Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 180806
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
406 AM EDT THU SEP 18 2014

.SYNOPSIS...
A RELATIVELY WEAK COLD FRONT WILL SETTLE SOUTH ACROSS OUR FORECAST
AREA THIS MORNING...AND THIS WILL BE FOLLOWED BY STRONG CANADIAN
HIGH PRESSURE THAT WILL BUILD ACROSS THE LOWER GREAT LAKES IN ITS
WAKE. THIS WILL SUPPORT A COOL BUT OTHERWISE PLEASANT DAY ON
FRIDAY...THEN AS THE HIGH MOVES OFF THE COAST...ITS CLOCKWISE
CIRCULATION WILL PUMP NOTICEABLY WARMER AIR ACROSS OUR REGION FOR
SATURDAY. A FRONTAL SYSTEM WILL LIKELY GENERATE SOME SHOWERS FOR THE
SECOND HALF OF THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
A WEAK...WAVY COLD FRONTAL BOUNDARY...STRETCHING WEST FROM THE ST
LAWRENCE VALLEY ACROSS THE LENGTH LAKE ONTARIO AT 06Z WILL SETTLE TO
THE SOUTH AND MOVE ACROSS OUR FORECAST AREA BY MIDDAY. THE FRONT IS
NOT EXPECTED TO GENERATE ANYTHING MORE THAN INCREASED CLOUD COVER
AND MAYBE SOME SPRINKLES THOUGH...AS THERE IS A LACK OF UPPER LEVEL
SUPPORT AND A LIMITED SUPPLY OF MOISTURE.

THE MAJORITY OF THE CLOUD COVER ASSOCIATED WITH THIS FRONT WILL BE
FOUND IN ITS WAKE THOUGH...AS `MILDER` AIR NEAR THE FRONTAL BOUNDARY
WILL BE LIFTED A FEW THOUSAND FEET ON THE POLEWARD SIDE OF THE
BOUNDARY (IE. ANABATIC PROCESS)...WHILE AT THE SAME TIME A LOW LEVEL
UPSLOPE FLOW OF LAKE ENHANCED AIR WILL BECOME ESTABLISHED. AT THE
PEAK OF THIS COMBINED PROCESS...THE ENHANCED STRATO-CU DECK COULD
PRODUCE SOME SPRINKLES OR ISOLATED LIGHT SHOWERS. THE FLAVOR OF THE
DAY THOUGH WILL BE PARTLY TO MOSTLY CLOUDY SKIES. TEMPERATURES TODAY
WILL BE SEVERAL DEGREES LOWER THAN THOSE FROM YESTERDAY...ESPECIALLY
NEAR LAKE ONTARIO WHERE A COOL NORTHEAST FLOW WILL BE IN PLACE BY
LATE MORNING.

TONIGHT...SFC HIGH PRESSURE WILL PASS BY TO OUR NORTH. THIS WILL
EFFECTIVELY REMOVE OUR UPSLOPE FLOW AS WINDS WILL VEER TO THE EAST-
SOUTHEAST WHILE DRYING WILL TAKE PLACE AT ALL LEVELS. THE CLEARING
SKIES AND LIGHT SFC WINDS WILL THEN PROMOTE FAVORABLE RADIATIONAL
COOLING OF A FRESH CANADIAN AIRMASS. TEMPERATURES AWAY FROM THE
LAKES WILL DROP INTO THE 30S...WITH SOME FROST EXPECTED ACROSS THE
SOUTHERN TIER AND POSSIBLY IN THE FINGER LAKES REGION. MEANWHILE A
FREEZE WILL BE LIKELY ACROSS THE NORTH COUNTRY...SO HAVE UPGRADED A
FREEZE WATCH TO A WARNING FOR THOSE TWO COUNTIES. COULD NOT GET
ENOUGH CONSISTENCY BETWEEN THE GUIDANCE PACKAGES OR CONSENSUS WITH
SURROUNDING WFO`S TO GO WITH A FROST ADVISORY FOR THE SRN TIER..SO
WILL LET THE FORECAST SPEAK FOR ITSELF FOR NOW. THE DAYSHIFT WILL
HAVE TO RE EXAMINE FOR POSSIBLE ADVISORIES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
THIS PERIOD WILL OPEN WITH HIGH PRESSURE DRIFTING FROM THE UPPER
SAINT LAWRENCE VALLEY TO THE NEW ENGLAND COAST ON FRIDAY. PLENTY OF
DRY AIR AND SUBSIDENCE ASSOCIATED WITH THE DEPARTING HIGH WILL LEAD
TO DRY WEATHER AND PLENTIFUL SUNSHINE. AFTER A CHILLY START...THE
COMBINATION OF THE AFOREMENTIONED SUNSHINE AND WARM ADVECTION AROUND
THE BACKSIDE OF THE DEPARTING HIGH WILL HELP TEMPERATURES TO RECOVER
QUITE NICELY...WITH READINGS PEAKING IN THE MID TO UPPER 60S IN MOST
LOCATIONS FRIDAY AFTERNOON.

