Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 301752
AFDBUF

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

.SYNOPSIS...
THE WEEKEND WILL GET OFF TO A WARM AND HUMID START BUT A COLD
FRONT WILL DROP ACROSS THE REGION THIS EVENING AND BRING MUCH
COOLER TEMPERATURES FOR SUNDAY. THERE WILL BE WIDESPREAD SHOWERS
AND THUNDERSTORMS WITH THIS FRONT...WITH THE POTENTIAL FOR HEAVY
RAINFALL LASTING THROUGH SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY THIS AFTERNOON SHOWING SHOWERS AND STORMS BECOMING
MORE WIDESPREAD FROM THE SOUTHERN TIER INTO THE GENESEE VALLEY AND
CENTRAL NY. EXPECT MOST OF THE CONVECTION TO REMAIN IN THIS AREA...
WITH STABLE LAKE SHADOWS KEEPING THE NIAGARA FRONTIER TO ROCHESTER
AND ALSO JEFFERSON COUNTY MAINLY DRY. EXTENSIVE CLOUD COVER WILL
LIMIT INSTABILITY THROUGH THE REST OF THE AFTERNOON WHERE CONVECTION
HAS FORMED...WITH CLOSELY SPACED UPDRAFTS COMPETING FOR THE LIMITED
INSTABILITY AND LIKELY NOT ALLOWING ANY ONE STORM TO BECOME
PARTICULARLY STRONG. SOME OF THE STRONGER CELLS WILL PRODUCE VERY
HEAVY RAIN...SMALL HAIL...AND A FEW MODEST WIND GUSTS BUT NO SEVERE
WEATHER IS EXPECTED.

SO FAR STORMS HAVE NOT TRAINED OVER ONE PARTICULAR AREA...ALTHOUGH
THIS MAY BECOME POSSIBLE LATER THIS AFTERNOON ALONG THE SOUTHERN
EDGE OF THE LAKE ERIE BREEZE FROM THE WESTERN SOUTHERN TIER INTO THE
FINGER LAKES AND CENTRAL NY WHERE SOME LOCALLY HEAVY RAINFALL IS
POSSIBLE.

WINDS ALOFT WILL NOT BE THAT STRONG WITH 850MB WINDS ONLY ABOUT
25 KTS THIS AFTERNOON WHEN CONVECTION DEVELOPS. SPC HAS A MARGINAL
RISK FOR SEVERE WEATHER ACROSS OUR CWA AND THERE IS CHANCE FOR A FEW
STRONG TO MARGINALLY SEVERE PULSE STORMS...BUT NOTHING ORGANIZED OR
WIDESPREAD IS EXPECTED.

MODEL CONSENSUS BRINGS THE FRONT THROUGH THIS EVENING...WHICH WILL
BRING LARGE SCALE FORCING WHEN THE COOLER AIR UNDERCUTS THE WARM
MOIST AIRMASS. THUS THERE IS A HIGHER CONFIDENCE (NEARLY CERTAIN) IN
MEASURABLE PRECIPITATION TONIGHT WITH A WIDESPREAD SHOWERS AND SOME
EMBEDDED THUNDERSTORMS. TEMPERATURES ARE MUCH COOLER BEHIND THE
FRONT...WITH TEMPERATURES LIKELY TO FALL INTO THE UPPER 40S TO MID
50S BY DAYBREAK SUNDAY. PATCHY FOG IS ALSO POSSIBLE AS THE MOIST AIR
MASS MIXES WITH THE COOLER AIR AND GETS SQUEEZED BY THE DEVELOPING
INVERSION.

&&

.SHORT TERM /SUNDAY 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 FRIDAY/...
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 /18Z 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 WILL INCREASE AHEAD OF A COLD FRONT WITH THE
STRONGEST WINDS ACROSS THE SAINT LAWRENCE RIVER WHERE A SMALL CRAFT
ADVISORY HAS BEEN ISSUED.

