Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 241128
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
728 AM EDT TUE MAR 24 2015

.SYNOPSIS...
HIGH PRESSURE CENTERED JUST TO OUR NORTH WILL CONTINUE TO SUPPORT
CHILLY AND DRY WEATHER TODAY. A STRONG WARM FRONT WILL THEN PUSH
NORTH ACROSS THE AREA WEDNESDAY WITH RAIN SHOWERS AND NOTABLY HIGHER
TEMPERATURES FOR THE MIDDLE OF THE WEEK BEFORE COLD WEATHER RETURNS
BY FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING AN AREA OF HIGH PRESSURE CENTERED JUST TO OUR NORTH
WILL PROVIDE FOR DRY...BUT CHILLY WEATHER TODAY. A MID LEVEL
SHORTWAVE CROSSING FROM THE CENTRAL GREAT LAKES TO THE EASTERN GREAT
LAKES THIS MORNING WILL BRING A SEVERAL HOUR PERIOD OF MID AND HIGH
LEVEL CLOUDINESS ACROSS MUCH OF THE REGION THIS MORNING. AS THIS
SHORTWAVE CARRIES EASTWARD MIDDAY...SUBSIDENCE BEHIND THE FEATURE
WILL BRINGS A WEALTH OF SUNSHINE TO THE AREA THIS AFTERNOON.

IT WILL REMAIN BELOW NORMAL TEMPERATURE-WISE THOUGH NOT AS COLD AS
YESTERDAY. A RETREATING COLD AIRMASS ALOFT WILL ALLOW FOR AFTERNOON
HIGHS TO CLIMB TOWARDS 30F EAST OF LAKE ONTARIO...AND A FEW DEGREES
ABOVE FREEZING SOUTH OF LAKE ONTARIO.

TONIGHT WILL START WITH CLEAR SKIES AND LIGHT WINDS...ALLOWING FOR
TEMPERATURES TO QUICKLY DROP THROUGH THE EVENING HOURS. TEMPERATURES
WILL DROP THE LONGEST EAST OF LAKE ONTARIO WHERE OVERNIGHT LOWS WILL
REACH THE LOW TEENS. TO OUR WEST MID AND HIGH LEVEL CLOUDS WILL
BEGIN TO INCREASE WITHIN A SOUTHERLY FLOW. THIS WILL SLOW THE
OVERNIGHT COOLING...AND LIKELY START TO WARM THE SURFACE
TEMPERATURES LATE OVERNIGHT.

FLOW FROM BOTH THE ATLANTIC AND GULF OF MEXICO WILL INCREASE
MOISTURE THROUGH THE LATE NIGHT OVER THE OHIO VALLEY. AS A WARM
FRONT NEARS THE REGION FROM THE OHIO VALLEY A RAIN OR LOWER
CHANCE...WET SNOW SHOWER IS POSSIBLE JUST BEFORE DAYBREAK WEDNESDAY
MORNING ACROSS THE FAR WESTERN SOUTHERN TIER.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
PRECIPITATION WILL EXPAND INTO THE AREA FROM THE SOUTHWEST
WEDNESDAY...STARTING ACROSS WESTERN NEW YORK BY EARLY TO MID MORNING
AND REACHING THE NORTH COUNTRY BY EARLY AFTERNOON. THE PRECIPITATION
WILL BE ASSOCIATED WITH A FAST MOVING SURFACE WAVE MOVING FROM THE
CENTRAL GREAT LAKES INTO ONTARIO AND SURFACE WARM FRONT. MODEL
GUIDANCE HAS BEEN QUITE CONSISTENT DEPICTING A 50-65 KNOT LOW LEVEL
JET DEVELOPING INTO THE SOUTHERN AND EASTERN GREAT LAKES. STRONG
LOW LEVEL MOISTURE ADVECTION/TRANSPORT ASSOCIATED WITH THIS LOW
LEVEL JET WILL ADVECT A 0.75 INCH PRECIPITABLE WATER AXIS INTO
WESTERN NEW YORK WEDNESDAY MORNING. RAINFALL AMOUNTS CONTINUE TO
LOOK RELATIVELY LIGHT WITH BASIN AVERAGES LESS THAN A TENTH OF AN
INCH. PRECIPITATION COULD START AS A VERY BRIEF WINTRY MIX
ESPECIALLY ACROSS THE SOUTHERN TIER VALLEYS...BUT FOR THE MOST
PART THIS WILL BE A RAIN EVENT.

PRONOUNCED DRY SLOT SHOULD OVERSPREAD THE AREA BEHIND THE WARM FRONT
AS STRONGER DPVA LIFTS NORTH OF THE AREA. THIS WILL BRING A
TEMPORARY LULL IN THE RAIN WEDNESDAY AFTERNOON AND EVENING.  GIVEN
STRENGTH OF ADVECTIVE FIELDS...WILL MAINTAIN HIGHS IN THE LOWER TO
MID 50S...AND MID 40S ACROSS THE INTERIOR SOUTHERN TIER AND EAST OF
LAKE ONTARIO. WEDNESDAY STILL LOOKS TO BE RATHER BREEZY...AS A
PORTION OF THE STRONG LOW LEVEL JET MIXES DOWN.

