Area Forecast Discussion
Issued by NWS Buffalo, NY

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037
FXUS61 KBUF 171517
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1117 AM EDT SUN MAY 17 2015

.SYNOPSIS...
THE REMAINDER OF THE WEEKEND WILL FEATURE ABOVE NORMAL WARMTH WITH
WIDESPREAD 70S ACROSS THE REGION TODAY. A MOISTURE RICH AIRMASS WILL
REMAIN WITH SCATTERED SHOWERS AND A FEW THUNDERSTORMS ACROSS THE
SOUTHERN TIER. ANOTHER PERIOD OF THUNDERSTORMS WITH LOCALIZED HEAVY
RAIN AND GUSTY WINDS WILL PUSH ACROSS THE AREA MONDAY AND MONDAY
NIGHT AHEAD OF A COLD FRONT. A COOLER AND DRY AIRMASS WILL ARRIVE
BEHIND THE FRONT MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
WARM AND HUMID WEATHER WILL CONTINUE TODAY AS A 500MB RIDGE CRESTS
ACROSS THE EASTERN GREAT LAKES. SURFACE HIGH PRESSURE IS CENTERED
OVER WESTERN QUEBEC THIS MORNING AND EXPANDED ACROSS THE FORECAST
AREA. TO THE WEST...LOW PRESSURE IS CENTERED OVER SOUTH DAKOTA WITH
AN EASTWARD EXTENDING WARM/STATIONARY FRONT STRETCHING ACROSS LAKE
ERIE TO THE SOUTHERN TIER. SURFACE OBS SHOW DEWPOINTS IN THE LOW 60S
SOUTH OF THE FRONT WITH 50S TO THE NORTH. THESE WARM DEWPOINTS AND
LIGHT WINDS CONTINUE TO SUPPORT AREAS OF FOG MAINLY ACROSS AND EAST
OF THE LAKES AS THIS HIGH DEWPOINT ADVECTS OVER THE COOL LAKE WATERS.

EXPECT THE FRONTAL BOUNDARY TO EDGE SLIGHTLY FURTHER NORTHWARD WITH
THE AREAS OF FOG DISSIPATING BY LATE MORNING AS SURFACE TEMPS WARM.
THE COMBINATION OF THESE DEWPOINTS IN THE 60S WITH DIURNAL HEATING
AND CAPE VALUES RISING TO 2000 J/KG WILL LIKELY SUPPORT SHOWERS AND
THUNDERSTORMS FIRING ON A LAKE BREEZE THIS AFTERNOON AND EVENING
ACROSS THE SOUTHERN TIER WITH CHANCE POPS FURTHER NORTH TO BUFFALO.
ACROSS THE NORTH COUNTRY AND EASTERN FINGER LAKES HIGH PRESSURE AND
WARMING TEMPS ALOFT WILL HOLD A STRONG CAP IN PLACE PREVENTING ANY
THREAT FOR PRECIPITATION.

THE MAIN CONCERN WITH ANY SOUTHERN TIER STORMS THIS AFTERNOON WILL
BE THE POTENTIAL FOR HEAVY RAINFALL. WIND SHEAR WILL BE TOO WEAK TO
SUPPORT ANY ORGANIZED SEVERE STORM RISK. PRECIPITABLE WATER VALUES
WILL CONTINUE TO CREEP UP WITH THE INCREASED SOUTHERLY FLOW...RISING
TO BETWEEN 1.25 AND 1.5 INCHES. THIS DEEP-LAYER MOISTURE...COMBINED
WITH SKINNY FORECAST CAPE PROFILES...AND SHORT BUFKIT MBE VECTORS/
SLOW STORM MOTION WILL BRING A THREAT FOR LOCALIZED FLOODING WITH
ANY STRONGER CONVECTION. OTHERWISE TEMPERATURES WILL WARM NICELY
INTO THE 70S WITH A FEW SPOTS POSSIBLY REACHING 80 DEGREES THIS
AFTERNOON.

