Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 302208
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
608 PM EDT SAT MAY 30 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY SOUTH ACROSS THE AREA TONIGHT THEN
STALL OVER PENNSYLVANIA THROUGH MONDAY BRINGING PERIODS OF RAIN.
SOME OF THE RAIN MAY BE HEAVY AT TIMES. A DRAMATICALLY COOLER
AIRMASS WILL MOVE INTO THE REGION SUNDAY AND MONDAY BEFORE A SLOW
WARMING TREND AND RETURN TO DRIER WEATHER BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
WITH CONVECTION ACROSS THE FINGER LAKES AND NORTH COUNTRY SPREADING
A BIT FURTHER NORTHWARD THAN PREVIOUSLY FORECAST FOR THIS POINT IN
THE EVENING...HAVE ISSUED A QUICK UPDATE TO THE GRIDS AND MOST TEXT
PRODUCTS TO ACCOUNT FOR THIS...OTHERWISE THE PREVIOUS FORECAST
REMAINS UNCHANGED AS OF THIS WRITING.

LATER THIS EVENING THE SURFACE COLD FRONT OVER ONTARIO WILL BEGIN TO
SAG SLOWLY SOUTH ACROSS THE REGION...INCREASING LOW LEVEL
CONVERGENCE. A MORE ORGANIZED AREA OF CONVECTION OVER INDIANA AND
OHIO ASSOCIATED WITH A LOW AMPLITUDE MID LEVEL WAVE WILL MOVE
NORTHEASTWARD ALONG THE FRONTAL ZONE AND BRING INCREASING SHOWERS
AND SCATTERED THUNDERSTORMS. LATER TONIGHT MOST OF THE THUNDERSTORMS
WILL END AS THE COLD FRONT MOVES SOUTH AND A MUCH MORE STABLE LOW
LEVEL AIRMASS BUILDS INTO THE REGION. THE RAIN WILL CONTINUE HOWEVER
AS THE FRONT BECOMES ANABATIC IN NATURE...WITH ASCENT FOCUSING ON
THE COLD SIDE OF THE BOUNDARY.

LATE TONIGHT THROUGH SUNDAY THE FRONTAL ZONE WILL STALL FROM OHIO TO
PENNSYLVANIA. A STRONG DIFFERENTIAL TEMPERATURE ADVECTION REGIME
WILL DEVELOP ACROSS THE BOUNDARY...WITH LOW LEVEL COLD ADVECTION
TOPPED BY MID LEVEL WARM ADVECTION. THIS WILL PRODUCE STRONG
FRONTOGENSIS AND DEFORMATION ALONG AND NORTH OF THE BOUNDARY WHICH
WILL SUPPORT PERIODS OF RAIN ACROSS THE ENTIRE REGION. A FEW
SCATTERED THUNDERSTORMS ARE POSSIBLE NEAR THE PA STATE LINE...BUT
FOR THE REST OF THE AREA LITTLE INSTABILITY WILL REMAIN. RAIN TOTALS
TONIGHT THROUGH SUNDAY WILL APPROACH AN INCH...WITH LOCALLY HIGHER
AMOUNTS FROM CONVECTION THIS EVENING. ADDITIONAL RAIN WILL FALL
BEYOND SUNDAY.

TEMPERATURES WILL TURN DRAMATICALLY COOLER BEHIND THE FRONT LATE
TONIGHT AND SUNDAY. TEMPS IN THE MID 50S PRE-DAWN ON SUNDAY WILL
LIKELY DROP INTO THE UPPER 40S BY MID MORNING AS COLD ADVECTION AND
RAIN CONTINUE. TEMPS WILL THEN ONLY RECOVER TO THE LOWER 50S LATE IN
THE DAY AT BEST IN MOST AREAS. MILD TEMPERATURES AT MIDNIGHT WILL
PREVENT THE RECORD COLD HIGH TEMPS FROM BEING APPROACHED.

