Area Forecast Discussion
Issued by NWS Buffalo, NY

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683
FXUS61 KBUF 301852
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
252 PM EDT SAT APR 30 2016

.SYNOPSIS...
A WARM FRONT LIFTING OUT OF THE LOWER OHIO VALLEY WILL SPREAD
RAIN ACROSS THE FORECAST AREA TONIGHT INTO SUNDAY WITH A CHANCE
OF THUNDERSTORMS SUNDAY AFTERNOON AND EVENING AS AN AREA OF LOW
PRESSURE MOVES ACROSS THE LOWER GREAT LAKES. SHOWERS SHOULD TAPER
OFF MONDAY AS THE LOW MOVES AWAY FROM THE REGION. COOL AND
UNSETTLED WEATHER IS EXPECTED TO PREVAIL FOR MUCH OF THE COMING
WEEK AS A DEEP UPPER LEVEL TROUGH SETTLES OVER THE REGION.

&&

.NEAR TERM /THROUGH SUNDAY/...
LATEST MODELS CONTINUING TO SUGGEST AN INCREASINGLY FAVORABLE
ENVIRONMENT FOR A SOLID RAINFALL EVENT ACROSS WESTERN NEW YORK
HEADING INTO TONIGHT. WATER VAPOR LOOP DISPLAYING A CLEAR SIGNAL OF
DEEP LAYER NORTHEASTWARD MOISTURE TRANSPORT LODGED WITHIN THE
ATTENDANT STRENGTHENING MID LEVEL SOUTHWESTERLIES...IMMEDIATELY
DOWNSTREAM OF THE CLOSED LOW/HEIGHT FALLS NOW LIFTING INTO THE
CENTRAL PLAINS.

RAPID ADVANCEMENT OF HIGH CLOUD COMBINED WITH PESKY LINGERING
STRATUS WILL KEEP SKIES MAINLY CLOUDY EARLY TONIGHT WITH A SHRINKING
WINDOW FOR CLEAR SKIES TONIGHT ALONG THE SOUTH SHORE OF LAKE ONTARIO
AND ACROSS THE NORTH COUNTRY.

A WELL DEFINED MOISTURE AXIS LOCKED ALONG AN EMERGING STRONG WING OF
MID LEVEL ISENTROPIC ASCENT/WARM AIR ADVECTION EXPECTED TO RAPIDLY
ADVANCE INTO WESTERN NEW YORK AFTER 00Z...AHEAD OF ADVANCING SURFACE
WARM FRONT. ADDITIONAL CONTRIBUTIONS COMING FROM SHORTWAVE ENERGY
AND LOW LEVEL JET FORCING IMPINGING ON THE REGION WILL CONTRIBUTE TO
AN EXPANSIVE REGION OF RAINFALL LIFTING ACROSS THE ENTIRE AREA
TONIGHT AND THEN CONTINUING INTO SUNDAY.

HIGHER RESOLUTION MODELS HINTING AT DIMINISHING STABILITY BEHIND THE
NORTHWARD LIFTING SURFACE WARM FRONT WITH A POTENTIAL CONVECTIVE
ELEMENT DEVELOPING ACROSS THE REGION DURING THE DAY SUNDAY. LOOKING
AT THE POTENTIAL FOR SOME ISOLATED THUNDER WITH RAINFALL AMOUNTS IN
EXCESS OF A HALF INCH CERTAINLY IN PLAY.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
BY SUNDAY EVENING...THE INITIAL SURFACE WAVE WILL BE SITUATED
OVER THE FINGER LAKES REGION. OUT AHEAD OF THIS FEATURE...SOME
LINGERING RAIN WILL BE IN THE PROCESS OF DIMINISHING ACROSS THE
NORTH COUNTRY... WHILE THE REMAINDER OF THE AREA WILL LIKELY BE
UNDER THE INFLUENCE OF SHALLOWER MOISTURE AND MUCH WEAKER LARGE-
SCALE LIFT...AND THUS IN A RELATIVE LULL IN THE PRECIP WITH JUST
SOME SCATTERED SHOWERS AROUND INITIALLY.

ALL OF THIS WILL CHANGE AS THE NIGHT PROGRESSES THOUGH...AS
ANOTHER VIGOROUS MID LEVEL TROUGH SLIDES EASTWARD ACROSS THE
GREAT LAKES...AND ITS ASSOCIATED SURFACE WAVE OVER THE OHIO VALLEY
QUICKLY BECOMES BETTER ORGANIZED AND DEVELOPS NORTHEASTWARD INTO
NEW YORK STATE...WITH THIS FEATURE ULTIMATELY ABSORBING THE
INITIAL LOW AND REACHING CENTRAL NEW YORK BY MONDAY MORNING. THE
COMBINATION OF THE WARM AIR ADVECTION REGIME OUT AHEAD OF THE LOW
AND AN ATTENDANT IMPRESSIVE LOW-MID LEVEL JET WILL SPREAD
INCREASING AMOUNTS OF MOISTURE AND LARGE-SCALE LIFT BACK ACROSS
OUR REGION THROUGH THE NIGHT...WHICH IN TURN WILL RESULT IN
WIDESPREAD RAIN REDEVELOPING ACROSS THE REGION FROM SOUTHWEST
TO NORTHEAST. WITH THIS IN MIND...HAVE BUMPED UP POPS FOR THIS
PERIOD FROM LOW LIKELY TO CATEGORICAL.

