Skip Navigation Links weather.gov 
NOAA logo-Select to go to the NOAA homepage NOAA's National Weather Service   Select to go to the NWS homepage
Storm Prediction Center
navigation bar left  
  navigation bar end cap


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

Mesoscale Discussion 1187
< Previous MD         Next MD >
MD 1187 graphic

   MESOSCALE DISCUSSION 1187
   NWS STORM PREDICTION CENTER NORMAN OK
   0112 PM CDT SAT JUN 28 2014

   AREAS AFFECTED...PORTIONS OF SOUTHERN MINNESOTA...NORTHERN
   IOWA...AND EXTREME WEST-CENTRAL WISCONSIN

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 281812Z - 282015Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE AND
   INTENSITY THROUGH THE AFTERNOON. LARGE HAIL AND LOCALIZED DAMAGING
   WIND WILL BE THE MAIN THREATS. THE AREA IS BEING MONITORED FOR A
   POSSIBLE WATCH ISSUANCE.

   DISCUSSION...THUNDERSTORMS ARE DEVELOPING IN A ZONE OF CONVERGENCE
   ARCING FROM NORTHEAST NORTH DAKOTA SOUTHEASTWARD INTO WEST-CENTRAL
   MINNESOTA SOUTHWARD INTO NORTH-CENTRAL IOWA. THESE THUNDERSTORMS ARE
   EXPECTED TO INCREASE IN COVERAGE THROUGH THE AFTERNOON AS
   LARGE-SCALE ASCENT INCREASES WITH THE APPROACH OF THE NEGATIVELY
   TILTED SHORT-WAVE TROUGH. RECENT SPC MESOANALYSIS DATA SUGGESTS
   INSTABILITY IS INCREASING ACROSS THE AREA...ESPECIALLY DOWNSTREAM
   FROM THE DEVELOPING CONVECTION...WHERE MLCAPE VALUES ARE NOW BETWEEN
   1000-1500 J/KG DESPITE THE PRESENCE OF WIDESPREAD CLOUD COVER.
   CURRENTLY DEEP-LAYER SHEAR IS BETWEEN 40 AND 50 KNOTS IN THE
   VICINITY OF THE ONGOING/DEVELOPING CONVECTION AND DROPS OFF MARKEDLY
   TO THE EAST. HOWEVER...DEEP-LAYER SHEAR IS EXPECTED TO INCREASE
   DOWNSTREAM OF THE TROUGH /WHERE THE GREATEST INSTABILITY CURRENTLY
   RESIDES/ AS A 50 KNOT MID-LEVEL SPEED MAX CONTINUES TO OVERSPREAD
   THE AREA. THUS AS THUNDERSTORMS MOVE EAST INTO THE STRONGER
   INSTABILITY...AND DEEP-LAYER SHEAR INCREASES...A GRADUAL INCREASE IN
   THUNDERSTORM INTENSITY IS EXPECTED.

   DESPITE THE APPROACHING MID-LEVEL SPEED MAX...MID-LEVEL FLOW SHOULD
   REMAIN PARALLEL TO THE LOW-LEVEL CONVERGENCE ZONE. THIS WILL TEND TO
   FAVOR A MORE LINEAR MODE TO THE CONVECTION. GIVEN THE EXPECTED
   LINEAR CONVECTIVE MODE...AN ISOLATED LARGE HAIL AND LOCALIZED
   DAMAGING WIND THREAT WILL BE THE MAIN THREAT WITH THE STRONGEST
   STORMS.

   ..MARSH/WEISS.. 06/28/2014


   ATTN...WFO...DLH...ARX...MPX...DMX...FGF...FSD...

   LAT...LON   45729585 46229564 46419452 45809305 44639209 43269198
               42359230 41969315 41879388 41939463 42779557 44199562
               45729585 

Top/All Mesoscale Discussions/Forecast Products/Home
Weather Topics:
Watches, Mesoscale Discussions, Outlooks, Fire Weather, All Products, Contact Us

NOAA / National Weather Service
National Centers for Environmental Prediction
Storm Prediction Center
120 David L. Boren Blvd.
Norman, OK 73072 U.S.A.
spc.feedback@noaa.gov
Page last modified: June 28, 2014
Disclaimer
Information Quality
Help
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities