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Mesoscale Discussion 1872
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   MESOSCALE DISCUSSION 1872
   NWS STORM PREDICTION CENTER NORMAN OK
   0108 PM CDT MON OCT 13 2014

   AREAS AFFECTED...PORTIONS OF CENTRAL/EASTERN ILLINOIS

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 131808Z - 132015Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...THERE WILL EXIST SOME POTENTIAL FOR CONVECTION OVER THE
   MID-MS VALLEY TO CONTINUE BUILDING NNEWD INTO CNTRL/ERN IL DURING
   THE NEXT SEVERAL HOURS...AND HAVE THE POTENTIAL TO PRODUCE DMGG
   WINDS AND POSSIBLY A COUPLE OF TORNADOES. THE AREA IS BEING
   MONITORED FOR THE POSSIBLE ISSUANCE OF A TORNADO WATCH.

   DISCUSSION...SFC OBSERVATIONS HIGHLIGHT A CORRIDOR OF 2-4-MB/2-HR
   SFC PRESSURE FALLS FROM NRN MO INTO CNTRL IL WITHIN PROXIMITY TO A
   FRONTOGENETIC BOUNDARY/BAROCLINIC ZONE BRANCHING ENEWD FROM 997-MB
   SFC CYCLONE IN NRN/WRN MO. ABUNDANT MASS FLUXES ALONG A STRONG LLJ
   SURMOUNTING A STATICALLY STABLE PBL ARE ASSOCIATED WITH CONTINUED
   MOISTURE INFLUXES...WITH SFC DEWPOINTS OF 64-66F CONTINUING TO EDGE
   NWD ALONG THE AXIS OF MAXIMUM ISALLOBARIC FLOW. THIS WILL ENCOURAGE
   VERY MARGINAL BUOYANCY TO EXTEND NWD WITH TIME...PERHAPS AS FAR N AS
   SRN PARTS OF NERN IL /FAR SRN PARTS OF THE CHICAGO-ROMEOVILLE CWA/.
   DESPITE THE PAUCITY OF BUOYANCY...SUBSTANTIAL LOW-LEVEL SHEAR
   BENEATH 55 KT OF 1-KM-AGL FLOW SAMPLED BY THE ILX RAOB SUGGESTS THAT
   STORM-INDUCED HYDRODYNAMIC PERTURBATION PRESSURE GRADIENT FORCES
   WILL HAVE A PROCLIVITY OF ENHANCING UPDRAFTS AND SOME RISK FOR DMGG
   WIND GUSTS/A COUPLE OF TORNADOES. THE NRN EXTENT OF NON-ZERO CAPE
   WILL GOVERN SUCH POTENTIAL...FOR WHICH SOME UNCERTAINTY
   REMAINS...THOUGH IT MAY EXTEND FAR ENOUGH NE OF TORNADO WATCH 535
   FOR THE ISSUANCE OF A NEW TORNADO WATCH ACROSS THE AREA.

   ..COHEN/CORFIDI.. 10/13/2014


   ATTN...WFO...LOT...ILX...LSX...

   LAT...LON   39898953 40708926 40648796 39988761 38648780 39158883
               39898953 

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Page last modified: October 13, 2014
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