Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 291346
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
946 AM EDT FRI MAY 29 2015

.SYNOPSIS...
WARM AIR WILL SURGE NORTHWARD ACROSS THE EASTERN GREAT LAKES REGION
TODAY WHERE SUNSHINE AND LIGHT SOUTH WINDS WILL PRODUCE A VERY WARM
AFTERNOON. A FEW SHOWERS OR THUNDERSTORMS MAY BLOSSOM WITHIN THE
AFTERNOON HEAT ACROSS WESTERN NEW YORK THOUGH TONIGHT...WITH
ACTIVITY IN A MUCH WEAKER STATE AS IT NEARS THE LAKE ONTARIO REGION.
THE GREATER COVERAGE AND INTENSITY TO SHOWERS AND THUNDERSTORMS WILL
BE SATURDAY NIGHT AND SUNDAY ALONG A COLD FRONT THAT WILL PUSH
ACROSS THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
LATEST VISIBLE IMAGERY SHOWING THE REGION UNDER MAINLY CLEAR
SKIES...WITH JUST SOME THIN CIRRUS LEVEL PASSING BY. AN ELONGATED
AREA OF HIGH PRESSURE STRETCHES FROM SOUTHERN QUEBEC TOWARDS
EASTERN NEW YORK STATE WITH THIS FEATURE ALLOWING FOR LIGHT AND
VARIABLE WINDS.

FOR TODAY...AS THIS AREA OF HIGH PRESSURE SLIDES EASTWARD A
SOUTHERLY FLOW WILL ENSUE. THIS FLOW WILL BRING WARMER AIR MASS
NORTHWARD...WITH 850 HPA TEMPERATURES RISING TO +14 TO +15C THIS
AFTERNOON. THIS WARMING ALOFT WILL TRANSLATE TO AFTERNOON HIGHS IN
THE LOWER TO MID 80S ACROSS THE REGION. SYNOPTIC FLOW WILL
CONTINUE TO REMAIN LIGHT SUCH THAT LOCAL LAKE BREEZE CIRCULATIONS
WILL DEVELOP WITH SLIGHTLY COOLER TEMPERATURES NEAR LAKE
SHORELINES.

HIGHS TODAY WILL NEAR RECORD VALUES...ESPECIALLY FOR TWO OF OUR
CLIMATE STATIONS. RECORD HIGHS TODAY ARE: BUFFALO 87/1987, ROCHESTER
92/2006, WATERTOWN 87/2012. OF THE THREE ROCHESTER`S VALUE WILL BE
HARDEST TO REACH. THIS HEAT WILL ALSO ADD TO OUR UNUSUALLY WARM MAY.
SEE THE CLIMATE SECTION BELOW FOR THE WARMEST MAYS...AND DRIEST MAYS
ON RECORD.

IN ADDITION TO THE INCREASE IN WARMTH THE HUMIDITY WILL ALSO BE
INCREASING. DEWPOINTS WILL RISE INTO THE UPPER 50S THROUGH THE
AFTERNOON HOURS. HOWEVER IT WILL NOT BE UNTIL TONIGHT THAT ANY
REAL MUGGINESS TO THE AIR IS FELT WHEN DEWPOINTS RISE FURTHER INTO
THE LOW 60S.

