Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 050306
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1106 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/...
REGIONAL RADARS LATE THIS EVENING SHOWING NEARLY ALL THE SHOWER
ACTIVITY ASSOCIATED WITH THE PRE-FRONTAL TROUGH HAVE MOVED EAST
OF THE AREA. ILL-DEFINED SURFACE COLD FRONT STRETCHING FROM THE
SAINT LAWRENCE VALLEY TO THE NIAGARA PENINSULA WILL CROSS THE
AREA THROUGH THE EARLY OVERNIGHT HOURS. LITTLE IF ANY ACTIVITY
CURRENTLY ASSOCIATED WITH THE FRONT...BUT WE STILL COULD SEE A
FEW ISOLATED SHOWERS DEVELOP AS THE FRONT PASSES THROUGH. WINDS
WILL DROP OFF WITH TEMPERATURES FALLING INTO THE UPPER 40S TO MID
50S.

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/...
FRONTAL BOUNDARY
THAT IS PASSING ACROSS THE CWA TONIGHT IS STILL FORECASTED TO LIE
JUST TO THE SOUTH OF OUR CWA ON TUESDAY NIGHT WHERE IT WILL THEN
STALL. WILL NUDGE WEDNESDAY TEMPERATURES UP A BIT (SEE BELOW)
OTHERWISE NO MAJOR CHANGES ARE NEEDED TO THE FORECAST BASED ON
CURRENT OBSERVATIONS FOR THE EVENING FORECAST UPDATE.

MOST MODEL GUIDANCE DEVELOPS A CONVECTIVE WAVE ALONG THIS STALLED
FRONTAL BOUNDARY...BUT DIFFERS ON THE TIMING AND POSITION OF THE
FRONT WHICH LOWERS FORECAST CONFIDENCE. THE END RESULT WILL PROBABLY
BE JUST SHOWERS TUESDAY EVENING...BUT CAN/T RULE OUT A FEW
THUNDERSTORMS. MODEL CONSENSUS SUGGESTS THE BEST CHANCE FOR
PRECIPITATION IS ACROSS FAR SOUTHERN AREAS WHICH WILL BE 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.

SINCE IT HAS BEEN DRY AND THIS MONDAY EVENING`S COLD FRONT SPARSE
WITH RAINFALL WILL NUDGE TEMPERATURES UP A FEW DEGREES ON WEDNESDAY
WHERE PLENTY OF SUNSHINE NORTH OF THE PA BORDER COULD BRING A FEW
80F READINGS TO THE REGION.

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 LAKESHORES. 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 /03Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL REMAIN IN PLACE THIS EVENING...DESPITE THE
ARRIVAL OF A COLD FRONT WITH ITS ASSOCIATED SHOWERS. AS WE PUSH
DEEPER INTO THE NIGHT...CIGS WILL NEAR MVFR LEVELS AT MOST SITES
BETWEEN 06Z 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...MAINLY VFR WITH A CHANCE OF MVFR IN RAIN SHOWERS.

&&

.MARINE...
A COLD FRONT WILL SETTLE ACROSS THE LOWER GREAT LAKES TONIGHT. A
WEAKENING PRESSURE GRADIENT WILL LEAD TO A LESSENING OF THE
WINDS.

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

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

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


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