Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 041954
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
354 PM EDT MON MAY 4 2015

.SYNOPSIS...
A WEAK COOL FRONT WILL SAG ACROSS OUR FORECAST AREA EARLY
TONIGHT TO PRODUCE SOME BADLY NEEDED SHOWERS AND POSSIBLY A
COUPLE THUNDERSTORMS...BUT SIGNIFICANT RAINFALL AMOUNTS ARE NOT
EXPECTED. THE FRONT WILL STALL OVER PENNSYLVANIA ON TUESDAY...
WHILE HIGH PRESSURE WILL DRIFT ACROSS THE GREAT LAKES REGION.
OTHER THAN A SHOWER OR TWO OVER THE SOUTHERN TIER ON TUESDAY...
DRY WEATHER WITH ABOVE NORMAL TEMPERATURES CAN BE EXPECTED
THROUGH THE REST OF THE WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
A WEAK COOL FRONT OVER LOWER MICHIGAN AND SOUTHERN ONTARIO WILL
SETTLE ACROSS OUR FORECAST AREA DURING THE FIRST HALF OF TONIGHT.
WHILE THE AIRMASS OVER OUR REGION WAS UNUSUALLY DRY TODAY WITH
PWAT VALUES UNDER A HALF INCH...AMSU IMAGERY DEPICTS A PLUME OF
>1" PWAT VALUES ALONG THE APPROACHING FRONTAL BOUNDARY.

IN TERMS OF SYNOPTIC FORCING...THERE WILL ONLY BE LIMITED LIFT
OFFERED BY THE FRONT ITSELF. THE FRONT IS WEAKENING WITH TIME...AS
DEPICTED BY THE FORECAST TREND OF FRONTOGENTIC FORCING...ALTHOUGH
THERE WILL BE SOME JET ASSISTANCE FROM A PASSING 110KT H25 JET OVER
QUEBEC. THE MINIMAL FORCING OFFERED BY THE FRONT MAY BE OFFSET BY
AN INCREASINGLY UNSTABLE AIRMASS THOUGH. MUCAPE VALUES LATE
THIS AFTERNOON AND EVENING SHOULD EXCEED 500 J/KG AWAY FROM THE LAKE
SHADOWS...AND WITH LOW LEVEL LAPSE RATES OF 8-10DEG C/KM...THERE
COULD BE A COUPLE THUNDERSTORMS OVER THE FINGER LAKES AND WESTERN
SOUTHERN TIER.

AS OF 19Z...KBUF RADAR DEPICTS THE LAKE ERIE BOUNDARY PRESSING EAST
FROM A LINE STRETCHING FROM NEAR KROC TO NORTHERN WYOMING COUNTY TO
NORTHEASTERN CATTARAUGUS COUNTY. A FEW LIGHT SHOWERS HAVE TRIED TO
FIRE UP ALONG THIS BOUNDARY...BUT HAVE FAILED IN THE STILL DRY
AIRMASS. WOULD EXPECT MORE SHOWERS AND POSSIBLE THUNDERSTORMS TO
BECOME FOCUSED ALONG THIS BOUNDARY FOR THE NEXT SEVERAL
HOURS...WHILE THE CURRENT SWATH OF SHOWERS WILL APPROACH AND WEAKEN
SOMEWHAT OVER THE LAKE ITSELF.

AS THE FRONT AND CROSSES THE REGION THIS EVENING...ADDITIONAL
SHOWERS AND WIDELY SEPARATED THUNDERSTORMS ARE EXPECTED. RAIN FALL
AMOUNTS WILL GENERALLY BE UNDER A TENTH OF AN INCH...ALTHOUGH
AMOUNTS UP TO A QUARTER INCH WILL BE POSSIBLE CLOSE TO THE
PENNSYLVANIA BORDER.

AS THE OVERNIGHT PROGRESSES...THE SUPPORTING DIURNAL INSTABILITY
WILL BE REMOVED...AND WITH THE LIMITED FRONTAL FORCING FOCUSED TO
OUR SOUTH AND EAST...SHOWERS WILL GREATLY DIMINISHED IN COVERAGE.

FOR TUESDAY...THE FRONTAL BOUNDARY IS EXPECTED TO STALL ACROSS
PENNSYLVANIA. THE BULK OF ANY SFC BASED CONVERGENCE WILL THUS STAY
SOUTH OF THE PA BORDER...ALTHOUGH THE AIRMASS WILL STILL BE SOMEWHAT
UNSTABLE OVER THE SOUTHERN TIER...SO LOW CHC POPS WILL REMAIN IN
PLACE FOR SHOWERS AND A STRAY THUNDERSTORM. OTHERWISE...SKIES SHOULD
AT LEAST PARTIALLY CLEAR OVER MUCH OF THE REGION AS HIGH PRESSURE
WILL BUILD ACROSS THE LOWER GREAT LAKES.