TONIGHT...SHOWER/THUNDERSTORM ACTIVITY SHOULD DISSIPATE THIS EVENING
WITH THE LOST OF DAYTIME HEATING. ONLY A NARROW SLIVER OF CHANCE
POPS WILL REMAIN ALONG THE NY/PA BORDER. THE WARM FRONT WILL EDGE
EVEN FURTHER NORTH WITH DEWPOINTS CLIMBING TOWARD THE MID 60S ACROSS
WNY AND U50S FOR THE NORTH COUNTRY. THIS WILL LEAVE A VERY MUGGY
FEEL TO THE AIR OVERNIGHT WITH LOW TEMPERATURES ONLY SLIPPING BACK
INTO THE L60S/U50S. AGAIN NARROWING DEWPOINT DEPRESSIONS AND LIGHT
WINDS WILL SUPPORT AREAS OF FOG OVERNIGHT WITH THE MOST LIKELY AREAS
OF FOG BEING ANYWHERE THAT PICKED UP AFTERNOON PRECIPITATION ACROSS
THE SOUTHERN TIER.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
THE UPPER LEVEL RIDGE CURRENTLY CRESTING ACROSS THE LOWER GREAT
LAKES WILL SHIFT EAST ACROSS NEW ENGLAND ON MONDAY...PAVING THE WAY
FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY AND MONDAY
NIGHT AHEAD OF AN APPROACHING COLD FRONT. GUIDANCE DEPICTS THE
DEVELOPMENT OF A SHARP THETA-E RIDGE ACROSS THE REGION IN THE WARM
SECTOR OF A SURFACE LOW THAT WILL BE TRACKING FROM THE UPPER GREAT
LAKES INTO CENTRAL QUEBEC...INDICATIVE OF THE VERY WARM AND MOIST
AIRMASS THAT WILL BE ADVECTING INTO THE FORECAST AREA AHEAD OF THE
SYSTEM`S COLD FRONT. AS TEMPERATURES SURGE INTO THE 80S BY MONDAY
AFTERNOON...EXPECT SHOWERS AND THUNDERSTORMS TO FIRE ALONG LAKE
BREEZE BOUNDARIES WITH ACTIVITY INCREASING IN COVERAGE AND SHIFTING
ACROSS THE FORECAST AREA THROUGH THE LATE AFTERNOON AND EVENING
HOURS AS A PRE-FRONTAL TROUGH CROSSES THE AREA. REASONABLY WARM
TEMPERATURES IN THE MID/UPPER LEVELS WILL LIMIT INSTABILITY TO
AROUND 1000 J/KG AND MODEST VERTICAL SHEAR DO NOT SUGGEST ANY
SIGNIFICANT SEVERE WEATHER THREAT MONDAY OR MONDAY NIGHT...HOWEVER
GIVEN THE WEAK FLOW AND VERY MOIST ENVIRONMENT WITH PWATS RUNNING
AROUND 1.6 INCHES...LOCALIZED HEAVY RAINFALL WILL BE
POSSIBLE...PARTICULARLY FROM THE GENESEE VALLEY EAST AS THE PRE-
FRONTAL TROUGH CROSSES THE AREA...ENHANCING MOISTURE TRANSPORT AND
SURFACE CONVERGENCE.

