FXUS61 KBUF 310749
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
349 AM EDT SAT JUL 31 2010

.SYNOPSIS...
A BROAD SURFACE HIGH OVER THE REGION WILL WITHDRAW SLOWLY EAST TODAY 
BRINGING GENERALLY FAIR WEATHER WITH TEMPERATURES A TAD COOLER
THAN NORMAL FOR THIS TIME OF YEAR. AN UPPER LEVEL DISTURBANCE WILL
APPROACH FROM THE UPPER LAKES...BRINGING A ROUND OF SHOWERS TO
PARTS OF THE AREA AND POSSIBLY A THUNDERSTORM AS IT CROSSES THE
REGION SUNDAY. WARMER...MORE HUMID AIR WILL FOLLOW THIS SYSTEM AND
MAY TOUCH OFF MORE CONVECTION MONDAY AFTERNOON AND
EVENING...MAINLY FROM THE UPPER GENESEE VALLEY ACROSS THE FINGER
LAKES AND INLAND SECTIONS OF THE EASTERN LAKE ONTARIO COUNTIES.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE CENTERED OVER THE EASTERN PART OF OUR CWA THIS MORNING 
WILL WITHDRAW SLOWLY EAST TODAY AND BRING A FAIR DAY TO ALL. CAPES 
WILL BE ON THE INCREASE THIS AFTERNOON BUT ANY CONVECTION WOULD BE 
OVER THE WEST AND VERY ISOLATED. WE WILL NOT BE MENTIONING ANYTHING 
OTHER THAN A LITTLE INCREASE IN CLOUDS FROM DIURNAL HEATING AND A 
MID DECK MOVING INTO THE AREA LATE FROM AN APPROACHING WARM FRONT 
STRETCHING FROM THE UPPER GREAT LAKES TO THE OHIO VALLEY.

A CHANGE IN TIMING FROM THE EARLIER FORECAST FOR TONIGHT. WE EXPECT 
THE MID CLOUD DECK TO OVERSPREAD MOST OF THE REGION EXCEPT FOR THE 
EASTERN LAKE ONTARIO COUNTIES WHICH WILL TAKE A LITTLE LONGER. WE 
HAVE LOWERED OVERNIGHT POPS TO SLIGHT CHANCE OR LESS FOR THE WESTERN 
AND SOUTHERN PORTIONS OF THE CWA.

AS FAR AS TEMPERATURES GO...SLIGHTLY WARMER TODAY THAN THE PAST TWO 
DAYS BUT STILL SLIGHTLY BELOW NORMAL FOR THIS TIME OF 
YEAR...GENERALLY MID TO UPPER 70S. TONIGHT WILL BE MILDER THAN 
RECENT NIGHTS AS THE MID CLOUD DECK RESTRICTS RADIATIONAL COOLING.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
MODEL GUIDANCE IS BEGINNING TO CONVERGE ON A COMMON SOLUTION FOR THE 
SECOND HALF OF THE WEEKEND ALTHOUGH THERE REMAINS SOME SUBTLE 
DIFFERENCES. SEVERAL WEAK SHORTWAVES WILL HELP TO CARVE OUT A MID 
LEVEL TROUGH OVER NY/PA ON SUNDAY. THE LOW LEVEL RESPONSE TO THIS 
WILL BE JUST ENOUGH TO DRAW DEEPER MOISTURE FROM THE MID ATLANTIC 
NORTHWARD TOWARDS THE REGION AIDED BY A MODEST 15-20 KNOT SOUTHERLY 
LOW LEVEL JET OVER AND JUST EAST OF THE APPALACHIAN SPINE. PWAT WILL 
RISE TO ABOUT 1.5 INCHES ACROSS THE FINGER LAKES AND CENTRAL NY ON 
SUNDAY. LARGE SCALE FORCING FOR ASCENT WILL REMAIN WEAK GIVEN THE 
WEAK NATURE OF THE MID LEVEL TROUGH AND ASSOCIATED SHORTWAVES. THE 
REGION WILL BECOME FAVORABLY POSITIONED IN THE LEFT EXIT REGION OF A 
100+ KNOT UPPER LEVEL JET...IMPLYING UPPER LEVEL DIVERGENCE. THE 
MOST ORGANIZED FORCING APPEARS TO LINE UP OVER THE FINGER LAKES AND 
CENTRAL NY WHERE MODEST LOW LEVEL CONVERGENCE ON THE NOSE OF THE LOW 
LEVEL JET WILL COUPLE WITH UPPER LEVEL DIVERGENCE TO PRODUCE A DEEP 
COLUMN OF LIFT. THIS IS ALSO THE SAME AREA WHERE LOW LEVEL MOISTURE 
RETURN WILL BE THE MOST ROBUST.