BEHIND THE COLD FRONT... WINDS AND WAVES WILL INCREASE ACROSS THE
LOWER LAKES TONIGHT AND SUNDAY AS NORTH THEN NORTHEAST WINDS DEVELOP
IN A COLD AIR ADVECTION REGIME. SMALL CRAFT ADVISORIES HAVE BEEN
ISSUED FOR MOST OF THE WATERS STARTING LATE TONIGHT. WINDS WILL
DIMINISH ON MONDAY WHEN THE NORTHERLY FLOW IS EXPECTED TO DIMINISH.

&&

.CLIMATE...
MAY 2015 WILL GO DOWN AS ONE OF THE WARMEST MAYS ON RECORD...AND
POSSIBLY ONE OF THE DRIEST FOR BUFFALO AND WATERTOWN. A MOISTURE
LADEN COLD FRONT WILL CROSS THE REGION TO END THE MONTH...AND
SHOWERS AND THUNDERSTORMS ALONG THIS FEATURE MAY REMOVE CLIMATE
SITES FROM A TOP 10 DRIEST MAY`S ON RECORD. BELOW ARE THE WARMEST
MAYS ON RECORD.

BUFFALO     RANK      MEAN TEMPERATURE   YEAR
            1               64.3         1991
            2               63.8         2012
            3               63.4         1944
            4               62.8         1998
            5               62.3         2015 (THROUGH 5/29)
            6               62.2         1975

ROCHESTER   RANK     MEAN TEMPERATURE    YEAR
            1               63.7         1911
            2               63.6         2015 (THROUGH 5/29)
            3               63.2         2012
            4               63.2         1944

WATERTOWN   RANK     MEAN TEMPERATURE    YEAR
            1               60.5         2012
            2               60.0         1998
            3               59.3         1975
            4               58.8         2015 (THROUGH 5/29)
            5               58.8         1960
            6               58.3         1991


MAY HAS ALSO BEEN A DRY MONTH. OUTSIDE OF A FEW LOCALIZED HEAVY
THUNDERSTORMS MANY LOCATIONS ARE WELL BELOW NORMAL FOR THE MONTH.
BELOW IS MONTHLY PRECIPITATION FOR THE DRIEST MONTHS ON RECORD FOR
OUR THREE CLIMATE SITES.

BUFFALO     RANK    PRECIP       YEAR
            1        0.53        1877
            2        0.54        1934
            3        0.60        2005
            4        0.83        2015    (THROUGH 5/29)
            5        0.90        2012
            ..
            10       1.11        1926


ROCHESTER   RANK    PRECIP       YEAR
            1        0.24        2007
            ..
            27       1.52        2015 (THROUGH 5/29)
            28       1.55        1876
            29       1.59        1954
            30       1.64        1926


WATERTOWN   RANK    PRECIP       YEAR
            1        0.70        1965
            2        0.87        2005
            3        0.88        1980
            4        0.90        1974
            5        0.99        1966
            6        1.04        2015      (THROUGH 5/29)
            7        1.08        1972
            8        1.09        1951
            9        1.14        1949
            10       1.16        1962

AGAIN WITH THUNDERSTORMS IN THE FORECAST TO CLOSE OUT THE MONTH
NONE OF OUR THREE CLIMATE SITES MAY HAVE A TOP TEN DRIEST MAY ON
RECORD. HOWEVER ALL THREE SITES MAY CONTINUE THE STRETCH OF BELOW
NORMAL PRECIPITATION MONTHS. BELOW ARE LISTED THE LATEST MONTH
FOR WHEN PRECIPITATION RECORDED WAS ABOVE NORMAL FOR EACH OF OUR
THREE CLIMATE LOCATIONS.

BUFFALO - OCTOBER 2014
ROCHESTER - FEBRUARY 2015
WATERTOWN - AUGUST 2014

&&

.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...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...CHURCH/THOMAS
AVIATION...HITCHCOCK
MARINE...APFFEL/THOMAS
CLIMATE...THOMAS


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