THE AFOREMENTIONED SURFACE COLD FRONT WILL MOVE INTO WESTERN NEW
YORK TUESDAY MORNING AND CROSS THE FORECAST AREA THROUGH THE DAY.
WHILE A FEW SHOWERS WILL BE POSSIBLE ALONG/AHEAD OF THE FRONT
TUESDAY AFTERNOON ACROSS THE EASTERN HALF OF THE FORECAST AREA...THE
ADVECTION OF MUCH COOLER AND DRIER AIR BEHIND THE FRONT SHOULD YIELD
A DRY DAY ACROSS WESTERN NEW YORK WITH A DECENT AMOUNT OF SUNSHINE
TO GO AROUND...THOUGH BY MONDAY EVENING MID CLOUDS WILL ONCE AGAIN
BE SPREADING ACROSS THE REGION AS THE MID-LEVEL TROUGH AXIS SHIFTS
ACROSS THE REGION. TEMPERATURES WILL BE ON THE ORDER OF 10-15
DEGREES COOLER BEHIND THE FRONT WITH HIGHS IN THE UPPER 60S TO UPPER
70S...WITH COOLEST AREAS DOWNWIND OF THE LAKES AND WARMEST ACROSS
THE FINGER LAKES.

TEMPERATURES WILL CONTINUE TO FALL TUESDAY NIGHT AS THE UPPER LEVEL
TROUGH AXIS SETTLES ACROSS THE LOWER GREAT LAKES WITH TEMPERATURES
DROPPING INTO THE 40S...WITH TYPICALLY COOLER SPOTS IN THE SOUTHERN
TIER PERHAPS TOUCHING THE 40 DEGREE MARK. A SHORTWAVE MOVING THROUGH
THE CYCLONIC FLOW ALOFT WILL BRING A CHANCE OF SHOWERS TO THE NORTH
COUNTRY...HOWEVER GIVEN THE LIMITED MOISTURE THERE WILL BE TO WORK
WITH...WILL KEEP POPS AT ONLY A SLIGHT CHANCE THERE FOR NOW WITH A
DRY FORECAST ELSEWHERE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE LONGWAVE TROUGH WILL RE-ASSERT IT`S DOMINANCE ACROSS THE GREAT
LAKES AND THE NORTHEAST THROUGH THE PERIOD AS STRONG CROSS-POLAR
FLOW SENDS A SURGE OF ARCTIC AIR INTO EASTERN CANADA WITH GLOBAL
MODELS SHOWING THE ALL-TOO-FAMILIAR UPPER LOW BECOMING RE-
ESTABLISHED OVER QUEBEC. THIS WILL PRODUCE A RETURN TO COOL AND DRY
CONDITIONS ACROSS THE LOWER GREAT LAKES THROUGH THE REST OF THE WEEK
AND INTO THE WEEKEND. HOWEVER...THE COOLEST CONDITIONS WILL ACTUALLY
FALL EARLY IN THE PERIOD ON WEDNESDAY AND INTO WEDNESDAY NIGHT AS
THE REMNANTS OF THE POTENT UPPER LEVEL LOW CURRENTLY OVER THE GREAT
PLAINS LIFT ACROSS THE UPPER GREAT LAKES AND INTO EASTERN CANADA.
THE CORE OF THE COLD AIR ALOFT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE LOWER GREAT LAKES WEDNESDAY INTO WEDNESDAY
NIGHT...YIELDING DAYTIME HIGHS THAT WILL ONLY TOP OUT IN THE 50S
WEDNESDAY. IN FACT IT IS QUITE POSSIBLE THAT WE MAY SEE WIDESPREAD
LAKE EFFECT CLOUDINESS DEVELOP FOR A TIME ON WEDNESDAY AS 850MB
TEMPS DROP TO AROUND -4C.

WHILE THE CLOUD COVER SHOULD DIMINISH WEDNESDAY NIGHT AS THE CORE OF
THE COLD AIR MOVES OFF TO OUR EAST...HIGH PRESSURE BUILDING IN
ACROSS THE LOWER GREAT LAKES MAY HELP PRODUCE ENOUGH CLEARING
WEDNESDAY NIGHT TO DROP READINGS INTO THE UPPER 30S ACROSS PORTIONS
OF THE SOUTHERN TIER AND WELL INLAND IN THE NORTH COUNTRY...RAISING
THE POTENTIAL FOR FROST ACROSS THESE AREAS WEDNESDAY NIGHT. FROST
SHOULD NOT BE A THREAT ELSEWHERE AS READINGS SHOULD ONLY BOTTOM OUT
IN THE LOW TO MID 40S.