AS WE MOVE INTO MONDAY...THE MID LEVEL TROUGH AND SECOND SURFACE
LOW WILL QUICKLY SLIDE EASTWARD INTO NEW ENGLAND...WITH HIGH
PRESSURE AND DRIER AIR OVER THE UPPER GREAT LAKES RAPIDLY BUILDING
EASTWARD INTO OUR REGION IN THEIR WAKE. THIS WILL RESULT IN FAIRLY
WIDESPREAD RAIN AT THE START OF THE DAY QUICKLY TAPERING OFF FROM
WEST TO EAST...THOUGH A FEW SHOWERS MAY STILL MANAGE TO HANG ON
THROUGH LATE AFTERNOON EAST OF LAKE ONTARIO. THIS STATED...CLOUDS
WILL BE SLOWER TO DEPART GIVEN BOTH FAIRLY PLENTIFUL LINGERING
MOISTURE AND A GENERAL NORTHWESTERLY FLOW AT THE LOWER LEVELS...
WITH SOME PARTIAL SUNSHINE ONLY RETURNING TO AREAS FROM THE
GENESEE VALLEY WEST BY LATE AFTERNOON.

USING A MULTI-MODEL CONSENSUS AS A GUIDE...IT APPEARS THAT OUR
REGION WILL LIKELY RECEIVE ANOTHER ONE TO TWO THIRDS OF AN INCH OF
RAINFALL OUT OF THIS NEXT SYSTEM. AS FOR TEMPS SUNDAY NIGHT AND
MONDAY...THE FAIRLY WIDESPREAD CLOUD COVER AND PRECIP EXPECTED
SHOULD RESULT IN A SMALLER DIURNAL RANGE IN READINGS THAN WHAT
MIGHT BE TYPICALLY EXPECTED...WITH SLIGHTLY ABOVE NORMAL LOWS IN
THE LOWER TO MID 40S SUNDAY NIGHT FOLLOWED BY BELOW NORMAL HIGHS
IN THE MID 50S MONDAY.

MONDAY NIGHT AND TUESDAY...OUR REGION WILL BE SITUATED DIRECTLY
UNDER A RIDGE OF HIGH PRESSURE BETWEEN YET ANOTHER WAVE OF LOW
PRESSURE TRACKING ACROSS VIRGINIA AND THE DELMARVA REGION...AND A
DEVELOPING FRONTAL SYSTEM THAT WILL BE IN THE PROCESS OF SLIDING
ACROSS THE UPPER GREAT LAKES. AT THIS POINT...IT STILL APPEARS
THAT THE RELATIVELY DRIER AIR AND ZONE OF COMPENSATING SUBSIDENCE
ASSOCIATED WITH THE SURFACE RIDGE SHOULD LARGELY TEND KEEP OUR
REGION QUIET AND DRY THROUGH TUESDAY... THOUGH WE WILL NEED TO
KEEP AN CLOSE EYE ON THE SYSTEM PASSING BY TO OUR SOUTH OVER THE
NEXT DAY OR TWO...AS SOME OF THE GUIDANCE HAS TRENDED A BIT
FURTHER NORTH WITH ITS TRACK OVER THE PAST 24 HOURS. WERE THIS
TREND TO CONTINUE...IT IS POSSIBLE THAT ITS NORTHERN FRINGES COULD
BRING SOME ADDITIONAL RAIN TO PORTIONS OF OUR AREA FOR AT LEAST A
BRIEF PERIOD LATER MONDAY NIGHT AND TUESDAY. OTHERWISE...TEMPERATURES
MONDAY NIGHT AND TUESDAY SHOULD AVERAGE OUT RIGHT AROUND NORMAL
FOR EARLY MAY...WITH LOWS IN THE UPPER 30S TO LOWER 40S MONDAY
NIGHT FOLLOWED BY DAYTIME HIGHS IN THE LOWER TO MID 60S ON
TUESDAY.

