363  
FXUS61 KBUF 181554  
AFDBUF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BUFFALO NY  
1154 AM EDT FRI AUG 18 2017  
   
SYNOPSIS
 
 
A COLD FRONT WILL MOVE ACROSS THE AREA THIS AFTERNOON AND PRODUCE A  
FEW MORE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS MAINLY SOUTHEAST  
OF THE LAKES. ANOTHER WEAK FRONT WILL CROSS THE AREA SATURDAY WITH  
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS, ESPECIALLY ACROSS THE  
SOUTHERN TIER. HIGH PRESSURE WILL THEN BRING A RETURN TO DRY WEATHER  
SUNDAY AND MONDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
REGIONAL RADAR THIS MORNING SHOWS THE LAST OF THE OVERNIGHT  
PRECIPITATION HAS PULLED WELL AWAY TO THE EAST, WHILE REGIONAL  
VISIBLE SATELLITE IMAGERY SHOWS A WELL-DEVELOPED CU FIELD, INLAND OF  
THE PROMINENT LAKE SHADOWS NORTHEAST OF THE LAKES. THE VERY MOIST  
AIRMASS, FEATURING DEWPOINTS IN THE UPPER 60S TO LOW 70S IS  
SUPPORTING THIS CLOUD FIELD. GIVEN ALL OF THE MOISTURE IN PLACE,  
EXPECT PLENTY OF CLOUDS TO HANG AROUND OUTSIDE OF LAKE SHADOW AREAS,  
WHICH WILL BE MAINTAINED THANKS TO A BREEZY SOUTHWESTERLY FLOW AHEAD  
OF AN APPROACHING COLD FRONT ON THE SOUTHEAST FLANK OF A WELL-  
DEVELOPED LOW CENTERED JUST NORTH OF THE SOO. THIS BREEZY SOUTHWEST  
FLOW, COMBINED WITH THE WARM AND MUGGY AIRMASS THAT IS IN PLACE WILL  
MAKE FOR AN ESPECIALLY WARM DAY ACROSS THE LAKE ONTARIO PLAINS AND  
THE GENESEE VALLEY, WHERE HIGHS WILL CLIMB INTO THE MID 80S, WHILE  
READINGS WILL BE MORE MILD DOWNWIND OF THE LAKES, WHERE TEMPERATURES  
WILL TOP OUT IN THE UPPER 70S TO LOW 80S.  
 
THE WARM AND MUGGY AIRMASS, COMBINED WITH TROUGHING ALOFT WILL  
PROVIDE A FAVORABLE ENVIRONMENT FOR THE DEVELOPMENT OF SCATTERED  
AFTERNOON SHOWERS AND PERHAPS A FEW THUNDERSTORMS, ALONG LAKE BREEZE  
BOUNDARIES, WHICH SHOULD BE PUSHED WELL INLAND BY THE RELATIVELY  
STRONG FLOW ALOFT. MOST LIKELY LOCATIONS FOR CONVECTION IN OUR AREA  
WILL RUN FROM THE SOUTHERN TIER ACROSS THE FINGER LAKES INTO THE  
SOUTHERN TUG HILL/WESTERN ADIRONDACKS THIS AFTERNOON, WHILE AREAS  
TO THE WEST WILL REMAIN WELL WITHIN THE STABLE LAKE SHADOW AND  
SHOULD SEE A SUNNY AND DRY, ALBEIT BREEZY AFTERNOON, AS BRISK WINDS  
ALOFT MIX DOWN TO THE SURFACE, WITH GUSTS OF 25-35MPH EXPECTED.  
 
THE DIURNALLY DRIVEN WIDELY SCATTERED CONVECTION WILL MOSTLY END BY  
MID EVENING AS THE BOUNDARY LAYER BEGINS TO COOL AND STABILIZE, AND  
THE WEAK SYNOPTIC SCALE COLD FRONT MOVES EAST OF THE AREA. THIS WILL  
LEAVE MAINLY DRY WEATHER OVERNIGHT, ALTHOUGH COOLING ALOFT  
INTERACTING WITH THE WARM LAKE WATERS MAY ALLOW A FEW SCATTERED  
SHOWERS TO DEVELOP LATE TONIGHT OVER AND EAST OF LAKES ERIE AND  
ONTARIO. EXPECT LOWS IN THE MID 60S ON THE LAKE PLAINS, AND AROUND  
60 ACROSS THE INTERIOR SOUTHERN TIER AND TUG HILL REGION. THE  
AIRMASS WILL SLOWLY BECOME LESS MUGGY OVERNIGHT AS WEAK COOL/DRY  
ADVECTION CONTINUES.  
 