FRIDAY NIGHT AND SATURDAY...THE SURFACE RIDGE WILL DRIFT FURTHER
EAST AND OFF THE NEW ENGLAND COAST...WHILE COMPLEX LOW PRESSURE
DRAPED FROM HUDSON BAY TO THE NORTHERN PLAINS BODILY SLIDES EAST
INTO ONTARIO AND QUEBEC PROVINCES. IN BETWEEN THESE TWO SYSTEMS...
A STRENGTHENING WARM AIR ADVECTION REGIME WILL HELP TO TRANSPORT
PROGRESSIVELY WARMER AIR INTO OUR REGION. THIS WILL RESULT IN A
CONSIDERABLY MILDER TEMPERATURES FRIDAY NIGHT WHEN LOWS WILL BE SOME
15 TO 20 DEGREES WARMER THAN THOSE OF THE PREVIOUS NIGHT...AND A
DOWNRIGHT SUMMERLIKE DAY ON SATURDAY WHEN READINGS WILL SURGE INTO
THE LOWER TO MID 70S ACROSS THE NORTH COUNTRY...AND TO THE MID TO
UPPER 70S SOUTH OF LAKE ONTARIO. OTHERWISE...EXPECT LARGELY DRY
WEATHER TO CONTINUE WITH THE BULK OF ANY DEEPER MOISTURE AND WARM
FRONTAL FORCING REMAINING TO OUR NORTH...WITH BREEZY CONDITIONS ALSO
DEVELOPING ON SATURDAY IN RESPONSE TO A TIGHTENING PRESSURE
GRADIENT. DOWNWIND OF THE LAKES...THIS WILL LEAD TO WIND GUSTS INTO
THE 30-35 MPH RANGE SATURDAY AFTERNOON.

SATURDAY NIGHT AND SUNDAY...A MORE SIGNIFICANT SHORTWAVE WILL DROP
INTO THE BROAD UPPER LEVEL TROUGH OVER THE UPPER MISSISSIPPI VALLEY/
UPPER GREAT LAKES...WHICH WILL RESULT IN THIS FEATURE SHARPENING UP
AND DIGGING SOUTHEASTWARD ACROSS THE GREAT LAKES REGION. AT THE
SURFACE...THIS WILL HELP SHUNT THE COMPLEX FRONTAL SYSTEM
EASTWARD...WITH ITS TRAILING COLD FRONTAL BOUNDARY INITIALLY
APPROACHING FAR WESTERN NEW YORK BY SUNDAY MORNING...BEFORE PUSHING
EAST ACROSS THE AREA THROUGH THE COURSE OF THE DAY. THIS WILL RESULT
IN SHOWER CHANCES SPREADING INTO THE AREA FROM WEST TO EAST LATER
SATURDAY NIGHT...FOLLOWED BY THE LIKELIHOOD OF SOME SHOWERS AS THE
FRONT PUSHES THROUGH THE REGION ON SUNDAY...WHEN SOME LIMITED
INSTABILITY MAY ALSO ALLOW FOR THE DEVELOPMENT OF A FEW ISOLATED
THUNDERSTORMS. WITH RESPECT TO TEMPS...THESE WILL REMAIN ABOVE
NORMAL...PARTICULARLY DURING SATURDAY NIGHT WHEN A VERY MILD/BRISK
SOUTHWESTERLY FLOW WILL KEEP OVERNIGHT LOWS FROM FALLING BELOW THE
LOWER TO MID 60S IN MANY LOCATIONS...LEVELS THAT WILL BE SOME 10
TO 15 DEGREES ABOVE LATE SEPTEMBER AVERAGES.

BY SUNDAY EVENING...THE LATEST GUIDANCE SUITE SUGGESTS THAT THE COLD
FRONT AND ITS ATTENDANT BAND OF SHOWERS SHOULD BE LARGELY TO OUR
EAST. A SWATH OF DRY SLOTTING/SUBSIDENCE WORKING IN BEHIND THE FRONT
SHOULD RESULT IN A BRIEF PERIOD OF MAINLY DRY WEATHER IMMEDIATELY
FOLLOWING THE FROPA...BEFORE LOWER-END SHOWER CHANCES RETURN WITH
THE ARRIVAL OF THE MAIN UPPER TROUGH AXIS. OTHERWISE...GOOD COOL AIR
ADVECTION IN THE WAKE OF THE FRONT WILL RESULT IN MUCH COOLER TEMPS
COMPARED TO THOSE OF THE SATURDAY NIGHT...WITH OVERNIGHT LOWS
AVERAGING IN THE UPPER 40S TO LOWER 50S.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
IN THE EXTENDED PORTION OF THE FORECAST...PRONOUNCED UPPER LEVEL
TROUGHING WILL LINGER ACROSS THE GREAT LAKES AND NEW ENGLAND MONDAY
AND TUESDAY. THE RESULTANT COOL CYCLONIC FLOW ACROSS OUR REGION WILL
ONCE AGAIN LEAD TO ANOTHER ROUND OF BELOW NORMAL TEMPERATURES...AS
WELL AS THE POTENTIAL FOR SOME INSTABILITY/LAKE EFFECT CLOUDS AND
SHOWERS. GIVEN THE MORE DISTANT TIME FRAME...HAVE KEPT POPS FOR THIS
PERIOD MUCH MORE BROADBRUSH IN NATURE...AND CONFINED TO THE SLIGHT
CHANCE/LOW CHANCE RANGE FOR NOW.

