Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 252344
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
744 PM EDT SAT JUL 25 2015

.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TONIGHT AND SUNDAY IN A
HUMID AIRMASS...AS AN UPPER LEVEL DISTURBANCE AND WEAK SURFACE FRONT
CROSS THE AREA. HIGH PRESSURE WILL BRING A RETURN TO DRY WEATHER AND
SEASONABLY WARM TEMPERATURES THROUGH AT LEAST THE MID-WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
THE SURFACE WARM FRONT HAS NOW EDGED
INTO EASTERN NEW YORK STATE...WITH CONVECTION FORMING ACROSS
SOUTHERN CANADA AND THE EASTERN GREAT LAKES REGION IN A NOW MORE
UNSTABLE AIRMASS. THE MAIN CLUSTERS OF SHOWERS AND THUNDERSTORMS ARE
FOUND JUST TO THE NORTH OF LAKE ONTARIO WHERE ACTIVITY IS FORMING
WITH ADDITIONAL LIFT FROM A PASSING SHORTWAVE. ADDITIONAL ACTIVITY
THAT SPRUNG FORTH OVER THE BRISTOL HILLS REGION WILL CONTINUE TO
ADVANCE EASTWARD THIS EVENING...POSSIBLY JOINING WITH THE CONVECTION
OVER LAKE ONTARIO AND SOUTHERN CANADA TO FORM A LOOSELY CONNECTED
LINE OF CONVECTION OVER OSWEGO AND THE NORTH COUNTRY THIS EVENING. A
WEAK COLD FRONT OVER THE CENTRAL GREAT LAKES WILL REMAIN JUST TO OUR
WEST THROUGH THE OVERNIGHT PERIOD.

THE CONVECTION ACTIVITY WILL DIMINISH FROM WEST TO EAST OVERNIGHT AS
DIURNAL INSTABILITY WANES. THERE WILL BE LITTLE AIR MASS CHANGE
BEHIND THE COLD FRONT WITH SURFACE DEWPOINTS REMAINING IN THE 60S.
THIS WILL MAINTAIN OVERNIGHT LOWS IN THE LOWER TO MID 60S.

A TEMPORARY DIP IN THE UPPER HEIGHT FIELDS OVER THE NEXT 24 HOURS
WILL HELP EASE THE ATTENDANT WEAK COLD FRONT INTO THE OHIO VALLEY BY
SUNDAY. POST-FRONTAL ENVIRONMENT SUNDAY WILL BE FOR A SLIGHT
REDUCTION IN HUMIDITY RELATIVE TO TODAY...WITH NO REAL CHANGE
EXPECTED IN THE TEMPERATURES. THE SLIGHTLY DRIER AND MORE STABLE
CONDITIONS AS HIGH PRESSURE SLIDES THROUGH WILL TRANSLATE INTO A
HIGH DEGREE OF SUNSHINE. THIS INSOLATION POTENTIAL INTO A DRIER AND
MODESTLY MIXED PROFILE FAVORS A GREATER DIURNAL TEMPERATURE
RESPONSE...AND WILL BRING HIGHS A COUPLE DEGREES WARMER THAN TODAY
FOR SUNDAY AFTERNOON.

CONVECTIVE ACTIVITY THAT EMERGES SHOULD FOR THE MOST PART REMAIN
SOUTH OF THE AREA CLOSER TO THE FRONTAL BOUNDARY...HOWEVER WITH
INCREASING INSTABILITY ALONG THE SOUTHERN TIER FEEL SOME SCATTERED
ACTIVITY IS NOT OUT OF THE QUESTION...ESPECIALLY SOUTH AND EAST OF
EXPECTED LAKE ERIE LAKE BREEZE.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
DURING THE FIRST HALF OF THIS PERIOD...SURFACE HIGH PRESSURE
INITIALLY ANCHORED OVER THE CENTRAL GREAT LAKES AND OHIO VALLEY
WILL SLOWLY BUILD EASTWARD INTO THE MID ATLANTIC STATES...WHILE A
BROAD NORTHWESTERLY FLOW ALOFT WILL PERSIST IN BETWEEN AN UPPER
LEVEL LOW OVER CENTRAL QUEBEC...AND AN UPPER LEVEL RIDGE AXIS
SLOWLY DRIFTING FROM THE NORTHERN PLAINS STATES INTO THE WESTERN
GREAT LAKES.

