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Area Forecast Discussion
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000
FXUS61 KBUF 301413
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1013 AM EDT WED JUL 30 2014

.SYNOPSIS...
A COOL AIRMASS WILL REMAIN IN PLACE THROUGH MUCH OF THE WEEK AS AN 
UPPER LEVEL LOW LINGERS OVER THE GREAT LAKES.  THIS WILL RESULT IN 
SOME SHOWERS AND EVEN LAKE ENHANCED SHOWERS AND THUNDERSTORMS AT 
TIMES.  WARMER AIR WILL RETURN BY THE WEEKEND...BUT A LINGERING 
UPPER LEVEL TROUGH WILL RESULT IN A CONTINUED CHANCE FOR SHOWERS 
AND THUNDERSTORMS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN UNSEASONABLY COOL UPPER LEVEL LOW IS OVER THE GREAT LAKES REGION 
THIS MORNING WITH THREE NOTABLE SHORTWAVE TROUGHS EMBEDDED IN THE 
STUBBORN LONGWAVE PATTERN.  THE FIRST IS OVER LAKE MI WHILE A 
SECOND IS MOVING SOUTH FROM HUDSON BAY.  THERE IS IS A SUBTLE THIRD 
SHORTWAVE TROUGH ENHANCING THE CONVECTION OVER LAKE ERIE AS WELL 
WITH A LAND BREEZE AIDING IN SLOW MOVING LAKE EFFECT SHOWERS 
PRIMARILY OFFSHORE.  SOME SPILLOVER IS OVER PORTIONS OF CHAUTAUQUA 
COUNTY.  BUT CIGS...VISIBILITY...AND PRECIPITATION ESTIMATES 
TOGETHER WITH DUAL POL DATA AND OBSERVATIONAL ANALYSIS SHOW THAT 
MUCH OF THE PRECIPITATION THERE IS UNDER THE RADAR BRIGHT BAND...SO 
IT LOOKS WORSE THAN WHAT IS REALLY HAPPENING.  THIS THIRD SHORTWAVE 
WILL MOVE EAST OF THE REGION THIS MORNING WITH A DECREASE IN LAKE 
ENHANCED COVERAGE.  

FOR TODAY...THE LAKE MI SHORTWAVE TROUGH WILL HAVE SOME LIMITED 
INFLUENCE ON WESTERN NY THIS AFTERNOON BY AIDING LIFT AS LAND 
BREEZES FADE AND LAKE BREEZES DEVELOP LATER THIS 
MORNING/AFTERNOON.  WITH WITH THE FALL-LIKE PATTERN QUICKLY 
TRANSITIONING BACK TO A MORE TYPICAL SUMMERTIME PATTERN...EXPECT TO 
SEE SOME CLEARING OVER THE LAKES EVENTUAL SHOWERS DEVELOP INLAND.  

FOR TONIGHT THE NEXT SHORTWAVE THROUGH WILL APPROACH WITH SLIGHTLY 
LOWER TEMPERATURES ALOFT.  SO AFTER A BREAK IN SHOWERS THROUGHOUT 
WESTERN NY WITH THE LOSS OF DAYTIME HEATING AND INSTABILITY...EXPECT 
A RESURGENCE OF SHOWERS OVER LAKE ERIE AND PORTIONS OF FAR WESTERN 
NY LATER TONIGHT.  

