161  
FXUS61 KBUF 031810  
AFDBUF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BUFFALO NY  
210 PM EDT MON AUG 3 2015  
   
SYNOPSIS
 
 
A COLD FRONT WILL SLOWLY PUSH ACROSS THE REGION THROUGH THIS  
EVENING WITH SOME SHOWERS AND THUNDERSTORMS. A SECONDARY COLD  
FRONT WILL TOUCH OFF A COUPLE MORE SHOWERS TUESDAY AND TUESDAY  
NIGHT...OTHERWISE IT WILL BECOME COOLER AND MORE COMFORTABLE FOR  
THE REMAINDER OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
BASED ON RADAR TRENDS WE HAVE LOWERED POPS FOR THE EARLY  
AFTERNOON UPDATE. AT 200 PM...SCATTERED CONVECTION HAS DEVELOPED  
ALONG A SUBTLE PRE-FRONTAL BOUNDARY EXTENDING FROM JHW-ROC-ART.  
THE STEADIEST OF THIS ACTIVITY IS ACROSS EASTERN LAKE ONTARIO.  
A CONSENSUS OF MESOSCALE GUIDANCE MATCHES THESE TRENDS FAIRLY  
WELL IN TERMS OF POSITIONING...BUT SO FAR IS OVERDONE IN COVERAGE.  
FOR THE REMAINDER OF THIS AFTERNOON...EXPECT SHOWERS AND  
THUNDERSTORMS TO EXPAND A BIT ALONG THIS BOUNDARY...TAKING  
ADVANTAGE OF MODEST INSTABILITY (500 J/KG) IN PLACE. THIS LINE  
SHOULD CONTINUE TO PROGRESS EASTWARD THROUGH THIS EVENING. THE  
ONLY OTHER AREA OF CONCERN IS AN AREA OF CONVERGENCE SURFACE WINDS  
JUST NORTH OF BUFFALO WHERE SHOWERS AND THUNDERSTORMS MAY DEVELOP.  
THIS ALSO SIGNALS A LOWERED CHANCE FOR SEVERE WEATHER...HOWEVER  
SOME STORMS MAY PULSE AND BECOME STRONG TO SEVERE ACROSS EASTERN  
SECTIONS OF THE CWA.  
 
THE INITIAL COLD FRONT WILL LIMP TO OUR EAST TONIGHT...WHILE A  
SECONDARY COLD FRONT WILL SETTLE ACROSS SOUTHERN ONTARIO TO OUR  
DOORSTEP BY DAYBREAK. IT WILL BE THIS SECOND FRONT THAT WILL  
ACTUALLY USHER IN A DIFFERENT AIRMASS...AS COOLER AND LESS HUMID  
AIR WILL FOLLOW FOR THE REMAINDER OF THE WEEK. IN TERMS OF  
PCPN...ANY LEFTOVER SHOWERS FROM THE FIRST FRONTAL BOUNDARY WILL  
QUICKLY END DURING THE EVENING HOURS...BUT SHOWERS FROM THE  
APPROACHING SECONDARY FRONT COULD BLOSSOM OVER AN INCREASINGLY  
UNSTABLE AIRMASS OVER THE WARM WATERS OF LAKE ONTARIO BY DAYBREAK.  
THIS IS A HINT OF THINGS TO COME.  
 

 
   
