Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 070006 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 806 PM EDT FRI MAY 6 2016 .SYNOPSIS... AN UPPER LEVEL LOW ACROSS THE MID ATLANTIC STATES WILL WEAKEN AND SLIDE OFF THE EASTERN SEABOARD ON SATURDAY. THIS SYSTEM WILL BRING A CHANCE FOR SOME SHOWERS ACROSS THE REGION TONIGHT...BEFORE DRIER WEATHER RETURNS FOR SATURDAY. A COLD FRONT WILL THEN CROSS THE REGION SATURDAY NIGHT ALONG WITH ANOTHER ROUND OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS...FOLLOWED BY COOLER AIR SUNDAY AND MONDAY. && .NEAR TERM /THROUGH SATURDAY/... AN UPPER LEVEL LOW WITH SURFACE LOW REFLECTION IS CENTERED OVER THE CHESAPEAKE BAY THIS EVENING. RADAR AND SATELLITE LOOPS SHOW THIS FEATURE IS RESPONSIBLE FOR CIRCULATING WESTERLY MOVING BANDS OF SHOWERS AND OVERCAST TO BROKEN CLOUD COVER. THE CURRENT BAND OF SHOWERS SHIFTING WEST OF BUFFALO BUT STRETCHED NORTH AND EAST OF LAKE ONTARIO IS ASSOCIATED WITH A SURFACE TROUGH PIVOTING WESTWARD. GOING INTO THE EVENING HOURS MUCH OF WESTERN NEW YORK WILL SEE SOME DRY TIME BEHIND THIS SURFACE TROUGH WHILE SHOWERS ARE EXPECTED TO CONTINUE TO SHIFT WEST ACROSS AREAS SOUTHEAST AND EAST OF LAKE ONTARIO. MESO MODELS THEN SHOW ANOTHER WEAKER TROUGH/VORT LOBE WILL PIVOT AROUND THE LOW AND WEST ACROSS THE NORTH COUNTY TOWARD THE GENESEE VALLEY OVERNIGHT WHERE ANOTHER ROUND OF SHOWERS ARE LIKELY. HAVE UPDATED THE POP FORECAST TO REFLECT THIS FRESHER TIMING IN RECENT RUNS OF THE MESO MODELS. OVERNIGHT LOWS ARE EXPECTED TO RANGE FROM THE UPPER 40S IN THE NORTH COUNTY DUE TO THE RAIN AND THICKER CLOUD COVER TO LOWER 40S ACROSS THE INTERIOR WESTERN SOUTHER TIER. EXPECT SATURDAY TO START OF WITH SOME SUNSHINE IN WESTERN AREAS...ALONG WITH TEMPERATURES NEAR NORMAL FOR EARLY MAY. CLOUDS WILL THEN INCREASE AGAIN FROM THE WEST THIS TIME AHEAD OF AN APPROACHING COLD FRONT. CHANCES FOR SHOWERS AND A FEW THUNDERSTORMS WILL INCREASE SATURDAY AFTERNOON. TEMPERATUREWISE...LOOK FOR HIGHS TO PEAK IN THE UPPER 60S TO LOW 70S. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... SATURDAY NIGHT A COLD FRONT WILL CONTINUE TO PUSH ACROSS THE CWA...WITH A LINE OF SHOWERS ALONG AND AHEAD OF THE FEATURE. GREATEST INSTABILITY OF MUCAPES OF 200 TO 400 J/KG WILL BE FOUND NEAR THE NYS/PA STATE LINE AND WILL CONTINUE TO MENTION THUNDER NEAR LAKE ERIE AND THEN ALONG THE STATE LINE...WITH JUST SHOWERS ELSEWHERE. IT WILL REMAIN MILD AHEAD OF THE FRONT...WITH 50S AND LOWER 60S LINGERING INTO THE EVENING HOURS AHEAD OF THE FRONT. THEN POST FRONT TEMPERATURES WILL DROP BACK INTO THE LOWER 40S. SUNDAY WILL REMAIN COOL AS AN UPPER LEVEL LOW AND ITS ASSOCIATED COOL POOL