FXUS61 KBUF 010009 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 809 PM EDT SAT JUL 31 2010 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL SLOWLY CROSS THE EASTERN GREAT LAKES AND NEW YORK STATE LATER TONIGHT AND SUNDAY...BRINGING A ROUND OF SHOWERS AND POSSIBLE THUNDERSTORMS TO PARTS OF THE AREA. WARMER MORE HUMID AIR WILL FOLLOW THIS SYSTEM AND MAY TOUCH OFF ADDITIONAL SHOWERS AND THUNDERSTORMS MONDAY. && .NEAR TERM /THROUGH SUNDAY/... SHOWER ACTIVITY CONTINUING TO ATTEMPT TO PUSH INTO WESTERN NEW YORK THIS AFTERNOON FROM SOUTHERN ONTARIO AND LAKE ERIE...BUT ERODING ON THE LEADING EDGE AS DRIER AIR REMAINS IN PLACE ACROSS THE REGION. UPSTREAM OBSERVATIONS ARE SHOWING THAT PRECIPITATION FALLING MAINLY OUT OF MID LEVEL CLOUD. EVEN IF SOME OF THIS HOLDS TOGETHER LONG ENOUGH TO REACH WESTERN NEW YORK...IT WILL BE VERY LIGHT IN NATURE. HAVE ALLOWED FOR A SLIGHT CHANCE FOR AN EARLY EVENING SHOWER TO ACCOUNT FOR THIS ACTIVITY. OTHERWISE...FOR TONIGHT PROBABLY JUST LOOKING AT A GRADUALLY INCREASE FROM WEST TO EAST IN MID LEVEL CLOUDINESS WORKING IN FROM THE CENTRAL LAKES REGION. TONIGHT WILL BE MILDER THAN RECENT NIGHTS AS THE MID LEVEL CLOUD DECK RESTRICTS RADIATIONAL COOLING. WATER VAPOR LOOP THIS AFTERNOON REVEALING A MID/UPPER LEVEL TROUGH AXIS PUSHING DOWN ACROSS THE UPPER LAKES REGION. THIS FEATURE WILL PUSH DOWN ACROSS THE AREA DURING THE DAY SUNDAY WITH THE SEMBLANCE OF A WEAK SURFACE INVERTED TROUGH ACROSS THE AREA. MOISTURE PUSHING NORTHWARD ON THE WESTERN SIDE OF THE WITHDRAWING HIGH WILL ALLOW FOR INCREASING CHANCES FOR CONVECTION DURING THE DAY...ESPECIALLY ACROSS SOUTHEAST SECTIONS. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... DURING SUNDAY NIGHT...THE MID LEVEL TROUGH AND ASSOCIATED WEAK SURFACE REFLECTION WILL CONTINUE TO DRIFT VERY SLOWLY TO THE EAST... WITH THE DEEPEST MOISTURE AND LIFT SHIFTING FROM THE FINGER LAKES AND CENTRAL NEW YORK TO EASTERN NEW YORK. IN CONJUNCTION WITH NOCTURNAL STABILIZATION OF THE BOUNDARY LAYER...THIS SHOULD RESULT IN A GRADUAL DECREASE IN COVERAGE/INTENSITY OF PRECIP THROUGH THE NIGHT. HAVE THEREFORE CONTINUED TO INDICATE A GRADUAL DOWNWARD TREND IN POPS...WITH AREAS FROM THE GENESEE VALLEY WEST BECOMING DRY AFTER MIDNIGHT. ON MONDAY...MID LEVEL TROUGH WILL SHIFT FURTHER EAST INTO NEW ENGLAND AND DEAMPLIFY...WHILE PLENTIFUL LOW LEVEL MOISTURE SHOULD LINGERS ACROSS OUR AREA OWING TO THE LACK OF ANY REAL DRY AIR ADVECTION IN THE WAKE OF THE SYSTEM. EXPECT THE POSSIBILITY OF A FEW LINGERING SHOWERS AND THUNDERSTORMS ACROSS THE NORTH COUNTRY ON MONDAY GIVEN THE CLOSER PROXIMITY OF THIS AREA TO THE DEPARTING TROUGH. AREAS FARTHER TO THE WEST SHOULD SEE A DRY MORNING...WITH A FEW SHOWERS AND STORMS THEN BECOMING POSSIBLE SOUTH AND EAST OF BUFFALO AND ROCHESTER IN THE AFTERNOON AS DIURNAL HEATING OF THE STILL-MOIST AIRMASS LEADS TO DECENT AMOUNTS OF INSTABILITY...AND THE SOUTHERN EDGE OF A WEAK LAKE ERIE BREEZE BOUNDARY/TERRAIN