FINALLY...WITH THE DEEP LOW LEVEL MOISTURE AND NORTHERLY UPSLOPE
FLOW PATCHY FOG WILL DEVELOP LATER TONIGHT AND CONTINUE THROUGH
SUNDAY. EXPECT FOG TO BE MOST WIDESPREAD ACROSS THE HIGHER TERRAIN
WHERE LOW STRATUS WILL INTERSECT THE TERRAIN. FOG MAY ALSO BECOME
MORE WIDESPREAD ALONG THE SOUTH SHORE OF LAKE ONTARIO WITH A MOIST
AIRMASS CROSSING THE STILL COLD LAKE WATERS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
A COMPLEX STORM AND MOISTURE LADEN STORM SYSTEM WILL CONTINUE TO
EVOLVE THROUGH THIS TIME PERIOD. ON SUNDAY THE SURFACE BAROCLINIC
BOUNDARY WILL LIE FROM NEW ENGLAND SOUTHWESTWARD ACROSS THE
SOUTHERN MID ATLANTIC STATES AND BACK TOWARDS THE MID WEST. A
SURFACE WAVE RIDING SLOWLY ALONG THIS BAROCLINIC BOUNDARY FROM THE
OHIO VALLEY WILL SEND ANOTHER WAVE OF RAINFALL ACROSS THE REGION
ON SUNDAY. PWATS SUNDAY WILL AVERAGE 1.50 TO 1.75
INCHES...INDICATING THE MOISTURE RICH ENVIRONMENT. SHARP
ISENTROPIC LIFT IN THE MID LEVELS NORTHEAST OF THE SURFACE WAVE
AND THE STILL PRESENT RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET
WILL PROVIDE FOR BROAD LIFT ACROSS THE EASTERN GREAT LAKES
REGION...WITH THIS LIFT PRODUCING A PERIOD OF RAIN SHOWERS THROUGH
THE DAY. FAVORABLE CONDITIONS FOR RAIN SHOWERS SUNDAY WILL SLOWLY
PUSH EASTWARD THROUGH THE DAY AS THE UPPER LEVEL JET AND SURFACE
WAVE SLIDE EASTWARD. BY SUNDAY NIGHT THE AREAS MOST PRONE TO RAIN
SHOWERS WILL BE CENTRAL PORTIONS OF NEW YORK STATE. HOWEVER WITH
THE SURFACE WAVE STALLING OVER PENNSYLVANIA SUNDAY NIGHT...ALL
AREAS OF THE CWA WILL HAVE AT LEAST LIKELY POPS.

INSTABILITY WILL BE MARGINAL FOR THUNDERSTORMS SUNDAY AND SUNDAY
NIGHT...WITH WHAT INSTABILITY TO BE HAD THIS DAY LYING ACROSS THE
SOUTHERN TIER. WILL PLACE THUNDER CHANCES HERE...WHILE JUST CALLING
IT PLAIN RAIN SHOWERS ACROSS THE REMAINDER OF THE REGION.

WE HAVE NOT HAD A WIDESPREAD, LONG DURATION SYNOPTIC PRECIPITATION
EVENT OF THIS MAGNITUDE IN QUITE SOME TIME. RAINFALL AMOUNTS SUNDAY
AND SUNDAY NIGHT WILL AVERAGE AROUND A HALF AN INCH OF
PRECIPITATION...WITH A FEW AREAS UPWARDS TO THREE QUARTERS OF AN
INCH. ALL TOLD BY THE END OF THE WEEKEND AN INCH TO TWO INCHES OF
RAINFALL IS LIKELY ACROSS THE CWA. WITH THE VERY DRY CONDITIONS AND
LOW CREEK AND STREAM FLOWS RIVER FLOODING IS NOT A BIG CONCERN AT
THIS POINT...AND WOULD ONLY BECOME A CONCERN IN AREAS WHERE STORMS
TRAIN AND PRODUCE LOCALLY SIGNIFICANT AMOUNTS.

BY MONDAY THE MID LEVEL SHORTWAVE WILL BE EAST OF THE REGION.
HOWEVER AT THE SURFACE A WAVE OF LOW PRESSURE WILL STILL BE NEAR THE
REGION AND WILL ADVANCE FROM WESTERN PENNSYLVANIA TOWARDS THE
EASTERN MID ATLANTIC REGION. A NORTHWEST FLOW BEHIND THIS SURFACE
LOW AND EASTERLY FLOW AHEAD OF THE SURFACE LOW WILL PROVIDE FOR
AMPLE LOW LEVEL CONVERGENCE ACROSS THE REGION. A MOISTURE RICH
ENVIRONMENT WILL REMAIN AND LIGHT RAIN SHOWERS WILL AGAIN DEVELOP
ACROSS THE EASTERN GREAT LAKES REGION ON MONDAY. THE POOR LAPSE
RATES AND LITTLE SURFACE INSTABILITY ON MONDAY WILL NOT MAKE FOR A
FAVORABLE ENVIRONMENT FOR THUNDERSTORM DEVELOPMENT.