AS FAR AS INSTABILITY GOES...CLOUDS WILL LIMIT DESTABILIZATION 
SOMEWHAT...BUT STILL EXPECT POCKETS OF 500-1000J/KG OF CAPE BY 
AFTERNOON. VERY WEAK WIND FIELDS AND TALL SKINNY NATURE OF THE CAPE 
PROFILE WILL PREVENT ANY STRONG STORMS...BUT THERE ARE LIKELY TO BE 
A FEW SLOW MOVING THUNDERSHOWERS WITH LOCALLY HIGHER RAINFALL. WILL 
GO WITH LIKELY POPS FOR MUCH OF THE AREA...HIGHEST ACROSS THE 
INTERIOR SOUTHERN TIER/FINGER LAKES AND CENTRAL NY. WILL GO WITH 
CHANCE POPS NEAR LAKE ERIE AND THE NIAGARA FRONTIER AND ALSO THE 
NORTH COUNTRY IN AREAS FARTHER AWAY FROM THE BEST MOISTURE. THE 
SAINT LAWRENCE VALLEY WILL REMAIN DRY AS A SURFACE RIDGE HOLDS TOUGH 
FROM NEW ENGLAND TO SOUTHERN QUEBEC. 

SUNDAY NIGHT ALL THE MAIN PLAYERS WILL MOVE VERY SLOWLY EAST WITH 
THE DEEPEST MOISTURE AND ASCENT SPREADING SLOWLY EAST THROUGH 
CENTRAL NY TOWARDS EASTERN NY. EXPECT A GRADUAL DECREASE IN COVERAGE 
AND INTENSITY OF SHOWERS THROUGH THE NIGHT WITH THE LOSS OF DAYTIME 
HEATING AND SLOW STABILIZATION OF THE BOUNDARY LAYER. WILL INDICATE 
A GRADUAL DOWNWARD TREND IN POPS OVERNIGHT WITH AREAS FROM THE 
GENESEE VALLEY WEST BECOMING DRY AFTER MIDNIGHT. 

ON MONDAY THE WEAK MID LEVEL TROUGH WILL SHIFT INTO NEW ENGLAND AND 
MINOR OUT WITH TIME. WEAK SOUTHERLY RETURN FLOW WILL REMAIN IN PLACE 
THROUGH THE DAY HOWEVER...AND THE SYSTEM IS SO WEAK IT WILL LEAVE 
BEHIND MUCH OF THE LOW LEVEL MOISTURE FIELD. A FEW SHOWERS MAY 
LINGER DURING THE MORNING ACROSS LEWIS COUNTY IN CLOSER PROXIMITY TO 
THE DEPARTING MID LEVEL TROUGH. DURING THE AFTERNOON WITH DAYTIME 
HEATING AND SOME WEAK INSTABILITY DEVELOPING...MAY SEE A FEW SPOTTY 
SHOWERS AND ISOLATED THUNDERSHOWERS ONCE AGAIN. EXPECT MOST OF THIS 
TO FOCUS ON THE HIGHER TERRAIN OF THE SOUTHERN TIER AND FINGER LAKES 
AND ALSO EAST OF LAKE ONTARIO...WITH THE LAKE PLAINS REMAINING DRY. 
EVEN ACROSS THE HIGHER TERRAIN THE VAST MAJORITY OF THE DAY WILL BE 
RAIN FREE WITH JUST A FEW PASSING AFTERNOON SHOWERS.