THERE WILL BE A LITTLE COOLING BEHIND THE FRONT...AS H85 TEMPS WILL
DROP BACK TO AROUND 8C. NEVERTHELESS...WE WILL STAY ON THE WARM SIDE
OF NORMAL AS MOST AREAS WILL REACH INTO THE UPPER 60S TO LOWER 70S.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL STALL JUST TO THE SOUTH OF OUR CWA ON
TUESDAY NIGHT. MOST MODEL GUIDANCE DEVELOPS A CONVECTIVE WAVE ALONG
THIS...BUT DIFFERS ON THE TIMING AND POSITION OF THE FRONT WHICH
LOWERS FORECAST CONFIDENCE. THIS WILL PROBABLY BE JUST SHOWERS...BUT
CAN/T RULE OUT A FEW THUNDERSTORMS TUESDAY EVENING. MODEL CONSENSUS
SUGGESTS THE BEST CHANCE FOR PRECIPITATION IS ACROSS FAR SOUTHERN
AREAS WHICH IS CLOSEST TO THE FRONT. OTHERWISE A BROAD AREA OF HIGH
PRESSURE WILL EXPAND ACROSS THE GREAT LAKES REGION AND CLEAR OUT THE
REGION FROM NORTH TO SOUTH. LOW TEMPERATURES SHOULD GENERALLY BE IN
THE 40S...WITH THE COLDEST TEMPERATURES TO TO NORTH WHERE CLEAR
SKIES AND LIGHT WINDS WILL BRING GOOD RADIATIONAL COOLING
CONDITIONS.

MEDIUM RANGE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT WITH THE
FRONTAL ZONE EXPECTED TO WASH OUT TO OUR SOUTH AS HIGH PRESSURE
BECOMES ESTABLISHED ACROSS THE REGION ON WEDNESDAY. THE 12Z
GGEM/ECMWF BOTH HANG ONTO SOME SHOWERS ACROSS CHAUTAUQUA COUNTY...BUT
MOST OTHER GUIDANCE IS DRY FOR WEDNESDAY.

THE SURFACE HIGH WILL CONTINUE TO INFLUENCE OUR WEATHER THROUGH
THURSDAY WHILE THE UPPER LEVEL RIDGE AXIS GRADUALLY SHIFTS FROM THE
CENTRAL LAKES TO THE LOWER GREAT LAKES REGION. THIS SHOULD BRING
ANOTHER COUPLE DAYS OF EXCEPTIONAL SPRING WEATHER. HIGHS SHOULD
AVERAGE IN THE 70S ON WEDNESDAY AND THEN RANGE FROM THE MID 70S TO
LOWER 80S ON THURSDAY. THE EXCEPTION WILL BE ALONG THE IMMEDIATE
LAKESHORES WHERE THE LIGHT GRADIENT FLOW WILL ALLOW A LAKE BREEZE TO
DEVELOP EACH AFTERNOON NEAR THE LAKES. THERE MAY BE AN ISOLATED
SHOWER ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER THURSDAY
AFTERNOON...OTHERWISE EXPECT FAIR WEATHER AND MOSTLY CLEAR SKIES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A SUMMER-LIKE PATTERN WILL SET UP FOR MOST OF THE LONG TERM PERIOD
WITH UPPER LEVEL RIDGING ACROSS THE NORTHEASTERN STATES THROUGH THE
PERIOD. INITIALLY THIS RIDGE AXIS WILL BE ACROSS OUR REGION...BUT
THIS AXIS WILL SHIFT TO THE EAST THROUGH MONDAY WHICH WILL SET UP A
PROGRESSIVELY MORE MOIST FLOW. GFS/ECMWF/GGEM GUIDANCE IS IN FAIRLY
GOOD AGREEMENT ON THE BIG PICTURE...WITH THE 12Z GFS FASTER
BREAKING THIS RIDGE DOWN THAN THE GGEM.

THIS WILL BRING MUCH ABOVE NORMAL TEMPERATURES TO THE REGION FOR
FRIDAY AND SATURDAY...WITH WIDESPREAD HIGHS IN THE 80S LIKELY.
TEMPERATURES WILL BE A BIT COOLER ALONG THE LAKESHROES. THERE IS A
SMALL CHANCE FOR MAINLY DIURNALLY DRIVEN SHOWERS OR THUNDERSTORMS
DURING THE AFTERNOON HOURS...BUT THE VAST MAJORITY OF THIS TIMEFRAME
SHOULD REMAIN DRY.

