIRCULATIONS...POORLY
   REFLECTED IN THE SURFACE PRESSURE FIELD...ARE EMBEDDED WITHIN A
   SLUGGISH ZONAL SOUTHERN BRANCH FROM TX EAST ACROSS THE LOWER MS
   VALLEY TO THE SOUTHEAST.

   ...LOWER MI ACROSS THE MIDWEST TO EASTERN MO...
   THE BAND OF WEAKENING THUNDERSTORMS MOVING ACROSS SOUTHWEST LOWER MI
   PRECEDES THE WEAK FRONTAL ZONE ASSOCIATED WITH THE GREAT LAKES UPPER
   TROUGH AND SURFACE LOW. STORM-SCALE GUIDANCE IS IN GENERALLY GOOD
   AGREEMENT IN SIMULATING THIS LINEAR ACTIVITY OVER MI...ALBEIT
   SEVERAL HOURS LATER THAN CURRENT TRENDS SUGGEST. ONGOING STORMS
   SHOULD CONTINUE EAST INTO A MARGINALLY UNSTABLE AIRMASS OVER LOWER
   MI THIS MORNING WITH SOME GUSTY WINDS AND MARGINAL HAIL POTENTIAL.
   ADDITIONAL DEVELOPMENT SHOULD OCCUR THROUGH LATER TODAY...IN A
   LINEAR FASHION ALONG/AHEAD OF THE FRONT/WIND SHIFT...SOUTHWESTWARD
   ACROSS IND/IL...AS LARGE SCALE ASCENT ACTS ON A MOIST AND
   INCREASINGLY UNSTABLE AIRMASS ACROSS THESE AREAS. SOMEWHAT MARGINAL
   UNIDIRECTIONAL SHEAR AOB 30KT SHOULD BE OFFSET BY LARGE SCALE ASCENT
   AND MAGNITUDE OF INSTABILITY TO SUPPORT HIGH WINDS AND HAIL FROM
   STORMS SPREADING EAST THROUGH THIS EVENING.

   MEANWHILE...ENHANCED MASS TRANSPORT AND WARM ADVECTION ACROSS/ATOP
   TRAILING FRONT EXTENDING SOUTHWESTWARD TO THE CENTRAL PLAINS WAS
   LIKELY CONTRIBUTING TO A FEW VIGOROUS BUT MARGINALLY ORGANIZED
   STORMS OVER NORTHERN MO/SOUTHERN IA THIS MORNING. THERE IS GREATER
   UNCERTAINTY REGARDING THE FUTURE OF THIS ACTIVITY AS STORM-SCALE
   GUIDANCE PROVIDES MIXED SIGNALS ABOUT ITS EXISTENCE AND/OR
   EVOLUTION. GIVEN PROXIMITY TO WEAK HEIGHT FALLS AND MODEST MID-LEVEL
   FLOW OF 25-35KT ON THE SOUTHERN FLANK OF THE GREAT LAKES
   TROUGH...AND FEED OF STEEPER MID-LEVEL LAPSE RATES ON THE EDGE OF
   PLAINS CAPPING INVERSION...IT SEEMS PROBABLE THAT THESE STORMS MAY
   PERSIST WHILE MOVING EAST TOWARD THE MS RIVER AND WESTERN IL THIS
   MORNING. SOME INCREASE IN SEVERE WIND/HAIL POTENTIAL MAY OCCUR IF
   THIS ACTIVITY CAN PERSIST ACROSS THE MS RIVER AND STRONGER
   SURFACE-BASED INSTABILITY BECOMES REALIZED. ADDITIONALLY...OUTFLOW
   AND DIFFERENTIAL HEATING ON THE SOUTHERN FLANK AND IN THE WAKE OF
   MORNING STORMS COULD PROMPT AFTERNOON  INITIATION ACROSS
   EASTERN/SOUTHEASTERN MO...IN THE PRESENCE OF VERY WARM AND UNSTABLE
   CONDITIONS.

   ...GREAT BASIN TO CENTRAL HIGH PLAINS/CENTRAL PLAINS LATE...
   A BELT OF 30-40KT MID-LEVEL FLOW AND ENHANCED DEEP-LAYER ASCENT
   SHOULD ACCOMPANY THE SHORTWAVE IMPULSE EJECTING EAST-NORTHEASTWARD
   FROM THE GREAT BASIN TO THE CONTINENTAL DIVIDE LATER TODAY AND
   TONIGHT. IN ADDITION TO TERRAIN EFFECTS...NUMEROUS STORMS SHOULD
   ERUPT AS THE COMPACT IMPULSE ACTS TO BREAKDOWN THE UPPER RIDGE
   IMBUED WITH RELATIVELY HIGH PW. A FEW MULTICELL STORMS WITH ISOLATED
   HAIL AND/OR WIND POTENTIAL MAY SPREAD ACROSS THE GREAT BASIN AND
   INTERMOUNTAIN WEST THROUGH THE LATE AFTERNOON.

   ADDITIONAL STORMS ARE LIKELY EAST OF THE DIVIDE AND ALONG THE FRONT
   RANGE WHERE WEAK UPSLOPE FLOW AND RESIDUAL FRONT WILL COEXIST.
   LEE-SIDE PRESSURE FALLS AND STRENGTHENING LOW LEVEL JET MAY SUSTAIN
   A SMALL MCS EVOLVING FROM THIS LATE-DAY ACTIVITY...ESPECIALLY AS
   HEIGHT FALLS WITH THE MID/UPPER DISTURBANCE EMERGE OVER THE CENTRAL
   HIGH PLAINS LATER TONIGHT. ISOLATED WIND/HAIL THREATS MAY PERSIST
   FROM EASTERN WY INTO ADJACENT AREAS OF SD/NEB. LATE NIGHT/EARLY
   MORNING HAIL MAY ALSO OCCUR AS THE POTENTIAL FOR THUNDERSTORMS
   INCREASES ALONG A DEVELOPING/STRENGTHENING WARM FRONT ANTICIPATED
   ACROSS THE CENTRAL PLAINS BY EARLY WED.

   ...SOUTHEAST...
   WEAK PERTURBATIONS AND SOMEWHAT STRONGER MID-LEVEL FLOW AROUND 25KT
   WILL SPREAD ACROSS THE SOUTHEAST COINCIDENT WITH DAYTIME HEATING OF
   VERY MOIST AIRMASS. EXPECT STORMS TO REMAIN POORLY ORGANIZED.
   HOWEVER...A FEW STRONGER COLLAPSING CORES COULD RESULT IN ISOLATED
   WET DOWNBURSTS BUT EXPECT ANY SEVERE WIND RISK TO DIMINISHING BY
   EARLY EVENING.

   ..CARBIN/COHEN.. 08/19/2014

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z