Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 271741
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
141 PM EDT WED MAY 27 2015

.SYNOPSIS...
A WARM AND HUMIDITY AIRMASS WILL REMAIN ACROSS THE EASTERN GREAT
LAKES REGION THIS AFTERNOON. SHOWERS AND THUNDERSTORMS WILL
BLOSSOM THIS AFTERNOON...ESPECIALLY FROM THE GENESEE VALLEY
EASTWARD...WHILE WESTERN NEW YORK WILL WAIT UNTIL A WEAK COLD
FRONT PASSAGE THIS EVENING FOR MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS. FOLLOWING THIS COLD FRONT PASSAGE LATE
TONIGHT...SLIGHTLY COOLER AIR...BUT MORE NOTICEABLY DRIER AIR WILL
BE IN STORE FOR THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
WESTERN NEW YORK RESIDING IN BETWEEN TWO OF THE BEST INSTABILITY
AREAS. ONE JUST OFF TO OUR EAST ACROSS EASTERN NEW YORK AND THE
OTHER OVER THE OHIO VALLEY. THESE TWO AREAS WILL HAVE THE
GREATEST POTENTIAL FOR WIDESPREAD AND POTENTIALLY SEVERE
CONVECTION THROUGH THIS AFTERNOON. SCATTERED THUNDERSTORMS WILL
BE POSSIBLE FOR WESTERN NEW YORK BUT LIKELY CONFINED TO A LAKE
BREEZE BOUNDARY SOUTHEAST OF LAKE ERIE. HIGHS THIS AFTERNOON WILL
BE A HUMID UPPER 70S TO MID 80S.

FOR TONIGHT ATTENTION WILL TURN TO THE COLD FRONT AND ASSOCIATED
THUNDERSTORMS. THIS COLD FRONT WILL HAVE ADDITIONAL LIFT OF A MID
LEVEL SHORTWAVE THAT WILL PASS ACROSS THE EASTERN GREAT LAKE REGION.

THE BULK OF THE CONVECTIVE SHOWER ACTIVITY WILL BE ACROSS WNY...IN
AREAS THAT DID NOT RECEIVE DAYTIME THUNDERSTORMS. EXPECT AN AREA OF
SHOWERS AND THUNDERSTORMS TO DROP SOUTHEASTWARD ACROSS WNY THROUGH
THE EVENING HOURS. WE WILL BE LOSING SOME DAYTIME INSTABILITY...
THOUGH THE EARLY EVENING ARRIVAL OF THE CONVECTION MAY BE ABLE TO
TAP INTO SOME STILL MODEST INSTABILITY TO PRODUCE A FEW GUSTY
THUNDERSTORMS THIS EVENING...ESPECIALLY OVER LAKE ERIE AND INLAND
ACROSS SOUTHERN ERIE...AND CHAUTAUQUA COUNTY. EXPECT SOME
WEAKENING AND DIMINISHMENT IN COVERAGE AREA OF THE CONVECTION AS
IT REACHES CNY WHERE LOWER INSTABILITY WILL RESIDE. WILL CONTINUE
WITH CHANCE POPS ACROSS THE FINGER LAKES AND EASTERN LAKE ONTARIO
REGION.

AS THE WEAK COLD FRONT PASSES OVERNIGHT TEMPERATURES WILL NOT DROP
MUCH...BUT THE DEWPOINTS WILL. THIS FRONT WILL ERASE THE HIGH PWATS
OVER OUR REGION...AND LOWER DEW POINTS INTO THE MID TO UPPER 50S BY
DAYBREAK. A FEW SHOWERS MAY LINGER ACROSS THE EASTERN LAKE ONTARIO
REGION TOWARDS DAYBREAK...CLOSER TO THE UPPER LEVEL SHORTWAVE.

IT WILL REMAIN MUGGY AND STILL WARM THROUGH THE EVENING HOURS.
THEN LATER TONIGHT TEMPERATURES WILL DROP BEHIND THE WEAK COLD
FRONT INTO THE UPPER 50S AND LOWER 60S.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
A PROGRESSIVE FLOW FOUND OVER NORTH AMERICA WILL OFFER TWO FAIRLY
SIGNIFICANT COLD FRONTAL PASSAGES OVER THE GREAT LAKES DURING THIS
PERIOD....BUT THE BULK OF THE TIME WILL BE DOMINATED BY A STRONG
EAST COAST RIDGE. THIS WILL TRANSLATE INTO MAINLY DRY...UNEVENTFUL
WEATHER. THE GOOD NEWS FOR AGRICULTURALISTS IS THAT THE STRETCH
OF DRY WEATHER WILL LIKELY END WITH A `WET` FRONTAL PASSAGE AS
THIS TIME FRAME COMES TO A CLOSE.