FOR THE VAST MAJORITY OF OUR AREA...THE ABOVE WILL RESULT IN
QUIET AND DRY WEATHER THROUGH MONDAY NIGHT. THE ONE POTENTIAL
EXCEPTION TO THIS WILL BE ACROSS THE NORTH COUNTRY AND SAINT
LAWRENCE VALLEY MONDAY AFTERNOON AND EVENING...WHERE THE
COMBINATION OF DAYTIME HEATING...MOISTURE POOLING NORTHEAST OF
LAKE ONTARIO...AND A WEAK SHORTWAVE DROPPING THROUGH THE
PREVAILING NORTHWESTERLY FLOW ALOFT COULD LEAD TO THE DEVELOPMENT
OF SOME ISOLATED TO WIDELY SCATTERED CONVECTION. WITH MORE OF THE
OPERATIONAL GUIDANCE SUITE LATCHING ONTO THIS IDEA OVER THE PAST
24 HOURS...HAVE UPPED POPS FOR THIS REGION/TIMEFRAME UP INTO THE
UPPER PART OF THE SLIGHT CHANCE RANGE.

OTHERWISE...TEMPERATURES WILL REMAIN ON THE WARMER SIDE OF
AVERAGE THROUGH MONDAY NIGHT...WITH SLOW WARMING OF OUR AIRMASS
SUPPORTIVE OF WIDESPREAD HIGHS IN THE MID TO UPPER 80S ON
MONDAY...AND LOWS IN THE UPPER 50S TO MID 60S SUNDAY NIGHT WARMING
A COUPLE OF DEGREES OR SO FOR MONDAY NIGHT. SUCH READINGS WILL BE
ACCOMPANIED BY MODERATELY HUMID CONDITIONS...AS SURFACE DEWPOINTS
WILL RANGE THROUGH THE LOWER HALF OF THE 60S.

AFTER THAT...THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE WILL
DRIFT EASTWARD AND OFF THE ATLANTIC COASTLINE THROUGH
MIDWEEK...WHILE THE AXIS OF ITS PARENT 594 DM UPPER LEVEL RIDGE
BUILDS FROM THE UPPER GREAT LAKES INTO NEW YORK STATE...IN ADVANCE
OF A MID LEVEL TROUGH PUSHING EAST ACROSS CENTRAL CANADA. AS A
RESULT...OUR REGION WILL COME UNDER THE INFLUENCE OF A BROAD
SOUTHWESTERLY FLOW AT THE LOWER LEVELS AND BUILDING
HEIGHTS/INCREASING SUBSIDENCE ALOFT...WITH THE COMBINATION OF
THESE FACTORS LEADING TO HEAT AND HUMIDITY LEVELS STEADILY RISING
ACROSS OUR AREA TUESDAY AND WEDNESDAY.

WITH 850 MB TEMPS CLIMBING TO BETWEEN +17C AND +18C TUESDAY AND
TO THE +19C TO +21C RANGE WEDNESDAY PER A CONSENSUS OF THE
GFS/ECMWF... DAYTIME HIGHS SHOULD EASILY REACH INTO THE 85-90
RANGE AREAWIDE ON TUESDAY AND TO THE UPPER 80S TO LOWER 90S IN
MOST PLACES ON WEDNESDAY...WHEN SOME OF OUR NORMALLY WARMER SPOTS
IN THE GENESEE VALLEY AND FINGER LAKES COULD EVEN SEE MERCURY
LEVELS REACH AS HIGH AS THE MID 90S. AT THE SAME TIME...SURFACE
DEWPOINTS WILL STEADILY CLIMB INTO THE UPPER 60S BY LATER
WEDNESDAY...RESULTING IN HEAT INDICES PUSHING INTO THE LOWER TO
MID 90S AREAWIDE WEDNESDAY AFTERNOON. WHILE SUCH READINGS WOULD
REMAIN SHY OF HEAT ADVISORY CRITERIA...SUCH WARMTH AND HUMIDITY
WILL STILL EASILY MAKE FOR DOWNRIGHT OPPRESSIVE CONDITIONS.

IN TERMS OF PRECIPITATION CHANCES...WHILE A STRAY POP-UP SHOWER
OR THUNDERSTORM OR TWO CANNOT BE COMPLETELY RULED OUT WITH DAYTIME
HEATING OF OUR INCREASINGLY HOT AND HUMID AIRMASS BOTH TUESDAY AND
WEDNESDAY...AT THIS POINT IT STILL APPEARS THAT GENERAL LARGE-
SCALE SUBSIDENCE AND THE LACK OF AN APPRECIABLE TRIGGER SHOULD
KEEP OUR WEATHER MAINLY DRY THROUGH THE VAST MAJORITY OF THE DAY
ON WEDNESDAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
EARLY ON IN THIS PERIOD...THE MEDIUM RANGE GUIDANCE REMAINS IN
GOOD AGREEMENT ON THE NEXT MID LEVEL TROUGH SLIDING EAST ACROSS
CENTRAL CANADA...WHILE PUSHING ITS ATTENDANT COLD FRONT ACROSS OUR
REGION BETWEEN LATER WEDNESDAY NIGHT AND THURSDAY. IN THE
PROCESS...THIS FEATURE SHOULD GENERATE AT LEAST SOME SCATTERED
CONVECTION AS IT INTERACTS WITH THE HOT AND STICKY ANTECEDENT
AIRMASS THAT WILL BE IN PLACE ACROSS OUR REGION.