RAIN SHOWERS MAY NOT TAPER OFF AS QUICKLY MONDAY NIGHT. THOUGH THE
SURFACE LOW WILL BE TRACKING ACROSS NEW ENGLAND MONDAY NIGHT...AND
UPPER LEVEL SHORTWAVE TROUGH WILL ADVANCE TOWARDS OUR REGION FROM
THE CENTRAL GREAT LAKES. THIS FEATURE WILL CONTINUE CHANCE POPS
ACROSS THE REGION MONDAY NIGHT.

ON TUESDAY THIS UPPER LEVEL SHORTWAVE TROUGH WILL CROSS THE EASTERN
GREAT LAKES REGION. A COLD POOL ASSOCIATED WITH THIS TROUGH WILL
INCREASE LAPSE RATES THROUGH THE DAY SUCH THAT LOW TOP SHOWERS WILL
DEVELOP THROUGH THE DAYTIME. MOISTURE WILL BE FOUND GREATEST TOWARDS
THE EAST...FROM THE GENESEE VALLEY EASTWARD THERE WILL BE A CHANCE
FOR A BRIEF SHOWER. CLOUDS WILL LIKELY START THE DAY THICK ACROSS
THE EASTERN GREAT LAKES REGION...WITH CLEARING SLOWLY EDGING
EASTWARD THROUGH THE AFTERNOON HOURS. A MUCH DRIER AIRMASS BEHIND
THIS SHORTWAVE WILL CLEAR SKIES TUESDAY NIGHT...MAKING FOR A CHILLY
NIGHT UNDER GOOD RADIATIONAL COOLING CONDITIONS.

TEMPERATURES THIS TIME PERIOD WILL AVERAGE WELL BELOW NORMAL...WITH
HIGHS SUNDAY AND MONDAY IN THE 50S. A FEW LOW 60S ARE POSSIBLE NEAR
THE STATE LINE WHERE THE SURFACE BOUNDARY MAY EDGE NORTHWARD ENOUGH
TO ALLOW FOR WARMER AIR TO REACH INTO THE SOUTHERN TIER. TUESDAY
UNDER CLOUDY SKIES AND 850 HPA TEMPERATURES OF ONLY +4 TO +5C
DAYTIME HIGHS WILL STILL REMAIN IN THE 50S TO AROUND 60. LOWS
TUESDAY NIGHT WILL DROP BACK INTO THE 40S...5 TO 10F DEGREES BELOW
NORMAL.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
RIDGING ALOFT AND SURFACE HIGH PRESSURE FINALLY BUILD IN ACROSS
WESTERN NEW YORK FOR THE SECOND HALF OF THE WORK WEEK. WITH A DRIER
AIRMASS MOVING IN ON WEDNESDAY...EXPECT MOST LOCATIONS TO FINALLY
CLEAR OUT NICELY AFTER A GLOOMY START TO THE WEEK. NICE WEATHER WILL
REMAIN WITH US WEDNESDAY AND THURSDAY AS HIGH PRESSURE CROSSES THE
REGION. FRIDAY WILL BE THE NEXT CHANCE FOR SOME RAIN
SHOWERS...ALBEIT SMALL WITH A FEW THUNDERSTORMS POSSIBLY BLOSSOMING
ON A LAKE BREEZE BOUNDARY FRIDAY AFTERNOON.

