Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 021944
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
344 PM EDT SUN AUG 2 2015

.SYNOPSIS...
HIGH PRESSURE WILL MOVE EAST OFF THE MID ATLANTIC
COAST...THEN A STRONG COLD FRONT WILL BRING AN END TO OUR FAIR
WEATHER LATER TONIGHT AND MONDAY. STRONG TO SEVERE STORMS WILL BE
POSSIBLE AS THE COLD FRONT MOVES EAST ACROSS OUR REGION THROUGH
MONDAY AFTERNOON. A COMFORTABLY COOL AIRMASS WILL FOLLOW THE FRONT
MONDAY NIGHT AND SHOULD BE IN PLACE FOR AT LEAST THE REMAINDER OF
THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
HIGH PRESSURE SOUTH OF THE REGION WILL MOVE OFF THE MID ATLANTIC
COAST TONIGHT AS A COLD FRONT APPROACHES FROM THE WEST. CONVECTION
ALONG THE FRONT HAS BEEN ACTIVE ALL DAY ACROSS NORTHERN WISCONSIN
AND NORTHERN MICHIGAN...AND HAS BEEN MOVING EASTWARD WITH THE FRONT.
DEWPOINTS ACROSS OUR AREA ARE IN THE LOWER TO MID 50S AT MID
AFTERNOON...BUT WILL BE ON THE RISE AS SOUTHWESTERLY WINDS ADVECT
HIGHER DEWPOINT AIRMASS THIS EVENING AND TONIGHT. THE UPSTREAM
CONVECTION WILL NOT LIKELY SPREAD INTO THE DRIER AIR CURRENTLY IN
PLACE...BUT WITH INCREASINGLY MOIST AIR WILL COME HIGHER POPS LATER
TONIGHT. SOME SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT COULD
APPROACH WESTERN NY AND THE WATERS OF LAKE ERIE AND WESTERN LAKE
ONTARIO...BUT THE BULK OF THE PRECIPITATION WILL HOLD OFF UNTIL THE
LATE OVERNIGHT HOURS...CLOSER TO DAYBREAK. WITH THE SOUTHWESTERLY TO
SOUTHERLY WINDS TONIGHT...IT WILL BE A BREEZY AND WARM NIGHT. THE
STRENGTHENING WINDS WILL PREVENT TEMPERATURES IN MOST AREAS FROM
FALLING BELOW THE UPPER 60S OR LOWER 70S. AS THE PRESSURE GRADIENT
INCREASES OVERNIGHT...WINDS ACROSS THE HIGHER ELEVATIONS OF THE
SOUTHERN TIER AND CLOSE TO LAKE ERIE COULD GUST TO 35 MPH.

THE COLD FRONT WILL CONTINUE ACROSS THE REGION DURING THE DAY ON
MONDAY. DEWPOINT POOLING AHEAD OF THE FRONT WILL BOOST SURFACE
DEWPOINTS INTO THE MIDDLE TO UPPER 60S...MID AND UPPER LEVEL TEMPS
WILL FALL SLIGHTLY WITH THE APPROACH OF THE UPPER TROUGH ...AND LOW
LEVEL CONVERGENCE ALONG THE FRONT WILL PROVIDE LIFT AND INSTABILITY
TO SUPPORT CONVECTION. STRONG WINDS TOPPING THE BOUNDARY LAYER EARLY
MONDAY WILL ALSO PROVIDE A SEVERE WEATHER THREAT WITH DAMAGING WIND
RISK...LESSENING AS THE STRONG WINDS MOVE FARTHER ALOFT BEHIND THE
FRONT. TEMPERATURES DURING MONDAY WILL CLIMB TO THE UPPER 70S TO
LOWER 80S PRIOR TO THE FRONTAL PASSAGE.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
WATER VAPOR IMAGERY THIS AFTERNOON NICELY DISPLAYS A SHORTWAVE
TROUGH OF LOW PRESSURE REACHING NORTHERN MINNESOTA. THIS SHORTWAVE
WILL BE FORCING A SURFACE COLD FRONT EASTWARD ACROSS OUR REGION
MONDAY NIGHT. EXPECT SHOWERS AND THUNDERSTORMS TO END THROUGH THE
EVENING HOURS WITH THE PASSAGE OF THE COLD FRONT AND LOSS OF
DAYTIME INSTABILITY.