AFTER THAT...CONDITIONS SHOULD IMPROVE MARKEDLY BY MIDWEEK AS STRONG
RIDGING BUILDS ACROSS THE REGION AT ALL LEVELS. PLENTY OF ASSOCIATED
DRY AIR AND SUBSIDENCE/WARMING ALOFT SHOULD RESULT IN DRY WEATHER...
ALONG WITH TEMPERATURES MODERATING BACK CLOSER TO NORMAL.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
MAINLY VFR CONDITIONS WILL BE FOUND ACROSS WESTERN AND NORTH CENTRAL
NEW YORK THROUGH THE REMAINDER OF THE OVERNIGHT...WITH THE EXCEPTION
COMING ACROSS THE SRN TIER WHERE VALLEY FOG AND AREAS OF LOW STRATUS
WILL RESULT IN IFR CONDITIONS.

SYNTHETICALLY...
A COLD FRONT OVER LAKE ONTARIO AT 07Z WILL SLOWLY PUSH SOUTH ACROSS
OUR REGION DURING THE INITIAL DAYLIGHT HOURS. THIS FRONT COULD
GENERATE SOME SPRINKLES AS IT PUSHES SOUTH...BUT MORE IMPORTANTLY...
LAKE ENHANCED CLOUD COVER IN ITS WAKE WILL LEAD TO DETERIORATING
CIGS WITH MVFR CONDITIONS ANTICIPATED FOR MUCH OF THE DAY. THE
EXCEPTION WILL BE ACROSS THE NORTH COUNTRY WHICH WILL ESCAPE THE
LAKE INFLUENCES AND HAVE GREATER EXPOSURE TO THE COOL DRY AIR
FLOWING SOUTH OUT OF CANADA. THUS...A PERIOD OF MVFR/LOW MVFR CIGS
IS EXPECTED BEHIND THE FRONT...ESPECIALLY SOUTH OF LAKE ONTARIO AS
COOL...MOIST NORTH TO NORTHEAST FLOW OFF THE LAKE WILL ALSO ADD
WITHIN AN UPSLOPE COMPONENT. EXPECT MVFR/LOW MVFR CIGS TO HANG ON
THROUGH MUCH OF THE DAY ACROSS THE KBUF/KIAG/KROC TERMINALS...
BEFORE SCATTERING OUT LATER THIS AFTERNOON.

FOR TONIGHT...HIGH PRESSURE SLIDING BY TO OUR NORTH WILL PROMOTE VFR
CONDITIONS ACROSS THE MAJORITY OF OUR REGION. THE EXCEPTION WILL BE
IN THE VALLEYS OF THE SRN TIER WHERE FOG AND/OR LOW STRATUS COULD
DEVELOP LATE.

OUTLOOK...
FRIDAY THROUGH SATURDAY...VFR.
SUNDAY...VFR/MVFR WITH SHOWERS BECOMING LIKELY.
MONDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A COLD FRONT WILL PUSH SOUTH OF THE LOWER GREAT LAKES THIS
MORNING...WHILE HIGH PRESSURE WILL BUILD ACROSS THE LAKES IN ITS
WAKE. THIS WILL PRODUCE A FRESHENING NORTHEAST WIND...WHICH ON LAKE
ONTARIO...WILL RESULT A SHORT WINDOW OF SMALL CRAFT ADVISORY
CONDITIONS FROM HAMLIN BEACH TO IRONDEQUOIT BAY.

AS HIGH PRESSURE DRIFTS ACROSS TO THE NORTH OF LAKE ONTARIO
TONIGHT...THE WEAKENING SFC PRESSURE GRADIENT WILL ALLOW WINDS AND
WAVES TO SUBSIDE. MODERATE EASTERLIES WITH NEGLIGIBLE WAVES WILL
THEN BE FOUND ACROSS THE LOWER GREAT LAKES ON FRIDAY.

A DEEPENING SOUTHERLY FLOW WILL BECOME ESTABLISHED ACROSS THE LOWER
GREAT LAKES FRIDAY NIGHT AND SATURDAY...AND WHILE THE HIGHEST WAVES
WILL BE FOUND IN CANADIAN WATERS...THE STRONGER WINDS COULD LEAD TO
WIND BASED SMALL CRAFT ADVISORIES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FROST ADVISORY FROM 3 AM TO 9 AM EDT FRIDAY FOR NYZ006.
     FREEZE WARNING FROM 3 AM TO 9 AM EDT FRIDAY FOR NYZ007-008.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 5 PM EDT THIS
         AFTERNOON FOR LOZ043-044.

&&

$$

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






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