TEMPERATURES WILL REMAIN MILD WEDNESDAY NIGHT AND AT LEAST A
PORTION OF THURSDAY BEFORE COLDER AIR BEGINS TO FILTER BACK INTO
THE REGION.

RAIN CHANCES SHOULD RAMP UP AGAIN LATE WEDNESDAY NIGHT AND
THURSDAY...AS THE NEXT UPSTREAM WAVE INDUCES A MID LEVEL
FRONTOGENETIC RESPONSE ACROSS THE AREA. BETTER INSTABILITY LOOKS
TO BE SUPPRESSED JUST SOUTH OF LOCAL AREA SO HAVE OMITTED THUNDER
MENTION AT THIS TIME...BUT WITH A GULF MOISTURE CONNECTION SHOULD
SEE ENHANCED RAINFALL AMOUNTS OF AT LEAST A HALF INCH. FOR MORE
INFORMATION ON POTENTIAL HYDROLOGIC CONCERNS SEE THE HYDROLOGY
SECTION BELOW.

TEMPERATURES WILL BEGIN TO DROP FROM NORTH TO SOUTH LATER THURSDAY
AS COLDER AIR BLEEDS IN TO THE NORTH OF THE FRONTAL WAVE...WITH A
MORE SUBSTANTIAL DROP THURSDAY NIGHT THROUGH THE LONG TERM PERIOD.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
BEHIND THE MIDWEEK SYSTEM THE LONGWAVE PATTERN ACROSS NORTH AMERICA
WILL FLIP BACK TO THE SAME PATTERN WHICH HAS PLAGUED THE GREAT LAKES
AND NORTHEAST WITH COLD OVER THE PAST FEW MONTHS. A DEEP LONGWAVE
TROUGH WILL BECOME RE-ESTABLISHED ACROSS THE EASTERN HALF OF THE
NATION WHICH WILL DELIVER ANOTHER PUSH OF MUCH BELOW NORMAL
TEMPERATURES.

LOOKING AT THE DETAILS...THURSDAY NIGHT MOST OF THE RAIN WILL END
EARLY AS THE FRONTAL WAVE EXITS OFF THE NEW ENGLAND COAST. THIS WILL
LEAVE A BREAK BEFORE DEEPER WRAP AROUND MOISTURE AND ASCENT WITH THE
UPPER LEVEL TROUGH ARRIVE LATE THURSDAY NIGHT AND FRIDAY. STEADY
COLD ADVECTION WILL ALLOW ANY REMAINING PRECIP TO CHANGE FROM RAIN
TO SNOW THURSDAY NIGHT. COLD ADVECTION CONTINUES FRIDAY WITH AT
LEAST A FEW SNOW SHOWERS ASSOCIATED WITH THE UPPER LEVEL TROUGH AND
SOME ENHANCEMENT OFF LAKE ONTARIO IN NORTHWEST FLOW. LAKE EFFECT
SNOW SHOWERS WILL CONTINUE SOUTHEAST OF LAKE ONTARIO FRIDAY NIGHT
AND SATURDAY AS 850MB TEMPS BOTTOM OUT AROUND -18C. TEMPERATURES
WILL BE CLOSE TO 20F BELOW AVERAGE AGAIN BY SATURDAY WITH HIGHS ONLY
IN THE MID 20S AT LOWER ELEVATIONS AND BARELY 20 ACROSS HIGHER
TERRAIN.

THE LAKE EFFECT SNOW SHOWERS WILL END BY SATURDAY NIGHT AS HIGH
PRESSURE BUILDS INTO THE LOWER LAKES. THIS WILL MAINTAIN DRY
CONDITIONS THROUGH MOST OF SUNDAY. LATE SUNDAY THROUGH MONDAY
ANOTHER SYSTEM IS FORECAST TO MOVE ACROSS ONTARIO AND QUEBEC JUST
NORTH OF THE GREAT LAKES. THIS WILL BRING A CHANCE OF A FEW SNOW
SHOWERS AGAIN LATE SUNDAY AND SUNDAY NIGHT...WITH TEMPERATURES
BECOMING MILD ENOUGH MONDAY TO SUPPORT A RAIN/SNOW MIX.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR FLIGHT CONDITIONS AT 12Z WILL PERSIST THROUGH THE TAF CYCLE WITH
LIGHT AND VARIABLE WINDS. THERE WILL BE SOME PASSING MID AND HIGH
LEVEL CLOUDS THROUGH THE TAF CYCLE...AND SOME LOW END VFR CLOUDS
WILL SNEAK INTO THE WESTERN SOUTHERN TIER BY AROUND DAYBREAK
WEDNESDAY WITH THE NEXT WEATHER SYSTEM. A 50 KNOT LLJ AT 2K FEET MAY
BRING SOME WIND SHEAR TO THE FAR WESTERN SOUTHERN TIER AROUND
DAYBREAK AS WELL...WITH THIS JET THEN MOVING EASTWARD ACROSS THE
TAF REGION ON WEDNESDAY.