THIS SHORTWAVE TROUGH WILL ALSO DRAW A PERSISTENT UPPER LEVEL LOW
OVER EASTERN CANADA SOUTHWARD. ON TUESDAY A POOL OF COOL AIR ALOFT
WILL BE RESIDING OVER SOUTHERN CANADA AND THE GREAT LAKES REGION.
STEEPENING LAPSE RATES THROUGH THE DAY TUESDAY WILL LIKELY BRING
SCATTERED RAIN SHOWERS THROUGH THE PEAK HEATING OF THE AFTERNOON AND
EARLY EVENING HOURS. THIS COOL AIR ALOFT MAY EVEN BRING SOME LAKE
ENHANCED RAIN SHOWERS TO SE AND E OF LAKE ONTARIO WHERE +6 TO +8C AT
850 HPA WILL BE FLOWING OVER A +22C OR SO LAKE TEMPERATURE.

ON WEDNESDAY THE UPPER LEVEL LOW WILL REMAIN NEARBY THE GREAT LAKES
REGION...HOWEVER LOW LEVEL MOISTURE WILL BE MUCH LESS. EVEN THOUGH
INSTABILITY WILL AGAIN INCREASE THROUGH THE AFTERNOON HOURS THE
LESS PLENTIFUL MOISTURE WITHIN THE ATMOSPHERE SHOULD DECREASE THE
AMOUNT OF AFTERNOON SHOWERS. GREATEST CHANCES FOR A SHOWER WEDNESDAY
WILL BE ACROSS OUR EASTERN ZONES WHICH WILL HAVE SLIGHTLY BETTER
MOISTURE PROFILES.

WEDNESDAY NIGHT SHOWERS SHOULD DIMINISH WITH THE LOSS OF DAYTIME
HEATING AND THE INCREASING STABILITY OF THE ATMOSPHERE.

TEMPERATURES WILL AVERAGE 5 TO 10 DEGREES BELOW NORMAL FOR DAYTIME
HIGHS THIS PERIOD...WHILE OVER NIGHT LOWS WILL AVERAGE A FEW DEGREES
BELOW NORMAL.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FEATURE OF NOTE TO START THIS TIME PERIOD IS PRESENTLY FOUND
OVER THE STATE OF NEVADA AS A SHORTWAVE SLOWLY RIDES NORTHWARD
ALONG THE WESTERN FLANK OF A LONG RANGE RIDGE. TIMING THIS FEATURE
OVER THE ROCKIES...AND NORTHERN PLAIN STATES WILL BRING THE NEXT
WIDESPREAD THREAT OF SHOWERS AND THUNDERSTORMS INTO THE REGION
FRIDAY. THERE MAY BE A FEW STORMS THURSDAY AHEAD OF THIS FEATURE
NEAR THE STATE LINE...BUT BOTH THE 12Z GFS AND 12Z ECMWF SUGGEST
THAT FRIDAY WILL BE THE BEST DAY FOR PRECIPITATION CHANCES. WILL
MAINTAIN LOW CHANCE POPS FRIDAY AS THE MODELS CONTINUE A HIGH
DEGREE OF UNCERTAINTY TO THIS SHORTWAVE TRACK...POSSIBLY TRACKING
FARTHER SOUTHWARD WHICH WOULD LEAVE FRIDAY DRY...ESPECIALLY OUR
NORTHERN ZONES.

THIS SHORTWAVE MAY DRAW THE UPPER LEVEL LOW OVER EASTERN CANADA BACK
SOUTHWARD...LEAVING CHANCES FOR SHOWERS AND THUNDERSTORMS ON
SATURDAY ACROSS WESTERN AND NORTH CENTRAL NEW YORK STATE. THESE
SHOWERS AND THUNDERSTORMS MAY LINGER INTO SUNDAY DEPENDING UPON HOW
QUICKLY THE LOWER HEIGHTS ASSOCIATED WITH THE QUEBEC LOW LINGER OVER
THE EASTERN GREAT LAKES REGION.

WITH THE UPPER LEVEL LOW OVER QUEBEC NEARBY...TEMPERATURES ARE
EXPECTED TO REMAIN JUST BELOW SEASONAL NORMALS THROUGH THIS TIME
PERIOD.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE NOSING NORTHEAST FROM THE UPPER OHIO VALLEY WILL KEEP
FAIR VFR CONDITIONS IN PLACE THROUGH AT LEAST THIS EVENING.

