Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 241111
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
711 AM EDT FRI APR 24 2015

.SYNOPSIS...
A SURFACE AND UPPER LEVEL LOW NEAR MAINE WILL BRING CHILLY
TEMPERATURES AND A FEW SNOW SHOWERS TO THE EASTERN LAKE ONTARIO
REGION TODAY. HIGH PRESSURE WILL GRADUALLY BUILD ACROSS THE GREAT
LAKES WHILE THIS LOW MOVES FURTHER AWAY THROUGH SUNDAY. THIS WILL
RESULT IN SOME SUN AND SLIGHTLY WARMER TEMPERATURES THIS WEEKEND
WITH A MORE NOTABLE WARMING TREND IS EXPECTED BY THE MIDDLE OF
NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
DISTURBANCES WILL CONTINUE TO SPIN AROUND AN UPPER LEVEL LOW CENTERED
NEAR MAINE. SATELLITE SHOWS A WEAK DISTURBANCE DROPPING ACROSS THE
EASTERN LAKE ONTARIO AROUND DAYBREAK. THIS ALSO APPEARS TO BE
TAPPING INTO SOME MOISTURE OFF OF GEORGIAN BAY. THIS IS CAPTURED BY
MOST MESOSCALE GUIDANCE (NAM/RGEM/WRF/ARW)...AND SHOULD ENHANCE LAKE
EFFECT SNOW SHOWERS EAST OF LAKE ONTARIO THROUGH MID-MORNING.
RADAR SHOWS THIS FOCUSING ON OSWEGO COUNTY...WITH AN INCH OR TWO OF
SNOW IS POSSIBLE ON PORTIONS OF THE TUG HILL. MEANWHILE TO THE
WEST OF THIS IR SATELLITE SHOWS DRIER AIR BUILDING INTO FAR
WESTERN NEW YORK WITH THE APPROACH OF SURFACE HIGH PRESSURE.
FLURRIES SHOULD TAPER OFF WEST OF ROCHESTER WHERE THIS DRIER AIR
WILL RESULT IN A PARTIAL CLEARING.

SNOW SHOWERS SHOULD TAPER OFF TO FLURRIES OR SPRINKLES EVEN IN THE
EASTERN LAKE ONTARIO REGION THIS AFTERNOON WITH THE EXIT OF THE
DISTURBANCE LATE THIS MORNING. PARTIAL MORNING SUNSHINE IS LIKELY TO
FILL IN WITH DIURNAL CUMULUS LATE THIS MORNING BEFORE DRIER LOW-MID
LEVEL AIR FINALLY WINS OUT LATE THIS AFTERNOON IN MOST LOCATIONS.
EXPECT MOSTLY CLEAR SKIES TO DEVELOP TONIGHT IN MOST AREAS EXCEPT
EAST OF LAKE ONTARIO WHICH WILL STILL BE UNDER THE INFLUENCE OF THE
UPPER LOW.

MOST TEMPERATURE GUIDANCE WAS TOO WARM YESTERDAY...AND THIS TREND IS
LIKELY TO CONTINUE TODAY WITH THE SAME UNSEASONABLY COOL AIRMASS IN
PLACE. BREAKS OF SUN SHOULD ALLOW FOR SLIGHTLY WARMER HIGHS
TODAY...RANGING FROM THE MID 30S TO LOWER 40S. UNLIKE THE PAST
COUPLE NIGHTS...THERE WILL BE GOOD RADIATIONAL COOLING CONDITIONS
TONIGHT...ESPECIALLY IN THE VALLEYS OF THE SOUTHERN TIER AND WYOMING
HILLS WHERE THERE STILL MAY BE A SNOW PACK. THIS SHOULD OUTWEIGH THE
WARMER AIR ALOFT...AND ALLOW LOWS TO DROP INTO THE TEENS IN
TYPICALLY COLDER VALLEYS...WITH LOWS IN THE 20S IN MOST LOCATIONS.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
SATURDAY IS SHAPING UP TO BE THE SUNNIER OF THE TWO WEEKEND DAYS AS
WEAK SURFACE HIGH PRESSURE AND A NARROW SWATH OF DRIER AIR PROMOTES
A PARTLY TO MOSTLY SUNNY DAY. SATURDAY WILL REMAIN DRY ACROSS THE
EASTERN GREAT LAKES REGION...THOUGH RAIN SHOWERS WILL BE LURKING
NEARBY...TO OUR EAST UNDER AN UPPER LEVEL LOW PRESSURE...AND TO OUR
SOUTHWEST OVER THE MIDWEST WHERE A BAROCLINIC BOUNDARY AND PASSING
MID LEVEL SHORTWAVE WILL RESIDE. THOUGH OUR AIRMASS SATURDAY IS
ARRIVING FROM JUST SOUTH OF JAMES BAY AMPLE LATE APRIL SUNSHINE
SHOULD SEND AFTERNOON TEMPERATURES INTO THE LOWER 50S ACROSS MUCH OF
THE REGION...WITH A FEW SPOTS REMAINING IN THE UPPER 40S.