WITH THE COOL AIRMASS IN PLACE TEMPERATURES WILL CONTINUE TO BE 
BELOW NORMAL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AN ANOMALOUSLY DEEP LONGWAVE TROUGH WILL REMAIN IN PLACE ON THURSDAY 
ACROSS THE GREAT LAKES AND NORTHEAST. A STRONG SHORTWAVE EVIDENT ON 
WATER VAPOR IMAGERY THIS MORNING CHARGING SOUTH ACROSS NORTHWEST 
ONTARIO PROVINCE WILL ROTATE THROUGH THE MEAN LONGWAVE TROUGH AND 
CROSS OUR REGION THURSDAY MORNING. A BRIEF PERIOD OF ASCENT WITHIN 
THE DPVA REGION AHEAD OF THE SHORTWAVE WILL LIKELY PRODUCE A BROKEN 
BAND OF SHOWERS ALONG AND AHEAD OF AN ASSOCIATED SURFACE TROUGH. THE 
AIRMASS IS STILL COOL ENOUGH ALOFT TO SUPPORT LAKE ENHANCEMENT AS 
WELL...ESPECIALLY DURING THE MORNING WHEN LAKE INDUCED CAPES WILL 
RUN AROUND 1000J/KG WITH EQUILIBRIUM LEVELS AROUND 30K FEET. THE 
ADDED LAKE INSTABILITY WILL PRODUCE A RELATIVE MAX IN SHOWER 
COVERAGE OVER LAKE ERIE LATE TONIGHT...WITH THE LAKE ENHANCEMENT 
DETACHING FROM THE LAKE AND SPREADING EAST ACROSS THE AREA EARLY 
THURSDAY WITH THE PASSAGE OF THE MID LEVEL SHORTWAVE. THERE WILL 
ALSO BE SOME LAKE ENHANCEMENT FOR A FEW HOURS EAST OF LAKE ONTARIO 
AS WELL. GIVEN THE IMPRESSIVE LAKE INSTABILITY...STEEP LAPSE 
RATES...AND STRONG MID LEVEL FORCING SCATTERED THUNDERSTORMS ARE 
ALSO POSSIBLE.

BY THURSDAY AFTERNOON THE MID LEVEL SHORTWAVE WILL BE EXITING INTO 
NEW ENGLAND...WITH SUBSIDENCE IN ITS WAKE ALLOWING FOR A REDUCTION 
IN SHOWER COVERAGE. THE LAKES WILL ALSO TRY TO FLIP...WITH LAKE 
ENHANCEMENT TRANSITIONING TO DIURNAL SHOWERS INLAND FROM THE LAKES 
AS STABLE LAKE SHADOWS TRY TO DEVELOP. EXPECT THE COVERAGE OF 
AFTERNOON SHOWERS TO BE LOW...WITH THE GREATEST CHANCES ACROSS THE 
HIGHER TERRAIN EAST OF LAKE ONTARIO AND ALSO PERHAPS ALONG LAKE 
BREEZE CONVERGENCE ZONES ACROSS WESTERN NY. AFTER A CLOUDY START 
THERE SHOULD BE AT LEAST A FEW BREAKS OF SUN IN THE AFTERNOON FROM 
THE GENESEE VALLEY WESTWARD. TEMPERATURES WILL STILL BE BELOW 
AVERAGE WITH HIGHS IN THE LOWER TO MID 70S AT LOWER ELEVATIONS AND 
UPPER 60S TO AROUND 70 ACROSS HIGHER TERRAIN.

THURSDAY NIGHT AND FRIDAY THE LONGWAVE TROUGH WILL TEMPORARILY 
DE-AMPLIFY AND RETREAT INTO CENTRAL AND NORTHERN QUEBEC. AT THE 
SURFACE A WEAK RIDGE OF HIGH PRESSURE WILL BUILD FROM THE OHIO 
VALLEY TO OFF THE EAST COAST. THIS WILL ALLOW THE AREA TO FINALLY 
DRY OUT WITH AT LEAST PARTIAL CLEARING THURSDAY NIGHT AND SOME 
SUNSHINE ON FRIDAY. 850MB TEMPS WILL RECOVER TO AROUND +14C BY 
FRIDAY AFTERNOON...AND THIS WILL SUPPORT A RETURN TO SUMMER WARMTH 
WITH HIGHS IN THE LOWER 80S AT LOWER ELEVATIONS AND UPPER 70S ACROSS 
HIGHER TERRAIN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LONGWAVE TROUGH WILL RELOAD OVER THE WEEKEND AS ANOTHER DEEP 
TROUGH IS CARVED OUT OVER THE GREAT LAKES AND OHIO VALLEY ON 
SATURDAY...THEN MOVING EAST ON SUNDAY. THIS WILL BRING ANOTHER 
PERIOD OF UNSETTLED WEATHER AS INCREASING SOUTHERLY FLOW TRANSPORTS 
ATLANTIC AND GULF MOISTURE NORTHWARD AND BACK INTO OUR REGION. A 
SERIES OF SUBTLE SHORTWAVES WILL LIFT NORTHEASTWARD ALONG THE 
EASTERN EDGE OF THE LONGWAVE TROUGH AND COMBINE WITH INCREASING 
MOISTURE AND INSTABILITY TO PRODUCE SCATTERED SHOWERS AND 
THUNDERSTORMS BOTH SATURDAY AND SUNDAY. IT STILL APPEARS IN LATEST 
MODEL GUIDANCE THAT THE BEST COVERAGE OF CONVECTION WILL BE ACROSS 
THE HIGHER TERRAIN...WITH LESSER COVERAGE ON THE LAKE PLAINS.

