363  
ACUS11 KWNS 122118  
SWOMCD  
SPC MCD 122117  
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-WVZ000-122245-  
 
MESOSCALE DISCUSSION 1480  
NWS STORM PREDICTION CENTER NORMAN OK  
0417 PM CDT SAT AUG 12 2017  
 
AREAS AFFECTED...CENTRAL/EASTERN NY...EASTERN PA...CENTRAL MD...FAR  
NORTHEAST VA  
 
CONCERNING...SEVERE THUNDERSTORM WATCH 447...448...  
 
VALID 122117Z - 122245Z  
 
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 447, 448  
CONTINUES.  
 
SUMMARY...THREAT FOR DAMAGING WIND GUSTS AND HAIL CONTINUES ACROSS  
CENTRAL/EASTERN NY AS WELL AS ACROSS SOUTHEASTERN PA AND CENTRAL MD.  
 
DISCUSSION...TWO SEPARATE AREAS OF RELATIVELY HIGHER THUNDERSTORM  
COVERAGE HAVE EVOLVED OVER THE REGION COVERED BY WW 447 AND 448.  
STORMS ACROSS THE MORE NORTHERN AREA (OVER CENTRAL NY) HAVE SHOWN  
TRANSIENT SUPERCELL STRUCTURES AND HAVE PRODUCED ISOLATED SEVERE  
HAIL AS WELL AS DAMAGING WIND GUSTS. SURFACE ANALYSIS PLACES THE  
COLD FRONT FROM JUST EAST OF RME SOUTHWESTWARD THROUGH ELM.  
CONTINUED EASTWARD PROGRESSION OF THIS FRONT WILL IMPINGE UPON THE  
REMAINING INSTABILITY ACROSS EASTERN NY, LIMITING THE SPATIAL EXTEND  
OF POTENTIAL SEVERE STORMS. EVEN SO, THREAT FOR ISOLATED SEVERE  
THUNDERSTORMS WILL REMAIN FOR THE NEXT FEW HOURS. PRIMARY SEVERE  
THREAT IS DAMAGING WIND GUSTS, ALTHOUGH SOME HAIL IS POSSIBLE WITHIN  
THE STRONGER UPDRAFTS RESULTING FROM NEW DEVELOPMENT AND/OR STORM  
MERGERS.  
 
SEPARATE AREA OF THUNDERSTORMS ACROSS SOUTHEAST PA AND ADJACENT  
CENTRAL MD IS A BIT MORE LINEAR THAN THOSE FARTHER NORTH, LIKELY A  
RESULT OF CLOSER STORM PROXIMITY, MORE MOIST STORM INFLOW, AND COLD  
POOL AMALGAMATION. GIVEN THE FAVORABLE DOWNSTREAM AIRMASS, THREAT  
FOR DAMAGING WIND GUSTS AND HAIL WILL PERSIST WITHIN THIS LINE OF  
STORMS AS IT CONTINUES SOUTHEASTWARD FOR THE NEXT FEW HOURS.  
 
..MOSIER.. 08/12/2017  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...  
 
LAT...LON 42097679 43207569 43697461 43127351 39257575 39227828  
42097679  
 
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