AS THE UPPER LEVEL RIDGE AXIS AND ITS ASSOCIATED SUBSIDENCE SHIFTS
INTO NEW ENGLAND TONIGHT A FEW SHOWERS OR THUNDERSTORMS MAY BLOSSOM
LATE THIS AFTERNOON AND EVENING ACROSS WNY. GREATEST CHANCES FOR
CONVECTION WILL BE AREAS FARTHEST FROM THE UPPER LEVEL RIDGE
AXIS...WHICH WILL BE AREAS ACROSS FAR SW NYS THIS AFTERNOON WHERE
MODEST INSTABILITY LIES. A LAKE BREEZE BOUNDARY WILL PROVIDE A
FAVORABLE FOCAL POINT FOR CONVECTION TO BLOSSOM LATE THIS
AFTERNOON AND EVENING. AS THE INSTABILITY IS TIED TO THE HEATING
OF THE DAY...IT WILL LOSS ITS STRENGTH THROUGH THE EVENING
HOURS...WHICH WILL WEAKEN THE SHOWERS AND THUNDERSTORMS AS THEY
LIFT NORTHWARD TOWARDS LAKE ONTARIO. THERE WILL BE MINOR ELEVATED
INSTABILITY REMAINING THROUGH THE NIGHT AND PWATS NEARING AN INCH
AND A HALF. THIS ELEVATED INSTABILITY MAY BE ENOUGH TO MAINTAIN
ISOLATED TO SCATTERED SHOWERS ACROSS THE ENTIRE REGION THAT IS NOW
WITHIN A VERY MOIST AIRMASS.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
LOW PRESSURE IS FORECAST TO TRACK ACROSS NORTHERN QUEBEC WHICH WILL
DROP A STRONG COLD FRONT ACROSS OUR REGION LATE SATURDAY. AHEAD OF
THIS FRONT WILL BE MUGGY CONDITIONS...WITH DEW POINTS IN THE 60S AND
DAYTIME HIGHS SATURDAY IN THE 80S ON SATURDAY. INCREASING
INSTABILITY WILL RESULT IN SHOWERS AND THUNDERSTORMS ACROSS INTERIOR
LOCATIONS BY SATURDAY AFTERNOON. A FRESH SOUTHWESTERLY FLOW AHEAD OF
THIS FRONT SHOULD KEEP THE BOUNDARY LAYER AND DELAY THE START OF
SHOWERS ACROSS AND NORTHEAST OF THE LAKES. LAKE SHADOWING WILL BREAK
DOWN SATURDAY EVENING WITH THE APPROACH AND PASSAGE OF THE COLD
FRONT AND BRING A SOAKING RAINFALL TO NEARLY ALL LOCATIONS SATURDAY
NIGHT.

THERE IS A POTENTIAL FOR HEAVY RAIN SATURDAY AFTERNOON AND EVENING
WITH PWATS FORECAST TO BE 1.5 TO 1.75 AHEAD OF THE FRONT. THE MAIN
CONCERN IS IF THUNDERSTORMS TRAIN ACROSS INTERIOR SECTIONS ALONG A
LAKE BREEZE OR SOME OTHER SUBTLE BOUNDARY. IT IS UNCERTAIN IF THIS
WILL HAPPEN. MODEL GUIDANCE CONTINUES TO DIFFER ON THE TIMING AND
STRUCTURE OF THE FRONT WHICH PROBABLY LEADS DIFFERENCES IN QPF.
THERE ALSO MAY BE A FEW STRONG TO SEVERE THUNDERSTORMS SATURDAY
AFTERNOON WITH A MODESTLY STRONG 850MB FLOW AND INSTABILITY AHEAD OF
THE FRONT. THE SMALL POTENTIAL FOR FLASH FLOODING AND SEVERE WEATHER
WILL BE MENTIONED IN THE HWO.