WEDNESDAY NIGHT SHOULD BE THE COLDEST POINT DURING THE PERIOD AS THE
AFOREMENTIONED COLD POCKET ALOFT WILL QUICKLY MOVE OFF TO THE
NORTHEAST IN THE BRISK CYCLONIC FLOW ALOFT. THAT SAID...IT WILL
STILL REMAIN COOL AND DRY THROUGH THE REST OF THE WEEK AND THE
COMING WEEKEND COURTESY OF THE DRY NORTHWESTERLY FLOW THAT WILL
PREVAIL AS THE LONGWAVE TROUGH BECOMES ESTABLISHED ACROSS THE REGION
ALONG WITH THE DOME OF HIGH PRESSURE THAT WILL BE DRIFTING ACROSS
THE LOWER GREAT LAKES. IN GENERAL LOOK FOR HIGHS TO RUN IN THE 60S
WITH LOWS IN THE 40S. THERE MAY BE A POTENTIAL WARM-UP IN THE WORKS
BY THE END OF NEXT WEEKEND AND INTO THE FOLLOWING WEEK AS YET ANOTHER
SOUTHERN STREAM UPPER LOW TRACKS ACROSS THE FOUR-CORNERS REGION.
THIS WOULD FORCE A RIDGE DOWNSTREAM ACROSS THE GREAT LAKES...LEADING
AT LEAST TO A TEMPORARY RETURN OF WARM...BUT LIKELY UNSETTLED
WEATHER TO WESTERN AND NORTH-CENTRAL NEW YORK.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
A HIGH MOISTURE AIRMASS IS CONTINUING TO SUPPORT LOW CLOUDS ACROSS
THE SOUTHERN TIER WITH IFR CONDITIONS AT KJHW. SOME IMPROVEMENT
WILL OCCUR HERE DURING THE ATERNOON WITH MVFR OR LOW END VFR
CONDITIONS BY MID TO LATE ATERNOON. VFR CONDITIONS WILL REMAIN IN
PLACE ELSEWHERE THROUGH THIS AFTERNOON.

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
AFTERNOON ACROSS THE SOUTHERN TIER WITH POSSIBLE RESTIRCTIONS
DEVELOPING IN HEAVIER SHOWERS. WINDS WILL REMAIN LIGHT AND VARIABLE
THROUGH TONIGHT.

ANY PCPN FROM THIS AFTERNOON WILL END TONIGHT WITH THE LOSS OF
DAYTIME HEATING AND WITH NO FORCING MECHANISM. AREAS OF IFR FOG WILL
AGAIN BE POSSIBLE ESPECIALLY IN AREAS WHICH PICK UP RAIN.

OUTLOOK...
MONDAY...VFR/MVFR WITH SHOWERS AND THUNDERSTORMS LIKELY.
TUESDAY THROUGH THURSDAY...VFR.

&&

.MARINE...
LIGHT WINDS AND MINIMAL WAVES WILL CONTINUE ON THE EASTERN GREAT
LAKES THROUGH TODAY WITH LINGERING AREAS OF FOG AS A WARM AND HUMID
AIRMASS REMAINS OVER THE COOL LAKE WATERS. CONDITIONS ON THE LAKES
SHOULD REMAIN QUIET OUTSIDE OF ANY FOG AND SCATTERED THUNDERSTORMS
PRODUCING ASSOCIATED HIGHER WINDS AND WAVES INTO MONDAY. A COLD
FRONT WILL SWEEP ACROSS THE EASTERN GREAT LAKES LATE MONDAY
NIGHT/TUESDAY WITH AN INCREASE IN WIND SPEED AND WAVE ACTION INTO
TUESDAY. SMALL CRAFT ADVISORIES MAY BE NEEDED.

&&

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

&&

$$

SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...SMITH/TMA
MARINE...SMITH



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