MONDAY NIGHT THIS ACTIVITY WILL END WITH THE LOSS OF DAYTIME 
HEATING. EXPECT AT LEAST A PARTIAL CLEARING TREND OVERNIGHT AS THE 
DEEPER MOISTURE BEGINS TO SHIFT EAST INTO WESTERN NEW ENGLAND. 
SOUTHERLY RETURN FLOW WILL CONTINUE OVERNIGHT AND HELP KEEP LOWS 
QUITE MILD WITH UPPER 60S TO AROUND 70 ON THE LAKE PLAINS AND LOWER 
60S ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE MAIN FEATURE OF INTEREST IN THE EXTENDED CONTINUES TO BE A COLD 
FRONTAL PASSAGE THAT IS EXPECTED TO OCCUR IN THE TUESDAY 
NIGHT-WEDNESDAY TIME FRAME. THE SLOWER PROGRESSION OF THIS BOUNDARY 
DEPICTED IN LAST NIGHTS 00Z MEDIUM RANGE GUIDANCE HAS REMAINED 
INTACT WITH THE PAST SEVERAL RUNS OF THE GFS AND ECMWF WITH THE 
LATEST 00Z/31 RUNS NO EXCEPTION. CHANCE POPS WILL ARRIVE BY TUESDAY 
AFTERNOON WITH BUILDING INSTABILITY AND INCREASING MID LEVEL FLOW. 
THE BEST RAIN CHANCES STILL APPEAR TO BE TUESDAY NIGHT INTO EARLY 
WEDNESDAY AS THE FRONT GRADUALLY EASES ACROSS THE AREA. THERE STILL 
APPEARS TO BE SOME SUGGESTION OF A FRONTAL WAVE RIDING ALONG THE 
FRONT...WHICH MAY HANG UP SOME PRECIP THROUGH WEDNESDAY. 

AHEAD OF THE APPROACHING FRONT...850 MB TEMPS WILL CLIMB TO +18C TO 
+20C TUESDAY AFTERNOON...WHICH SHOULD SUPPORT HIGHS AROUND 90 ACROSS 
THE LOWER ELEVATIONS AWAY FROM LAKE INFLUENCES. INCREASING 
SOUTHWEST FLOW WILL KEEP AREAS NORTHEAST OF THE LAKES A LITTLE 
COOLER INCLUDING BUF-ART AREAS. THE RENEWED HEAT WILL ALSO BE 
ACCOMPANIED BY A NOTICEABLE INCREASE IN HUMIDITY LEVELS...AS A DEEP 
SOUTH TO SOUTHWESTERLY FLOW TRANSPORTS PLENTIFUL LOW LEVEL MOISTURE 
NORTHWARD INTO THE AREA.  

FOLLOWING THE MIDWEEK FRONTAL PASSAGE...HIGH PRESSURE WILL BUILD 
BACK INTO THE GREAT LAKES WITH SOMEWHAT COOLER AND LESS HUMID AIR. 
EXPECT TEMPS TO DROP BACK TO CLOSE TO AVERAGE FOR THURSDAY AND 
FRIDAY WITH A RETURN TO SUNSHINE.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS AND LIGHT WINDS WILL PERSIST ACROSS THE REGION FOR
THE REMAINDER OF THE NIGHT...WITH THE EXCEPTION OF THE SOUTHERN
TIER WHERE AREAS OF FOG WILL LIKELY FORM LOWERING VISIBILITIES TO
AT LEAST IFR.

SFC HIGH PRESSURE OVER THE REGION WILL SLOWLY SLIDE TO THE EAST 
TOWARDS NEW ENGLAND BY THIS AFTERNOON. HIGH AND MID LEVEL
CLOUDS WILL BEGIN TO BUILD INTO THE REGION IN THE DAY IN ADVANCE
OF A WEAK WARM FRONT. UNSTABLE ENOUGH DURING THE AFTERNOON MAINLY
WESTERN NEW YORK FOR A BROKEN CU DECK BUT AT VFR LEVELS. MID
CLOUDS WILL BECOME OVERCAST OVER THE WESTERN SITES THIS EVENING.

OUTLOOK...
SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS. SHOWERS LIKELY CHANCE
TSTMS FROM THE GENESEE VALLEY EAST TO THE EASTERN FINGER LAKES REGION.
MONDAY...MAINLY VFR. 
TUESDAY AND WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS.

&&

.MARINE...
NO MARINE HEADLINES WILL BE NEEDED OVER THE WEEKEND WITH A WEAK 
PRESSURE GRADIENT IN PLACE AS HIGH PRESSURE MOVES SLOWLY TO THE EAST 
COAST. 

A GENERALLY QUIET PATTERN SHOULD CONTINUE INTO MID-WEEK...WITH NO 
HEADLINES ANTICIPATED.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...SAGE
NEAR TERM...SAGE
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK/JJR
AVIATION...SAGE
MARINE...SAGE