A STRONG COLD FRONT OVER THE UPPER GREAT LAKES WILL THEN APPROACH
OUR REGION DURING THE OVERNIGHT HOURS. WHILE VFR CONDITIONS WILL
REMAIN IN PLACE FOR MUCH OF THE NIGHT...SHOWERS AND THUNDERSTORMS
AHEAD OF THE FRONT COULD IMPACT THE REGION AFTER MIDNIGHT.

ALONG WITH THE THREAT FOR LATE NIGHT THUNDERSTORMS...A 40 TO 50
KNOT LOW LEVEL JET AHEAD OF THE FRONT COULD PRODUCE CONDITIONS
FAVORABLE FOR SOME LOW LEVEL WIND SHEAR. THE HIGHEST CHANCE FOR THIS
WILL COME OVER THE HILLS OF THE SOUTHERN TIER TO THE FINGER LAKES
REGION WHERE THE STRONGER WINDS ALOFT WILL HAVE A LOWER CHANCE OF
MIXING TO THE SFC.

THUNDERSTORMS WILL ACCOMPANY THE COLD FRONTAL PASSAGE ON MONDAY.
THERE MAY BE LOWER MVFR TO IFR CONDITIONS WITH THE STORMS...AS WELL
AS THE RISK OF SEVERE CATEGORY WIND GUSTS...BUT MOST OF THE TIME
WILL BE VFR.

OUTLOOK...

SUNDAY NIGHT...MAINLY VFR. SCATTERED SHOWERS AND THUNDERSTORMS AND
ASSOCIATED BRIEF/LOCAL MVFR/IFR CONDITIONS AFTER 06Z.
MONDAY...VFR TO OCCASIONALLY MVFR WITH SHOWERS AND STORMS LIKELY.
TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
FRIDAY...CHANCE OF THUNDERSTORMS OVER THE SOUTHERN TIER...OTHERWISE VFR.

&&

.MARINE...
SOUTHWEST WINDS SUSTAINED 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS WILL
INCREASE ENOUGH TO 15 TO 20 KNOT GUSTING 25 KNOTS THIS AFTERNOON...
SUFFICIENT FOR SMALL CRAFT ADVISORIES ON LAKE ERIE...NIAGARA RIVER
AND WESTERN LAKE ONTARIO.

CONDITIONS WILL FURTHER DETERIORATE TONIGHT AS A STRONG COLD FRONT
WILL TAKE AIM ON OUR REGION FROM THE UPPER GREAT LAKES AND THE
SURFACE PRESSURE GRADIENT INCREASES. WINDS WILL INCREASE TO NEAR 30
KNOTS ON LAKE ERIE AND PARTS OF WESTERN LAKE ONTARIO LATER
TONIGHT...WITH THE RISK FOR THUNDERSTORMS INCREASING AS WELL. WAVES
ON NORTHEASTERN LAKE ERIE WILL LIKELY REACH 6 FEET AT TIMES BY
DAYBREAK...WITH WIDESPREAD COVERAGE OF WAVES AVERAGING MORE THAN 4
FEET BY 06Z.

THE COLD FRONT WILL MAKE ITS WAY ACROSS THE LOWER GREAT LAKES MONDAY
MORNING...WITH STRONG TO SEVERE THUNDERSTORMS POSSIBLE. THE SEVERE
THREAT FROM THESE STORMS WILL BE WIND GUSTS NEARING OR EXCEEDING 50
KNOTS. ALONG WITH THE THREAT OF CONVECTION...SMALL CRAFT ADVISORIES
WILL BE IN EFFECT ACROSS THE LOWER GREAT LAKES FOR THE BULK OF THE
DAY. WINDS WILL TEMPORARILY SUBSIDE ACROSS THE REGION LATE MONDAY
AND MONDAY NIGHT.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT MONDAY FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT MONDAY NIGHT FOR
         LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT MONDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO MIDNIGHT
         EDT MONDAY NIGHT FOR LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT MONDAY NIGHT FOR
         LOZ042.

&&

$$

SYNOPSIS...WCH
NEAR TERM...WCH
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...WCH
MARINE...WCH



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