BY MONDAY THIS LATEST TROUGH AMPLIFICATION WILL RETREAT BACK INTO 
QUEBEC WITH WEAK HIGH PRESSURE BUILDING INTO THE OHIO VALLEY AND 
LOWER LAKES. THIS SHOULD PROVIDE A RETURN TO MAINLY DRY WEATHER. 
BOTH THE GFS AND ECMWF THEN SHOW A WEAK MID LEVEL TROUGH CROSSING 
THE GREAT LAKES BY TUESDAY WITH THE NEXT CHANCE OF SCATTERED SHOWERS 
AND STORMS.

TEMPERATURES WILL REMAIN NEAR AVERAGE THROUGH THE LONG TERM WITH 
HIGHS GENERALLY IN THE LOWER 80S AT LOWER ELEVATIONS MOST DAYS WITH 
MODERATE HUMIDITY RETURNING.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AN UPPER LEVEL LOW WILL CONTINUE TO CIRCULATE COLD AIR ACROSS THE 
LAKES OVER THE NEXT 24 HOURS WITH SOME LAKE ENHANCED SHOWERS 
DECREASING THIS MORNING BUT WITH INLAND SHOWERS AND ISOLATED 
THUNDERSTORMS DEVELOPING FROM LAKE BREEZE BOUNDARIES DURING THE 
DAY.  VFR CONDITIONS ARE EXPECTED HOWEVER WITH ONLY BRIEF PERIODS OF 
LOWER VISIBILITY AND CEILINGS. 

OUTLOOK... 
WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH SCATTERED SHOWERS. 
FRIDAY...VFR
SATURDAY AND SUNDAY...MAINLY VFR WITH CHANCE SHOWERS AND
THUNDERSTORMS.

&&

.MARINE...
AN UNSEASONABLY COOL AIRMASS OVER THE WARM WATERS OF LAKES ERIE AND 
ONTARIO HELPED TO GENERATE SOME LAKE INDUCED SHOWERS LAST NIGHT...
AND DURING THE COURSE OF THE NEXT 24 TO 30 HOURS...WILL ALSO BE 
FAVORABLE FOR THE DEVELOPMENT OF WATERSPOUTS. 

THIS FORECAST IS SUPPORTED BY THE EXCELLENT GUIDANCE OFFERED BY THE 
SZILAGYI NOMOGRAM. OUR H85 TEMPS IN THE VCNTY OF 8C COMBINED WITH A 
CONVECTIVE CLOUD DEPTH IN EXCESS OF 30K SUGGESTS THE POSSIBILITY OF 
WATERSPOUTS. THESE HAVE BEEN IN THE FORECAST FOR SOME TIME NOW AND 
WILL REMAIN IN PLACE. ANY SHOWERS THAT DEVELOP WILL THUS CARRY THE 
RISK OF ALSO HAVING A WATERSPOUT. 

OTHERWISE...A RELATIVELY WEAK SFC PRESSURE GRADIENT WITHIN A VERY 
COOL CYCLONIC FLOW SHOULD KEEP WINDS AND WAVES BELOW SMALL CRAFT 
ADVISORY CRITERIA THROUGH THURSDAY. AS MENTIONED THOUGH...BOATERS 
SHOULD BE ALERT TO SHORT FUSED MARINE FLAGS DUE TO THE RISK OF 
WATERSPOUTS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...ZAFF
NEAR TERM...ZAFF
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...ZAFF
MARINE...RSH







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