 
   
SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/
 
 
ON SATURDAY, A PROGRESSIVE AMPLIFIED TROUGH WILL SWING ACROSS THE  
FORECAST AREA. WEAK WARM ADVECTION AHEAD OF THE TROUGH PASSAGE WILL  
BRING SOME MODEST INSTABILITY BACK INTO THE WESTERN SOUTHERN TIER  
DURING THE MORNING WITH INCREASING WIND SHEAR. A FEW STRONGER  
THUNDERSTORMS MAY DEVELOP WITH THE TROUGH PASSAGE IN THE WESTERN  
SOUTHERN TIER, WITH STORMS POSSIBLY BEING AIDED BY THE DEVELOPING  
LAKE ERIE LAKE BREEZE BOUNDARY. SPC HAS INCLUDED THIS AREA IN A  
MARGINAL RISK FOR SEVERE WEATHER. OTHERWISE, MORE WIDELY SCATTERED  
SHOWERS AND RUMBLES OF THUNDER ARE POSSIBLE SATURDAY AFTERNOON AND  
EARLY EVENING FOR THE REST OF THE FORECAST AREA WITH THE TROUGH  
PASSAGE. WITH SLIGHTLY COOLER AIR ALOFT UNDER THE TROUGH AND SOME  
CLOUD COVER, EXPECT HIGH TEMPERATURES WILL RUN JUST BELOW NORMAL IN  
THE MID 70S. SHOWERS AND ANY THUNDER WILL DIMINISH OVERNIGHT IN THE  
WAKE OF THE TROUGH AXIS PASSAGE AND LOSS OF DIURNAL HEATING. LOWS  
SATURDAY NIGHT WILL BE A BIT COOLER THAN PREVIOUS NIGHTS, IN THE MID  
50S TO LOW 60S.  
 
A BROAD SURFACE HIGH WILL BUILD IN ACROSS THE UPPER OHIO VALLEY  
SUNDAY BRINGING MODERATING TEMPERATURES AND DRIER AIR. THIS WILL  
RESULT IN HIGH TEMPERATURES NEAR NORMAL VALUES. AS THE SURFACE HIGH  
SLIDES OFF THE MID-ATLANTIC COAST MONDAY, RETURN FLOW DEVELOPING  
WILL PUSH HIGH TEMPERATURES INTO THE LOW TO MID 80S. SKIES WILL  
REMAIN MOSTLY CLEAR SUNDAY INTO MONDAY, WHICH SHOULD PROVIDE PRIME  
VIEWING CONDITIONS FOR THE ECLIPSE ON MONDAY. LOW TEMPERATURES  
SUNDAY NIGHT AND MONDAY WILL FOLLOW THE SAME WARMING TREND AS THE  
HIGH TEMPERATURES, WITH LOWS MONDAY NIGHT WELL INTO THE 60S WITH  
BUILDING HUMIDITY.  
 

 
   
LONG TERM /TUESDAY THROUGH THURSDAY/
 
 
THIS PERIOD WILL BE DOMINATED BY A STEADILY AMPLIFYING LONGWAVE  
TROUGH OVER EASTERN CANADA AND THE LOWER GREAT LAKES. THIS WILL LEAD  
TO NOTABLY LOWER DAY TO DAY TEMPERATURES...ALTHOUGH AT THE ONSET OF  
THE TIME FRAME...OUR TEMPERATURES WILL BE WELL ABOVE NORMAL. AS FOR  
THE DAY TO DAY DETAILS...  
 
OUR REGION WILL FIND ITSELF BETWEEN SYSTEMS ON TUESDAY...AS HIGH  
PRESSURE ANCHORED OFF THE COAST AND A COLD FRONT APPROACHING FROM  
THE UPPER GREAT LAKES WILL SUPPORT A VERY WARM AND INCREASINGLY  
HUMID ENVIRONMENT. TEMPERATURES SHOULD EASILY CLIMB INTO THE MID TO  
UPPER 80S ACROSS THE LAKE PLAINS AND IN THE VALLEYS. THIS AIRMASS  
WILL ALSO BE INCREASINGLY UNSTABLE...AND WHILE THE VAST MAJORITY OF  
THE DAY WILL BE RAIN FREE...SOME SHOWERS AND THUNDERSTORMS WILL BE  
POSSIBLE LATER IN THE DAY. THIS WILL MAINLY BE THE CASE OVER THE  
WESTERN COUNTIES WHERE LAKE BREEZE INTERACTIONS AND/OR THE PRESENCE  
OF A PRE-FRONTAL TROUGH COULD FOCUS CONVECTION.  
 
A COLD FRONT WILL THEN PUSH SOUTHEAST ACROSS OUR FORECAST AREA  
TUESDAY NIGHT AND EARLY WEDNESDAY, LIKELY BRINGING WIDESPREAD  
SHOWERS AND/OR THUNDERSTORMS ACROSS THE FORECAST AREA.  
 