FEATURES ACT AS POSSIBLE TRIGGERS. WILL COVER ALL OF THIS WITH LOW-MID RANGE CHANCE POPS FOR NOW...WITH SLIGHT CHANCE OR LOWER POPS INDICATED FURTHER NORTH ACROSS THE LAKE PLAINS FROM BUFFALO TO ROCHESTER. ALL OF THE ABOVE ACTIVITY SHOULD THEN WIND DOWN FAIRLY QUICKLY WITH THE LOSS OF HEATING MONDAY EVENING...WITH POPS DROPPING BACK TO BELOW THE CHANCE THRESHOLD FOR MOST OF THE AREA AS A RESULT. THE LONE EXCEPTION TO THIS WILL BE ACROSS THE NORTH COUNTRY...WHERE A DEVELOPING WARM FRONTAL ZONE WILL BE LOCATED THROUGH THE NIGHT. ALONG AND JUST NORTH OF THIS BOUNDARY...THE PRESENCE OF SEVERAL MIGRATING SHORTWAVE IMPULSES AND CONVERGENCE AT THE NOSE OF A 20-30 KT WIND MAXIMA WILL KEEP AT LEAST A LOW PRECIP THREAT GOING RIGHT THROUGH THE NIGHT...WITH THE 12Z NAM/GFS BOTH SUGGESTING AT LEAST SOME POTENTIAL FOR AN MCS-TYPE SYSTEM TO EITHER MOVE ACROSS OR CLOSELY BRUSH THIS AREA DURING THE NIGHT. WILL LEAVE CHANCE POPS IN PLACE TO COVER THIS POSSIBILITY...WITH A GENERALLY DRY AND WARM NIGHT EXPECTED ELSEWHERE OWING TO THE PREVAILING SOUTHERLY LOW-LEVEL FLOW. ON TUESDAY...THE AFOREMENTIONED WARM FRONTAL BOUNDARY SHOULD SLOWLY LIFT NORTHEAST INTO THE SAINT LAWRENCE VALLEY...WITH ANY ASSOCIATED CONVECTION LIFTING NORTH OF THE NORTH COUNTRY BY EARLY-MID AFTERNOON. ELSEWHERE...THE MORNING IS EXPECTED TO BE GENERALLY DRY. AS WE GET INTO THE AFTERNOON HOURS HOWEVER...A PRE-COLD FRONTAL TROUGH WILL DEVELOP ACROSS THE AREA...POSSIBLY SERVING AS THE FOCAL POINT FOR ANOTHER ROUND OF CONVECTION AS IT INTERACTS WITH THE VERY WARM AND HUMID AIRMASS THAT SHOULD BE IN PLACE. WILL INDICATE CHANCE POPS FOR TUESDAY AFTERNOON OWING TO THIS FEATURE...WITH THE HIGHEST VALUES FOUND FROM THE SOUTHERN TIER AND GENESEE VALLEY EAST ACROSS THE FINGER LAKES AND NORTH COUNTRY...WHICH SHOULD SEE THE TROUGH ARRIVE DURING PEAK HEATING. AS MENTIONED ABOVE...TUESDAY WILL BE A VERY WARM AND HUMID...IF NOT HOT AND HUMID DAY. UNDER THE PREVAILING DEEP SOUTH TO SOUTHWESTERLY FLOW...PLENTIFUL LOW LEVEL MOISTURE WILL CONTINUE TO BE ADVECTED NORTHWARD INTO THE AREA...AND 850 MB TEMPS WILL CLIMB TO +16C TO +18C BY TUESDAY AFTERNOON...WHICH SHOULD SUPPORT WIDESPREAD HIGHS IN THE 85 TO 90 DEGREE RANGE. AS WAS SEEN IN YESTERDAY AFTERNOON'S GUIDANCE...ANY POTENTIAL FOR LAKE COOLING LOOKS MINIMAL FOR AREAS EAST OF LAKE ONTARIO GIVEN THAT THE LOW LEVEL FLOW IN THIS AREA LOOKS TO REMAIN MORE SOUTHERLY...AND ONLY SOMEWHAT BETTER EAST OF LAKE ERIE...WITH THE 12Z NAM ONLY SUGGESTING A 220-230 DEGREE FLOW...WHICH WOULD RESULT IN ONLY VERY LIMITED COOLING ACROSS THE NORTHERN BUFFALO SUBURBS. DURING TUESDAY NIGHT...PRECIPITATION IS NOW APPEARING LESS LIKELY JUDGING FROM THE 12Z NAM/GFS/ECMWF SOLUTIONS. WHILE ALL THREE OF THESE MODELS KEEP THE MAIN COLD FRONTAL BOUNDARY TO OUR WEST WITH A VERY WARM AND HUMID AIRMASS REMAINING IN PLACE ACROSS OUR AREA...THE MAIN FORCING ASSOCIATED WITH THE FRONT APPEARS TO SPLIT AND BYPASS OUR AREA A BIT TO THE NORTH AND SOUTH...LEAVING US IN A RELATIVE LULL. GIVEN THIS CHANGE WILL LOWER POPS A BIT BACK TO THE LOW END OF THE CHANCE RANGE...BUT WILL NOT DROP THEM ENTIRELY GIVEN THE VERY WARM AND HUMID NATURE OF THE ANTECEDENT AIRMASS...WHICH WILL NOT NEED MUCH OF A NUDGE TO GENERATE CONVECTION. