FXUS61 KBUF 092238 AFDBUF AREA FORECAST DISCUSSION...MESOSCALE DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 638 PM EDT MON JUN 9 2003 AIRMASS STARTING TO STABILIZE ACROSS THE ENTIRE CWA AT THIS HOUR AS SETTING SUN IS STARTING TO SHOW ITS AFFECTS. AVG LI'S HAVE STABILIZED TO BETWEEN ZERO AND +2...WHILE CAPE VALUES HAVE NOW DECREASED TO LESS THAN 400 J/KG THROUGHOUT. VIS LOOP STILL SHOWS SOME FAIRLY THREATENING LOOKING BANDS OF MDT CU WORKING ACROSS THE REGION...AND A STEP OUTSIDE THE NWS OFFICE HERE REVEALED SOME ALTOCUMULUS MAMMATUS DURING THE PAST 15 MINUTES. STILL SOME INSTABILITY TO DEAL WITH...BUT WE SEEM TO PAST OUR PRIME. LATEST LOOK AT REGIONAL DOPPLERS SHOW ONE "FRISKY" SHOWER OVER IAG COUNTY...THAT HAS SINCE WEAKENED AND IS MOVING ACROSS TONAWANDA CREEK TOWARDS GENESEE COUNTY. RADAR PCPN ESTIMATES OF A QUARTER TO HALF INCH OF RAIN CORRESPOND TO THIS CELL OVER SW IAG COUNTY FROM EARLIER IN THE HOUR. THE ACTIVITY OVER THE FINGER LAKES STILL LOOKS THREATENING ON SATELLITE...BUT AS MENIONED...MSAS AND LAPS DISPLAYS SHOW ATMOSPHERE IS BECOMING A BIT MORE STABLE AND LESS MOISTURE CONVERGENCE BEING SHOWN. WILL STILL MONITOR FOR ANY ISOLATED ACTIVITY THROUGH NIGHTFALL. PREVIOUS AFD LEFT INTACT BELOW..... AVAILABLE INSTABILITY...AS LAPS AND MSAS ANALYSES SHOWING LIFTED INDICIES AS LOW AS -2C JUST WEST OF THE FORECAST AREA IN PROGRESSIVELY COOLER TEMPERATURES ALOFT...RESULTING IN SCATTERED SHOWERS...WITH THE BEST COVERAGE IN THE BETTER CONVERGENCE OVER THE NIAGARA PENINSULA. AS DIURNAL HEATING DIMINISHES...LOOKING FOR THE CHANCES FOR SHOWERS TO DIMINISH AS WELL AND REMAINING EVENING CLOUDS TO ERODE. EVEN INTO MICHIGAN DEW POINTS ARE IN THE 50S...SO ANTICIPATING MINS OVERNIGHT TO STAY MOSTLY IN THE 50S WITH NEAR 50 EAST OF LAKE ONTARIO AND INTO THE 40S IN PARTS OF THE SOUTHERN TIER. NGM MOS...NORMALLY GOOD WITH FOG...HAS NO MENTION OF FOG BUT WILL FORECAST SOME PATCHY FOG IN THE SOUTHERN TIER VALLEYS OVERNIGHT DUE TO DEW POINTS STAYING UP OVERNIGHT AND THE RECENT SHOWERS. MODEL SOUNDINGS FROM THE ETA SHOW WESTERN AND CENTRAL NEW YORK TO BE CAPPED FOR THE DAY TUESDAY...DESPITE AN INCREASE IN ISENTROPIC LIFT ON THE 305K SURFACE OVER FAR WESTERN NEW YORK LATE IN THE DAY. APPROACH OF THE FRONT APPEARS SLOWER ON THE LATEST RUNS OF THE ETA AND GFS...AND THE USUALLY LIBERAL 0.01 QPF LINE ON THE AVN IS NOT EVEN INTO WESTERN NEW YORK BY 00Z WEDNESDAY. INSTABILITY REMAINS LOW FOR THE DAY...AND WILL PLAN TO KEEP PRECIPITATION CHANCES OUT TUESDAY. FRONT FINALLY MAKES IT TO