A STRONG SHORTWAVE CROSSING THE UPPER GREAT LAKES TODAY WILL DRIVE
A COLD FRONT ACROSS OUR REGION LATE TONIGHT AND EARLY THURSDAY.
THE MAIN FRONT SHOULD BE THROUGH MOST OF OUR FORECAST AREA BY
DAYBREAK WITH MID LEVEL DRYING ALREADY BECOMING ESTABLISHED OVER
THE WESTERN COUNTIES. A SECONDARY FRONTAL BOUNDARY WILL SWEEP
ACROSS THE NORTH COUNTRY BY MIDDAY THOUGH...AND THIS SHOULD DELAY
THE ONSET OF FAIR WEATHER FOR THAT AREA BY SOME 3 TO 6 HOURS.
OTHERWISE...HIGH PRESSURE CENTERED IN THE VCNTY OF JAMES BAY WILL
NOSE SOUTH ACROSS THE LOWER GREAT LAKES DURING THE COURSE OF THE
DAY....WITH SUBSIDENCE AND CONTINUED DRYING LEADING TO INCREASING
AMOUNTS OF SUNSHINE. IT WILL BE COOLER AND NOTICEABLY LESS HUMID
AS WELL...AS DEWPOINTS THAT HAD BEEN IN THE 60S WILL DROP BACK
THROUGH THE 50S. AFTERNOON MAX TEMPS WILL GENERALLY BE IN THE 70S.

THURSDAY NIGHT WILL FEATURE MOONLIT SKIES AS A BURGEONING H5 RIDGE
WILL SLIDE ACROSS THE LOWER GREAT LAKES. IT WILL BE A COMFORTABLE
NIGHT WITH TEMPERATURES GENERALLY SETTLING INTO THE 50S. SITES IN
THE COOLER SRN TIER VALLEYS AND IN THE FOOTHILLS OF THE ADIRONDACKS
COULD CONCEIVABLY EXPERIENCE MINS IN THE UPPER 40S.

WARMER WEATHER WILL RETURN TO OUR FORECAST AREA ON FRIDAY...AS A
STRENGTHENING RIDGE WILL TAKE SHAPE ALONG THE EAST COAST. THE
DEEPENING SOUTHERLY FLOW FOUND BETWEEN THE ASSOCIATED OFFSHORE SFC
HIGH AND A COLD FRONT OVER THE UPPER GREAT LAKES WILL PUMP H85
TEMPS BACK INTO THE MID TEENS CELSIUS...WHICH WILL EASILY SUPPORT
AFTERNOON MAX TEMPS IN THE MID 80S FOR ALL BUT THE LAKE SHORES
AND HIGHER TERRAIN. THE ONLY FLY ION THE OINTMENT FOR FRIDAY WILL
BE THE POTENTIAL FOR A LATE AFTERNOON THUNDERSTORM IN THE VCNTY
OF A LAKE BREEZE BOUNDARY OVER THE SRN TIER. FROM THIS VANTAGE
POINT THOUGH...THE AIRMASS LOOKS LIKE IT WILL STILL BE DRY ENOUGH
TO KEEP THIS THREAT FROM BEING TOO WIDESPREAD.

AFTER A VERY MILD AND UNEVENTFUL FRIDAY NIGHT WHEN MIN
TEMPERATURES WILL HOLD IN THE MID TO UPPER 60S...IT WILL LIKELY
TURN QUITE UNSETTLED FOR SATURDAY. A SHARP COLD FRONTAL BOUNDARY
STRETCHING FROM GEORGIAN BAY AND LOWER MICHIGAN TO ABOUT CHICAGO
AT DAYBREAK SATURDAY WILL SLOWLY PRESS SOUTHEAST TO LAKES ERIE
AND ONTARIO BY EVENING. A WARM UNSTABLE AIRMASS IN ADVANCE OF THE
FRONT WILL SUPPORT THE DEVELOPMENT OF NUMEROUS SHOWERS AND
THUNDERSTORMS BY AFTERNOON...WITH A STRONG 130KT H25 JET OVER
QUEBEC REINFORCING DEEP SYNOPTIC LIFT THROUGH THE ENTIRE BOUNDARY
LAYER. THIS SHOULD RESULT IN SOME AREAS OF SIGNIFICANT DOWNPOURS
WITH RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE.

HIGH PRESSURE OVER ONTARIO WILL SLOWLY PUSH THE FRONT ACROSS
WESTERN AND NORTH CENTRAL NEW YORK SATURDAY NIGHT. THE ANABATIC
NATURE OF THE SLOW MOVING COLD FRONT WILL LIKELY KEEP SHOWERS IN
PLACE SATURDAY NIGHT WHEN ANOTHER HALF INCH OR MORE OF RAIN
COULD FALL. THIS FRONTAL PASSAGE CERTAINLY HAS THE POTENTIAL TO
PRODUCE THE MOST WIDESPREAD SOAKING RAINFALL IN QUITE SOME TIME.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
ANOMALOUSLY STRONG HIGH PRESSURE WILL DRIFT ACROSS EASTERN CANADA
SUNDAY AND MONDAY...AND THIS WILL SHOVE A MOISTURE RICH COLD FRONT
FURTHER SOUTH ACROSS THE MID ATLANTIC STATES. LEFTOVER SHOWERS OVER
MUCH OF OUR REGION ON SUNDAY WILL FINALLY COME TO AN END AS A
RESULT...BUT A FAIR AMOUNT OF CLOUDS WILL LIKELY PERSIST. THIS WILL
ESPECIALLY BE THE CASE CLOSER TO THE PENNSYLVANIA BORDER.