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
 
 
ON TUESDAY...THE AXIS OF THE MAIN UPPER LEVEL TROUGH WILL SETTLE  
FROM THE WESTERN GREAT LAKES INTO SOUTHERN ONTARIO...ALONG WITH A  
CORRESPONDING SURFACE TROUGH/SECONDARY COLD FRONT. WITH DIURNAL  
HEATING OF THE COOLER AIRMASS THAT WILL BE IN PLACE ALOFT AND ONE  
OR MORE SHORTWAVE IMPULSES SLIDING THROUGH THE BASE OF THE UPPER  
LEVEL TROUGH AND ACROSS OUR REGION...EXPECT ANOTHER ROUND OF  
SCATTERED SHOWERS AND THUNDERSTORMS TO AFFECT OUR REGION THROUGH  
THE DAY ON TUESDAY. THE BEST POTENTIAL FOR THESE WILL MOST LIKELY  
BE FOUND ACROSS THE NORTH COUNTRY AS THIS REGION SHOULD BE MORE  
DIRECTLY IMPACTED BY THE PASSING MID AND UPPER LEVEL IMPULSES...  
WITH PRECIP CHANCES LARGELY EXHIBITING A GRADUAL DECREASE WITH  
INCREASING SOUTHWESTWARD EXTENT. OTHERWISE...THE CONTINUED GRADUAL  
BUT STEADY COOL AIR ADVECTION REGIME WILL LEAD TO 850 MB TEMPS  
FALLING TO THE +9C TO +12C RANGE BY AFTERNOON...WHICH SHOULD IN  
TURN TRANSLATE INTO DAYTIME HIGHS REACHING THE LOWER TO MID 70S IN  
MOST PLACES.  
 
DURING TUESDAY NIGHT THE SECONDARY COLD FRONT WILL TRAVERSE OUR  
REGION IN CONJUNCTION WITH THE MAIN UPPER LEVEL TROUGH AXIS. WHILE  
LINGERING DIURNALLY-DRIVEN SHOWERS AND STORMS AT THE START OF THE  
EVENING WILL PROBABLY BE FOLLOWED BY SOME ADDITIONAL SCATTERED  
SHOWER ACTIVITY AS THESE FEATURES PASS...IN GENERAL THE LOSS OF  
DAYTIME HEATING AND THE ARRIVAL OF DRIER AIR BEHIND THE SECONDARY  
FRONT SHOULD LEAD TO PRECIP CHANCES DIMINISHING OVER TIME. THE ONE  
EXCEPTION TO THIS WILL BE EAST OF LAKE ONTARIO... WHERE A WESTERLY  
FLOW OF PROGRESSIVELY COOLER AIR CROSSING THE WARMER LAKE WATERS  
WILL CONTINUE TO GENERATE SCATTERED SHOWERS RIGHT THROUGH THE  
NIGHT VIA A COMBINATION OF OROGRAPHIC AND LAKE EFFECT  
PROCESSES...AS 850 MB TEMPS WILL FALL TO BETWEEN +7C AND +8C. AS  
FOR TEMPERATURES...EXPECT COMFORTABLE CONDITIONS FOR SLEEPING WITH  
OVERNIGHT LOWS RANGING FROM THE LOWER TO MID 50S ACROSS INTERIOR  
PORTIONS OF THE SOUTHERN TIER/NORTH COUNTRY TO RIGHT AROUND 60  
ALONG THE IMMEDIATE LAKESHORES.  
 
ON WEDNESDAY...THE CORE OF THE UPPER LEVEL TROUGH WILL MEANDER  
ITS WAY EAST ACROSS QUEBEC PROVINCE...WHILE SURFACE-BASED RIDGING  
AND DRIER AIR DRAPED FROM THE WESTERN GREAT LAKES TO THE OHIO  
VALLEY BUILDS EASTWARD INTO THE CENTRAL GREAT LAKES. WHILE THE  
LATTER SHOULD RESULT IN A MAINLY DRY DAY FOR MOST AREAS SOUTH OF  
LAKE ONTARIO...THE FAR NORTHEASTERN FINGER LAKES REGION AND NORTH  
CENTRAL NEW YORK WILL BE SUBJECT TO SOME ADDITIONAL SCATTERED LAKE  
AND OROGRAPHICALLY-DRIVEN SHOWERS EARLY WEDNESDAY...FOLLOWED BY  
MORE GENERAL DIURNALLY-DRIVEN SHOWERS THE BALANCE OF THE DAY AS  
ANOTHER SHORTWAVE SWINGS THROUGH THE BASE OF THE UPPER TROUGH IN  
CONJUNCTION WITH RENEWED DAYTIME HEATING. ALL OF THIS SHOULD THEN  
QUICKLY WIND DOWN WEDNESDAY NIGHT WITH THE LOSS OF HEATING AND AS  
THE AFOREMENTIONED RIDGE BUILDS DIRECTLY OVERHEAD... RESULTING IN  
A RETURN TO DRY WEATHER AREAWIDE TO CLOSE OUT THE SHORT TERM  
PERIOD.  
 
