Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 291822
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
222 PM EDT SUN MAR 29 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLOWLY DRIFT AWAY FROM THE AREA TODAY AND STILL
SUPPORT PLENTY OF SUNSHINE. LOW PRESSURE WILL PASS JUST NORTH OF THE
GREAT LAKES TONIGHT AND MONDAY BRINGING GUSTY WINDS AND A LIGHT MIX
OF WET SNOW AND RAIN WITH SOME MINOR SLUSHY ACCUMULATIONS ACROSS
HIGHER TERRAIN. ANOTHER SYSTEM MAY BRING WET SNOW AND RAIN TO
WESTERN NY TUESDAY BEFORE HIGH PRESSURE BRINGS A RETURN TO DRY
WEATHER FOR WEDNESDAY. TEMPERATURES WILL REMAIN BELOW NORMAL EARLY
IN THE WEEK BEFORE A STRONG PUSH OF WARMING ARRIVES ON THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
FOR THE REMAINDER OF THE AFTERNOON HIGH PRESSURE RIDGING INTO
EASTERN NEW YORK WILL GRADUALLY SLIDE OFF THE COAST. THIS WILL
RESULT IN MOSTLY SUNNY SKIES AND COOL TEMPERATURES RANGING FROM
THE MID 30S TO AROUND 40.

THINGS GET A BIT MORE COMPLICATED TONIGHT WITH THE APPROACH AND PASSAGE
OF AN OCCLUDED FRONT AND UPPER LEVEL TROF. AHEAD OF THIS A 50-60KT
LLJ WILL ENTER THE REGION LATE THIS EVENING MOVE EASTWARD OVERNIGHT.
EARLY THIS AFTERNOON RADAR SHOWS AN AREA OF SHOWERS WITH THIS LLJ
ACROSS INDIANA...WITH THE HRRR CAPTURING THESE SHOWERS AND
ADVECTING THEM INTO FAR WESTERN NEW YORK AROUND 10 PM. THIS IS
SUPPORTED BY 12Z NAM/RGEM GUIDANCE WHICH ALSO CAPTURE THE FEATURE
AND GENERATE MID AND UPPER LEVEL LIFT ABOUT THE SAME TIME.

P-TYPE WILL BE A CHALLENGE FOR THIS EVENT WITH MARGINAL BOUNDARY
LAYER TEMPERATURES AND A THE GFS/RGEM SLIGHTLY WARMER THAN THE
NAM. AT LEAST THIS INITIAL ROUND SHOULD BE MAINLY SNOW THOUGH IT
MAY START BRIEFLY AS RAIN UNTIL THE SOUNDING COOLS EVAPORATIVELY.
THIS WILL LAST ONLY AN HOUR OR TWO AT MOST LOCATIONS.

ANOTHER ROUND OF PRECIPITATION WILL FOLLOW QUICKLY ON ITS HEELS
WITH THE FRONT AND SHORTWAVE. THIS IS LIKELY TO ARRIVE SHORTLY
AFTER MIDNIGHT...AND EXIT THE EASTERN LAKE ONTARIO REGION JUST
AFTER DAYBREAK. THIS SHOULD BRING ANOTHER ROUND OF PRECIPITATION
TO THE REGION. BOUNDARY LAYER TEMPERATURES SHOULD AGAIN BE
MARGINAL BEHIND THE INITIAL WAVE...BUT DOWNSLOPE WARMING NORTH OF
I-90 FROM BUF-ROC MAY TIP THE SCALE IN FAVOR OF RAIN. EXPECT
MOSTLY SNOW ACROSS HIGHER TERRAIN...WHERE SOME UPSLOPE ENHANCEMENT
IS LIKELY AS WINDS SHIFT FROM SSW TO WSW. IN GENERAL SNOW
ACCUMULATIONS TONIGHT SHOULD BE LIGHT...WITH LESS THAN AN INCH
NEAR THE LAKES...BUT AN INCH OR TWO ACROSS WESTERN PORTIONS OF
THE SOUTHERN TIER...BOSTON HILLS...AND THE TUG HILL.

