Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 220018
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
818 PM EDT MON APR 21 2014

.SYNOPSIS...
A COLD FRONT WILL BRING A ROUND OF SHOWERS LATE TONIGHT AND TUESDAY.
COOLER AIR WILL BUILD BEHIND THIS FRONT...WITH RAIN OR SNOW SHOWERS
LINGERING ACROSS HIGHER TERRAIN TUESDAY NIGHT. TEMPERATURES WILL
THEN GRADUALLY WARM THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 00Z...A WEAK SHORT WV LOCATED OVER IL/IN WILL EJECT NEWD THIS
EVENING AHEAD OF A COLD FRONT EXPECTED TO MOVE THROUGH THE LOWER
GREAT LAKES TUESDAY. REGIONAL RADARS SHOW A BROAD SWATH OF MAINLY
LT/MOD SHRA ORIENTED SW TO NE ACROSS MICHIGAN INTO NORTHERN IL/IN.
SCT LT RETURNS CAN BE FOUND OVER OH...WHICH IS PRIMARILY FALLING AS
VIRGA W/SUCH A DRY AIR MASS IN PLACE AT THE LOWER LEVELS. AS THE
SHORT WV OVER IL/IN CONTINUES TO MOVE NEWD EXPECT A RAPID INCREASE
IN MID/HIGH LEVEL CLOUDINESS ACROSS THE EASTERN GREAT LAKES W/MOSTLY
CLOUDY SKIES AND POSSIBLY A FEW SPRINKLES TONIGHT.

THE UPPER LEVEL SHORTWAVE OVER ONTARIO CANADA AND ITS ASSOCIATED
COLD FRONT WILL APPROACH THE REGION LATE TONIGHT. LATEST MODEL
GUIDANCE (NAM/RGEM/SREF/GFS) IS FAIRLY CLOSE IN TERMS OF
TIMING...BUT THE CONSENSUS IS AN HOUR OR TWO FASTER THAN PREVIOUS
RUNS. THE FRONTAL PASSAGE SHOULD BE FAIRLY WELL ALIGNED WITH THE
UPPER TROF...WHICH INCREASES CONFIDENCE IN LIGHT BUT MEASURABLE
PRECIPITATION. SHOWERS SHOULD ONLY LAST A FEW HOURS...FIRST ENTERING
FAR WESTERN NEW YORK AROUND DAYBREAK...THEN SWEEPING ACROSS THE
GENESEE VALLEY AROUND NOON BEFORE EXITING EAST OF THE CWA LATE
AFTERNOON. BOTH SURFACE BASED AND ELEVATED INSTABILITY APPEAR
LIMITED WITH THIS FRONT...WHICH STILL SUGGESTS THERE WILL PROBABLY
NOT BE ANY THUNDERSTORMS. EXPECT ABOUT A QUARTER INCH OF RAIN FROM
THIS SYSTEM.

CLOUDS AND INCREASING WINDS SHOULD LIMIT RADIATIONAL COOLING
TONIGHT...WITH LOWS MAINLY IN THE LOWER 50S. TEMPERATURES WILL RISE
VERY LITTLE ON TUESDAY WITH THE FRONTAL PASSAGE. THE WARMEST
TEMPERATURES WILL BE TO THE SOUTH AND EAST...WITH HIGHS IN THE LOWER
60S BEFORE TEMPERATURES DROP LATE IN THE DAY BEHIND THE FRONT.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A MID LEVEL DRY SLOT WILL PROVIDE A BRIEF BREAK IN PRECIP TUESDAY
EVENING FOR MOST AREAS...ALTHOUGH A FEW SHOWERS MAY LINGER ACROSS
THE NORTH COUNTRY ESPECIALLY IN UPSLOPE AREAS. OVERNIGHT THE MID
LEVEL TROUGH WILL SHARPEN OVER NEW ENGLAND...WITH A NOTABLE
SECONDARY VORTICITY MAXIMA ROTATING ACROSS LAKE ONTARIO AND NORTHERN
NY BETWEEN 06Z AND 12Z WED. THIS WILL PROVIDE SOME INCREASE IN LARGE
SCALE ASCENT...AND ALSO BRING WITH IT AN AREA OF WRAP AROUND
MOISTURE. THIS WILL PRODUCE INCREASING CHANCES OF PRECIPITATION
AGAIN OVERNIGHT AND INTO WEDNESDAY MORNING. THE MOIST CYCLONIC
NORTHWEST FLOW WILL ALSO ALLOW FOR ENHANCEMENT FROM UPSLOPE
PROCESSES ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND
NORTHERN/WESTERN FINGER LAKES AND EVENTUALLY EAST OF LAKE ONTARIO.

