401  
FXUS61 KBUF 241847  
AFDBUF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BUFFALO NY  
247 PM EDT SAT JUN 24 2017  
   
SYNOPSIS
 
 
TEMPERATURES WILL RUN COOLER THAN AVERAGE THIS WEEKEND AND INTO  
EARLY NEXT, AS UPPER LEVEL TROUGHING MOVES ACROSS THE REGION. THE  
COOLER TEMPERATURES WILL BE ACCOMPANIED BY SHOWERS AT TIMES, AS A  
SERIES OF UPPER LEVEL DISTURBANCES MOVING THROUGH THE TROUGH CROSS  
THE AREA. THE TROUGH WILL MOVE EAST BY WEDNESDAY, WITH WARMER  
TEMPERATURES EXPECTED BY MID-WEEK.  
 

 
   
NEAR TERM /THROUGH SUNDAY/
 
 
REGIONAL RADARS SHOWING A NARROW LINE OF CONVECTION FOCUSED  
ALONG THE LAKE BREEZE CONVERGENCE BETWEEN NIAGARA  
FALLS/ROCHESTER AND BUFFALO/BATAVIA. THIS LINE HAS BEEN NEARLY  
STATIONARY, BUT WILL HAVE A TENDENCY TO NUDGE ITS WAY NORTHWARD  
WITH A STRONGER COMPONENT COMING IN FROM THE SOUTHWEST. WILL  
STILL NEED TO WATCH THIS AREA OVER THE NEXT HOUR OR SO WITH  
TRAINING HEAVY DOWNPOURS.  
 
ANY CONVECTIVE ACTIVITY WILL COME TO AN END DURING THE EVENING  
HOURS, WITH THE LOSS OF DIURNAL HEATING, LEAVING QUIET AND COOL  
NIGHT ACROSS THE AREA. THE COOLER TEMPERATURES ALOFT, COMBINED WITH  
DIMINISHED CLOUD COVER WILL TRANSLATE TO COOLER READINGS THAN WE HAVE  
SEEN AT NIGHT OF LATE, WITH LOWS DIPPING INTO THE UPPER 50S ALONG  
THE LAKE PLAINS, WITH MID 50S ACROSS THE HIGHER ELEVATIONS INLAND.  
 
ON SUNDAY, A BROAD MID-LEVEL LONGWAVE TROUGH WILL EXTEND FROM THE  
NORTHERN PLAINS ACROSS THE GREAT LAKES AND INTO THE NORTHEAST  
REGION. LATEST GUIDANCE CONTINUING TO SUPPORT THE IDEA OF A SHARP  
MID LEVEL SHORTWAVE AND EMBEDDED VIGOROUS VORTICITY MAX MOVING  
THROUGH THE BASE OF THE LONGWAVE TROUGH AND CROSSING WESTERN AND  
CENTRAL NEW YORK DURING THE DAY. SYNOPTIC SCALE LIFT FROM THIS  
SHORTWAVE AND LOW-LEVEL FORCING FROM A SURFACE TROUGH AND 30+ KNOT  
LOW LEVEL JET WILL CONTRIBUTE TO SCATTERED SHOWERS AND ISOLATED  
THUNDERSTORMS. THE MOST WIDESPREAD COVERAGE WILL BE DURING THE  
AFTERNOON CORRESPONDING TO PEAK HEATING AND CLOSER TO THE PASSAGE OF  
THE SURFACE TROUGH.  
 
GUSTY SOUTHWEST WINDS 25-30KTS DOWNWIND OF THE LAKES SHOULD PROVIDE  
A LAKE SHADOW TO KEEP SHOWER/STORM COVERAGE MAINLY INLAND.  
TEMPERATURES WILL TOP OUT A FEW DEGREES BELOW NORMAL DUE TO THE  
INFLUENCE OF THE LONGWAVE TROUGH AND ASSOCIATED POOL OF COOL AIR  
ALOFT. HIGHS ARE FORECAST TO TOP OUT WITHIN A FEW DEGREES OF 70.  
DEWPOINTS ONLY AROUND 50 WILL YIELD VERY COMFORTABLE HUMIDITY  
LEVELS.  
 

 
   
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
 
 
THROUGH THE COURSE OF THIS PERIOD A LONG WAVE TROUGH WILL PASS  
ACROSS THE GREAT LAKES REGION, REACHING ITS GREATEST DEPTH MONDAY  
NIGHT AS A STRONG SHORTWAVE PASSES THROUGH. WITHIN THIS TROUGH  
TEMPERATURES AT 850 HPA WILL BOTTOM OUT AROUND +5 TO +6C, AND AT 500  
HPA TEMPERATURES OF -20C WITHIN THIS TROUGH WILL BE AROUND 4SD BELOW  
NORMAL FOR THIS TIME OF YEAR CENTERED ACROSS THE OHIO VALLEY.  
 
