Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 182325
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
725 PM EDT SAT APR 18 2015

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL TONIGHT AND SUNDAY...BRINGING
MAINLY CLEAR SKIES AND MILD TEMPERATURES TO THE REGION THROUGH THE
DAYLIGHT HOURS ON SUNDAY. BY SUNDAY NIGHT A SERIES OF LOW PRESSURE
SYSTEMS MOVING OUT OF THE PLAINS STATES WILL BRING PERIODS OF
RAINFALL FOR SUNDAY NIGHT THROUGH TUESDAY. SOME RUMBLES OF THUNDER
ARE ALSO POSSIBLE ON MONDAY ACROSS WESTERN NEW YORK. THE REST OF
THE WORK WEEK WILL SEE BELOW NORMAL TEMPERATURES AND PERIODS OF
UNSETTLED WEATHER AS AN UPPER-LEVEL LOW REMAINS IN CONTROL.

&&

.NEAR TERM /THROUGH SUNDAY/...
VISIBLE SATELLITE IMAGERY SHOWING DIURNAL CUMULUS ACROSS THE NORTH
COUNTRY QUICKLY DISSIPATING THIS EVENING WITH ONGOING DRY ADVECTION
AND THE LOSS OF DAYTIME HEATING. CLEAR SKIES WILL BE THE RULE
TONIGHT BESIDES A FEW HIGH/THIN CIRRUS BRUSHING AREAS NEAR THE PA
STATE LINE.

HIGH PRESSURE WILL BUILD ACROSS THE REGION TONIGHT INTO SUNDAY AS
THE CORE OF THE SURFACE HIGH SLIDES ACROSS ONTARIO INTO QUEBEC.
NORTH WINDS WILL QUICKLY DIMINISH THIS EVENING WITH THE LOSS OF
DAYTIME MIXING. THE LIGHT NORTHERLY WINDS OVERNIGHT WILL SLOWLY TURN
EASTERLY TO SOUTHEASTERLY THROUGH THE DAY SUNDAY AS THE CENTER OF
THE SURFACE MOVES TO THE EAST OF THE FORECAST AREA.

TEMPERATURES TONIGHT WILL COOL QUICKLY WITH SOME WEAK COLD AIR
ADVECTION THROUGH THE FIRST PART OF THE EVENING...THEN LIGHT WINDS
AND CLEAR SKIES WILL ALLOW FOR EFFICIENT RADIATIONAL COOLING THROUGH
THE EARLY MORNING. TEMPERATURES FOR MOST LOCATIONS WILL BOTTOM OUT
IN THE 30S...MAKING FOR A CRISP START TO THE DAY ON SUNDAY MORNING.
AS THE WINDS BECOME INCREASING SOUTHEASTERLY BY SUNDAY AFTERNOON...
AND WEAK WARM ADVECTION BECOMES ESTABLISHED...TEMPERATURES WILL
RECOVER INTO THE 60S FOR MANY LOCATIONS AS 850 MB TEMPERATURES
RETURN TO +4 TO +6C. THIS WIND DIRECTION SHOULD KEEP DOWNTOWN
BUFFALO FROM BEING INFLUENCED BY THE LAKE BREEZE. HOWEVER...THE
SOUTH SHORE OF LAKE ONTARIO WILL BE KEPT CONSIDERABLY COOLER BY THE
GRADIENT ONSHORE FLOW.

CLOUD COVER WILL START TO INCREASE FROM SOUTHWEST TO NORTHEAST LATE
IN THE DAY SUNDAY...AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. BUT
MORE ON THIS WILL BE DISCUSSED IN THE SHORT TERM.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
THIS AFTERNOON AN UPPER LEVEL LOW SPIRALS OVER THE FOOTHILLS OF THE
ROCKIES...AND THIS FEATURE WILL GUIDE A STORM SYSTEM ACROSS OUR
AREA.

THROUGH THE DAY ON SUNDAY DEEP MOISTURE WILL BE STREAMING NORTHWARD
FROM THE GULF OF MEXICO. THIS MOISTURE WILL FEED A PERIOD OF
RAIN...WHICH WILL DEVELOP ACROSS THE EASTERN GREAT LAKES SUNDAY
NIGHT. AT THE SURFACE SUNDAY EVENING AN AREA OF LOW PRESSURE WILL BE
FOUND OVER THE MIDWEST...WITH A WARM FRONT EXTENDING EASTWARD ACROSS
THE OHIO VALLEY AND TOWARDS WEST VIRGINIA. THIS LOW PRESSURE WILL
DEEPEN AS THE AFOREMENTIONED UPPER LEVEL LOW NEARS...WITH BOTH
FEATURES ADVANCING NORTHWARD AHEAD OF A DEEPER AND MORE POTENT UPPER
LEVEL TROUGH OF LOW PRESSURE.