THE COLD FRONT WILL SLOWLY PUSH SOUTH LATE SATURDAY NIGHT BEFORE
STALLING OUT ON SUNDAY. THE MAJORITY OF GUIDANCE PUSHES THE FRONT TO
THE SOUTH OF THE CWA BEFORE IT STALLS WHICH WOULD RESULT IN FAIR
WEATHER ON SUNDAY. HOWEVER SOME GUIDANCE STALL THE FRONT ACROSS THE
SOUTHERN TIER (00Z NAM/ECMWF) WHICH WOULD RESULT IN ANOTHER ROUND OF
SHOWERS ON SUNDAY. ALTHOUGH THE LATTER GUIDANCE IS LESS LIKELY TO
VERIFY...IT IS WORTH CHANCE POPS SUNDAY INTO SUNDAY NIGHT ACROSS
SOUTHERN PORTIONS OF THE CWA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
MOST MODEL GUIDANCE CONTINUES TO BUILD HIGH PRESSURE AND UPPER LEVEL
RIDGING INTO THE REGION ON MONDAY AND TUESDAY. HOWEVER...THE 00Z
ECMWF DIFFERS CONSIDERABLY WITH A COOLER AND WETTER SOLUTION
COURTESY OF A SHORTWAVE ON MONDAY AND TUESDAY. THIS DIFFERS
SIGNIFICANTLY FROM OTHER GUIDANCE AND PREVIOUS RUNS SO WILL ONLY UP
POPS TO SLIGHT CHANCE UNTIL THERE IS ANOTHER RUN TO SUPPORT THIS.
HIGHS ARE LIKELY TO BE IN THE UPPER 60S ON MONDAY AND A FEW DEGREES
WARMER TUESDAY.

STRONG SURFACE HIGH PRESSURE AND RIDGING ALOFT OVER EASTERN CANADA
AND THE NORTHEAST STATES WILL SET UP MID-WEEK WHICH WILL KEEP THE
AREA RAIN FREE. H85 TEMPS WILL RISE TO +13 TO +15C BY
THURSDAY...SUPPORTING MAX SURFACE TEMPS IN THE MID 70S TO LOWER 80S
WEDNESDAY...AND IN THE 80S ON THURSDAY.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION LATE THIS
MORNING AND THESE CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE
TAF PERIOD. A FEW SCATTERED SHOWERS OR ISOLATED THUNDERSTORMS
WILL DRIFT ACROSS SW NYS LATE THIS AFTERNOON AND EVENING...WITH
CONVECTION WEAKENING AS IT REACHES NORTHWARD TOWARDS
KBUF/KIAG/KROC.

OUTLOOK...
SATURDAY...MAINLY VFR THOUGH SHOWERS AND THUNDERSTORMS MAY
BRING BRIEF FLIGHT RESTRICTIONS.
SATURDAY NIGHT...AREAS OF MVFR/IFR WITH SHOWERS AND SCATTERED
THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...MAINLY VFR.

&&

.MARINE...
A PERIOD OF NON SCA CONDITIONS ARE EXPECTED ON THE EASTERN GREAT
LAKES THROUGH EARLY SATURDAY AS HIGH PRESSURE CROSSES OVER THE
REGION. LATER SATURDAY SOUTHWEST WINDS WILL INCREASE AHEAD OF A
STRONGER COLD FRONT...POSSIBLY NECESSITATING THE HOISTING OF
ADDITIONAL SMALL CRAFT FLAGS...ESPECIALLY ON THE RIVERS THROUGH
THE DAY WHERE WINDS MAY REACH 20 KNOTS. BEHIND A COLD FRONT WINDS
AND WAVES WILL INCREASE ON THE EASTERN GREAT LAKES SATURDAY NIGHT.

&&

.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 TEMPERATUREYEAR

164.31991
263.82012
363.41944
462.81998
562.3 2015 (THROUGH 5/29)
 662.21975


ROCHESTERRANKMEAN TEMPERATUREYEAR

163.71911
263.62015 (THOUGH 5/29)
363.22012
463.21944


WATERTOWNRANKMEAN TEMPERATUREYEAR

160.52012
260.01998
359.31975
458.82015 (THROUGH 5/29)
558.81960
658.31991


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.

BUFFALORANKPRECIPYEAR
10.531877
20.541934
30.602005
40.832015(THROUGH 5/29)
50.902012
..
101.111926


ROCHESTERRANKPRECIPYEAR
10.242007
..
 271.52 2015 (THROUGH 5/29)
281.551876
291.591954
301.641926


WATERTOWNRANKPRECIPYEAR
10.701965
20.872005
30.881980
40.901974
50.991966
61.042015  (THROUGH 5/29)
71.081972
81.091951
91.141949
101.161962

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...NONE.

&&

$$

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


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