SUNDAY NIGHT A SWATH OF DEEPER MOISTURE WILL SETTLE SOUTHWARD ACROSS  
LAKE ONTARIO AND LATER LAKE ONTARIO. AS TEMPERATURES AT 925/850 HPA  
DROP TO AROUND +10/+6C LAKE INSTABILITY WILL INCREASE OVER A +22C  
(LAKE ERIE) AND +19C (LAKE ONTARIO) LAKE SURFACE. WHILE RAIN SHOWERS  
WILL BE POSSIBLE ACROSS THE LAKE PLAINS, GREATEST CHANCES WILL BE  
ACROSS THE HIGHER TERRAIN OF SW NYS AND THE TUG HILL TO SE OF LAKE  
ONTARIO REGION WHERE OROGRAPHIC UPLIFT ON A WEST TO NORTHWESTERLY  
WIND IN ADDITION TO LAKE INDUCED CAPE VALUES OF 1500 TO 2000 J/KG  
SHOULD GENERATE RARE LATE JUNE LAKE ENHANCED PRECIPITATION. ANY LAKE  
ENHANCED RAIN WILL BECOME MORE SCATTERED DURING THE LATE MORNING  
HOURS DURING INCREASED DAYTIME MIXING. THE APPROACH OF AN UPPER  
LEVEL SHORTWAVE LATER MONDAY WILL AGAIN INCREASE THE COVERAGE AREA  
OF SHOWERS AND THUNDERSTORMS OVER THE REGION. THE DEEP 500 HPA  
TROUGH AND ITS ASSOCIATED COOL POOL WILL ENCOURAGE SOME THUNDERSTORM  
DEVELOPMENT, AND WITH LOW FREEZING LEVELS AND WBZ HEIGHTS AROUND 6-  
8K FEET SOME GRAUPEL OR SMALL HAIL WILL BE POSSIBLE. HOWEVER THE  
SKINNY CAPE PROFILES SUGGEST THAT LARGER HAIL WILL BE UNLIKELY.  
 
SHOWERS AND THUNDERSTORMS WILL DIMINISH MONDAY NIGHT WITH THE  
PASSAGE OF THE SHORTWAVE WITHIN THE BASE OF THE LONG WAVE TROUGH.  
THERE MAY LINGER A FEW LAKE ENHANCED RAIN SHOWERS DEEPER INTO THE  
NIGHT, ESPECIALLY ACROSS THE NORTH COUNTRY WHICH WILL LIE UNDER THE  
COOLER AIR ALOFT.  
 
TUESDAY WE WILL REMAIN WITHIN THE INFLUENCES OF THE UPPER LEVEL  
TROUGH, THROUGH NOW BEHIND THE ROBUST SHORTWAVE, AND SLOWLY RISING  
HEIGHTS ALOFT THE RAIN SHOWER COVERAGE/INTENSITY SHOULD BE LESS THAN  
MONDAY. THE STILL COOL POOL ALOFT WILL CONTINUE THE CHANCES FOR A  
FEW THUNDERSTORMS. BY TUESDAY NIGHT THE UPPER LEVEL TROUGH WILL BE  
PUSHING AWAY FROM OUR REGION WITH ANY LINGER RAIN SHOWERS LARGELY  
ENDING BY THE LATE EVENING HOURS. A FEW LAKE EFFECT RAIN SHOWERS MAY  
DEVELOP OFF LAKE ONTARIO AS LOW LEVEL CONVERGENCE INCREASES ON A  
WESTERLY FLOW. HOWEVER WE WILL ALSO BEGIN TO WARM A DEGREE OR TWO AT  
850 HPA, SO LAKE INSTABILITY WILL NOT BE AS GREAT AS PREVIOUS  
NIGHTS.  
 
TEMPERATURES WILL BE WELL BELOW NORMAL MONDAY AND TUESDAY WITH BOTH  
DAYS ONLY PUSHING MID TO UPPER 60S FOR HIGHS. OVERNIGHT LOWS WILL  
DROP BACK INTO THE UPPER 40S TO MID 50S CLOSER TO THE LAKES.  
 