DROP ACROSS THE REGION. WHILE SUNDAY MORNING MAY START MOSTLY SUNNY...ESPECIALLY IN THE WEST...BOTH THE 12Z GFS AND 12Z ECMWF DISPLAY ADDITIONAL MOISTURE PUSHED SOUTHWARD WITH THE UPPER LEVEL LOW...AND THE CYCLONIC FLOW AND COOL POOL ALOFT COMBINED WITH STEEP 800-1000 HPA LAPSE RATES MAY BE ENOUGH TO TRIGGER INSTABILITY SHOWERS IN THE AFTERNOON. WILL CONTINUE THE CHANCE FOR SUCH SHOWERS SUNDAY AFTERNOON WITH THIS LATE MORNING UPDATE...WITH GREATEST CHANCES FOR SUCH ACTIVITY ACROSS THE NORTHERN 2/3RDS OF THE CWA WHERE MOISTURE WILL BE DEEPEST. SUNDAY WILL ALSO BE CHILLY FOR EARLY MAY STANDARDS. TEMPERATURES AT 850 HPA OF ONLY A FEW DEGREES CELSIUS...AND A THICKENING AFTERNOON CLOUD COVER WILL HOLD AFTERNOON HIGHS IN THE 50S...SOME 10F DEGREES BELOW NORMAL. SUNDAY NIGHT ANY SHOWER ACTIVITY WILL QUICKLY END WITH THE LOSS OF DAYTIME HEATING...WEAKENING OF THE LOW LEVEL LAPSE RATES AND THE AXIS OF THE UPPER LEVEL LOW NOW TO OUR EAST. AS HIGH PRESSURE AT THE SURFACE EDGES EASTWARD TOWARDS THE EASTERN GREAT LAKES SKIES WILL BEGIN TO CLEAR. WILL A COOL START...OVERNIGHT LOWS WILL DROP BACK INTO THE MID 30S TO LOWER 40S. ON MONDAY THIS HIGH PRESSURE WILL BRING FAIR WEATHER WITH TEMPERATURES A BIT WARMER THAN SUNDAY WITH TEMPERATURES RETURNING TO THE UPPER 50S TO UPPER 60S. COOLEST AREAS WILL BE EAST AND NORTH EAST OF LAKE ERIE WHERE SOUTHWESTERLY WINDS WILL MAINTAIN COOLER 50S ALONG THE LAKE SHORE AND INLAND ACROSS BUFFALO METRO AREA...AND ALSO THE NORTH COUNTRY WILL LIKELY REMAIN IN THE UPPER 50S. WARMEST REGIONS WILL BE THE VALLEYS OF THE SOUTHERN TIER AND GENESEE VALLEY WHERE DOWNSLOPE WINDS COULD BRING MID TO UPPER 60S. MONDAY NIGHT THIS HIGH PRESSURE WILL DRIFT EASTWARD AND ALLOW FOR A SOUTHERLY FLOW TO DEVELOP. THIS FLOW WILL ALSO BRING ADDITIONAL MOISTURE NORTHWARD WITH CHANCES FOR A FEW SHOWERS ACROSS WESTERN NEW YORK BY DAYBREAK TUESDAY MORNING. COOLEST AREAS WILL BE TOWARDS THE EAST WHERE THIS SOUTHERLY FLOW WILL DEVELOP LATER...AND HERE OVERNIGHT LOWS MAY DROP DOWN TO AROUND 40. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ON TUESDAY...MODEL CONSENSUS HAS A NARROW UPPER LEVEL RIDGE ACROSS OUR REGION...WITH AND UPPER LEVEL LOW ACROSS THE CANADIAN MARITIMES AND A TROUGH ACROSS THE UPPER PLAINS. THIS NARROW RIDGE WILL EVENTUALLY BREAK DOWN...HOWEVER GUIDANCE DISAGREES EXACTLY WHEN THIS WILL HAPPEN. 