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE EXTENDED PORTION OF THE FORECAST WILL BEGIN WITH A TROUGH OVER THE NORTHEAST...AND A BROAD RIDGE OF HIGH PRESSURE OVER THE SOUTHERN PLAINS AND SOUTHEAST. TEMPERATURES WILL AVERAGE A FEW DEGREES ABOVE NORMAL...THOUGH HUMIDITY SHOULD BE TOLERABLE THROUGH MOST OF THE PERIOD. WEDNESDAY BOTH THE 00Z ECMWF AND THE 12Z GFS AND GGEM MODELS SLIDE A SECONDARY COOL FRONT ACROSS THE REGION. WITH MOISTURE DIMINISHED FROM THE PRIMARY COOL FRONT EXPECT JUST SCATTERED SHOWERS AND THUNDERSTORMS WEDNESDAY...AND WILL MAINTAIN LOW CHC POPS. A SLIGHTLY DEEPER POOL OF MOISTURE TOWARDS THE SOUTHERN TIER AHEAD OF THIS SECONDARY COOL FRONT WILL WARRANT SLIGHTLY HIGHER CHANCE POPS...POTENTIALLY LINGERING INTO THE EVENING HOURS. BEHIND THIS COOL FRONT...DRIER AIR FOR WEDNESDAY NIGHT WITH A SFC HIGH PRESSURE BUILDING INTO THE REGION. THE 00Z ECMWF IS A LITTLE LESS AGGRESSIVE WITH THE SOUTHWARD PUSH OF THE COOL FRONT THAN THE 12Z GFS...BUT WILL MAINTAIN A DRY FORECAST FOR THURSDAY WITH SUNSHINE AND A FEW CLOUDS. THE AREA TO WATCH WILL BE THE SOUTHERN TIER WHICH FOR NOW APPEARS TO BE JUST NORTH OF THE FRONTAL BOUNDARY AND ASSOCIATED MOISTURE. THE PLAINS/SE UPPER LEVEL RIDGE WILL PUSH EASTWARD TOWARDS THE END OF THE WEEK. THIS WILL BOOST AFTERNOON HIGH TEMPERATURES UP A FEW DEGREES ALONG WITH DEWPOINTS STARTING TO CREEP UPWARDS. WILL KEEP THE BEGINNING OF THE WEEKEND DRY FOR NOW WITH A PARTLY TO MOSTLY SUNNY SKY. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... WHILE VFR CONDITIONS WILL BE FOUND ACROSS ALL OF WESTERN AND NORTH CENTRAL NEW YORK TONIGHT AND SUNDAY...AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION AND PRODUCE PLENTY OF CLOUD COVER. THIS CLOUD COVER WILL BE ACCOMPANIED BY SOME LIGHT SHOWERS OVER THE FAR WESTERN COUNTIES EARLY TONIGHT...WITH MORE WIDESPREAD SHOWERS AND POSSIBLE THUNDERSTORMS OVER THE REGION ON SUNDAY. OUTLOOK... SUNDAY NIGHT...VFR/MVFR WITH A CHANCE OF SHOWERS EAST OF THE GENESEE VALLEY. MONDAY...MAINLY VFR. TUESDAY AND WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS. THURSDAY...VFR. && .MARINE... HIGH PRESSURE TO OUR EAST WILL TEND TO MAINTAIN A SOUTHERLY FLOW THROUGH THE NEXT SEVERAL DAYS. HOWEVER...THESE WINDS WILL BE LIGHT...TO THE POINT OF ALLOWING PERIODS OF LIGHT/VARIABLE CONDITIONS...AND AFTERNOON ONSHORE LAKE BREEZES. NO MARINE HEADLINES ARE ANTICIPATED THROUGH AT LEAST MID-WEEK. THE ONLY MARINE HAZARDS WILL BE ISOLATED THUNDERSTORMS SUNDAY AFTERNOON AND MONDAY AFTERNOON. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...RSH/TMA NEAR TERM...TMA SHORT TERM...JJR LONG TERM...THOMAS AVIATION...RSH MARINE...TMA