Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 170303
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1003 PM EST TUE DEC 16 2014

.SYNOPSIS...
PERIODS OF RAIN SHOWERS WILL CONTINUE ACROSS THE AREA TONIGHT AS A
LOW PRESSURE SYSTEM MOVES THROUGH THE REGION. COLDER AIR WILL MOVE
IN BEHIND THIS SYSTEM FOR WEDNESDAY INTO THURSDAY...RESULTING IN A
MIX OF RAIN AND SNOW TRANSITIONING TO LAKE EFFECT SNOW SHOWERS EAST
AND SOUTHEAST OF THE GREAT LAKES. HIGH PRESSURE WILL RETURN BY
FRIDAY AND SATURDAY WITH DRYING CONDITIONS AND NEAR-NORMAL
TEMPERATURES.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
SURFACE ANALYSIS THIS EVENING HAS LOW PRESSURE ACROSS WESTERN LAKE
ONTARIO. THE INITIAL BATCH OF RAIN SHOWERS ALONG A WARM FRONT HAS
LIFTED UP THE SAINT LAWRENCE LEAVING SCATTERED SHOWERS AND DRIZZLE
ACROSS THE REGION LATE THIS EVENING. SURFACE TEMPERATURES EAST OF
LAKE ONTARIO ARE IN THE MID 30S SO THE THREAT OF FREEZING RAIN
WILL BE MINIMAL FOR THE THREE COUNTIES EAST OF LAKE ONTARIO.

FOR THE REMAINDER OF THIS EVENING ANOTHER BATCH OF RAIN SHOWERS
CAN BE SEEN ON RADAR ACROSS LAKE ERIE. THIS IS FORECAST TO MOVE
INTO FAR WESTERN NEW YORK AROUND MIDNIGHT...AND EXPAND AS IT
UPSLOPES ALONG A CONVERGENT SW FLOW UP LAKE ERIE. LOWS TONIGHT
WILL REMAIN MILD WITH OVERNIGHT LOWS RANGING FROM THE MID 30S TO
LOWER 40S...WITH WARMEST OVERNIGHT TEMPERATURES FOUND NEAR THE
LAKE PLAINS.

ON WEDNESDAY A FRESH SHOT OF COLD AIR WILL ARRIVE ACROSS THE REGION
AS WESTERLY FLOW INCREASES ON THE BACK SIDE OF THE SURFACE LOW
CENTERED JUST NORTH OF LAKE ONTARIO. THE LOW CENTER WILL REDEVELOP
ALONG THE NEW ENGLAND COAST THROUGH THE DAY AS THE AXIS OF THE UPPER
LEVEL TROUGH SHIFTS ACROSS THE NORTHEAST. PERSISTENT COLD AIR
ADVECTION WILL KEEP TEMPERATURES ON A SLOW DOWNWARD TREND THROUGH
THE DAY FROM WEST TO EAST AND FROM HIGH ELEVATIONS TO LOW
ELEVATIONS. UPPER 30S TO LOW 40S EARLY WILL FALL TO UPPER 20S AND
LOW 30S BY THE LATE AFTERNOON.