AS THE MID-LEVEL SHORTWAVE OVER THE MIDWEST DIVES SOUTH OF OUR REGION
SATURDAY NIGHT...THE UPPER LEVEL LOW TO OUR EAST WILL RETROGRADE
WESTWARD...WITH A SPOKE OF ENERGY ROTATING AROUND THE LOW BRINGING
LIFT AND POSSIBLE SHOWERS OF RAIN AND SNOW TO THE REGION ON SUNDAY.
GREATEST THREAT FOR SHOWERS WILL BE EAST OF LAKE ONTARIO AND CLOSER
TO THE UPPER LEVEL LOW DURING THE DAYTIME SUNDAY. THE BULK OF
WESTERN NEW YORK WILL REMAIN DRY THROUGH THE DAY SUNDAY THOUGH
CLOUDS WILL BE GREATER IN NUMBER AS THE UPPER LEVEL LOW RETURNS BACK
TO THE REGION. SUNDAY NIGHT AS THE SHORTWAVE TROUGH DIVES SOUTHWARD
ACROSS THE CWA THERE WILL BE A LOW CHANCE FOR A SHOWER (LOWER
ELEVATION RAIN...HIGHER ELEVATION RAIN/SNOW) REGION-WIDE.

AS THE COOL CANADIAN AIRMASS MODIFIES OVER TIME...AND THE UPPER
LEVEL LOW WILL BRINGS ATLANTIC SOURCED AIR WESTWARD DAYTIME HIGHS ON
SUNDAY SHOULD BE SIMILAR TO SATURDAY EVEN THOUGH CLOUDS WILL BE MORE
ABUNDANT OVER THE REGION. LOWS BOTH NIGHTS WILL DROP BACK INTO THE
30S. WINDS OVER THIS TIME PERIOD WILL BE LIGHT...GENERALLY FROM A
NORTHERLY DIRECTION DURING THE DAYTIME

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
WHILE GLOBAL MODEL GUIDANCE DIFFERS CONSIDERABLY ON THE
DETAILS...THE GENERAL CONSENSUS BETWEEN THE ECMWF/GFS IS THAT THE
UPPER LOW OVER THE NORTHEASTERN U.S. WILL OPEN UP INTO A WAVE AND
GRADUALLY RETREAT OFF THE EAST COAST THROUGH THE FIRST HALF OF NEXT
WEEK. WITH THE UPPER LEVEL TROUGH OVERHEAD THE REGION COUPLED WITH A
MODIFIED MARITIME AIRMASS WRAPPING ACROSS THE AREA FROM THE
NORTHEAST...EXPECT AT LEAST A CHANCE OF SHOWERS ON MONDAY INTO
TUESDAY...PARTICULARLY DURING THE AFTERNOONS WHEN DIABATIC HEATING
WILL BE MAXIMIZED.

BY WEDNESDAY CONFIDENCE IS SIGNIFICANTLY DEGRADED DUE TO
DISAGREEMENTS ON THE AMPLITUDE/TIMING OF AN UPSTREAM SHORTWAVE
TROUGH. FOR NOW WILL STICK WITH LOW CHANCE POPS REGARDING THIS
FEATURE...THOUGH IT IS POSSIBLE THAT WE MAY INSTEAD SEE A DECENT
AMOUNT OF SUNSHINE IF THE TROUGH IS SLOWER/STRONGER THAN CURRENTLY
PROGGED AND WE INSTEAD FALL UNDERNEATH A DOWNSTREAM RIDGE INSTEAD.
OTHERWISE...WITH THE GRADUAL RETREAT OF THE UPPER LOW...WE SHOULD
SEE A GRADUAL WARMING TREND DEVELOP ACROSS THE LOWER GREAT LAKES
WITH HIGHS WARMING THROUGH THE 50S...AND POSSIBLY INTO THE 60S BY
WEDNESDAY...WHILE LOWS WILL GENERALLY RUN IN THE 30S TO LOWER 40S.

&&

.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
AN UPPER LEVEL LOW NEAR MAINE WILL VERY GRADUALLY GIVEWAY TO
SURFACE HIGH PRESSURE APPROACHING FROM THE CENTRAL LAKES. PATCHY
MVFR CIGS/VSBY MAY BRIEFLY IMPACT ROC THROUGH THIS MORNING.
OTHERWISE...BREAKS IN CLOUD COVER WILL GRADUALLY SPREAD FROM W-E
TODAY...THOUGH THIS PROGRESSION WILL BE SLOWED BY DIURNAL LAKE
INDUCED CUMULUS WHICH SHOULD DEVELOP LATE THIS MORNING. CIGS
SHOULD GENERALLY RUN 4-5K FT WITH VFR CONDITIONS FOR THE VAST
MAJORITY OF THE TAF PERIOD. HIGH PRESSURE WILL BUILD TOWARD THE
REGION TONIGHT WITH MOSTLY CLEAR SKIES AND VFR CONDITIONS.

OUTLOOK...
SATURDAY AND SUNDAY...MAINLY VFR.
MONDAY AND TUESDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS.

&&

.MARINE...
AN UPPER LEVEL LOW NEAR MAINE WILL MAINTAIN PERSISTENT MODERATE WEST
TO NORTHWEST WINDS ON LAKE ONTARIO TODAY AND INTO THIS EVENING. THIS
WILL MAINTAIN SMALL CRAFT ADVISORY CONDITIONS ON LAKE ONTARIO
THROUGH TONIGHT. WINDS AND WAVES ARE EXPECTED TO BE CLOSE BUT JUST
SHY OF SMALL CRAFT CRITERIA ON LAKE ERIE TODAY. WINDS AND WAVES WILL
FINALLY DROP OFF THIS WEEKEND WHEN HIGH PRESSURE BUILDS INTO THE
REGION.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SATURDAY FOR LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR
         LOZ042.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/WOOD
AVIATION...APFFEL
MARINE...APFFEL/THOMAS




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