FXUS61 KBUF 191750 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 150 PM EDT SUN MAY 19 2013 .SYNOPSIS... HIGH PRESSURE CENTERED JUST OFF THE NEW ENGLAND COAST WILL CONTINUE TO DRIFT SLOWLY EASTWARD TODAY...WHILE CONTINUING TO PUMP WARMER AIR INTO THE AREA. ASIDE FROM A FEW LIGHT SHOWERS ACROSS THE NORTH COUNTRY TODAY...CONDITIONS SHOULD REMAIN MAINLY DRY THROUGH TONIGHT...BEFORE A FRONTAL BOUNDARY STALLS OUT OVER THE REGION FOR MUCH OF THE WORK WEEK AND ACTS AS THE FOCUS FOR PERIODS OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... LATEST RADAR IMAGERY STILL SHOWING A FEW WEAK RETURNS FROM THE TUG HILL NORTH TO THE SAINT LAWRENCE RIVER AS OF 1730Z. ANY LIGHT SHOWERS OR SPRINKLES WILL CONTINUE TO PUSH EAST AS WEAK ASCENT FROM A MID LEVEL SHORTWAVE MOVES EAST ACROSS NORTHERN NY AND INTO NEW ENGLAND THIS AFTERNOON. THIS SHOULD LEAVE THE EASTERN LAKE ONTARIO REGION DRY BY MID TO LATE AFTERNOON...ALTHOUGH CLOUD COVER WILL LINGER. FARTHER WEST...SUNSHINE CONTINUES TO DOMINATE FROM THE NIAGARA FRONTIER EAST TO ROCHESTER. DIURNAL CUMULUS ARE DEVELOPING NICELY NOW ACROSS THE WESTERN SOUTHERN TIER...AND THEY HAVE BECOME FAIRLY CONGESTED BRINGING A GOOD AMOUNT OF CLOUD COVER INTO THE AFTERNOON ACROSS HIGHER TERRAIN. THIS EVENING...EXPECT MAINLY DRY CONDITIONS TO CONTINUE TO PREVAIL AS THE BEST SWATH OF WARM ADVECTION/ASSOCIATED MOISTURE SHIFTS EASTWARD AND OUT OF THE AREA...WHICH SHOULD LEAD TO A CORRESPONDING DECREASE IN MID AND HIGH CLOUD COVER THROUGH THE EARLY OVERNIGHT HOURS. LATER ON IN THE NIGHT...CLOUD COVER WILL BEGIN TO INCREASE AGAIN FROM THE NORTH AS A WEAK FRONTAL BOUNDARY OVER ONTARIO PROVINCE BEGINS TO SAG SOUTHWARD TOWARD OUR REGION...HOWEVER EXPECT ANY SHOWER CHANCES ASSOCIATED WITH THIS TO REMAIN IN THE SLIGHT CHANCE RANGE GIVEN BOTH ITS SLOW APPROACH AND THE UNFAVORABLE TIME OF DAY...AND MAINLY CONFINED TO THE NORTH COUNTRY AT THAT. WITH RESPECT TO TEMPERATURES...850 MB TEMPS WILL CLIMB TO BETWEEN +10C AND +13C TODAY...WITH THE WARMEST AIR FOUND ACROSS FAR WESTERN NEW YORK. COUPLED WITH A SOUTHERLY DOWNSLOPE FLOW...THIS SHOULD BE ENOUGH TO BOOST HIGHS BACK INTO THE MID TO UPPER 70S ACROSS THE BULK OF THE CWA TODAY...SAVE FOR TWO AREAS. THE FIRST OF THESE WILL BE ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER AND NORTH COUNTRY WHERE TEMPS SHOULD REMAIN CONFINED TO THE LOWER 70S...AND THE SECOND WILL BE ALONG THE IMMEDIATE LAKE ONTARIO SHORE FROM ROCHESTER OVER TO THE NIAGARA RIVER WHERE AN EAST-NORTHEASTERLY ONSHORE FLOW WILL HELP KEEP HIGHS CONFINED TO THE 60S. WITH A CONTINUED SOUTHERLY FLOW AND SURFACE DEWPOINTS REMAINING IN THE MID-UPPER 50S...RATHER MILD OVERNIGHT LOWS WILL THEN FOLLOW FOR TONIGHT...WITH READINGS RANGING FROM THE MID-UPPER 50S IN INTERIOR PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE LOWER 60S ACROSS THE LAKE PLAINS. