426  
ACUS11 KWNS 121741  
SWOMCD  
SPC MCD 121741  
NYZ000-PAZ000-MDZ000-121945-  
 
MESOSCALE DISCUSSION 1477  
NWS STORM PREDICTION CENTER NORMAN OK  
1241 PM CDT SAT AUG 12 2017  
 
AREAS AFFECTED...CENTRAL PA...CENTRAL NY  
 
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE  
 
VALID 121741Z - 121945Z  
 
PROBABILITY OF WATCH ISSUANCE...40 PERCENT  
 
SUMMARY...THUNDERSTORM COVERAGE IS EXPECTED TO CONTINUE INCREASING  
OVER THE NEXT FEW HOURS. SOME HAIL AND DAMAGING WIND GUSTS ARE  
POSSIBLE WITH THE STRONGER, MORE ORGANIZED CELLS AND TRENDS WILL BE  
MONITORED FOR POSSIBLE WATCH ISSUANCE.  
 
DISCUSSION...THUNDERSTORM ACTIVITY HAS INCREASED ACROSS CENTRAL PA  
AND CENTRAL NY OVER THE PAST HOUR OR SO WITHIN A BROAD REGION OF  
SURFACE CONFLUENCE AHEAD OF AN APPROACHING COLD FRONT. LOW-LEVEL  
AIRMASS AHEAD OF THE COLD FRONT IS CHARACTERIZED BY DEWPOINTS IN THE  
UPPER 60S/LOW 70S, WHICH IS SUPPORTING MODEST INSTABILITY (I.E.  
MLCAPE AROUND 1000 J/KG PER THE LATEST MESOANALYSIS), DESPITE  
FILTERED SUNSHINE AND WARM MID-LEVEL TEMPERATURES. GENERAL  
EXPECTATION IS FOR MLCAPE TO REMAIN AROUND 1000 J/KG WITH INCREASING  
STORM COVERAGE AS BOTH THE COLD FRONT AND ITS PARENT SHORTWAVE  
TROUGH CONTINUE EASTWARD INTO THE REGION.  
 
DESPITE MODEST THE INSTABILITY, OCCASIONALLY STRONG/ORGANIZED  
UPDRAFTS ARE POSSIBLE GIVEN THE STRENGTHENING MID-LEVEL FLOW AND  
RELATED MODERATE SHEAR. RECENT CCX VAD SAMPLED 0-6 KM BULK SHEAR  
OVER 45 KT AND A LONG HODOGRAPH, FAVORABLE FOR STORM SPLITS. SOME  
HAIL WILL BE POSSIBLE WITH THE ANY STRONGER/DISCRETE CELLS WITH  
GUSTY WINDS ALSO POSSIBLE AS MULTICELL STORMS ORGANIZE IN SMALL  
BOWING STRUCTURES. CONVECTIVE TRENDS WILL BE MONITORED FOR POSSIBLE  
WATCH ISSUANCE.  
 
..MOSIER/GUYER.. 08/12/2017  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...ALY...PHI...BGM...BUF...CTP...LWX...PBZ...  
 
LAT...LON 42747788 43427626 43067457 41027579 39767695 39687939  
42747788  
 
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