TEMPERATURES WILL ALSO RECOVER THROUGH THE SECOND HALF OF THE WEEK
AS SOUTHERLY FLOW DEVELOPS ON THE BACK SIDE OF THE HIGH PRESSURE AND
WARM AIR ADVECTION PUSHES 850 MB TEMPERATURES BACK INTO THE LOW
TEENS CELSIUS ABOVE ZERO. THE WARMING TREND WILL BRING 70S BACK TO
THE FORECAST ON WEDNESDAY WITH MID 80S POSSIBLE BY FRIDAY.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
SHOWERS AND STORMS ARE INCREASING THIS AFTERNOON FROM THE SOUTHERN
TIER INTO THE GENESEE VALLEY AND CENTRAL NY. EXPECT SCATTERED TO
NUMEROUS COVERAGE TO CONTINUE IN THIS AREA THROUGH THE EVENING. VFR
WILL PREVAIL MOST OF THE TIME...BUT THE HEAVIER STORMS WILL PRODUCE
BRIEF MVFR/IFR CONDITIONS LOCALLY. A SOUTHWEST WIND OFF LAKE ERIE
AND ONTARIO WILL SUPPORT STABLE LAKE SHADOWS NORTHEAST OF BOTH LAKES
WITH LITTLE OR NO CONVECTION THROUGH LATE AFTERNOON...INCLUDING MOST
OF THE TAF SITES.

TONIGHT THE STABLE LAKE SHADOWS WILL BREAK DOWN WITH THE LOSS OF
DAYTIME HEATING. A COLD FRONT WILL SAG SLOWLY SOUTH ACROSS THE AREA
AND PROVIDE THE FOCUS FOR INCREASING RAIN COVERAGE FOR THE ENTIRE
REGION. SCATTERED THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING
BEFORE DIMINISHING OVERNIGHT AS A MORE STABLE AIRMASS MOVES INTO THE
REGION. DURING THE EVENING CIGS/VSBY WILL STAY MAINLY VFR OUTSIDE OF
THE HEAVIER SHOWERS AND STORMS WHICH WILL CONTINUE TO PRODUCE BRIEF
MVFR/IFR LOCALLY.

OVERNIGHT EXTENSIVE LOW LEVEL MOISTURE WILL MOVE INTO THE AREA
BEHIND THE SURFACE COLD FRONT AND BECOME TRAPPED BENEATH A STEEP
FRONTAL INVERSION. THIS WILL SET THE STAGE FOR A RARE LATE SPRING
EXTENDED PERIOD OF IFR CIGS ACROSS MUCH OF THE REGION FROM LATER
TONIGHT THROUGH SUNDAY AND BEYOND. CIGS WILL BE LOWEST ACROSS THE
HIGHER TERRAIN...BUT EVEN THE LAKE PLAINS WILL SEE PLENTY OF IFR.
PATCHY FOG WILL ALSO REDUCE VSBY AT TIMES...ESPECIALLY ACROSS HIGHER
TERRAIN AND ALONG THE SOUTH SHORE OF LAKE ONTARIO. PERIODS OF RAIN
WILL CONTINUE ALONG AND NORTH OF THE STALLED FRONTAL BOUNDARY LATE
TONIGHT THROUGH SUNDAY.

OUTLOOK...
SUNDAY NIGHT AND MONDAY...WIDESPREAD IFR WITH PERIODS OF RAIN.
TUESDAY THROUGH WEDNESDAY...MAINLY VFR.

&&

.MARINE...
SOUTHWEST WINDS AHEAD OF A COLD FRONT WILL BECOME NORTH TONIGHT AS
THE FRONT SAGS SLOWLY SOUTH OF THE LOWER GREAT LAKES. THIS WILL
BRING A PERIOD OF MODERATE NORTH TO NORTHEAST WINDS LATER TONIGHT
THROUGH SUNDAY NIGHT WITH SMALL CRAFT ADVISORY CONDITIONS ON BOTH
LAKES ERIE AND ONTARIO.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 AM SUNDAY TO 8 AM EDT MONDAY FOR
         LEZ040-041.
         SMALL CRAFT ADVISORY FROM 2 AM SUNDAY TO 2 AM EDT
         MONDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 8 AM EDT MONDAY
         FOR LOZ042-043.
         SMALL CRAFT ADVISORY FROM 4 AM SUNDAY TO 5 AM EDT MONDAY
         FOR LOZ044-045.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         SLZ022-024.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK/JJR
SHORT TERM...CHURCH
LONG TERM...CHURCH
AVIATION...HITCHCOCK
MARINE...HITCHCOCK



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