LOW LEVEL COLD ADVECTION WILL BRING STEADILY FALLING TEMPERATURES
OVERNIGHT. BY DAYBREAK WEDNESDAY EXPECT TEMPS IN THE MID TO UPPER
30S ACROSS THE LOW ELEVATIONS...AND LOWER 30S ACROSS HIGHER TERRAIN.
THIS WILL ALLOW RAIN SHOWERS TO MIX WITH AND CHANGE TO WET SNOW LATE
TUESDAY NIGHT INTO WEDNESDAY MORNING ACROSS THE HIGHER TERRAIN...AND
A FEW WET FLAKES MAY ALSO MIX IN AT LOWER ELEVATIONS IF ENOUGH
PRECIP REMAINS BY THE TIME TEMPERATURES BOTTOM OUT EARLY WEDNESDAY.
THERMAL PROFILES AND HIGHER RESOLUTION MODEL GUIDANCE SUCH AS THE
NAM AND CANADIAN REGIONAL GEM EVEN POINT TO THE POTENTIAL FOR ENOUGH
UPSLOPE TO PRODUCE SOME MINOR SLUSHY ACCUMULATIONS ON THE HILLS WITH
UP TO AN INCH POSSIBLE ABOVE ABOUT 1200FT.

ON WEDNESDAY DEEPER WRAP AROUND MOISTURE AND ANY REMAINING SYNOPTIC
SCALE ASCENT WILL SLOWLY MOVE EAST OF THE AREA...BRINGING AN END TO
THE RAIN/SNOW SHOWERS FROM WEST TO EAST. COLD AIR ALOFT AND CYCLONIC
NORTHWEST FLOW REMAIN...SO CLOUDS WILL LIKELY HANG TOUGH MUCH OF THE
DAY BEFORE SOME CLEARING LATER IN THE AFTERNOON. THIS CLEARING WILL
LIKELY START AT LOWER ELEVATIONS NEAR THE LAKES AS LAKE SHADOWS
DEVELOP...WITH CLEARING LAST ACROSS HIGHER TERRAIN DUE TO UPSLOPE
FLOW. 850MB TEMPS REMAIN AROUND -5C ALL DAY...WHICH WILL ONLY
SUPPORT HIGHS IN THE UPPER 40S AT LOWER ELEVATIONS AND MID 40S AT
BEST ACROSS HIGHER TERRAIN. THE COOL TEMPERATURES WILL ALSO BE
ACCOMPANIED BY A BRISK NORTHWEST FLOW WITH GUSTS IN THE 30-35 MPH
RANGE.

WEDNESDAY NIGHT AND THURSDAY A SURFACE RIDGE WILL GRADUALLY BUILD
FROM THE MIDWEST INTO THE LOWER LAKES REGION. THIS WILL ALLOW
CLEARING SKIES WEDNESDAY NIGHT AND DIMINISHING WINDS FROM WEST TO
EAST. THE COOL AIRMASS AND CLEARING SKIES WILL ALLOW FOR A COLD
NIGHT BY LATE APRIL STANDARDS...WITH LOWS IN THE UPPER 20S TO LOWER
30S ON THE LAKE PLAINS AND LOW TO MID 20S IN THE COOLER INTERIOR
LOCATIONS.

TEMPERATURES WILL BEGIN TO RECOVER SOME ON THURSDAY WITH HIGHS BACK
INTO THE MID 50S IN MANY AREAS. EXPECT PLENTY OF SUNSHINE WITH JUST
SOME INCREASE IN MID/HIGH CLOUDS ESPECIALLY ACROSS WESTERN NY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE LONG TERM HAS THE POTENTIAL TO BE QUITE UNSETTLED WITH A BRIEF
WARM-UP AT THE END OF THE WEEK FOLLOWED BY WELL BELOW AVERAGE
TEMPERATURES NEXT WEEKEND.

LOOKING AT THE DETAILS...LATE THURSDAY NIGHT AND FRIDAY A MID LEVEL
SHORTWAVE AND WARM OCCLUSION AT THE SURFACE WILL SWING QUICKLY EAST
ACROSS THE REGION WITH A CHANCE OF A FEW SHOWERS. THE RAIN SHOULD BE
BRIEF AT ANY GIVEN LOCATION AND SHOULD BE MAINLY IN THE MORNING
ACROSS WESTERN NY. A WARMER AIRMASS WILL MAKE A BRIEF APPEARANCE
INTO THE LOWER LAKES REGION WITH MOST AREAS REACHING THE LOW TO MID
60S FOR HIGHS.