WINDS WILL ALSO PICK UP TONIGHT...BOTH WITH THE LLJ AND FRONTAL
BOUNDARY. ALTHOUGH THE LLJ WILL BE QUITE STRONG...ITS CORE IS
BETWEEN 925-850MB WHICH MAY STRUGGLE TO MIX TO THE SURFACE. EXPECT
LIMITED DOWNSLOPE GUSTS THIS EVENING WHEN THE FLOW IS
SOUTHERLY...BUT THESE GUSTS SHOULD DIMINISH WITH THE CORE OF THE
LLJ SINCE WINDS ALOFT WILL SHIFT TO THE SSW AND BECOME LESS
PERPENDICULAR TO THE CHAUTAUQUA RIDGE. WINDS WILL BE GUSTY AGAIN
JUST BEHIND THE FRONT DUE TO TYPICAL FUNNELING DOWN THE
LAKES...HOWEVER BUFKIT SHOWS DIMINISHING WINDS ALOFT BEHIND THE
FRONT. FOR THESE REASONS...HAVE HELD OFF ON ANY HEADLINES...BUT DO
EXPECT PEAK GUSTS IN THE 40-45MPH RANGE WHICH IS JUST BELOW
ADVISORY CRITERIA.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
TROUGHING OVERHEAD ON MONDAY WILL MAKE FOR A SHOWERY AND COOLER DAY.
STEEP LAPSE RATES UNDER THE UPPER-LEVEL TROUGH WILL SUPPORT SOME
SCATTERED...LOW-TOPPED CONVECTIVE RAIN AND SNOW SHOWERS THROUGH THE
DAY MONDAY. AN EMBEDDED VORTICITY MAX IS PROGGED TO SWING THROUGH
THE BASE OF THE TROUGH / AND ACROSS WESTERN NY / BY MID-DAY MONDAY.
THIS SHOULD HELP TO REINVIGORATE SHOWER ACTIVITY AND MAKE IT BRIEFLY
MORE WIDESPREAD. PRECIPITATION TYPE REMAINS SOMEWHAT OF A QUESTION
GIVEN THE RELATIVELY WARM SURFACE TEMPERATURES. HOWEVER WITH STEEP
LAPSE RATES ABOVE THE SURFACE...THE MAJORITY OF THE COLUMN WILL BE
BELOW FREEZING. GIVEN ANY ENHANCED PRECIPITATION RATES IN THE
CONVECTIVE SHOWERS /AND DYNAMICAL COOLING/ EXPECT SNOW WILL LIKELY
BE THE DOMINATE P-TYPE...BUT WILL NOT RULE A LITTLE RAIN MIX AT
TIMES. NEVERTHELESS...SNOW ACCUMULATIONS ARE MAINLY OUT OF THE
QUESTION THROUGH THE DAY MONDAY...EXCEPT FOR A BRIEF LIGHT DUSTING
UNDER A HEAVIER SNOW SHOWER.

WINDS WILL BE NOTICEABLY STRONGER ON MONDAY...AS THE SURFACE LOW
TRACKS JUST NORTH OF THE FORECAST AREA TIGHTENING THE PRESSURE
GRADIENT ACROSS THE AREA. A CORE OF 40 KT WINDS AT 925 - 850 MB WILL
TRACK ACROSS THE FORECAST AREA...HOWEVER WITH ASCENT ASSOCIATED WITH
THE UPPER-LEVEL LOW AND WEAK CAA...IT WILL BE DIFFICULT TO MIX THESE
STRONGER WINDS TO THE SURFACE FOR MUCH OF THE DAY. SOME WIND GUSTS
UP TO 40 MPH COULD BE MIXED DOWN THROUGH THE CONVECTIVE
SHOWERS...AND POTENTIALLY LATER IN THE DAY BEHIND THE VORT MAX
ROTATING ACROSS THE AREA. OTHERWISE WINDS OF 20 TO 30 MPH WILL BE
COMMON ON MONDAY.

BY MONDAY NIGHT...THE TROUGH AXIS PIVOTS OFF THE NEW ENGLAND COAST
AND DRIER AIR WILL FILTER IN FROM THE WEST. GIVEN THE LACK OF
SIGNIFICANT COLD AIR CONNECTION BEHIND THE SURFACE LOW...LOW
TEMPERATURES MONDAY NIGHT INTO TUESDAY MORNING WILL MAINLY BE IN THE
UPPER 20S.

BY TUESDAY...MODELS ARE IN GOOD AGREEMENT ABOUT A CLIPPER SHORTWAVE
DIVING FROM THE UPPER GREAT LAKES INTO PENNSYLVANIA. DISCREPANCIES
BETWEEN THE MODELS ARISE IN THE NORTH-SOUTH POSITION OF THE WAVE AS
IT PASSES BY THE FORECAST AREA. THE NAM REMAINS ON THE MORE
NORTHERLY EDGE OF THE MODEL SPREAD...WHILE THE ECMWF REMAINS ON THE
MORE SOUTHERLY EDGE OF THAT SPREAD. A MORE SOUTHERLY TRACK MEANS
LESS IMPACT TO THE FORECAST AREA...SUPPRESSING THE BULK OF THE
PRECIP INTO PA...AND ALSO COOLER TEMPERATURES ON TUESDAY AS THE
BAROCLINIC ZONE IS SET UP FARTHER SOUTH. HAVE TAKEN A CONSENSUS
APPROACH TO THIS PORTION OF THE FORECAST...WITH THE OFFICIAL FORECAST
USING A BLEND OF THE GFS/NAM/EC/GEM/SREF SOLUTIONS. KEPT LOW END
LIKELY POPS LIMITED TO THE SOUTHERN TIER...WHICH IS THE ONLY PORTION
OF THE FORECAST AREA THAT IS IMPACTED BY BOTH ENDS OF THE MODEL
SPECTRUM. OTHERWISE...POPS TAPER OFF TO CHANCE TOWARD LAKE
ONTARIO...AND NEAR ZERO IN THE NORTH COUNTRY WHICH SHOULD REMAIN OUT
OF THE IMPACT OF THIS SYSTEM. PRECIPITATION TYPE IS AGAIN TRICKY
WITH THIS SYSTEM...AS THE COLD AIR TAP IS LIMITED. FORECAST
SOUNDINGS AGAIN INDICATE A SHALLOW LAYER OF ABOVE FREEZING
TEMPERATURES AT THE SURFACE...AND THUS P-TYPE MAY BECOME DEPENDED ON
RATE / DYNAMICAL COOLING PROCESSES. THUS HAVE CONTINUED TO MAINTAIN
A RAIN / SNOW MIX IN THE FORECAST.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY INTO THURSDAY...MODELS ARE IN GOOD AGREEMENT FOR SOME
LOW-AMPLITUDE RIDGING WORKING ACROSS THE AREA. THIS WILL BRING
TEMPERATURES WARMING INTO MID 40S ON WEDNESDAY / WHICH LOOKS LIKE
THE ONLY CERTAIN DRY DAY IN THE EXTENDED FORECAST. AS THE RIDGE AXIS
WORK ACROSS THE AREA ON THURSDAY AND SOUTHWESTERLY FLOW BECOMES
ESTABLISHED ALOFT...TEMPERATURES COULD PUSH WELL INTO 50S / IF NOT
THE LOW 60S IN PORTIONS OF THE AREA. THE TRADE OFF FOR THESE WARMER
TEMPERATURES WILL BE INCREASING CLOUD COVER AND CHANCES FOR
PRECIPITATION TO CLOSE OUT THE WEEK.