NEAR BUFFALO AROUND 12Z WEDNESDAY...EXITING THE FORECAST AREA WEDNESDAY AFTERNOON. THE BEST UPPER SUPPORT IN TERMS OF PVA MOVES NORTH OF THE FORECAST AREA OVER CANADA...AND THE UPPER DIVERGENCE IS FORECAST TO DECREASE ON THE ETA AS THE FRONT APPROACHES LATE TUESDAY NIGHT...HOWEVER...THERE IS A DECENT INCREASE IN THETA-E VALUES AT BOTH 850MB AND 700MB TUESDAY NIGHT. THE NOSE OF AN 80KT 300MB JET ALSO MOVES OVER WESTERN AND CENTRAL NEW YORK TUESDAY NIGHT INTO WEDNESDAY MORNING. WITH WEAKENING CONVERGENCE... CURRENT THINKING IS THAT A WEAKENING...NARROWING LINE OF SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH WESTERN AND CENTRAL NEW YORK OVERNIGHT TUESDAY. QPF VALUES ARE NOT TOO IMPRESSIVE...BUT THE MOS GUIDANCE POPS ARE ALL CREEPING UP FOR TUESDAY NIGHT VERSUS THE 00Z MODEL RUNS. WILL HAVE LIKELY POPS TUESDAY NIGHT...WITH LINGERING CHANCES FOR SHOWERS MAINLY IN EASTERN AREAS WEDNESDAY. SLOW PROGRESS OF THE FRONT...ALONG WITH INCREASING LIFT...CAPE...AND INSTABILITY WEDNESDAY AFTERNOON COULD RESULT IN A FEW SHOWERS REINTENSIFYING MAINLY IN EASTERN ZONES BEFORE MOVING INTO EASTERN NEW YORK DURING THE MID AND LATE AFTERNOON HOURS. CURRENT TREND OF THE GFS...AND EVEN THE MRF...IS TO HAVE THE LOW PRESSURE SYSTEM MOVING THROUGH PENNSYLVANIA LATE THURSDAY AND FRIDAY...AND THE ASSOCIATED FRONTAL BOUNDARY...FARTHER SOUTH. WITH THE DEEPER MOISTURE EXPECTED TO BE MORE TO THE SOUTH...WILL REMOVE THE CHANCES FOR RAIN ESPECIALLY FOR JEFFERSON COUNTY FRIDAY. FRIDAY CHANCES FOR RAIN MAY EVEN BE A LITTLE OVERDONE TOWARD LAKE ONTARIO BASED ON THE LATEST GFS...WHICH HAS DEEP MOISTURE ONLY ABOUT INTO THE SOUTHERN TIER LATE THURSDAY NIGHT AND FRIDAY. WILL CONTINUE WITH CONTINUITY FOR NOW DUE TO SOME UNCERTAINTY IN THE MODEL TRACK OF THE LOW AND THE TIGHT NORTHERN GRADIENT ON THE GFS FROM HEAVY RAIN OVER PENNSYLVANIA TO LITTLE OVER MUCH OF THE BUF CWFA. HIGH PRESSURE BUILDS IN FOR THE WEEKEND...WHICH IS SUPPORTED AT LEAST INTO THE EARLY PART OF THE WEEKEND BY EXTRAPOLATION OF THE CANADIAN GLOBAL MODEL. NCEP EXTENDED DISCUSSION ALSO LEANS TOWARD A FARTHER SOUTH SOLUTION...WHICH IF IT HOLDS TRUE SHOULD ALLOW FOR A DRY WEEKEND. UPPER LOW THAT IS CURRENTLY FORECAST TO DEVELOP OVER THE MIDDLE PART OF THE U.S. STAYS THERE FOR THE WEEKEND. PATTERN SHIFT OF DEEPENING TROUGH IN THE WEST AND INCREASING HEIGHTS IN THE EAST...ALONG WITH ANTICIPATED SOUTHEAST SURFACE FLOW BY EARLY NEXT WORKWEEK...COULD GET TEMPERATURES FINALLY INTO THE 80S BY THE END OF THIS FORECAST PERIOD. .BUF...NONE. $$ RSH/DJF