Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 281107
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
707 AM EDT THU APR 28 2016

.SYNOPSIS...
A WEAKENING AREA OF LOW PRESSURE WILL PASS TO THE SOUTH ACROSS
PENNSYLVANIA OVER THE NEXT 24 TO 36 HOURS...BRINGING A CHANCE OF
SHOWERS TO THE SOUTHERN TIER THIS AFTERNOON THROUGH TONIGHT WITH
ANOTHER WAVE OF LOW PRESSURE EXPANDING SHOWERS CHANCES NORTH TOWARDS
BUFFALO AND ROCHESTER ON FRIDAY. HIGH PRESSURE RETURNS FRIDAY NIGHT
KEEPING CONDITIONS DRY UNTIL SUNDAY WHEN ANOTHER LOW PRESSURE SYSTEM
BRINGS SHOWERS BACK TO THE REGION THROUGH MONDAY. TEMPERATURES WILL
GENERALLY REMAIN NEAR TO SLIGHTLY BELOW AVERAGE.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH CLOUDS ASSOCIATED WITH WARM ADVECTION ALOFT IN ADVANCE OF A
VERTICALLY STACKED LOW OVER THE MISSOURI VALLEY CONTINUE TO SPREAD
ACROSS WESTERN AND NORTH-CENTRAL NEW YORK THIS MORNING. THIS LOW
PRESSURE SYSTEM WILL CONTINUE TO FILL ON TODAY AS IT GETS SHEARED
OUT ACROSS THE MIDWEST AND SOUTHERN GREAT LAKES. AS THE PIECES OF
THIS DISSIPATING LOW ARE ADVECTED ACROSS THE MIDWEST TO THE MID-
ATLANTIC STATES...THEY WILL PRODUCE ENOUGH WEAK LIFT ALOFT AND
SURFACE CONVERGENCE TO GENERATE SHOWERS ACROSS PENNSYLVANIA.

BY THIS AFTERNOON THESE SHOWERS MAY EXTEND INTO THE SOUTHERN
TIER, THOUGH THE HIGHEST CHANCES WILL REMAIN NEAR THE PENNSYLVANIA
BORDER AS LOW- LEVEL MOISTURE WILL DIMINISH SHARPLY AS ONE MOVES
NORTH TOWARDS LAKE ONTARIO. IN ADDITION...STRONG CONVERGENCE ALOFT
NORTH OF THE THRUWAY SHOULD PRECLUDE SHOWERS FROM EXTENDING NORTH
OF THE SOUTHERN TIER. HOWEVER THIS SHOULD NOT PREVENT MID AND HIGH
CLOUDS FROM CONTINUING TO THICKEN AS THEY PRESS NORTHWARDS ACROSS
THE FORECAST AREA COURTESY OF THE INCREASING WARM ADVECTION ALOFT.
THE THICKENING CLOUDS AND COOL NORTHEASTERLY SURFACE FLOW THAT
WILL REMAIN IN PLACE WILL KEEP TEMPERATURES RATHER COOL FOR LATE
APRIL WITH HIGHS RUNNING IN THE LOW TO MID 50S...WITH WARMEST
AREAS IN THE NORTH COUNTRY WHERE FLOW WILL BE OFFSHORE/DOWNSLOPING
AND HIGH CLOUDS THINNEST.