WEAK SYNOPTIC LIFT FROM THE SURFACE LOW AND UPPER LEVEL TROUGH AXIS
CROSSING THE REGION COMBINED WITH PLENTY OF LOW LEVEL MOISTURE WILL
KEEP SHOWERS IN THE FORECAST THROUGH THE DAY WITH HIGHEST CHANCES
FOCUSED EAST OF THE LAKES WITH SOME LAKE ENHANCEMENT AND UPSLOPE.
AS 850MB TEMPS FALL TO AROUND -6C LAKE INDUCED EQUILIBRIUM LEVELS
WILL CLIMB TO AROUND 5KFT. PTYPE WILL BE RAIN EARLY IN THE DAY AND
ACROSS LOW ELEVATIONS MIXING WITH SNOW GOING INTO THE AFTERNOON.
ACROSS HIGHER ELEVATIONS A MIX EARLY ON WILL CHANGE OVER TO ALL SNOW
THROUGH THE DAY WITH ACCUMULATIONS UP TO AN INCH. COLD ADVECTION
WILL BRING GUSTY WINDS DURING THE DAY UP TO AROUND 35 MPH.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AN ELONGATED SURFACE LOW WILL CONSOLIDATE NEAR NOVA SCOTIA WEDNESDAY
NIGHT. THIS WILL SET UP A WESTERLY FLOW WEDNESDAY EVENING...WHICH
WILL SHIFT TO THE WNW LATER IN THE NIGHT. EQUILIBRIUM LEVELS WILL BE
LOW THROUGHOUT THE PERIOD...WITH A PERSISTENT INVERSION FORECAST TO
REMAIN NEAR OR JUST ABOVE 5K FT THROUGH FRIDAY. THIS WILL RESULT IN
SMALL LAKE INDUCED CAPES WITH CLOUD TOPS MARGINALLY COLD ENOUGH FOR
DENDRITIC SNOW GROWTH. THE MOST SIGNIFICANT LIFT WILL COME FROM
UPSLOPING RATHER THAN LAKE INDUCED INSTABILITY...WITH THE GREATEST
SNOW ACCUMULATIONS INLAND FROM THE LAKES ACROSS HIGHER TERRAIN.

THE STEADIEST SNOW WILL LIKELY BE WEDNESDAY EVENING WHEN MOISTURE
ASSOCIATED WITH AN EXITING UPPER LEVEL LOW HELPS ENHANCE LAKE SNOWS.
OFF LAKE ERIE A SHARPER INVERSION WILL BE IN PLACE BUT AIR BENEATH
THIS WILL BE COLDER. 12Z NAM/RGEM GUIDANCE BOTH HINT AT A LAKE
HURON MOISTURE CONNECTION...WHICH COULD ENHANCE SNOWFALL ON THE
CHAUTAUQUA RIDGE AND BOSTON HILLS. GENERALLY EXPECT 1 TO 3 INCHES IN
THESE AREAS....BUT IT IS NOT OUT OF THE QUESTION THAT A PROLONGED
UPSTREAM LAKE CONNECTION COULD RESULT IN LOCALLY HIGHER AMOUNTS
WEDNESDAY NIGHT. LAKE ONTARIO IS A BIT MORE STRAIGHTFORWARD WITH A
LESS PRONOUNCED INVERSION AND DEEPER MOISTURE. THE W-WNW FLOW WILL
UPSLOPE THE HIGHER TERRAIN...ESPECIALLY THE TUG HILL. FORECAST
CONFIDENCE FALLS JUST SHY OF ANY WINDER HEADLINES...BUT IF
NOTHING CHANGES COULD SEE 3 TO 6 INCH ADVISORY AMOUNTS ON THE TUG
HILL WEDNESDAY NIGHT INTO THURSDAY.

AS WINDS SHIFT TO THE WSW LATE WEDNESDAY NIGHT INTO THURSDAY...THIS
WILL PUSH WHATEVER MOISTURE THIS IS ON LAKE ONTARIO SOUTH INTO THE
LAKE PLAINS. THIS IS LIKELY TO BRING SNOW SHOWERS TO THE I-90
CORRIDOR FROM BUF-ROC-SYR...BUT ACCUMULATIONS SHOULD BE
LIGHT...GENERALLY AN INCH OR LESS. MEANWHILE...THE EXIT OF THE UPPER
LEVEL TROUGH WILL RESULT IN A LOWERING INVERSION AND LESS ORGANIZED
LAKE EFFECT SNOW. WHAT DOES LAST WILL AGAIN FOCUS ON HIGHER
TERRAIN...WITH MINIMAL ACCUMULATION NEAR THE IMMEDIATE LAKESHORES
EAST OF LAKE ERIE AND ONTARIO.