 
   
LONG TERM /TUESDAY THROUGH FRIDAY/
 
 
LATEST RUNS OF THE MEDIUM RANGE GUIDANCE INDICATE THAT THE AXIS OF  
THE LONGWAVE TROUGH AND ASSOCIATED VORT MAX WILL BE IN THE PROCESS  
OF SHIFTING EAST OF THE FORECAST AREA ON TUESDAY. THE COOL AIR ALOFT  
WITHIN THE TROUGH (AGAIN 850MB T AROUND 6C) WILL SUPPORT MAINLY A  
DIURNAL THREAT FOR SHOWERS AND POSSIBLY SOME THUNDERSTORMS. SIMILAR  
TO MONDAY, TALLER SHOWER/STORM CELLS IN THIS COOL ENVIRONMENT MAY  
BRING SOME SMALL HAIL WITH A SUB-10KFT WBZ HEIGHT. AGAIN WITH  
LINGERING COOL AIR ALOFT, HIGH TEMPS WILL TOP OUT AGAIN IN THE 60S.  
 
SURFACE HIGH PRESSURE CENTERED OVER THE SOUTHERN APPALACHIANS WILL  
RIDGE NORTH ACROSS THE REGION TUESDAY NIGHT AND WEDNESDAY ALLOWING  
FOR DRY WEATHER WITH MAINLY CLEAR TO PARTLY CLOUDY SKIES. TEMPS WILL  
STILL RUN A DEGREE OR TWO BELOW NORMAL.  
 
THURSDAY AND FRIDAY, THE HIGH IS FORECAST TO SHIFT OFF THE MID-  
ATLANTIC COAST WITH SOUTHERLY WINDS BRINGING A RETURN OF INCREASING  
MOISTURE AND WARMTH ACROSS WESTERN AND CENTRAL NY. HIGHS LOOK TO  
PUSH BACK ABOVE NORMAL WITH READINGS IN THE UPPER 70S TO LOW 80S. A  
COOL FRONT LOOKS TO BE THE MAIN FOCUS FOR SHOWER AND THUNDERSTORM  
ACTIVITY AS BOTH THE GFS AND EC MODELS INDICATE IT MAY BECOME  
STALLED/STATIONARY SOMEWHERE OVER THE FORECAST AREA.  
 

 
   
AVIATION /19Z SATURDAY THROUGH THURSDAY/
 
 
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE DAY, THOUGH DIURNAL  
SHOWERS AND A FEW ISOLATED THUNDERSTORMS MAY DEVELOP IN THE  
AFTERNOON, LARGELY ALONG LAKEBREEZE BOUNDARIES ALONG THE KIAG/KROC  
CORRIDOR. CONVECTION SHOULD RAPIDLY DIMINISH THIS EVENING, WITH THE  
LOSS OF DIURNAL HEATING, GIVING WAY TO MORE VFR CONDITIONS  
OVERNIGHT.  
 
OUTLOOK...  
SUNDAY THROUGH TUESDAY...MAINLY VFR WITH SCATTERED TO  
NUMEROUS SHOWERS AND THUNDERSTORMS...MAINLY IN THE AFTERNOONS.  
WEDNESDAY...MAINLY VFR.  
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.  
 

 
   
MARINE
 
 
WESTERLY FLOW DEVELOPING IN THE WAKE OF A COLD FRONT CROSSING THE  
AREA WILL GENERATE A MODERATE CHOP ACROSS THE EASTERN ENDS OF THE  
LAKES, WITH WAVES TO 3 FEET. WAVES WILL RISE HIGHER ON SUNDAY,  
PARTICULARLY ON THE EASTERN HALF OF LAKE ERIE, AS WINDS STRENGTHEN  
FURTHER AS A STRONG UPPER LEVEL DISTURBANCE MOVES THROUGH. SMALL  
CRAFT ADVISORY CONDITIONS WILL DEVELOP ON THE EASTERN END OF LAKE  
ERIE BY SUNDAY AFTERNOON AND PERHAPS ON THE EASTERN END OF  
LAKE ONTARIO BY SUNDAY NIGHT.  
 
AFTER A BRIEF RESPITE MONDAY MORNING, ANOTHER PASSING UPPER LEVEL  
DISTURBANCE WILL LIKELY BRING ANOTHER PERIOD OF SMALL CRAFT ADVISORY  
CONDITIONS TO LAKE ERIE MONDAY NIGHT.  
 

 
   
BUF WATCHES/WARNINGS/ADVISORIES
 
 
NY...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 2 AM EDT MONDAY FOR  
LEZ040-041.  
 

 
 

 
 
SYNOPSIS...TMA  
NEAR TERM...TMA  
SHORT TERM...THOMAS  
LONG TERM...SMITH  
AVIATION...TMA  
MARINE...TMA  
 
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