12Z GUIDANCE IS A BIT SLOWER THAN PREVIOUS RUNS WITH SHOWERS LIKELY ACROSS THE SOUTHERN TIER BY TUESDAY NIGHT...AND LOWER CHANCES TO THE NORTH WHICH WILL BE CLOSER TO THE SURFACE HIGH. AFTER THIS...THE HIGH WILL TRY TO PUSH BACK SOUTHWARD ACROSS OUR REGION LATE WEDNESDAY AND WEDNESDAY NIGHT WITH MAINLY DRY CONDITIONS OUTSIDE OF A FEW LINGERING SHOWERS ACROSS SOUTHERN AREAS. TEMPERATURES SHOULD BE NEAR TO A BIT ABOVE NORMAL WITH DAYTIME HIGHS IN THE MID TO UPPER 60S. THESE COULD TURN OUT A BIT WARMER IF DRIER/WARMER GUIDANCE TURNS OUT TO BE CORRECT...BUT THE FORECAST WILL STAY NEAR MODEL CONSENSUS GIVEN THE MODEL DISAGREEMENT. THE 12Z GFS/ECMWF BOTH FINALLY PIVOT THE UPPER LEVEL TROUGH ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY WHICH WILL BRING A CHANCE OF SHOWERS. THURSDAY SHOULD BE MOSTLY DRY AHEAD OF THIS...WITH TEMPERATURES LIKELY TO CLIMB INTO THE 70S WITH A SOUTHERLY PRE- FRONTAL FLOW AS LONG AS THE SHOWERS HOLD OFF LONG ENOUGH. FRIDAY WILL BE COOLER...BUT HIGHS IN THE MID TO UPPER 60S ARE STILL NEAR NORMAL FOR THIS TIME OF YEAR. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ARE EXPECTED INTO THE OVERNIGHT HOURS BUT APPROACHING MVFR AT KROC/KART DUE TO SOME PASSING SHOWERS. THE SHOWERS AND CLOUD COVER ARE DUE TO AN UPPER LOW CENTERED OVER THE CHESAPEAKE BAY WHICH CONTINUES TO SPREAD THESE CLOUDS AND BANDS OF SHOWERS IN A REVERSE FASHION EAST TO WEST ACROSS THE FORECAST AREA. AT 00Z THE INITIAL BAND OF SHOWERS IS PUSHING WEST OF KBUF BUT MODELS ARE HINTING AT ANOTHER BAND OF SHOWERS THAT WILL SHIFT EAST TO WEST DURING THE OVERNIGHT HOURS WHICH WILL MAINLY REACH KROC/KART. SATURDAY...AS THE UPPER LOW MOVES EAST...A COLD FRONT BEGINS TO APPROACH FROM THE NORTHWEST. VFR REMAIN AT ALL LOCATIONS THROUGH EARLY AFTERNOON. SHOWERS WILL ARRIVE AHEAD OF THE FRONT WITH A POSSIBLE TSTM IN THE FAR WEST (BUF/IAG) LATE SATURDAY AFTERNOON. OUTLOOK... SATURDAY NIGHT...MVFR WITH SHOWERS AND A CHANCE OF THUNDERSTORMS. SUNDAY...MAINLY VFR WITH A CHANCE OF MORNING SHOWERS EAST OF KROC/KDSV. MONDAY...VFR. MONDAY NIGHT AND TUESDAY...MAINLY VFR WITH A LOW CHANCE OF SHOWERS. WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS. && .MARINE... A RELATIVELY WEAK PRESSURE GRADIENT WILL PERSIST ACROSS THE LOWER LAKES REGION THROUGH SATURDAY. THIS WILL RESULT IN LIGHT TO MODEST WINDS PREDOMINATING...ALONG WITH CORRESPONDINGLY MINIMAL WAVES. A COLD FRONT WILL THEN CROSS THE LOWER LAKES SATURDAY NIGHT...WITH FRESHENING NORTHWESTERLIES IN ITS WAKE POTENTIALLY BRINGING A ROUND OF ADVISORY-WORTHY CONDITIONS TO LAKE ONTARIO LATER SATURDAY NIGHT AND SUNDAY. ON LAKE ERIE WINDS WILL BE A BIT WEAKER AND ALSO MORE WESTERLY...LIKELY YIELDING CONDITIONS THAT WILL REMAIN BELOW ADVISORY THRESHOLDS THROUGH THE WEEKEND. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...AR/APFFEL NEAR TERM...SMITH SHORT TERM...THOMAS LONG TERM...APFFEL AVIATION...SMITH MARINE...AR/SMITH

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