THE NORTHWEST FLOW WILL CONTINUE THURSDAY NIGHT AND FRIDAY. LOW
EQUILIBRIUM LEVELS AND LIMITED MOISTURE WILL RESULT IN LIGHT
ACCUMULATIONS WHICH WILL MAINLY BE CONFINED TO THE CHAUTAUQUA RIDGE
OFF LAKE ERIE AND JUST EAST OF ROCHESTER TO OSWEGO COUNTY AND THE
TUG HILL OFF LAKE ONTARIO. TEMPERATURES AT THE TOP OF THE 5K
EQUILIBRIUM LEVEL WILL BE MARGINALLY COLD ENOUGH FOR DENDRITIC SNOW
GROWTH WITH A SMALL CHANCE FOR SOME FREEZING DRIZZLE THURSDAY NIGHT.
GIVEN FORECAST THERMAL PROFILES AND SPOTTY MID-LEVEL MOISTURE EXPECT
PRECIPITATION WILL PRIMARILY BE LIGHT SNOW OR FLURRIES...AND WILL
MAINTAIN THIS IN THE FORECAST.

TEMPERATURES WILL CONTINUE TO BE CHILLY...WITH A MINIMAL DIURNAL
RANGE DUE TO PERSISTENT CLOUD COVER WITH STRATUS TRAPPED BENEATH THE
INVERSION. HIGHS ON THURSDAY AND FRIDAY WILL GENERALLY BE NEAR
FREEZING...WITH OVERNIGHT LOWS IN THE MID TO UPPER 20S.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
HIGH PRESSURE WILL BUILD ACROSS THE REGION FRIDAY NIGHT AND
SATURDAY...WHICH WILL DIMINISH WINDS AND END THE LAKE EFFECT. LOW
MOISTURE WILL LINGER...BUT THERE SHOULD BE AT LEAST SOME BREAKS OF
SUNSHINE ON SATURDAY.

SATURDAY NIGHT AND SUNDAY THE FOCUS TURNS TO A SOUTHERN STREAM
SYSTEM. MODEL GUIDANCE HAS STRUGGLED WITH THE TRACK AND INTENSITY
DETAILS OF THIS FEATURE OVER THE PAST FEW DAYS. FOLLOWING A SHIFT IN
THE OTHER DIRECTION YESTERDAY...12Z GUIDANCE HAS TRENDED TOWARD A
WEAKER NON-PHASED SOLUTION INSTEAD OF A STRONG COASTAL LOW. IF THIS
PLAYS OUT...IT WOULD BRING SOME LIGHT SNOW TO WESTERN NEW YORK WITH
MINIMAL ACCUMULATION. GIVEN THE TIMEFRAME...THERE IS STILL A CHANCE
FUTURE RUNS WILL CHANGE...SO FORECAST UPS THE POPS A BIT...BUT STILL
REMAIN IN THE CHANCE CATEGORY TO REFLECT THE UNCERTAINTY IN MODEL
GUIDANCE. EITHER WAY...THE SYSTEM DOES NOT APPEAR LIKELY TO HAVE A
MAJOR IMPACT ON OUR REGION...WITH SEASONABLY COOL TEMPERATURES
EITHER WAY.

BEHIND THIS SYSTEM WEAK HIGH PRESSURE SHOULD BRING A RETURN TO DRY
WEATHER FOR MONDAY AND MONDAY NIGHT. TEMPERATURES WILL BE VERY CLOSE TO
AVERAGE FOR MID TO LATE DECEMBER WITH NO PUSH OF ARCTIC AIR THROUGH
EARLY NEXT WEEK.