EXPECT LITTLE CHANGE IN OVERALL FORECAST FOR THURSDAY NIGHT AS SMALL
PIECES OF UPPER LEVEL ENERGY WILL CONTINUE TO RIPPLE BY ALONG THE
NY/PA BORDER AND A WEAK INVERTED SURFACE TROUGH APPROACHES WESTERN
NEW YORK. THIS WILL SERVE TO CONTINUE THE CHANCE FOR A FEW SHOWERS
ACROSS THE SOUTHERN TIER WITH DRY CONDITIONS EXPECTED ELSEWHERE.
LINGERING CLOUDS AND WARMER TEMPERATURES ALOFT WILL YIELD A SLIGHTLY
WARMER NIGHT WITH LOWS RANGING FROM THE UPPER 30S IN WESTERN NEW
YORK TO THE LOWER 30S IN THE NORTH COUNTRY.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
LATEST 00Z MODELS ARE ALL IN AGREEMENT WITH QUICKLY SHIFTING A MID
LEVEL SHORTWAVE TROUGH AND EMBEDDED VORT MAX WEST TO EAST ACROSS THE
GREAT LAKES AND INTO NORTHERN PA WITHIN THE ZONAL FLOW ALOFT ON
FRIDAY. SYNOPTIC SCALE LIFT AND WEAK MOISTURE TRANSPORT WILL SUPPORT
A LIKELY PERIOD OF RAIN SHOWERS ACROSS MAINLY THE WESTERN SOUTHERN
TIER WITH CHANCES OF SHOWERS EXTENDING NORTH TO THE SOUTHERN SHORE
OF LAKE ONTARIO. THE NORTH COUNTY WILL REMAIN DRY WITH THE TRACK OF
THE SYSTEM WELL TO THE SOUTH. EVEN IF A FEW RADAR RETURNS DO SHOW UP
NORTH OF A BUFFALO TO ROCHESTER LINE... DRY AIR IMMEDIATELY SOUTH OF
LAKE ONTARIO WOULD MOSTLY ONLY ALLOW SPRINKLES ALONG THE NY THRUWAY
WITH THE BEST QPF ALONG THE PA STATE LINE.

CANADIAN HIGH PRESSURE WILL NOSE SOUTH ACROSS THE EASTERN GREAT
LAKES FRIDAY NIGHT AND SATURDAY WITH WEAK MID LEVEL RIDGING ARRIVING
IN THE WAKE OF THE DEPARTING SHORTWAVE. THIS WILL PROVIDE A PERIOD
OF DRY WEATHER LEADING INTO THE WEEKEND BEFORE MORE SHOWERS BECOME
POSSIBLE AHEAD OF A WEAK SURFACE LOW AND MID-LEVEL TROUGH MOVING
INTO THE OHIO VALLEY SATURDAY NIGHT. MOISTURE FROM THIS SECOND
SYSTEM LOOKS TO REACH INTO THE NORTH COUNTY THIS TIME WITH A
GRADIENT RANGING FROM LOW CHANCE POPS AT WATERTOWN RISING TO LIKELY
POPS IN THE WESTERN SOUTHERN TIER.

TEMPERATURES WILL BE COOLEST ON FRIDAY WITH CLOUD COVER AND SHOWERS
MOVING ACROSS THE FORECAST AREA. MOST LOCATIONS WILL SEE L/M 50S
WITH A CHANCE AT 60 IN THE NORTH COUNTY WHERE CLEARER SKIES WILL BE
FOUND. MAINLY SUNNY SKIES SATURDAY WILL ALLOW MAX TEMPS TO REACH TO
60 OR BETTER FOR MOST EVERYONE EXCEPT ALONG THE IMMEDIATE LAKE
SHORES. OVERNIGHT TEMPERATURES WILL RUN NEAR NORMAL WITH U30S TO
L40S EXPECTED.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
SUNDAY AND SUNDAY NIGHT THE OHIO VALLEY MID LEVEL TROUGH WILL SHIFT
ITS AXIS TOWARD THE EASTERN GREAT LAKES. THE RESULT WILL BE SEVERAL
PERIODS OF RAIN SHOWERS WITH TEMPERATURES NEAR SEASONAL VALUES RIGHT
INTO MONDAY. GREATEST PRECIPITATION CHANCES WILL COME DURING THE DAY
SUNDAY INTO SUNDAY NIGHT. PLENTY OF QUESTIONS IN TERMS OF
INTENSITY/COVERAGE ACROSS THE REGION DEPENDING ON THE TRACK AND
AMOUNT OF MOISTURE ASSOCIATED WITH A SURFACE LOW MOVING ACROSS THE
CENTRAL APPALACHIANS AHEAD OF A DIGGING TROUGH.

