Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 301121
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
721 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 /12Z 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...
UPPER LEVEL LOW WILL KEEP A COOL AIRMASS IN PLACE ACROSS THE GREAT
LAKES THROUGH MUCH OF THE WEEK. THIS WILL RESULT IN A CHANCE
WATERSPOUTS THROUGH THURSDAY FOR BOTH LAKES ALONG WITH CHANCES OF
LAKE ENHANCED SHOWERS EACH NIGHT. WINDS AND WAVES WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.

&&

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

&&

$$

SYNOPSIS...ZAFF
NEAR TERM...ZAFF
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...ZAFF
MARINE...SMITH/ZAFF







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