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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