EXPANSIVE HIGH PRESSURE OVER THE UPPER MISSISSIPPI VALLEY WEDNESDAY  
AFTERNOON WILL GRADUALLY SETTLE TO THE SOUTHEAST ACROSS THE LOWER  
GREAT LAKES AND OHIO VALLEY BY THURSDAY. THIS WILL ALLOW FOR  
SIGNIFICANT IMPROVEMENT IN OUR WEATHER WITH FAIR WEATHER  
RETURNING...ALONG WITH A PRONOUNCED TURN TO COOLER AND MORE  
COMFORTABLE (LOWER DEW POINTS) CONDITIONS. TEMPERATURES BY THURSDAY  
WILL AVERAGE AT LEAST 5 DEG F BELOW NORMAL.  
 

 
   
AVIATION /15Z FRIDAY THROUGH TUESDAY/
 
 
STRATUS HAS LARGELY MIXED OUT THIS MORNING, LEAVING MOST LOCATIONS  
VFR, THOUGH A VERY MOIST BOUNDARY LAYER AIRMASS FEATURING SFC  
DEWPOINTS IN THE UPPER 60S/LOW 70S IS KEEPING CLOUD BASES LOWER,  
RESULTING IN MVFR CIGS HANGING ON AT KIAG/KJHW/KART. THESE CIGS  
SHOULD LIFT WITH INCREASING MIXING THIS MORNING, AND THE LAKE SHADOW  
WILL ALSO BECOME MORE PROMINENT AS WE MOVE INTO THE AFTERNOON HOURS,  
RESULTING IN CLEARING SKIES AT KIAG/KART.  
 
SCATTERED -SHRA/-TSRA CAN BE EXPECTED WELL INLAND OF THE LAKES THIS  
AFTERNOON, COURTESY OF A MOIST LOW LEVEL AIRMASS AND TROUGHING  
ALOFT, ALONG WITH AN APPROACHING COLD FRONT. THIS DIURNALLY DRIVEN  
CONVECTION IS NOT EXPECTED TO AFFECT ANY TAF TERMINALS, AND WILL BE  
ROUGHLY ALONG A LINE FROM KOLE-KFZY EASTWARDS. CONVECTION SHOULD  
DIMINISH AFTER SUNSET. WHILE THE AIRMASS IN THE REGION WILL BEGIN TO  
DRY OUT SOMEWHAT OVERNIGHT, DEWPOINTS WILL REMAIN THE 60S, AND IT IS  
LIKELY THAT WE WILL SEE MVFR CIGS RETURN AGAIN TONIGHT, WITH IFR  
ACROSS THE SOUTHERN TIER, AS CLOUD BASES LOWER ONCE AGAIN.  
 
OUTLOOK...  
 
SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.  
SUNDAY AND MONDAY...VFR EXCEPT FOR LATE NIGHT AND EARLY MORNING  
VALLEY FOG WITH LOCAL IFR.  
TUESDAY...MAINLY VFR, WITH A CHANCE OF SHOWERS AND THUNDERSTORMS LATE.  
 

 
   
MARINE
 
 
LOW PRESSURE WILL MOVE FROM JUST EAST OF LAKE SUPERIOR TODAY TO WEST  
CENTRAL QUEBEC BY SATURDAY, WITH A TRAILING COLD FRONT CROSSING THE  
EASTERN GREAT LAKES THIS AFTERNOON. SOUTHWEST WINDS WILL BECOME  
QUITE STRONG ON LAKE ERIE TODAY AS THEY FUNNEL UP THE LENGTH OF THE  
LAKE, WITH SOLID SMALL CRAFT ADVISORY CONDITIONS THIS AFTERNOON AND  
EVENING. THE SOUTHWEST WINDS WILL BE LIGHTER AT THE EAST END OF LAKE  
ONTARIO. WEST WINDS WILL SLOWLY INCREASE ON LAKE ONTARIO OVERNIGHT  
INTO SATURDAY, WITH SMALL CRAFT ADVISORY CONDITIONS PROBABLE ON AT  
LEAST THE EAST HALF OF THE LAKE FOR SATURDAY, WHILE WINDS REMAIN A  
LITTLE LIGHTER ON ERIE.  
 
HIGH PRESSURE WILL THEN BRING A RETURN TO LIGHT WINDS SUNDAY AND  
MONDAY ON BOTH LAKES.  
 

 
   
BUF WATCHES/WARNINGS/ADVISORIES
 
 
NY...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR  
NYZ010-019-085.  
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR LEZ040-041.  
SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR  
LEZ020.  
 

 
 

 
 
SYNOPSIS...HITCHCOCK  
NEAR TERM...HITCHCOCK/WOOD  
SHORT TERM...CHURCH  
LONG TERM...CHURCH/RSH  
AVIATION...WOOD  
MARINE...HITCHCOCK  
 
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