Area Forecast Discussion
Issued by NWS Buffalo, NY

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896
FXUS61 KBUF 020032
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
832 PM EDT SUN MAY 1 2016

.SYNOPSIS...
ANOTHER ROUND OF RAIN IS EXPECTED TONIGHT AS AN AREA OF LOW PRESSURE
MOVES ACROSS THE LOWER GREAT LAKES. RAIN SHOULD DIMINISH 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 MONDAY/...
AS ABUNDANT LOW LEVEL MOISTURE REMAINS ACROSS THE REGION THIS
EVENING WILL HAVE AREAS OF FOG AND PATCHY DENSE FOG. EXPECT SHOWERS
SLATED FOR LATER TONIGHT TO REDUCE THE FOG.

MOST AREAS WILL SEE A LULL IN THE PRECIPITATION ACTIVITY INTO THIS
EVENING AS A SURFACE WARM FRONT RETREATS...ALTHOUGH SOME DRIZZLE OR
A FEW STRAY SHOWERS ARE POSSIBLE IN THE MOIST SOUTHWEST FLOW ALOFT.

ANOTHER ROUND OF WIDESPREAD RAIN IS EXPECTED TO SPREAD EAST ACROSS
WESTERN NEW YORK AS THE MAIN UPPER LOW ENTERS THE GREAT LAKES LATER
THIS EVENING OR SHORTLY AFTER MIDNIGHT. COVERAGE OF SHOWERS MAY
INITIALLY BE MORE SCATTERED IN NATURE UNTIL THE SURFACE REFLECTION
TAKES SHAPE OVERNIGHT. NEARLY ALL 12Z GUIDANCE ALONG WITH HIGHER
RESOLUTION MODELS SIGNIFICANTLY RAMP UP PROBABILITIES OVERNIGHT INTO
THE FIRST HALF OF MONDAY. TEMPERATURES WILL AGAIN SLIP BACK INTO THE
40S OVERNIGHT. ANOTHER COOL DAY IN STORE MONDAY WITH MOST HIGHS IN
THE 50S.

&&

.SHORT TERM /MONDAY NIGHT THROUGH THURSDAY/...
BY 00Z TUESDAY...THE SURFACE LOW RESPONSIBLE FOR THE SECOND ROUND
OF WIDESPREAD RAINFALL DUE TO AFFECT OUR REGION LATER TONIGHT AND
MONDAY WILL HAVE SLID EASTWARD TO THE NEW ENGLAND COASTLINE...WITH
THE TRAILING EDGE OF ITS RAIN SHIELD ALREADY HAVING RECEDED INTO
EASTERN NEW YORK. THUS...EXPECT OUR AREA TO BE PRECIPITATION-FREE
BY THE TIME WE REACH SUNSET...THOUGH PLENTY OF LEFTOVER LOW CLOUDS
WILL LIKELY STILL BE IN PLACE AWAY FROM THE IMMEDIATE LAKE PLAINS.

AS MONDAY NIGHT PROGRESSES...SURFACE-BASED RIDGING AND DRIER AIR
WILL GRADUALLY EXTEND EASTWARD ACROSS NEW YORK STATE...WHILE YET
ANOTHER WEAK WAVE OF LOW PRESSURE RIPPLES ACROSS THE VIRGINIAS AND
DELMARVA REGION. THIS LATTER SYSTEM SHOULD THUS REMAIN ON A FAR
ENOUGH SOUTH TRACK TO KEEP ITS ASSOCIATED RAIN SHIELD CONFINED TO
OUR SOUTHEAST... THUS THE NIGHT SHOULD REMAIN DRY WITH GRADUAL
DRYING AND SLOWLY INCREASING SUBSIDENCE ALSO HELPING TO DRIVE THE
LIMITED CLEARING FROM MONDAY AFTERNOON A BIT FURTHER INLAND...THOUGH
SKIES WILL LIKELY STILL REMAIN FAIRLY CLOUDY ACROSS INTERIOR
PORTIONS OF THE SOUTHERN TIER AND FINGER LAKES. TEMPERATURE-
WISE...EXPECT NEAR NORMAL LOWS IN THE UPPER 30S TO LOWER 40S.