STRONG LOW LEVEL CONVERGENCE FROM A 65 TO 70 KNOT LLJ CENTERED NEAR
850 TO 900 HPA SUNDAY NIGHT WILL BRING LIFT ACROSS THE WARM
FRONT...SUCH THAT WIDESPREAD RAIN FALL UPON THE REGION. A
QUARTER TO HALF INCH OF RAINFALL IS EXPECTED SUNDAY NIGHT AND INTO
MONDAY MORNING FROM THIS SYSTEM. THERE IS HIGH CONFIDENCE IN
RAINFALL SUNDAY NIGHT DUE TO THE DEEPER MOISTURE AND UPWARD FORCING
ALONG THE WARM FRONT.

THERE WILL BE GUSTY WINDS THIS TIME PERIOD AS WELL. A SOUTHEAST WIND
WILL INCREASE IN SPEED NEAR THE LAKE ERIE SHORELINE AS IT
ACCELERATES DOWNWARD FROM THE HILLS OF SW NYS. SURFACE GUSTS 30 TO
40 KNOTS ARE POSSIBLE ALONG THE LAKE ERIE SHORELINE...INCLUDING
ACROSS THE NYS THRUWAY AND ROUTE 5 SUNDAY NIGHT. AS THE WARM FRONT
AND ASSOCIATED RAIN LIFTS NORTHWARD OUT OF THE REGION EARLY
MONDAY...THERE IS THE POTENTIAL FOR LIMITED SUNSHINE ALONG WITH A
BRIEF WINDOW OF RAINFREE CONDITIONS. WITH THE LLJ STILL
OVERHEAD...ANY SUNSHINE WILL INCREASE THE MIXING HEIGHTS SUCH THAT
WE COULD TAP INTO THIS LLJ...WITH WIND GUSTS MONDAY ALSO 30 TO 35
KNOTS ACROSS WESTERN AND NORTH CENTRAL NEW YORK.

LATER MONDAY AFTERNOON CLOUDS WILL THICKEN FROM WEST TO EAST...AND A
DECREASE IN THE GUSTY WINDS IS EXPECTED. A COLD FRONT FROM THIS
CENTRAL LAKES STORM SYSTEM WILL NEAR WESTERN NEW YORK LATE MONDAY
AFTERNOON. ANOTHER ROUND OF RAIN SHOWERS IS EXPECTED MONDAY
AFTERNOON AND MONDAY NIGHT ALONG AND AHEAD OF THE COLD FRONT. THERE
WILL BE SLIGHTLY LESS CONFIDENCE FOR RAINFALL WITH THIS COLD FRONT
DUE TO THE CONVECTIVE NATURE OF THE SHOWERS MONDAY NIGHT. THIS
RAINFALL EVENT WILL AVERAGE AROUND A QUARTER OF AN INCH...WITH A
GREATER RANGE IN RAIN REPORTS EXPECTED ACROSS THE REGION DUE TO THE
CONVECTIVE NATURE. WILL CONTINUE TO MENTION THUNDER FOR AREAS SOUTH
OF LAKE ONTARIO MONDAY NIGHT ALONG THE COLD FRONT WITH THE SMALL
AMOUNT OF CAPE VALUES PRESENT.

TUESDAY THERE WILL CONTINUE TO BE CHANCES FOR SHOWERS AS THE UPPER
LEVEL LOW NEARS THE REGION. SOME INCREASE IN SHOWERS IS EXPECTED
TUESDAY AFTERNOON WITH DIURNAL HEATING INCREASING MID LEVEL LAPSE
RATES. EXPECT ANOTHER BREEZY DAY TUESDAY ACROSS WNY WITH THE
STRONGEST BREEZE SE OF LAKE ERIE. WINDS SHOULD BE A LITTLE LIGHTER
EAST OF LAKE ONTARIO WHICH WILL TO THE NORTHEAST AND FARTHER AWAY
FROM A PV INTRUSION.