THE CHANCE FOR PRECIPITATION WILL INCREASE SUNDAY AND MONDAY AS A
DEEP SSW FLOW ALOFT BRINGS IN PROGRESSIVELY MORE MOIST AIR.
GFS/ECMWF CONSENSUS QPF INCREASES WITH THE PATTERN SHIFT WITH A GOOD
CHANCE OF SHOWERS AND THUNDERSTORMS...ESPECIALLY DURING THE
AFTERNOON HOURS. DAYTIME HIGHS WILL STILL BE WARM...BUT NOT AS MUCH
SO WITH THE INCREASED CLOUD COVER. HIGHS SHOULD AVERAGE IN THE UPPER
70S TO LOWER 80S ON SUNDAY AND MONDAY.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL REMAIN IN PLACE INTO THIS EVENING...DESPITE
THE ARRIVAL OF A COLD FRONT WITH ITS ASSOCIATED SHOWERS. THERE WILL
BE THE RISK FOR A THUNDERSTORM OR TWO AS WELL...MAINLY OVER THE
SOUTHERN TIER AND FINGER LAKES REGION. AS WE PUSH DEEPER INTO
THE NIGHT...CIGS WILL LOWER TO MVFR LEVEL ST MOST SITES BETWEEN
06 AND 12Z...WITH CIGS DROPPING TO IFR LEVELS ACROSS THE HIGHER
TERRAIN OF THE SOUTHERN TIER.

ON TUESDAY...THE AFOREMENTIONED COLD FRONT WILL BE STALLED OVER
PENNSYLVANIA WHILE MAINLY VFR CIGS WILL BE FOUND ACROSS WESTERN
NEW YORK AND CERTAINLY THE EASTERN LAKE ONTARIO REGION. WHILE
THERE WILL BE THE POTENTIAL FOR A SHOWER SOUTH OF BUFFALO AND
ROCHESTER...THE BULK OF THE DAY WILL BE RAIN FREE. A THUNDERSTORM
CANNOT BE RULED OUT ACROSS THE SOUTHERN TIER.

OUTLOOK...
TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY THROUGH FRIDAY...VFR.
SATURDAY AND SUNDAY...MAINLY VFR WITH A CHANCE OF MVFR IN RAIN
SHOWERS.

&&

.MARINE...
A RELATIVELY STRONG PRESSURE GRADIENT OVER THE LOWER GREAT LAKES
WILL REMAIN IN PLACE THIS EVENING...ALTHOUGH THE COOL WATERS OF
LAKES ERIE AND ONTARIO SHOULD KEEP THE STRONGEST WINDS A FEW HUNDRED
FEET ABOVE THE SURFACE. THE EXCEPTION WILL REMAIN TO BE IN THE SAINT
LAWRENCE VALLEY WHERE WINDS OF 20 TO 30 KNOTS THROUGH THE EARLY
EVENING WILL SUPPORT AN ON GOING SMALL CRAFT ADVISORY.

AS WE PUSH THROUGH THE EVENING THOUGH...A COLD FRONT WILL SETTLE
ACROSS THE LOWER GREAT LAKES. A WEAKENING PRESSURE GRADIENT WILL
NATURALLY LEAD TO A LESSENING OF THE BREEZY CONDITIONS.

ON TUESDAY AND WEDNESDAY...HIGH PRESSURE OVER THE LOWER GREAT LAKES
WILL ONLY PRODUCE LIGHT WINDS AND NEGLIGIBLE WAVES.

&&

.FIRE WEATHER...
A WARM...DRY AND BREEZY DAY TODAY WILL COMBINE WITH THE VERY DRY
FINE DEAD FUELS /DUE TO LACK OF RECENT PRECIPITATION/ TO PRODUCE
DANGEROUS FIRE WEATHER CONDITIONS ACROSS WESTERN AND NORTH CENTRAL
NEW YORK. TEMPERATURES WILL RISE INTO THE MID 70S TO LOWER 80S
AWAY FROM THE LAKE SHORES. AFTERNOON RH VALUES WILL FALL INTO THE
25 TO 30 PERCENT RANGE...AND WINDS WILL INCREASE TO 10 TO 20 MPH
WITH GUSTS 25 TO 35 MPH. GIVEN THE DOWNWARD TREND IN FORECAST RH
VALUES AND GUSTY AFTERNOON WINDS...FEEL THE WEATHER THRESHOLDS
HAVE BEEN MET OVER A LARGER AREA THAN DISCUSSED YESTERDAY...THUS
HAVE ISSUED A RED FLAG WARNING FOR ALL OF WESTERN AND NORTH
CENTRAL NEW YORK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR NYZ001>008-
     010>014-019>021-085.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SLZ022-
         024.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...RSH
MARINE...RSH
FIRE WEATHER...CHURCH



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