MODEL GUIDANCE QUICKLY DIVERGES WITH RESPECT TO THE SYNOPTIC SCALE
EVOLUTION OVER THE WEEKEND...ALTHOUGH BOTH THE GFS AND ECMWF AND
MOST ENSEMBLES SUPPORT A TURN TOWARDS MUCH COLDER TEMPERATURES. THE
ECMWF SWINGS A PROGRESSIVE MID LEVEL CUTOFF THROUGH ONTARIO AND
QUEBEC OVER THE WEEKEND BEFORE REACHING THE CANADIAN MARITIMES ON
MONDAY...WITH A TROUGH DELIVERING A MUCH COOLER AIRMASS INTO THE
GREAT LAKES AND NORTHEAST. THE CUTOFF LOW IN THIS SCENARIO WOULD BE
FAR ENOUGH NORTH AND EAST TO KEEP OUR REGION MAINLY DRY.

THE GFS ON THE OTHER HAND RETROGRADES THE CLOSED LOW ON SUNDAY AND
MONDAY...KEEPING IT OVER OR JUST EAST OF NEW ENGLAND. THIS WOULD BE
CLOSE ENOUGH TO KEEP MORE WRAP AROUND MOISTURE AND PRECIP CHANCES
ACROSS OUR REGION...AND WITH THE COLDER AIR SOME OF THIS MAY BE IN
THE FORM OF WET SNOW...ESPECIALLY DURING THE LATE NIGHT AND EARLY
MORNING HOURS. GIVEN THE MODEL DISAGREEMENT...HAVE KEPT CHANCE POPS
THROUGH THE WEEKEND AND INTO MONDAY WITH SOME MIX OF SNOW AT TIMES.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AS OF 00Z...A WEAK SHORT WV LOCATED OVER IL/IN WILL EJECT NEWD THIS
EVENING AHEAD OF A COLD FRONT EXPECTED TO MOVE THROUGH THE LOWER
GREAT LAKES TUESDAY. REGIONAL RADARS SHOW SCT LT RETURNS WHICH IS
PRIMARILY FALLING AS VIRGA W/SUCH A DRY AIR MASS IN PLACE AT THE
LOWER LEVELS. EXPECT CONTINUAL VFR W/INCREASING MID-HIGH LEVEL
CLOUDS AND POSSIBLY A FEW SPRINKLES THE FIRST HALF OF TONIGHT. AS
THE COLD FRONT APPROACHES...SHOWERS WILL LOWER CIGS AND POSSIBLY
VSBY TOWARD DAYBREAK ON TUESDAY...WITH MOST SITES LOWERING TO MVFR
FOR 3 TO 6 HOURS. A PERIOD OF IFR IS POSSIBLE...WITH THE BEST
CHANCE FOR THIS AT JHW. CONDITIONS SHOULD IMPROVE SOME TUESDAY
AFTERNOON WITH THE EXIT OF THE FRONT...WITH A MIX OF VFR/MVFR CIGS
LINGERING.

OUTLOOK...
TUESDAY NIGHT AND EARLY WEDNESDAY...VFR/MVFR. A CHANCE OF RAIN
SHOWERS OR SNOW SHOWERS ACROSS HIGHER TERRAIN.
WEDNESDAY AFTERNOON THROUGH THURSDAY...VFR.
FRIDAY AND SATURDAY...VFR/MVFR. A CHANCE OF SHOWERS.

&&

.MARINE...
WINDS WILL REMAIN ON THE LIGHT SIDE UNTIL WINDS INCREASE WITH A
FRONTAL BOUNDARY ON TUESDAY. NORTHWEST WINDS WILL INCREASE TO
SMALL CRAFT ADVISORY LEVELS LATE TUESDAY THROUGH THURSDAY MORNING
ON LAKE ONTARIO. HIGH PRESSURE WILL BUILD BACK ACROSS THE LOWER
LAKES LATER THURSDAY WITH DIMINISHING WINDS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM TUESDAY TO 11 AM EDT THURSDAY
         FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM 8 PM TUESDAY TO 11 PM EDT
         WEDNESDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM 8 PM TUESDAY TO 11 AM EDT
         THURSDAY FOR LOZ045.

&&

$$

SYNOPSIS...AR/APFFEL
NEAR TERM...AR/APFFEL
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...AR/APFFEL
MARINE...AR/APFFEL








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