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AN ANOMALOUSLY DEEP AND EXPANSIVE UPPER LEVEL LOW OVER THE NORTHERN PLAINS AT THE BEGINNING OF THE WEEK WILL KEEP A DOWNSTREAM RIDGE IN PLACE OVER THE LOWER GREAT LAKES INTO WEDNESDAY. THIS WILL GUARANTEE ABOVE NORMAL TEMPERATURES FOR THIS SHORT TERM PERIOD...BUT THE FLIP SIDE TO THIS COIN IS THAT WE WILL LIKELY EXPERIENCE FAIRLY UNSETTLED WEATHER AS WELL. THE TIMING OF SHOWERS AND THUNDERSTORMS WILL CERTAINLY BE A CHALLENGE THOUGH...AS MANY OF THESE WILL EITHER BE DIURNALLY DRIVEN OR TIED TO IMPULSES WITHIN THE UPPER LEVEL FLOW. THE DETAILS... WHILE A FAIRLY STRONG RIDGE WILL BE IN PLACE OVER THE UPPER OHIO VALLEY AND LOWER GREAT LAKES ON MONDAY...HIGH PRESSURE OVER JAMES BAY WILL PUSH A WEAK FRONTAL BOUNDARY SOUTH ACROSS LAKE ONTARIO. THIS FRONT WILL ENCOUNTER A SUMMER LIKE AIRMASS AS DEW POINTS ARE EXPECTED TO CLIMB INTO THE LOWER 60S WHILE H85 TEMPS IN THE VCNTY OF 15C WILL ENCOURAGE NR SFC TEMPS TO CLIMB INTO THE LOW 80S (MID 80S IN SOME VALLEYS). THIS COMBINATION WILL LEAD TO CAPES OF 1000-2000 J/KG...WITH THE MOST UNSTABLE AIR EXPECTED OVER THE FINGER LAKES AND SRN TIER. KEEPING THIS IN MIND...THE GENERAL SYNOPTIC SUBSIDENCE FROM THE AFOREMENTIONED RIDGE SHOULD HELP TO SUPPRESS ANY CONVECTION FOR A LARGE PORTION OF THE DAY. A FAIR AMOUNT OF HEATING THROUGH THE MIDDAY HOURS MAY BE ABLE TO OVERCOME THIS THOUGH...ESPECIALLY GIVEN THE PRESENCE OF THE WEAK FRONTAL BOUNDARY AND FAVORABLE LOW LEVEL THERMODYNAMICS. A LITTLE HIGHER UP...AM NOT IMPRESSED WITH THE FORECAST MID LEVEL LAPSE RATES AND THE NAM BUFKIT PROFILES ARE SUGGESTING A WEAK CAP ARND 10K FT. WHILE THESE ARE NOT CONDUCIVE FOR WIDESPREAD CONVECTION...IF SBCAPES OF 1000-2000 J/KG CAN BE REALIZED THEN THIS SHOULD NOT POSE TOO MUCH OF A PROBLEM FOR SCATTERED STORMS TO DEVELOP DURING THE COURSE OF THE AFTERNOON. A CLOSER LOOK AT THE UNDERLYING AIRMASS SUGGESTS THAT A VERY WEAK WIND FIELD WILL BE IN PLACE THROUGH 10K FT...AND WITH PWAT VALUES IN THE VCNTY OF 1.25"... THAT SHOULD HEIGHTEN THE CHANCE FOR SLOW MOVING DOWNPOURS WITHIN ANY CONVECTION THAT DOES DEVELOP. OTHERWISE...MONDAY WILL BE SUMMERY WITH MAINLY DRY CONDITIONS FOR THE BULK OF THE DAY. THE WEAK FRONTAL BOUNDARY WILL SLOWLY SETTLE SOUTH OF THE REGION MONDAY NIGHT. WHILE THE THREAT FOR THUNDERSTORMS WILL GENERALLY CEASE WITH THE REMOVAL OF DIURNAL HEATING...IMPULSES DROPPING DOWN THE FRONT SIDE OF THE H5 RIDGE (ALONG AND NORTH OF SFC FRONT) WILL KEEP THE CHANCE FOR SHOWERS IN PLACE. IT MAY ALSO BE UNCOMFORTABLY HUMID FOR PARTS OF THE FORECAST AREA...PENDING THE PROGRESSION OF THE SFC FRONTAL BOUNDARY. THE SOUTHERN TIER STANDS THE HIGHEST CHANCE FOR EXPERIENCING A SUMMERY NIGHT. THE PRESENCE OF THE NEARLY STALLED FRONTAL BOUNDARY IN THE VCNTY OF OUR FORECAST AREA WILL KEEP UNSETTLED CONDITIONS IN PLACE FOR TUESDAY AND TUESDAY NIGHT. CONFIDENCE IN THE TIMING AND EXTENT OF THIS PCPN WILL BE LOW AS THE MAINSTREAM GUIDANCE DIFFERS ON THE PLACEMENT OF THE FRONT. WE WILL LEAN MORE ON THE ECMWF SOLUTION... WHICH HANGS THE FRONT UP OVER OUR AREA. WILL THUS KEEP LIKELY POPS IN PLAY SOUTH OF LK ONTARIO FOR TUES/TUES NIGHT WHILE USING CHC POPS ACROSS THE NORTH COUNTRY. THE BLOCKING UPPER LEVEL LOW THAT WAS FOUND OVER THE NORTHERN PLAINS AT THE START OF THIS PERIOD WILL FINALLY OPEN UP AND BECOME ABSORBED WITHIN A DIGGING LONGWAVE TROUGH OVER EASTERN CANADA. THIS WILL KNOCK DOWN WHATS LEFT OF ANY H5 RIDGING OVER THE LOWER GREAT LAKES AND ALLOW BROAD SFC LOW PRESSURE TO SETTLE OVER OUR REGION. THE RESULT WILL BE MORE SHOWERS AND THUNDERSTORMS. WILL USE HIGH CHC POPS FOR NOW GIVEN THE