ON TUESDAY...OUR REGION WILL BE SITUATED IN BETWEEN SYSTEMS...WITH
THE WAVE TO OUR SOUTH SLIDING EASTWARD AND OFF THE ATLANTIC
COASTLINE...AND THE NEXT FRONTAL SYSTEM SLOWLY DROPPING ACROSS THE
UPPER GREAT LAKES...IN ASSOCIATION WITH A SIGNIFICANT SURGE OF
SHORTWAVE ENERGY DIVING SOUTHWARD FROM CENTRAL CANADA. IN BETWEEN...
OUR REGION WILL BE EMBEDDED WITHIN A COMPENSATING ZONE OF RELATIVELY
DRIER AIR AND LARGE-SCALE SUBSIDENCE WHICH SHOULD PROMOTE CONTINUED
FAIR/DRY WEATHER...ALONG WITH A GENERAL INCREASE IN SUNSHINE AS
DAYTIME HEATING HELPS TO AT LEAST PARTIALLY MIX OUT SOME OF THE
LINGERING LOWER CLOUD COVER. MEANWHILE... 850 MB TEMPS OF +2C TO
+4C SHOULD SUPPORT DAYTIME HIGHS IN THE LOWER TO MID 60S...WHICH
IS DEAD-ON AVERAGE FOR EARLY MAY.

TUESDAY NIGHT...THE AREA WILL BECOME INCREASINGLY SQUEEZED
BETWEEN THE LINGERING SURFACE WAVE/FRONTAL ZONE JUST OFFSHORE OF
THE EAST COAST... AND THE DEEPENING UPPER LEVEL TROUGH/ATTENDANT
FRONTAL SYSTEM DIGGING SOUTHEASTWARD ACROSS THE WESTERN AND
CENTRAL GREAT LAKES...WITH A NARROWING COMPENSATING RIDGE OF HIGH
PRESSURE/RELATIVELY DRIER AIR REMAINING DRAPED ACROSS WESTERN AND
NORTH CENTRAL NEW YORK. OVERALL PATTERN RECOGNITION AND PAST
EXPERIENCE BOTH SUGGEST THAT THIS SHOULD CONTINUE TO PROMOTE
MAINLY DRY WEATHER ACROSS OUR AREA THROUGH THE NIGHT...WHILE ALSO
CASTING CONSIDERABLE DOUBT UPON THE PRECIP BEING SPIT OUT BY THE
CANADIAN GEM AND ESPECIALLY THE NAM...WHICH LOOKS PARTICULARLY
OVERDONE. WITH THIS IN MIND...HAVE ELECTED TO PULL POPS FOR
TUESDAY NIGHT BACK INTO THE SLIGHT CHANCE RANGE...WITH MAINLY DRY
CONDITIONS AND PARTLY CLOUDY SKIES EXPECTED TO PREVAIL. AS FOR
TEMPS...LOWS SHOULD BE IN THE LOWER TO MIDDLE 40S...OR A LITTLE
ABOVE AVERAGE.

AFTER THAT...THE SECOND HALF OF THIS PERIOD WILL FEATURE A
DECIDED TURN TO MORE UNSETTLED AND EVENTUALLY COOLER WEATHER AS
PRONOUNCED UPPER LEVEL TROUGHING DIGS ACROSS THE EASTERN THIRD OF
THE NATION... AND BECOMES THE EASTERN COMPONENT OF A RATHER
IMPRESSIVE OMEGA BLOCK DEVELOPING ACROSS NORTH AMERICA. AT THE
SURFACE...THE DIGGING UPPER TROUGH WILL ENCOURAGE THE GRADUAL
MERGING OF THE GREAT LAKES AND COASTAL SURFACE WAVES INTO A
SINGLE...BUT ALSO RATHER BROAD AND DIFFUSE LOW THAT WILL EXTEND
ACROSS ALMOST THE ENTIRE LENGTH OF THE APPALACHIANS AND THE
EASTERN SEABOARD.

AS THE ABOVE PATTERN TAKES SHAPE...THE COMBINATION OF THE MERGING
SURFACE FEATURES...SPOKES OF ENERGY ROTATING THROUGH THE DEEPENING
UPPER TROUGH...AND SLOWLY COOLING AIR ALOFT WILL LEAD TO PERIODIC
OPPORTUNITIES FOR AT LEAST SOME SCATTERED SHOWERS IN THE WEDNESDAY
THROUGH THURSDAY TIME FRAME. GIVEN THE INHERENT DIFFICULTIES IN
PINNING DOWN THE EXACT TIMING AND PLACEMENT OF THE FEATURES
DRIVING ANY SUCH SHOWERS THIS FAR IN ADVANCE IN THIS KIND OF
PATTERN...FOR NOW HAVE ELECTED TO COVER THIS POTENTIAL WITH
BROADBRUSH HIGH CHANCE POPS FROM WEDNESDAY ON THROUGH THE END OF
THE PERIOD...THOUGH IT SHOULD BE NOTED THAT THERE WILL ALSO LIKELY
BE SOME RAIN FREE PERIODS.