MODELS ARE IN GOOD AGREEMENT ABOUT THE WEATHER PATTERN BECOMING MORE
UNSETTLED BY LATE THURSDAY THROUGH SATURDAY AS OVERALL TROUGHING
LOOKS LOOKS TO BE A SURE BET. HOWEVER MODELS CONTINUE TO STRUGGLE
WITH THE EXACT DETAILS AND TIMING OF ANY WEATHER SYSTEMS THAT
DEVELOP OUT OF THIS PATTERN.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
EXPECT VFR CONDITIONS TO LAST THROUGH THIS EVENING WITH HIGH
PRESSURE CONTINUING TO INFLUENCE OUR WEATHER. AFTER THIS...A LLJ
WILL MOVE ACROSS THE REGION FROM W-E LATE THIS EVENING AND EARLY
TONIGHT. THIS WILL BRING AN HOUR OR TWO OF SHOWERS WHICH SHOULD
MOSTLY FALL AS SNOW AND POSSIBLY IFR VSBY. DOWNSLOPING SHOULD KEEP
CIGS ABOVE 3K FT. WINDS ALOFT WILL APPROACH LLWS.

AFTER THIS...A FRONT WILL MOVE ACROSS THE REGION LATE TONIGHT WITH
ANOTHER ROUND OF PRECIPITATION AND LOWER CIGS. THIS IS LIKELY TO
LOWER CIGS TO MVFR-IFR WITH A MIX OF RAIN AND SNOW SHOWERS NEAR
THE LAKES...AND SNOW SHOWERS ACROSS HIGHER TERRAIN. CONDITIONS
SHOULD IMPROVE MODESTLY MONDAY MORNING BEHIND THE FRONT.

OUTLOOK...
MONDAY AFTERNOON...IFR/MVFR IN SNOW SHOWERS.
MONDAY NIGHT...MAINLY VFR.
TUESDAY...MVFR/IFR. SNOW SHOWERS LIKELY.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR/MVFR. A CHANCE OF RAIN SHOWERS.

&&

.MARINE...
HIGH PRESSURE WILL DRIFT AWAY FROM THE REGION AND TOWARDS THE
EASTERN SEABOARD TODAY. SSW WINDS WILL INCREASE TO 15-20 KNOTS IN
THE WAKE OF THE DEPARTING HIGH...BUT THAT WIND DIRECTION WILL KEEP
THE GREATER WAVE ACTION IN THE CANADIAN WATERS OF LAKE ONTARIO.

A MODERATELY STRONG AREA OF LOW PRESSURE WILL PASS BY JUST NORTH OF
THE GREAT LAKES TONIGHT AND MONDAY. THIS WILL BRING A RAPID INCREASE
IN SOUTHWEST WINDS TONIGHT...BECOMING WEST ON MONDAY. THE STRONGER
WINDS WILL BRING AT LEAST HIGH END SMALL CRAFT ADVISORY CONDITIONS
TO THE OPEN PORTIONS OF LAKE ONTARIO...WITH SUSTAINED WINDS REACHING
AROUND 30 KNOTS ON BOTH LAKES. THE GFS REMAINS STRONGER THAN THE NAM
OR CANADIAN GEM GUIDANCE...AND IF IT WERE TO VERIFY LOW END GALES
MAY BE POSSIBLE ON LAKE ONTARIO FOR A FEW HOURS ON MONDAY. FOR NOW
WE HAVE PEAKED THE WINDS AT 30 KNOTS WITH A HIGH END SMALL CRAFT.
WINDS WILL QUICKLY DIMINISH MONDAY NIGHT AS THE SYSTEM MOVES INTO
THE CANADIAN MARITIMES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EDT
         TUESDAY FOR LOZ042-043.

&&

$$

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







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