WITH RESPECT TO TEMPERATURES WEDNESDAY AND WEDNESDAY NIGHT...THESE  
SHOULD REMAIN SOLIDLY BELOW NORMAL...AND SHOULD IN FACT BOTTOM OUT  
FOR THE WEEK AS OUR AIRMASS REACHES ITS COOLEST OVERALL POINT OF  
THE NEXT SEVEN DAYS. 850 MB TEMPS OF ROUGHLY +7C TO +10C SHOULD  
TRANSLATE INTO HIGHS MOSTLY IN THE UPPER 60S TO LOWER 70S ON  
WEDNESDAY...WITH THE COOLEST READINGS ACROSS THE HIGHER  
TERRAIN...AND THE WARMEST OVERALL TEMPS FOUND IN THE GENESEE  
VALLEY/WESTERN FINGER LAKES... WHERE A FEW SPOTS COULD STILL REACH  
THE MID 70S. SUCH READINGS WILL THEN BE FOLLOWED BY LOWS RANGING  
THROUGH THE 50S WEDNESDAY NIGHT... WHEN THE COOLEST INTERIOR  
PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY COULD TICKLE THE  
50 DEGREE MARK.  
 

 
   
LONG TERM /THURSDAY THROUGH SUNDAY/
 
 
IN THE LONGER TERM PORTION OF THE FORECAST...THE MID AND UPPER  
LEVEL FLOW ACROSS OUR REGION WILL TEND TO GRADUALLY DEAMPLIFY  
THROUGH THE LATTER PORTIONS OF THE WORK WEEK AND INTO THE FIRST  
PART OF THE UPCOMING WEEKEND AS THE CORE OF THIS WEEK/S MAIN UPPER  
TROUGH LIFTS OUT INTO THE NORTHERN ATLANTIC...AND MAY EVEN BRIEFLY  
GO QUASI-ZONAL BEFORE A VERY MODEST MID-LEVEL TROUGH APPROACHES  
OUR REGION IN TIME FOR SUNDAY. AS A RESULT...INITIALLY BELOW  
NORMAL TEMPERATURES LATE IN THE WORK WEEK SHOULD TREND CLOSER TO  
SEASONAL AVERAGES BY NEXT WEEKEND. MORE SPECIFICALLY...DAYTIME  
HIGHS INITIALLY IN THE LOWER TO MID 70S ON THURSDAY SHOULD CLIMB  
BACK INTO THE MID AND UPPER 70S FOR NEXT WEEKEND...WHILE NIGHTTIME  
LOWS INITIALLY RANGING THROUGH THE 50S SHOULD SLOWLY MODERATE INTO  
THE 55-60 RANGE.  
 
AS FOR PRECIPITATION CHANCES...MAINLY DRY WEATHER SHOULD PREVAIL  
THURSDAY THROUGH SATURDAY AS EXPANSIVE CANADIAN HIGH PRESSURE  
DRAPED FROM ONTARIO PROVINCE TO THE UPPER OHIO VALLEY AT THE START  
OF THE PERIOD SLOWLY DRIFTS EASTWARD INTO QUEBEC...AND KEEPS THE  
MAIN SURFACE FRONTAL ZONE/ANY ATTENDANT WAVES OF LOW PRESSURE  
SUPPRESSED TO OUR SOUTH. AFTER THAT...THE AFOREMENTIONED MID-LEVEL  
TROUGH SHOULD PROVIDE ENOUGH OF AN INCREASE IN MOISTURE AND  
SYNOPTIC- SCALE LIFT TO RESULT IN LIMITED CHANCES FOR  
SHOWERS/THUNDERSTORMS RETURNING ON SUNDAY...WHICH AT THIS DISTANT  
VANTAGE POINT WILL BE COVERED WITH SOME VERY LOW CHANCE POPS.  
 