H85 TEMPS IN THE WAKE OF THE FRONT ARE FORECAST TO BE IN THE UPPER
SINGLE DIGITS (CELSIUS)...SO SUNDAY AND MONDAY WILL FEATURE BELOW
NORMAL TEMPERATURES WITH MAX TEMPS GENERALLY IN THE 60S.

AS THE AFOREMENTIONED SFC HIGH MOVES OFF THE NEW ENGLAND COAST
MONDAY NIGHT AND TUESDAY...ITS CLOCKWISE CIRCULATION WILL OPEN
THE DOOR FOR SOMEWHAT MILDER AIR TO RETURN TO THE REGION FROM THE
UPPER OHIO VALLEY. TEMPERATURES ON TUESDAY ARE THUS FORECAST TO
CLIMB BACK INTO THE LOW TO MID 70S.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
VFR FLIGHT CONDITIONS...WITH EMBEDDED HIGH END MVFR FOUND ACROSS WNY
LATE EARLY THIS AFTERNOON. SCATTERED SHOWERS OCCURRING EAST OF A
LINE FROM KELZ-KFZY-KART WILL BECOME MORE WIDESPREAD THIS AFTERNOON
WITH THE ADDITION OF DAYTIME HEATING POSSIBLY BLOSSOM A FEW
THUNDERSTORMS. EXPECT SOME RETURN TO SUNSHINE...WITH A GUSTY
SOUTHWEST BREEZE OVER FAR WNY.

THIS EVENING A COLD FRONT WILL NEAR THE REGION FROM THE WEST. AN
INCREASE IN INSTABILITY AND LINGERING MOISTURE COMBINED WITH LIFT
FROM A PASSING SHORTWAVE WILL BRING ANOTHER ROUND OF SHOWERS AND
POSSIBLE THUNDERSTORMS TO WNY THIS EVENING. THIS ACTIVITY WILL CARRY
EASTWARD WITH THE COLD FRONT THROUGH WEDNESDAY NIGHT...WEAKENING AS
IT REACHES CNY DUE TO THE LOSS OF DAYTIME HEATING.

SOME MVFR CIGS ARE POSSIBLE TONIGHT IN PASSING SHOWERS...AND
SHORTLY THEREAFTER.

OUTLOOK...
THURSDAY...MAINLY VFR WITH A LOW CHANCE OF EARLY MORNING SHOWERS
ACROSS THE NORTH COUNTRY.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN TIER AND INTERIOR PORTIONS OF THE FINGER
LAKES.
SATURDAY...MAINLY VFR THOUGH SHOWERS AND THUNDERSTORMS MAY
BRING BRIEF FLIGHT RESTRICTIONS.
SUNDAY...MAINLY VFR.

&&

.MARINE...
SOUTHWEST WINDS WILL OF UP TO 20 KNOTS WITH GUSTS APPROACHING 30
KNOTS WILL BE FOUND INLAND...AND WILL INCLUDE THE NIAGARA RIVER
AND THE SAINT LAWRENCE RIVER. A SMALL CRAFT ADVISORY WILL BE
MAINTAINED FOR THESE AREAS THIS AFTERNOON. ELSEWHERE THE COOLER
AND STABLE LAKE WATERS WILL KEEP WINDS AND WAVES BELOW ADVISORY
CRITERIA.

THERE WILL BE A SLIGHT VEERING TO THESE WINDS TO WESTERLY TONIGHT
FOLLOWING A COLD FRONTAL PASSAGE. THERE IS VERY LITTLE COLD AIR
BEHIND THIS FRONT AND WE DO NOT EXPECT MUCH INCREASE IN EITHER
WINDS OR WAVE HEIGHT LATER TONIGHT AND INTO THURSDAY.

EXPECT ANOTHER PERIOD OF NON SCA CONDITIONS ON THE AREA WATER BODIES
INTO THE BEGINNING OF THE WEEKEND. LATER SATURDAY SOUTHWEST WINDS
WILL INCREASE AHEAD OF A STRONGER COLD FRONT...POSSIBLY
NECESSITATING THE HOISTING OF ADDITIONAL SMALL CRAFT FLAGS ON AREA
LAKES AND RIVERS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         SLZ022-024.

&&

$$

SYNOPSIS...THOMAS/TMA
NEAR TERM...THOMAS/TMA
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...TMA
MARINE...THOMAS/TMA


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