THE WARMEST DAY THIS PERIOD WILL BE MONDAY WHEN BEFORE THE COLD
FRONT 850 HPA TEMPERATURES WILL SURGE TO +7 TO +10C. THESE READINGS
WILL SUPPORT HIGHS IN THE 60S...WITH 70S POSSIBLE ACROSS LOWER
ELEVATIONS ON A SOUTHEAST WIND. BEHIND THE COLD FRONT TUESDAY WILL
BE COOLER BY SOME 10 TO 15 DEGREES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
CLASSIC SPRING-TIME PATTERN CONTINUES THIS TIME PERIOD AS A
DEVELOPING NEGATIVE NAO ALLOWS FOR A UPPER LEVEL CUT OFF LOW TO
STALL OVER EASTERN CANADA AND THE NORTHEAST UNITED STATES. UNDER
THIS LOW PRESSURE EXPECT CLOUDY DAYS WITH SCATTERED RAIN SHOWERS.
RAIN SHOWER ACTIVITY WILL BE MOST PRONOUNCED IN THE AFTERNOON HOURS
WITH DAYTIME HEATING...WITH FEW SHOWERS TO BE FOUND BY NIGHT. THERE
MAY EVEN BE SOME WET SNOW MIXING IN AT NIGHT ACROSS THE REGION.
DAYTIME AIR TEMPERATURES WILL AVERAGE 5 TO 10 DEGREES BELOW NORMAL.

THIS CUT OFF LOW WILL SLOWLY MEANDER EASTWARD...SUCH THAT SOME
IMPROVEMENT IN BOTH TEMPERATURES AND PRECIPITATION IS POSSIBLE FOR
FRIDAY AND SATURDAY...THOUGH WILL MAINTAIN AT LEAST LOW CHC POPS IN
THE GRIDS.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH THE 00Z TAF CYCLE. HIGH PRESSURE
WILL BUILD EAST ACROSS QUEBEC TONIGHT WITH A RIDGE EXTENDING DOWN
INTO THE LOWER LAKES REGION. THIS WILL PROVIDE SKC IN MOST AREAS
WITH JUST SOME HIGH/THIN CIRRUS SKIRTING AREAS NEAR THE PA STATE
LINE.

HIGH CLOUDS WILL OVERSPREAD THE ENTIRE REGION LATER SUNDAY AS WARM
ADVECTION AND MOISTURE INCREASE AHEAD OF A POTENT SYSTEM LIFTING OUT
OF THE LOWER OHIO VALLEY. THE RAIN ASSOCIATED WITH THIS SYSTEM
SHOULD ENTER THE SOUTHWEST CORNER OF THE STATE NEAR KJHW AROUND OR
SHORTLY AFTER 00Z MON.

OUTLOOK...
SUNDAY NIGHT AND MONDAY...AREAS OF MVFR WITH OCCASIONAL SHOWERS AND
GUSTY WINDS.
TUESDAY THROUGH THURSDAY...VFR/MVFR WITH SCATTERED SHOWERS.

&&

.MARINE...
NORTHWEST WINDS WILL DIMINISH QUICKLY THIS EVENING AS HIGH PRESSURE
BUILDS EAST ACROSS QUEBEC AND THE PRESSURE GRADIENT RELAXES. CHOPPY
CONDITIONS ALONG THE SOUTH SHORE OF LAKE ONTARIO WILL IMPROVE
OVERNIGHT...AND WINDS OVER THE SAINT LAWRENCE VALLEY WILL DIMINISH.

ON SUNDAY...THE SFC PRESSURE GRADIENT WILL INTENSIFY OVER THE LOWER
GREAT LAKES AS THE SFC HIGH WILL MOVE EAST AND A COMPLEX STORM
SYSTEM WILL APPROACH FROM THE MID WEST. THIS WILL RESULT IN
FRESHENING EASTERLY WINDS...PARTICULARLY ON LAKE ONTARIO...FOR WHICH
A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR WESTERN LAKE ONTARIO
DURING THE DAY SUNDAY.

FRESH TO STRONG SOUTHEASTERLIES WILL BE FOUND ON LAKES ERIE AND
ONTARIO SUNDAY NIGHT AS AN INTENSIFYING STORM SYSTEM WILL PUSH NORTH
ACROSS MICHIGAN. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR ALL OF
LAKE ONTARIO...EASTERN LAKE ERIE AND THE UPPER NIAGARA RIVER FOR
SUNDAY NIGHT THROUGH MONDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM SUNDAY TO NOON EDT MONDAY FOR
         LEZ040-041.
         SMALL CRAFT ADVISORY FROM 11 PM SUNDAY TO 11 AM EDT MONDAY
         FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 8 PM EDT
         MONDAY FOR LOZ042-043.
         SMALL CRAFT ADVISORY FROM 8 PM SUNDAY TO 11 PM EDT MONDAY
         FOR LOZ044-045.

&&

$$

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




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