LOOKING A LITTLE FARTHER AHEAD...12Z GUIDANCE IS FAIRLY CONSISTENT
WITH PREVIOUS RUNS OF THE GFS/ECMWF WITH A DEEP TROUGH FORECAST TO
EXTEND DOWN THE MISSISSIPPI...THEN SWING AROUND AND CLOSE OFF AS A
COASTAL LOW DEVELOPS IN THE NORTHEAST ON CHRISTMAS DAY. IF THIS PLAYS
OUT...THIS WILL BRING A CHANCE OF RAIN SHOWERS ON TUESDAY OR
WEDNESDAY...FOLLOWED BY COOLER WEATHER THE LATTER HALF OF THE WEEK.
THE GEFS ENSEMBLE MEAN TRENDS THE NAO INDEX STEADILY DOWNWARD
THROUGH THE END OF THE MONTH INDICATING A GREATER POTENTIAL FOR HIGH
LATITUDE BLOCKING. EXPECT MID WINTER COLD TO ARRIVE NEAR CHRISTMAS
AND HAVE SOME STAYING POWER.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
AT 03Z...MOSTLY MVFR CONDITIONS WERE IN PLACE ACROSS THE REGION
WITH THE NOTABLE EXCEPTION OF BUF/AIG WHICH WERE LIFR IN LOW CIGS
AND FOG. THIS IS LIKELY DUE TO THE TRACK OF THE SURFACE LOW WHICH
IS ACROSS WESTERN LAKE ONTARIO WHICH SETS UP A MOIST SOUTHWESTERLY
FLOW UP LAKE ERIE. AS THIS LOW LIFTS NORTH...EXPECT A SLIGHTLY
DRIER WSW FLOW WHICH SHOULD ALLOW CIGS TO RISE. THIS MAY PLAY OUT
AT ART A FEW HOURS LATER...WITH LOWERING CIGS FOLLOWED BY RISING
CIGS LATER TONIGHT. OTHERWISE...EXPECT JHW TO LOWER BACK TO IFR
WITH THE MORE WESTERLY WIND DIRECTION LATE TONIGHT...WITH ROC
MAINLY MVFR.

IFR FLIGHT CONDITIONS WILL ONLY MODESTLY IMPROVE DURING THE DAYLIGHT
HOURS TOMORROW...WITH WIDESPREAD LOW END MVFR FLIGHT CONDITIONS
LIKELY ACROSS THE CWA. THE EXCEPTION WILL BE AGAIN BE KJHW WHERE IFR
FLIGHT CONDITIONS MAY JUST VERY WELL CARRY THROUGH THE ENTIRE 00Z
TAF PERIOD.

COLDER AIR WILL SWEEP ACROSS THE REGION DURING THE DAY TOMORROW WITH
SCATTERED RAIN SHOWERS BECOMING MIXED WITH AND CHANGING TO LIGHT
SNOW SHOWERS. WITHIN THESE SNOW SHOWERS TOWARDS THE END OF THE TAF
CYCLE MVFR/IFR VSBYS ARE AGAIN LIKELY.

WINDS WILL PREVAIL FROM THE SOUTHWEST THIS PERIOD. WITH THE COLD AIR
SWEEPING ACROSS THE EASTERN GREAT LAKES EXPECT SOME GUSTS TOWARDS 30
KNOTS ACROSS THE KBUF/KIAG/KROC AIRFIELDS....WITH 20 KNOT OR SO
GUSTS ACROSS KJHW AND KART.

OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH SCATTERED TO
OCCASIONALLY MORE NUMEROUS SNOW SHOWERS.
FRIDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS.
SATURDAY...VFR.
SUNDAY...VFR/MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
THE LOW PRESSURE WILL PIVOT NORTH AND EAST ACROSS THE LOWER GREAT
LAKES TONIGHT WITH A COLD FRONT THEN BRINGING WIDESPREAD ADVISORY
WINDS AND WAVES THROUGH THURSDAY NIGHT. GIVEN HIGH CONFIDENCE IN
THESE HIGHER WINDS AND WAVES SMALL CRAFT ADVISORIES ARE ISSUED FOR
BOTH LAKES FROM TONIGHT THROUGH THURSDAY NIGHT. HIGH PRESSURE
BUILDS IN FRIDAY AND SATURDAY WITH A RETURN TO MORE RELAXED
CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM WEDNESDAY TO 4 AM EST THURSDAY
         FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY FROM 7 AM WEDNESDAY TO 4 AM EST
         THURSDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 4 AM EST
         FRIDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM 8 AM WEDNESDAY TO 10 PM EST
         THURSDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 4 AM EST
         FRIDAY FOR LOZ045.

&&

$$

SYNOPSIS...SMITH
NEAR TERM...APFFEL/SMITH/THOMAS
SHORT TERM...APFFEL
LONG TERM...APFFEL/HITCHCOCK
AVIATION...APFFEL/THOMAS
MARINE...SMITH






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