Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 122005
SWODY1
SPC AC 122004

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0304 PM CDT SAT JUL 12 2014

VALID 122000Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN NEB INTO PARTS OF
IND/LOWER MI...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NERN ND AND NWRN MN...

...SUMMARY...
ISOLATED TO SCATTERED SEVERE STORMS ARE ANTICIPATED FROM PARTS OF
THE MID-MISSOURI VALLEY TO THE SOUTHERN LOWER MICHIGAN REGION DURING
THE LATE AFTERNOON INTO TONIGHT. DAMAGING WINDS SHOULD BE THE
PRIMARY HAZARD...BUT SEVERE HAIL AND A TORNADO OR TWO WILL BE
POSSIBLE.  ISOLATED TO SCATTERED STRONG TO SEVERE STORMS WILL ALSO
BE POSSIBLE INTO THE EARLY EVENING ACROSS NORTHEAST NORTH DAKOTA AND
NORTHWEST MINNESOTA.

...ND/MN...
MOSAIC RADAR IMAGERY SHOWED A BAND OF TSTMS MOVING SSEWD AROUND 45
KT THROUGH SRN MANITOBA TO ADJACENT SERN SASKATCHEWAN.  THESE STORMS
ARE EXPECTED TO MOVE INTO NERN ND/NWRN MN BETWEEN 22-23Z.  ALTHOUGH
INSTABILITY IS SOMEWHAT MARGINAL SOUTH OF THE INTERNATIONAL
BORDER...THE FORWARD SPEED OF THESE STORMS COULD POSE A SEVERE WIND
THREAT LATE THIS AFTERNOON AND EARLY EVENING ACROSS NERN ND AND NWRN
MN.  A SLIGHT RISK HAS BEEN INTRODUCED ACROSS THIS REGION.

...MIDWEST STATES...
THE AIR MASS ACROSS SERN NEB INTO IA AND NRN IL HAS BECOME
MODERATELY-STRONGLY UNSTABLE THIS AFTERNOON AND IS ALREADY
SUFFICIENTLY SHEARED TO SUPPORT ORGANIZED STORMS.  THUS...GIVEN THE
FAVORABLE ENVIRONMENT THIS PORTION OF THE SLIGHT RISK AREA WILL BE
MAINTAINED.  MEANWHILE...SURFACE DEWPOINTS TO AROUND 70 F HAVE
SPREAD INTO SWRN LOWER MI...WITH FURTHER DESTABILIZATION EXPECTED
THIS EVENING AS A WSWLY LLJ STRENGTHENS FROM THE LOWER MO VALLEY
INTO SRN LOWER MI.  THIS MOISTENING WILL FURTHER SUSTAIN LOWER
LCLS...WHILE INCREASING LOW-LEVEL SHEAR ALONG THE LLJ WILL ENHANCE
THE POTENTIAL FOR LOW-LEVEL STORM ROTATION/TORNADO THREAT.  FOR
THESE FACTORS...THE SLIGHT RISK AREA HAS BEEN EXPANDED EWD TO
INCLUDE MORE OF SWRN LOWER MI...INCLUDING THE 5% TORNADO THREAT
EXPANDING EWD TO INCLUDE MORE OF NRN IL AND INTO FAR NRN IND AND
SWRN LOWER MI.

..PETERS.. 07/12/2014

.PREV DISCUSSION... /ISSUED 1125 AM CDT SAT JUL 12 2014/

...MIDWEST STATES...
WATER VAPOR LOOPS SHOW A SHORTWAVE TROUGH OVER SD/NEB.  THIS FEATURE
WILL TRACK EASTWARD AND HELP TO INITIATE SCATTERED THUNDERSTORMS
THIS AFTERNOON ALONG/NORTH OF A REMNANT OUTFLOW BOUNDARY OVER IA.
SURFACE DEWPOINTS IN THE 70S COUPLED WITH INCREASING DIURNAL HEATING
THROUGH THE AFTERNOON WILL YIELD MLCAPE VALUES OVER 2000
J/KG...WHILE CYCLONIC FLOW ALOFT AND STRENGTHENING MID LEVEL WINDS
CONTRIBUTE TO FAVORABLE EFFECTIVE SHEAR VALUES.

THUNDERSTORMS ARE EXPECTED TO DEVELOP INITIALLY OVER CENTRAL/EASTERN
IA BY LATE AFTERNOON.  THESE STORMS WILL PROBABLY BE SUPERCELLULAR
AND TRACK EASTWARD INTO PARTS OF NORTHERN IL/SOUTHERN WI AND
EVENTUALLY INTO NORTHERN IND.  MID LEVEL LAPSE RATES ARE NOT
PARTICULARLY STEEP...SUGGESTING THAT DAMAGING WINDS WILL BE THE MAIN
THREAT INSTEAD OF HAIL.  LOW LEVEL VERTICAL SHEAR WILL STRENGTHEN
DURING THE EVENING POSING SOME RISK OF A FEW TORNADOES.

DURING THE EVENING...STORMS ARE FORECAST TO BUILD WESTWARD FROM
CENTRAL IA INTO SOUTHEAST NEB AND NORTHERN KS.  WEAKER VERTICAL
SHEAR WILL PROVIDE MORE UNCERTAINTY REGARDING CONVECTIVE INTENSITY
AND OVERALL SEVERE THREAT.

...ND/MN...
A VIGOROUS SHORTWAVE TROUGH IS DIGGING SOUTHEASTWARD ACROSS MANITOBA
TOWARD ND/MN.  MOST MODEL SOLUTIONS SUGGEST ISOLATED THUNDERSTORM
DEVELOPMENT AHEAD OF THIS FEATURE THIS AFTERNOON AND EARLY EVENING.
WIND FIELDS IN THIS AREA WILL BE QUITE STRONG...BUT INSTABILITY WILL
BE MARGINAL.  A FEW OF THE THUNDERSTORMS MAY PRODUCE GUSTY WINDS AND
HAIL.




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.