WITH RESPECT TO TEMPS...850 MB TEMPS STILL IN THE +2C TO +4C
RANGE SHOULD TRANSLATE INTO ANOTHER DAY OF HIGH TEMPERATURES IN
THE LOWER TO MID 60S ON WEDNESDAY...BEFORE SLOW COOLING OF OUR
AIRMASS RESULTS IN READINGS PULLING BACK TO THE MID AND UPPER 50S
FOR THURSDAY. IN BETWEEN...LOWS WEDNESDAY NIGHT WILL RANGE IN THE
LOWER TO MID 40S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS WAS THE CASE IN PREVIOUS GUIDANCE PACKAGES...THE ECMWF AND GFS
ENSEMBLES ARE STILL STRONGLY SUGGESTING THAT TWIN...DEEP CLOSED LOWS
WILL DEVELOP NEAR BOTH COASTS LATE IN THE WEEK...WHILE RIDGING WILL
DOMINATE THE CENTER OF THE COUNTRY. WHILE THERE IS HIGH CONFIDENCE
OF THIS GENERAL PATTERN...THERE HAS BEEN A FAIRLY SIGNIFICANT SHIFT
IN THE THINKING FOR THE POSITION OF THE EAST COAST CLOSED LOW BY THE
WEEKEND.

ALL OF THE MODELS ARE NOW PUSHING THE STACKED CLOSED LOW FURTHER TO
THE SOUTHEAST. THIS WILL ALLOW RIDGING FROM THE CENTER OF THE
COUNTRY TO NOSE ACROSS THE GREAT LAKES REGION...WITH THE BULK OF THE
MOISTURE FROM THE CLOSED LOW BEING SHUNTED ACROSS THE MID ATLANTIC
STATES. OUR FORECAST AREA WILL FIND ITSELF BETWEEN THE CLOSED MID
LEVEL CIRCULATION OFF THE COAST...AND EVENTUALLY A DIGGING TROUGH
OVER THE UPPER LAKES. THE GENERAL AREA OF SUBSIDENCE BETWEEN THE TWO
WILL OFFER MORE RAIN FREE CONDITIONS THAN ORIGINALLY ANTICIPATED...
AND CERTAINLY HIGHER TEMPERATURES. INSTEAD OF NEAR TO BELOW NORMAL
MERCURY READINGS...WE SHOULD CLIMB TO ABV NORMAL LEVELS FOR BOTH
DAYS OF THE WEEKEND WITH MAX`S RANGING FROM 65 TO AS HIGH AS 70 (SRN
TIER AND GEN VALLEYS).

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
EXPECT IFR CEILINGS FOR  MOST LOCATIONS THROUGH THE NIGHT AND LIFR
WITH AREAS OF FOG AND LOCALLY DENSE FOG ACROSS WESTERN NY TO THE
FINGER LAKES. CONDITIONS ARE EXPECTED TO IMPROVE AFTER 10Z AS STEADY
RAIN SHOWERS OVERSPREAD THE REGION AND THIN THE FOG OUT. LOW MVFR
CEILINGS SHOULD PERSIST THROUGH MUCH OF THE DAY ON MONDAY WITH THE
PRESENCE OF THE UPPER LOW.

OUTLOOK...
MONDAY...MVFR WITH SHOWERS.
TUESDAY...MAINLY VFR.
WEDNESDAY THROUGH FRIDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A EAST-NORTHEASTERLY FLOW OF 15 TO 20 KNOTS NORTH OF AN ADVANCING
SURFACE WARM FRONT ON LAKE ONTARIO WILL GRADUALLY DIMINISH THROUGH
TONIGHT. CHOPPY CONDITIONS WILL EXIT FOR A PERIOD INTO THIS EVENING
ON THE WESTERN END OF LAKE ONTARIO WITH WAVE HEIGHT AROUND 3 FEET.

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...NONE.

&&

$$

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



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