Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 010628
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
228 AM EDT SUN MAY 1 2016

.SYNOPSIS...
A WARM FRONT LIFTING OUT OF THE OHIO VALLEY WILL CONTINUE TO SPREAD
RAIN ACROSS THE FORECAST AREA THIS MORNING. RAIN WILL TAPER TO
SCATTERED SHOWERS WITH A CHANCE OF THUNDERSTORMS THIS AFTERNOON AND
EVENING WITH ANOTHER ROUND OF MORE WIDESPREAD RAIN TONIGHT AS AN
AREA OF LOW PRESSURE MOVES ACROSS THE LOWER GREAT LAKES. RAIN 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 TODAY/...
RADARS ARE SHOWING AN AREA OF WIDESPREAD RAIN SHIFTING NORTHEAST
ACROSS WESTERN NEW YORK EARLY THIS MORNING. THE RAIN IS OCCURRING AS
MOISTURE IS TRANSPORTED NORTH OVER AND AHEAD OF A SURFACE WARM FRONT
SHIFTING ACROSS THE OHIO VALLEY. EXPECTING THE RAIN TO CONTINUE TO
OVERSPREAD THE FINGER LAKES INTO CENTRAL NEW YORK THROUGH THE
MORNING HOURS WITH RAIN TAPERING OFF ON THE BACK EDGE ACROSS FAR
WESTERN NEW YORK TOWARD SUNRISE. TEMPERATURES THIS MORNING WILL
REMAIN MILD WITH CLOUDS AND RAIN ONLY SLIPPING INTO THE 40S.

WHILE THE SURFACE WARM FRONT IS NOT EXPECTED TO SHIFT NORTH OF THE
NY/PA LINE...ELEVATED WARM ADVECTION WILL OVERSPREAD THE FORECAST
AREA BY THIS AFTERNOON WITH SOME WEAK INSTABILITY AND LARGE SCALE
LIFT CONTRIBUTING TO CHANCES OF SCATTERED SHOWERS AND
THUNDERSTORMS. MESO-MODELS INDICATE THE BEST INSTABILITY IN THE FORM
OF 500-1000 J/KG OF MUCAPE AND MID-LEVEL LAPSE RATES IN EXCESS OF
7C/KM WILL DEVELOP ACROSS THE SOUTHERN TIER INTO THE FINGER
LAKES THIS AFTERNOON WHERE THE FORECAST HAS BEEN TWEAKED TO
HIGHLIGHT A LIKELY AREA OF SHOWERS AND THUNDERSTORMS. THE TRIGGER
FOR STORMS WILL LIKELY BE A WEAK LOW TRACKING TOWARD NORTHEAST PA.
BULK SHEAR IS FORECAST TO REACH 40-50KTS HERE WHERE A FEW STORMS MAY
BECOME STRONG. TEMPERATURES THIS AFTERNOON WILL MAX OUT IN THE
M/U50S FOR MUCH OF WESTERN NEW YORK WITH U40S/L50S EAST OF LAKE
ONTARIO.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
ANOTHER VIGOROUS MID LEVEL TROUGH IS FORECAST TO SLIDE EASTWARD
ACROSS THE GREAT LAKES TONIGHT...WITH ITS ASSOCIATED SURFACE WAVE
CROSSING OVER THE OHIO VALLEY. THE COMBINATION OF A 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 SATURDAY/...
IT WILL BE COOL AND UNSETTLED DURING THIS PERIOD...AS A HIGHLY
AMPLIFIED UPPER LEVEL FLOW OVER THE COUNTRY WILL EVENTUALLY EVOLVE
TYPICAL TWIN CLOSED LOWS NEAR EACH COAST. FOR OUR CONCERNS...THE
DEEPLY STACKED LOW IN THE EAST IS EXPECTED TO BE CENTERED OVER
PENNSYLVANIA OR WESTERN NEW YORK FOR A MAJORITY OF THIS PERIOD. THIS
SOLUTION HAS BEEN VERY CONSISTENT FOR SEVERAL RUNS OF THE ECMWF
ENSEMBLES...AND IS NOW BEING ADVERTISED BY THE BULK OF THE GEFS
MEMBERS. THE HIGHEST CHANCE FOR PRECIPITATION SHOULD COME THURSDAY
AND FRIDAY...ALTHOUGH NO ONE PERIOD IS EXPECTED TO BE PRECIPITATION
FREE. NOTE THAT I AM USING THE TERM PRECIPITATION RATHER THAN JUST
RAIN OR RAIN SHOWERS.

THE OPERATIONAL ECMWF IS A LITTLE `COLDER` WITH ITS GENERAL SOLUTION
THAN ITS NORTH AMERICAN COUNTERPART (GFS). THIS MAY BECOME AN ISSUE
THURSDAY AND/OR FRIDAY NIGHT(S) WHEN H85 TEMPS OVER OUR REGION ARE
FORECAST TO BE VERY CLOSE TO ZERO (C). IT WOULD NOT TAKE MUCH TO
ENVISION SOME WET SNOW ACROSS THE HIGHER TERRAIN WITH THIS SOLUTION.
THIS IS EXACTLY THE KIND OF UPPER LEVEL PATTERN THAT SUPPORTS SUCH
ANOMALOUS MAY SNOWFALL...SO IT WILL BE INTERESTING TO SEE HOW THIS
DEVELOPS. GIVEN THE LOW CONFIDENCE THOUGH...WILL NOT ACTUALLY
INTRODUCE SNOW TO THE FORECAST AT THIS TIME...BUT RATHER JUST BRING
IT UP IN THIS DISCUSSION. STAY TUNED.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
A WARM FRONT WILL CONTINUE TO SPREAD A BAND OF STEADY RAIN NORTHEAST
ACROSS THE FORECAST AREA THIS MORNING. CEILINGS WILL LOWER TO THE
LOWER END OF MVFR SCALE TOWARD SUNRISE AS THE FRONT STALLS ACROSS
THE AREA. EXPECT IFR TO LIFR AT JHW AND ACROSS THE HILLS OF THE
SOUTHERN TIER. WIDESPREAD RAIN WILL TAPER TO SCATTERED SHOWERS WITH
LINGERING MVFR CIGS THROUGH MUCH OF SUNDAY. THERE IS A CHANCE OF
CONVECTION ON SUNDAY AFTERNOON MAINLY TOWARD THE NY/PA BORDER AS
INSTABILITY DEVELOPS NEAR THE STALLED WARM FRONT. THIS MAY IMPACT
KJHW BUT CONFIDENCE IS TOO LOW AT THIS TIME TO INCLUDE VCTS IN THE
TAF.

SCATTERED SHOWERS WILL CONTINUE TO BE POSSIBLE THIS EVENING INTO THE
OVERNIGHT AHEAD OF A SECOND ROUND OF WIDESPREAD RAIN THAT WILL
OVERSPREAD MUCH OF THE FORECAST AREA LATE SUNDAY NIGHT. THIS WILL
AGAIN LOWER CIGS TO MVFR FOR MOST WITH IFR POSSIBLE IN THE SOUTHERN
TIER.

OUTLOOK...

MONDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
TUESDAY...MAINLY VFR.
WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A EAST-NORTHEASTERLY FLOW WILL FRESHEN TODAY AS A LOW PRESSURE
SYSTEM TRACKING OUT OF THE OHIO 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 LATER THIS MORNING...PROMPTING THE SMALL CRAFT ADVISORY
THROUGH THE DAY.

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

&&

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

&&

$$

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


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