SPC meso discussion
Posted by cypresstx on 11/20/2014, 2:30 pm
http://www.spc.noaa.gov/

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http://www.spc.noaa.gov/products/md/md1929.html


  MESOSCALE DISCUSSION 1929
  NWS STORM PREDICTION CENTER NORMAN OK
  1252 PM CST THU NOV 20 2014

  AREAS AFFECTED...AREAS OF NEW YORK NEAR AND SOUTH OF BUFFALO
  INCLUDING PORTIONS OF THE WESTERN SOUTHERN TIER

  CONCERNING...HEAVY SNOW

  VALID 201852Z - 202345Z

  SUMMARY...AN INTENSE LAKE-EFFECT SNOW BAND NEAR AND S OF THE BUFFALO
  AREA IS LIKELY PRODUCING SNOWFALL RATES OF 2-4 INCHES PER HOUR...AND
  WILL CONTINUE IN THE SHORT-TERM. OTHER AREAS FARTHER SOUTH INTO THE
  WESTERN SOUTHERN TIER WILL LIKELY EXPERIENCE HEAVY SNOW LATER THIS
  AFTERNOON INTO THE EVENING AS THE SNOW BAND EVOLVES.

  DISCUSSION...MOSAIC RADAR IMAGERY INDICATES A SOLITARY...HEAVY-SNOW
  BAND HAVING GRADUALLY EDGED NWD IN THE LEE OF LAKE ERIE. THIS
  EVOLUTION MAY BE IN RESPONSE TO SLIGHT BACKING OF FLOW BELOW 2 KM
  AGL SINCE 15Z...PER THE BUF VWP...PERHAPS RELATED TO AN ISALLOBARIC
  RESPONSE ACCOMPANYING MODEST SFC PRESSURE FALLS OVER THE ST LAWRENCE
  VALLEY.

  DURING THE NEXT FEW HOURS -- PERHAPS THROUGH 21Z OR 22Z -- THE SNOW
  BAND WILL LIKELY REMAIN IN A QUASI-STEADY-STATE CONFIGURATION FROM
  THE SRN TWO-THIRDS OF ERIE COUNTY INCLUDING THE SOUTH SUBURBS OF
  BUFFALO INTO WYOMING AND SRN GENESEE COUNTIES. KBUF SRM DATA
  INDICATE OCCASIONAL MESO-GAMMA-SCALE CIRCULATIONS EMBEDDED WITHIN
  THE SNOW BAND...WHICH MAY BE ACCOMPANIED BY SMALL-SCALE ENHANCEMENTS
  TO VERTICAL MOTION ALONG WITH THE HIGHEST SNOWFALL RATES -- PERHAPS
  REACHING 4 INCHES PER HOUR. OTHERWISE...SNOWFALL RATES OF 2-3 INCHES
  PER HOUR WILL BE COMMON WITH THE CORE OF THE SNOW BAND.
  ALSO...CONVECTIVE TURRETS EMBEDDED WITHIN THE SNOW BAND OVER
  MID-LAKE PER VIS IMAGERY CORRESPOND TO HIGHER REFLECTIVITY CORES PER
  MOSAIC RADAR IMAGERY. AN ISOLATED LIGHTNING STRIKE OR TWO MAY OCCUR
  OWING TO THE LAKE-ENHANCED CONVECTIVE BOUNDARY LAYER. SNOWFALL RATES
  TO 4 INCHES PER HOUR MAY ALSO OCCUR WITH THUNDERSTORMS.

  UPSTREAM OBSERVATIONS OVER LOWER MI INDICATE SFC WINDS VEERING...IN
  RESPONSE TO PRESSURE RISES ON THE SUBSIDENT/UPSTREAM SIDE OF A
  SUBTLE MID-LEVEL VORT MAX CROSSING THE GREAT LAKES. PRESENT
  INDICATIONS ARE THAT...IN THE 22-00Z TIME FRAME...THE BACKGROUND
  LOWER-TROPOSPHERIC FLOW WILL VEER INVOF THE INITIALLY SOLITARY SNOW
  BAND. THIS WILL LIKELY DISRUPT THE BAND...PERHAPS SHUNTING IT SWD
  TOWARD THE WRN SRN TIER INCLUDING PORTIONS OF CHAUTAUQUA AND
  CATTARAUGUS COUNTIES OR BREEDING A FRAGMENTATION OF THE BAND INTO
  MULTIPLE SHORTER SEGMENTS. ULTIMATELY...THE VEERING OF THE LOW-LEVEL
  FLOW WILL CORRESPOND TO A DECREASE IN OVER-LAKE FETCH LENGTH...WITH
  SNOWFALL RATES PROBABLY DECREASING BY EARLY EVENING.

  ..COHEN.. 11/20/2014


the enhanced RGB loop with animated radar for Buffalo is unreal




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seems like we are storms right into SNOW!! - freesong, 11/18/2014, 7:30 pm
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