 
   
AVIATION /18Z MONDAY THROUGH SATURDAY/
 
 
SCATTERED TO NUMEROUS CONVECTION WILL TAPER OFF LATE  
AFTERNOON...WITH TEMPORARY VSBY/CIG RESTRICTIONS POSSIBLE. ANY OF  
THESE SHOULD BE FAIRLY BRIEF IN NATURE. AFTER THIS...EXPECT  
MAINLY VFR CONDITIONS THIS EVENING AS THE FIRST OF TWO COLD  
FRONTS DROPS SOUTH OF THE REGION. THE SECOND COLD FRONT WILL REACH  
THE AREA TUESDAY MORNING...AND THIS MAY RESULT IN PATCHY LOW  
CLOUDS IN THE MVFR OR LOWER CATEGORY. ANY LOWER CIGS SHOULD LIFT  
MONDAY AFTERNOON...BUT SHOWERS WILL BECOME MORE NUMEROUS WITH  
POSSIBLY A THUNDERSTORM.  
 
OUTLOOK...  
 
TUESDAY NIGHT AND WEDNESDAY...MAINLY VFR WITH A CHANCE OF  
SHOWERS...MAINLY EAST OF LAKE ONTARIO NEAR ART.  
WEDNESDAY NIGHT THROUGH MONDAY...VFR.  
 

 
   
MARINE
 
 
A RELATIVELY TIGHT SFC PRESSURE GRADIENT WILL COMBINE WITH A  
STRONG LOW LEVEL JET AHEAD OF A COLD FRONT TO PRODUCE GUSTY WINDS  
ACROSS THE LOWER GREAT LAKES TODAY. A SMALL CRAFT ADVISORY IS  
ALREADY IN PLACE FOR ALL OF THE NEW YORK NEARSHORE WATERS...AS  
WELL AS BUF HARBOR. THE WINDS WILL DROP OFF THROUGH THIS EVENING  
IN THE WAKE OF A SLOW MOVING COLD FRONT.  
 
WINDS WILL DROP BELOW SMALL CRAFT ADVISORY LEVELS THIS EVENING  
AND REMAIN RELATIVELY LIGHT DURING THE OVERNIGHT HOURS. THESE  
WINDS WILL FRESHEN AGAIN ON TUESDAY AS ANOTHER FRONTAL BOUNDARY  
WILL PUSH SOUTH ACROSS THE LOWER GREAT LAKES. THIS WILL ENCOURAGE  
WAVES TO BUILD TO 3 TO 5 FEET...WITH ANOTHER ROUND OF SMALL CRAFT  
ADVISORIES LIKELY FOR THE NEARSHORE WATERS OF LAKE ERIE AND  
POSSIBLY FOR THE EASTERN END OF LAKE ONTARIO.  
 
A FALL LIKE AIRMASS IN THE WAKE OF THIS SECOND COLD FRONT COULD  
SET THE STAGE FOR WATERSPOUTS ON LAKE ONTARIO TUESDAY NIGHT AND  
WEDNESDAY. WILL CARRY SLIGHT CHC FOR SPOUTS IN THE GRIDDED DATA  
BASE FOR NOW. STAY TUNED.  
 

 
   
BUF WATCHES/WARNINGS/ADVISORIES
 
 
NY...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040-  
041.  
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR  
LEZ020.  
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR  
LOZ042>045.  
 

 
 

 
 
SYNOPSIS...APFFEL/RSH  
NEAR TERM...APFFEL/RSH  
SHORT TERM...JJR  
LONG TERM...JJR  
AVIATION...APFFEL  
MARINE...APFFEL/RSH  
 
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