FINALLY...TUESDAY NIGHT AND WEDNESDAY WILL FEATURE DEEPENING
LARGE-SCALE TROUGHING ACROSS THE UPPER GREAT LAKES...WITH ITS
ATTENDANT WEAK SURFACE WAVE AND TRAILING COLD FRONT SLOWLY
PROGRESSING EASTWARD INTO OUR REGION AND GRADUALLY BEGINNING TO
MERGE WITH ANOTHER RATHER BROAD AND ILL-DEFINED SYSTEM SITUATED
ALONG/NEAR THE EAST COAST. FOR OUR AREA...THIS WILL TRANSLATE INTO
THE POTENTIAL FOR SOME SCATTERED SHOWERS RETURNING TO OUR REGION
BY WEDNESDAY...WHILE TEMPERATURES REMAIN RIGHT AROUND NORMAL
LEVELS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
A COOLER PATTERN DEVELOPS FOR THE LATTER PORTIONS OF NEXT WEEK AS A
TROUGH IS FORECAST TO DEEPEN OVER THE EAST COAST. 00Z MODELS SHOW
THIS TROUGH WILL EVENTUALLY EVOLVE INTO A CLOSED LOW OVER THE MID
ATLANTIC STATES BY LATE WEEK. UNFORTUNATELY...THIS PATTERN IS NOT
CONDUCIVE FOR WARM WEATHER ACROSS THE GREAT LAKES REGION. H85 TEMPS
FOR OUR REGION WILL GENERALLY BE IN THE LOWER SINGLE DIGITS...AND
THIS WILL EQUATE TO TEMPERATURES THAT WILL AVERAGE NEAR OR JUST
BELOW NORMAL EARLY MAY VALUES.

IN TERMS OF PRECIPITATION...BOTH THE 00Z GFS AND 00Z ECMWF SHOW
SEVERAL WET PERIODS THROUGH THE LONG TERM FORECAST PERIOD. THIS WILL
ALL BE LED IN BY A COLD FRONT WEDNESDAY NIGHT. THE PASSAGE OF THIS
FEATURE WILL PRODUCE SCATTERED SHOWERS OVER THE REGION...THEN THE
FRONT WILL BECOME ABSORBED WITHIN A COMPLEX COASTAL STORM SYSTEM
LATER THURSDAY AND FRIDAY WHICH MODELS SHOW WILL STALL OR SLOWLY
RETROGRADE WEST DUE TO A BLOCKED PATTERN OVER THE NORTH ATLANTIC.
TIMING AND MORE SPECIFIC LOCATION OF SHOWERS THROUGH THIS PERIOD
REMAINS UNCERTAIN AT THIS POINT SO BROAD BRUSH CHANCE POPS WILL
CONTINUE TO BE THE FLAVOR UNTIL MESO-MODELS CAN LOCK ONTO MORE
DETAIL.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
A LAYER OF MOISTURE REMAINS TRAPPED UNDERNEATH AN AREA OF HIGH
PRESSURE CURRENTLY IN PLACE ACROSS THE REGION. THIS WILL RESULT IN
MAINLY MVFR CIGS ACROSS THE SOUTHERN TIER INTO THIS EVENING.
ELSEWHERE...VFR CONDITIONS WILL EXIST AT KIAG/KBUF/KROC AND KART
AS DRIER AIR FILTERS IN FROM THE NORTH.

MID/HIGH CLOUDS WILL INCREASE FROM WEST TO EAST FROM 22Z ONWARDS
AS A WARM FRONT APPROACHES THE REGION. ANY IMPROVEMENT ACROSS THE
SOUTHERN TIER WILL DETERIORATE TO IFR TOWARDS THE END OF THE
FORECAST PERIOD AS RAIN WORKS ITS WAY NORTH INTO THE AREA TONIGHT.

OUTLOOK...

SUNDAY...VFR/MVFR WITH RAIN LIKELY. IFR CONDITIONS LIKELY ACROSS THE
SOUTHERN TIER.
MONDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
TUESDAY...MAINLY VFR.
WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A BROAD AREA OF HIGH PRESSURE MOVING ACROSS THE REGION WILL
MAINTAIN TRANQUIL CONDITIONS ON THE LAKES INTO THIS EVENING.

A EAST-NORTHEASTERLY FLOW WILL FRESHEN TONIGHT AS A LOW PRESSURE
SYSTEM TRACKING OUT OF THE MISSISSIPPI VALLEY TRACKS TOWARDS THE
LOWER GREAT LAKES. AS THE EAST-NORTHEASTERLY WINDS STRENGTHEN TO
NEAR 20 KNOTS...WAVES WILL BUILD IN EXCESS OF 4 FEET ON THE WEST END
OF LAKE ONTARIO BY SUNDAY MORNING...PROMPTING THE ISSUANCE OF A
SMALL CRAFT ADVISORY THROUGH THE DAY SUNDAY.

A GENERALLY WEAK PRESSURE GRADIENT WILL RESULT IN TRANQUIL
CONDITIONS ON THE LAKES FROM SUNDAY NIGHT INTO THE MID PART OF NEXT
WEEK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM TO 8 PM EDT SUNDAY FOR LOZ042.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...JJR
LONG TERM...RSH/SMITH
AVIATION...TMA
MARINE...TMA



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