FOLLOWING THE PASSAGE OF THE COLD FRONT...HIGH PRESSURE AND
COOLER/DRIER AIR THEN LOOKS TO BUILD EAST ACROSS OUR REGION
BETWEEN THURSDAY AFTERNOON AND FRIDAY...WHILE USHERING IN A RETURN
TO DRY WEATHER AND MORE COMFORTABLE TEMPERATURES AND HUMIDITY
LEVELS.

FINALLY AS WE GET INTO NEXT WEEKEND...MAINLY DRY WEATHER SHOULD
CONTINUE ON SATURDAY IN ADVANCE OF THE NEXT BROAD MID LEVEL TROUGH
AND ITS ASSOCIATED WEAK COLD FRONT...ALONG WITH A LITTLE BUMP
UPWARD IN TEMPERATURES AGAIN AS SLIGHTLY WARMER AIR GETS ADVECTED
INTO OUR REGION IN ADVANCE OF THIS NEXT SYSTEM.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR FLIGHT CONDITIONS
ARE FOUND ACROSS THE REGION AT 00Z AND THESE CONDITIONS WILL BE
PREDOMINATE THROUGH THE TAF CYCLE. SHOWERS AND PERHAPS A
THUNDERSTORM MAY IMPACT THE KART AIRFIELD...AND THE NORTHERN FINGER
LAKES AND EASTERN LAKE ONTARIO REGION THROUGH 12Z. OTHERWISE EXPECT
JUST ISOLATED AND BRIEF SHOWER ACTIVITY OVER WESTERN NEW YORK.

SOME FOG WITH VSBYS LESS THAN A MILE MAY FORM IN THE VALLEYS OF THE
SOUTHERN TIER WITH THIS FOG EXPANDING TO THE KJHW TERMINAL LATE
TONIGHT AS WINDS AT 1K FEET RELAX FROM 15 KNOTS DOWN TO JUST A FEW
KNOTS. THERE IS A POTENTIAL FOR SOME FOG TONIGHT ACROSS KBUF/KIAG
HOWEVER A STRONG LAKE BREEZE HAS MAINTAINED DRY CONDITIONS THROUGH
THE EVENING AND THIS POTENTIAL FOR FOG WILL BE SMALL. THERE WILL BE
A SOMEWHAT GREATER CHANCE FOR SOME BRIEF LOW END MVFR VSBYS ACROSS
KART WHERE EVENING SHOWERS AND THUNDERSTORMS ARE LIKELY TO PASS
BY...INCREASING THE LOW LEVEL HUMIDITY.

SHOWERS AND THUNDERSTORMS WILL TAPER OFF OVERNIGHT WITH THE
REMAINING SECOND HALF OF THE TAF CYCLE DRY WITH DECREASING CLOUDS.
THERE MAY BE A SUNDAY SHOWER OR THUNDERSTORM...WITH ACTIVITY
EXPECTED TO REMAIN SOUTH AND EAST OF THE TAF SITES.

WINDS WILL BRIEFLY SHIFT TO NORTHWEST BEHIND THE COLD FRONT EARLY
SUNDAY MORNING...WITH LAKE BREEZE CIRCULATIONS RETURNING THE LIGHT
SOUTHWEST WINDS TO KBUF/KIAG/KART THROUGH THE AFTERNOON HOURS.

OUTLOOK...
SUNDAY NIGHT...MAINLY VFR WITH A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS. MONDAY THROUGH THURSDAY...VFR.

&&

.MARINE...
WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH SUNDAY NIGHT DESPITE THE PASSAGE OF A COLD FRONT TONIGHT.
THUNDERSTORMS ARE POSSIBLE WHILE THE COLD FRONT MOVES ACROSS OUR
NEARSHORE AREAS...BUT STRONG/SEVERE STORMS ARE NOT EXPECTED. HIGH
PRESSURE THEN RETURNS MONDAY WITH GENERALLY CALM CONDITIONS
PERSISTING INTO THE MIDDLE OF THE COMING WEEK.

&&

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

&&

$$

SYNOPSIS...THOMAS/TMA
NEAR TERM...THOMAS/TMA
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...THOMAS
MARINE...TMA


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