AMOUNT OF UNCERTAINTY WITHIN THE VARIOUS PACKAGES. && .LONG TERM /THURSDAY THROUGH SATURDAY/... IT WILL BE MUCH COOLER DURING THIS PERIOD...AS A LONGWAVE TROUGH OVER EASTERN CANADA WILL DIG SOUTH ACROSS NEW ENGLAND AND THE LOWER GREAT LAKES. TEMPERATURES WILL DROP BELOW NORMAL BY FRIDAY AND WILL FURTHER COOL AS WE HEAD INTO THE MEMORIAL DAY WEEKEND. IN TERMS OF PCPN...THERE WILL BE ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS THURSDAY AND THURSDAY NIGHT WHEN A SHORTWAVE FROM THE CENTRAL PLAINS WILL PASS TOWARDS OUR REGION. UPPER LEVEL HEIGHT FALLS AND LOW LEVEL CONVERGENCE AHEAD OF A COOL POOL OF AIR WILL BRING SHOWERS AND PERHAPS SOME THUNDERSTORMS. INSTABILITY WILL NOT BE AS GREAT THURSDAY...COMPARED TO TUESDAY AND WEDNESDAY. THE ECMWF WILL PHASE THIS CENTRAL PLAINS LOW WITH A SHORTWAVE DROPPING SOUTHWARD FROM EASTERN CANADA. THIS PHASING WILL DEVELOP A TROUGH THAT WILL DRIVE A COLD FRONT ACROSS THE REGION THURSDAY NIGHT. BEHIND THE COLD FRONT HIGH PRESSURE AND MUCH DRIER AND COOLER AIR WILL FILTER ACROSS THE EASTERN GREAT LAKES. HIGH PRESSURE WILL THEN BUILD ACROSS THE LOWER GREAT LAKES FOR FRIDAY AND SATURDAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... SCATTERED LIGHT SHOWERS EAST OF LAKE ONTARIO WILL END BY MID AFTERNOON WITH ASSOCIATED MVFR CIGS IMPROVING TO VFR FROM WEST TO EAST. ELSEWHERE SOME AREAS OF MVFR CIGS ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND FINGER LAKES WILL SLOWLY IMPROVE TO VFR THIS AFTERNOON. TONIGHT MOST OF THE LOWER CLOUD DECKS SHOULD ERODE AWAY...ALTHOUGH SOME MVFR OR EVEN IFR STRATUS MAY RE-DEVELOP ACROSS NORTH CENTRAL PA AND SNEAK INTO THE HIGHER TERRAIN OF THE SOUTHERN TIER OVERNIGHT ON PERSISTENT SSE FLOW. THE INCREASING LOW LEVEL MOISTURE MAY ALLOW FOR SOME FOG DEVELOPMENT OVERNIGHT...WITH VSBY DROPPING TO AT LEAST MVFR IN MANY LOCATIONS WITH IFR MORE PREVALENT ACROSS THE SOUTHERN TIER VALLEYS. ON MONDAY ANY FOG WILL BURN OFF BY MID MORNING...LEAVING MAINLY VFR FOR THE REST OF THE DAY ACROSS LOWER ELEVATIONS...WITH SOME MVFR CIGS STILL POSSIBLE IN A FEW SPOTS ACROSS HIGHER TERRAIN. A FEW SCATTERED SHOWERS MAY CROSS THE NORTH COUNTRY IN THE MORNING AS A WEAK BACKDOOR COLD FRONT BRUSHES ACROSS NORTHERN NY. ADDITIONAL SCATTERED SHOWERS AND EVEN A FEW THUNDERSTORMS MAY DEVELOP IN THE AFTERNOON ACROSS THE REST OF THE AREA...MAINLY INLAND FROM THE STABLE LAKE SHADOWS. EXPECT COVERAGE TO REMAIN RATHER SPARSE IN MOST AREAS...AND MOST IF NOT ALL OF THE TAF SITES SHOULD REMAIN BEHIND THE LAKE BREEZE BOUNDARIES AND IN STABLE AIR. OUTLOOK... TUESDAY THROUGH FRIDAY...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WITH ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR. && .MARINE... QUIET CONDITIONS WILL REMAIN IN PLACE ACROSS THE LOWER LAKES THROUGH TONIGHT...WITH RELATIVELY LIGHT TO MODEST SOUTHEASTERLY TO SOUTHERLY WINDS AND MINIMAL WAVES. AFTER THAT...GENERALLY LIGHT WINDS WILL CONTINUE THROUGH MUCH OF NEXT WEEK...ALBEIT WITH AN INCREASING RISK OF SHOWERS AND THUNDERSTORMS AS A FRONTAL BOUNDARY TAKES UP RESIDENCE ACROSS THE LOWER LAKES REGION. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...JJR NEAR TERM...HITCHCOCK/JJR SHORT TERM...RSH LONG TERM...RSH/THOMAS AVIATION...HITCHCOCK MARINE...JJR