OUTLOOK...
WEDNESDAY...AREAS OF MVFR IN RAIN SHOWERS.
THURSDAY...MVFR/IFR WITH RAIN.
FRIDAY AND SATURDAY...MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
AN AREA OF HIGH PRESSURE WILL SETTLE ACROSS THE LOWER LAKES TODAY
AND BRING A PERIOD OF LIGHT AND VARIABLE WINDS ALONG WITH MINIMAL
WAVES ON THE OPEN LAKE WATERS. BEHIND THE AREA OF HIGH PRESSURE A
SOUTHERLY FLOW WILL BECOME GUSTY ON WEDNESDAY BUT THE OFFSHORE FLOW
SHOULD KEEP THE HIGHER WAVE ACTION OF 2-4 FEET OUT IN THE OPEN
WATERS OF LAKE ONTARIO. WEST TO NORTHWEST WINDS LATER THIS WEEK WILL
INCREASE BEHIND A COLD FRONT WITH SMALL CRAFT CONDITIONS POSSIBLE ON
THE OPEN WATERS OF LAKE ONTARIO.

&&

.HYDROLOGY...
MODEL GUIDANCE CONTINUES TO SUGGEST THAT THERE WILL BE A SHARP
MID WEEK WARM WARMUP. A WARM FRONT WILL PRODUCE LIGHT RAIN ON
WEDNESDAY WITH A TENTH OF AN INCH OR SO OF QPF...NOT ENOUGH TO
CAUSE ANY CONCERNS. A SECOND WAVE OF LOW PRESSURE WILL MOVE ALONG
A SHARPENING BAROCLINIC ZONE LATE WEDNESDAY NIGHT AND THURSDAY
WITH THE POTENTIAL FOR GREATER RAIN AMOUNTS. MODEL GUIDANCE VARIES
ON THE EXACT TRACK OF THIS SYSTEM...WITH RAIN AMOUNTS ANYWHERE
FROM A QUARTER TO THREE QUARTERS OF AN INCH DEPENDING ON THE EXACT
TRACK.

THE COMBINATION OF AT LEAST SOME RAINFALL...AND NEW SNOWMELT CAUSED
BY THE MUCH WARMER TEMPERATURES WILL BRING A SIGNIFICANT INCREASE
IN RUNOFF. WHILE SNOWCOVER HAS BECOME SPARSE AT THE LOWER
ELEVATIONS ACROSS WESTERN NEW YORK...ENOUGH SNOWPACK REMAINS IN
THE WOODS ACROSS THE HIGHER TERRAIN IN THE RIVER HEADWATERS TO BE
A CONCERN.

LATEST MMEFS ENSEMBLE GUIDANCE CONTINUES TO SUGGEST SOME
POTENTIAL FOR ENOUGH RAIN AND SNOWMELT TO RESULT IN SIGNIFICANT
RISES ON AREA RIVERS AND CREEKS...ESPECIALLY THE BUFFALO CREEKS
AND THE UPPER GENESEE RIVER. ROUGHLY 30 PERCENT OF ENSEMBLE
GUIDANCE BRINGS THESE POINTS INTO MINOR FLOOD GIVEN THE EXPECTED
QPF AND SNOWMELT.

A VISUAL INSPECTION OF THE BUFFALO CREEKS MONDAY SHOWED LITTLE
ICE REMAINING...AT LEAST ON THE UPPER SECTIONS. OUR SURVEY FROM
HARLEM ROAD UPSTREAM FOUND LITTLE ICE LEFT...EXCEPT FOR SOME
CHUNKS OF ICE ALONG THE SHORELINE. IT IS STILL POSSIBLE THERE IS
SOME ICE IN THE LOWEST REACHES OF THE BUFFALO RIVER...AND THERE IS
STILL ICE IN THE RIVERS EAST OF LAKE ONTARIO. BASED ON OUR LATEST
FORECAST...THAWING DEGREE HOURS REACH ABOUT 600 ACROSS MUCH OF
WESTERN NY WHICH WILL BE ENOUGH TO GET THE ICE MOVING AGAIN WHERE
IT REMAINS.

HYDROLOGIC CONDITIONS ARE DISCUSSED IN THE LATEST FLOOD POTENTIAL
OUTLOOK (ESF) PRODUCT...AND THE RISK FOR FLOODING MID TO LATE WEEK
IS DISCUSSED IN THE HAZARDOUS WEATHER OUTLOOK (HWO). IF THERE IS
GOING TO BE FLOODING DUE TO SNOW MELT THIS SPRING...THIS WILL
PROBABLY HAVE TO BE THE SYSTEM TO DO IT FOR THE BUFFALO
CREEKS...GENESEE...AND ALLEGHENY BASINS. IF FORECAST CONFIDENCE
INCREASES ON HIGHER RAINFALL AMOUNTS IT IS POSSIBLE THAT FLOOD
WATCHES WILL BE NEEDED FOR SOME AREAS IN THE LATE WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT TIME FRAME.

&&

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

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...TMA
LONG TERM...HITCHCOCK
AVIATION...THOMAS
MARINE...THOMAS
HYDROLOGY...HITCHCOCK/TMA







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