00Z GUIDANCE BUILDS A BROAD AMPLIFIED TROUGH OVER THE GREAT LAKES
REGION THROUGH MUCH OF NEXT WEEK. THIS LEADS TO MORE CHANCES FOR
RAIN SHOWERS MID TO LATE WEEK AS NORTHERN STREAM SHORTWAVES PIVOT
AROUND THE TROUGH IN THE WEST/NORTHWEST FLOW ALOFT. TEMPERATURES
WILL RUN JUST BELOW SEASONAL NORMALS INTO THE START OF NEXT WEEK
THEN LOOK TO WARM BACK TOWARDS NORMAL MID WEEK. LOW TEMPERATURES
LOOK TO ONLY SLIP BACK INTO THE 40S EACH NIGHT WITH NO THREAT FOR
FROST/FREEZE.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE EXTENDING FROM NORTHERN MANITOBA TO THE MID-ATLANTIC
COAST WILL KEEP VFR CONDITIONS IN PLACE ACROSS THE FORECAST AREA
THROUGH THIS AFTERNOON. A WEAKENING AREA OF LOW PRESSURE WILL SLIDE
BY TO OUR SOUTH ACROSS PENNSYLVANIA, BRINGING A CHANCE OF SHOWERS,
MAINLY TO THE SOUTHERN TIER WITH HIGHEST CHANCES BEING RIGHT ALONG
THE PA BORDER.

OTHERWISE EXPECT VFR CONDITIONS TO PERSIST THROUGH THE DAY EVEN AS
HIGH CLOUDS THICKEN AND LOWER INTO A MIDDLE CLOUD DECK BETWEEN 7-
10KFT SOUTH OF LAKE ONTARIO. CIGS ARE EXPECTED TO LOWER INTO MVFR
RANGE ACROSS HIGHER ELEVATIONS OF THE SOUTHERN TIER WEDNESDAY NIGHT
AS ANOTHER WAVE OF LOW PRESSURE PASSES BY AND MOISTURE DEEPENS
SOMEWHAT. THIS WILL ALSO SERVE TO KEEP THE CHANCE OF SHOWERS IN
THROUGH WEDNESDAY NIGHT ACROSS THE SOUTHERN TIER WITH DRY CONDITIONS
AND GENERAL NORTHEASTERLY FLOW EXPECTED ELSEWHERE.

OUTLOOK...
THURSDAY NIGHT AND FRIDAY...VFR...WITH SCATTERED TO NUMEROUS
SHOWERS/POSSIBLE MVFR SOUTH OF LAKE ONTARIO.
SATURDAY...VFR.
SUNDAY AND MONDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
HIGH PRESSURE CURRENTLY IN PLACE ACROSS THE LOWER GREAT LAKES WILL
RETREAT SLIGHTLY TO THE NORTH AS A WEAK AREA OF LOW PRESSURE PASSES
TO THE SOUTH OF THE LAKES. RESULTING NORTHEASTERLY FLOW WILL FRESHEN
UP TO 15 KTS THIS AFTERNOON...GENERATING WAVES OF 2 TO 4 FEET ALONG
THE SOUTHERN SHORES OF LAKE ONTARIO. WAVE WILL DIMINISH SOMEWHAT
TONIGHT BEFORE ANOTHER WAVE OF LOW PRESSURE MOVES SOUTH OF THE AREA
AGAIN ON FRIDAY...REPEATING THE PROCESS WITH SIMILAR RESULTS. HIGH
PRESSURE WILL BUILD BACK ACROSS THE LAKES FRIDAY NIGHT WITH LIGHT
WINDS THEN EXPECTED THROUGH THE WEEKEND.

&&

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

&&

$$

SYNOPSIS...WOOD
NEAR TERM...WOOD
SHORT TERM...SMITH
LONG TERM...CHURCH/SMITH
AVIATION...WOOD
MARINE...WOOD



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