Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 291950
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
350 PM EDT MON JUN 29 2015

.SYNOPSIS...
WEAK HIGH PRESSURE OVER NEW YORK STATE LATE THIS AFTERNOON WILL
MOVE EAST OF THE AREA TONIGHT. LOW PRESSURE WILL LIFT ACROSS THE
GREAT LAKES TONIGHT THROUGH WEDNESDAY BRINGING MORE SHOWERS AND
POSSIBLE THUNDERSTORMS THROUGH MIDWEEK. HIGH PRESSURE WILL BUILD
INTO THE GREAT LAKES AND NORTHEAST FOR THURSDAY AND FRIDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
GENERALLY SCATTERED TO BROKEN CLOUDS WILL REMAIN OVER THE REGION
FOR THE REST OF THE AFTERNOON WITH CLOUDS INCREASING AGAIN ACROSS
THE WESTERN SOUTHERN TIER AND NIAGARA FRONTIER. CONVECTION ALONG
AND SOUTH OF THE NY-PA BORDER SHOULD MOVE EASTWARD AND STAY MAINLY
SOUTH OF THE BORDER LATE THIS AFTERNOON. OTHER CONVECTION OVER
SOUTHERN ONTARIO WILL REMAIN OVER THE NIAGARA PENINSULA THROUGH
EARLY EVENING.

NEXT SHORTWAVE TROUGH AND ATTENDANT SECOND SURFACE LOW WILL LIFT
NORTHEAST INTO LAKE ERIE TONIGHT...WHILE ALSO SPREADING INCREASING
AMOUNTS OF MOISTURE AND WARM ADVECTIVE LIFT BACK INTO OUR REGION.
THIS WILL RESULT IN MID AND HIGH CLOUD COVER INCREASING AGAIN ACROSS
FAR SOUTHWESTERN NEW YORK THIS AFTERNOON AND ACROSS THE REST OF THE
REGION TONIGHT...WITH A SIMILAR INCREASE IN SHOWER CHANCES FOLLOWING
A FEW HOURS LATER. AFTER MIDNIGHT...THE COMBINATION OF INCREASING
MOISTURE AND WARM ADVECTIVE LIFT ALONG AN ADVANCING WARM FRONT
SHOULD BECOME SUFFICIENT TO SUPPORT A LIKELIHOOD OF SHOWERS SOUTH OF
LAKE ONTARIO...ALONG WITH THE CHANCE FOR A FEW THUNDERSTORMS AS WELL
AS SOME WEAK TO MODEST ELEVATED INSTABILITY ALSO DEVELOPS.

THE LOW WILL PUSH THE WARM FRONT THROUGH OUR REGION DURING THE FIRST
HALF OF TUESDAY...WITH SHOWERS AND THUNDERSTORMS. THE BULK OF THIS
FIRST ROUND OF CONVECTION WILL BE FOUND EAST OF THE FINGER LAKES AND
EAST OF LAKE ONTARIO. WHILE THERE WILL BE THE POTENTIAL FOR A SHOWER
OR THUNDERSTORM OVER THE FAR WESTERN COUNTIES IN THE MORNING...IT
SHOULD LARGELY BE RAINFREE.

IN THE WAKE OF THE WARM FRONT...THE AIRMASS OVER THE WESTERN
COUNTIES WILL BECOME INCREASINGLY UNSTABLE DURING THE COURSE OF THE
MORNING AND MIDDAY. THIS WILL SET THE STAGE FOR THE NEXT ROUND OF
SHOWERS AND THUNDERSTORMS WHICH WILL COME THROUGH THE FORECAST AREA
DURING THE MID AND LATE AFTERNOON. AN ILL DEFINED SFC LOW WILL DRIFT
ACROSS SOUTHERN ONTARIO AT THAT TIME...WITH A PRE FRONTAL TROUGH
PASSING THROUGH OUR REGION. WHILE CONVECTION APPEARS LIKELY INLAND
AWAY FROM LAKE ERIE...THERE IS UNCERTAINTY AS TO THE AMOUNT OF CLOUD
COVER THAT WE WILL EXPERIENCE IN ADVANCE OF THE CONVECTION. THIS
WILL PLAY A SIGNIFICANT ROLE IN DETERMINING THE RISK FOR STRONG TO
SEVERE THUNDERSTORM ACTIVITY. THE GREATEST POTENTIAL FOR SIGNIFICANT
AFTERNOON CONVECTION IS OVER THE FINGER LAKES REGION AND THE SRN
TIER EAST OF JAMESTOWN.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS WE OPEN THE PERIOD TUESDAY NIGHT THE NEXT IN THE TRAIN OF SYSTEMS
WILL BE AFFECTING THE REGION IN THE FORM OF A SHARPLY AMPLIFIED UPPER
LEVEL TROUGH SWING ACROSS THE LOWER GREAT LAKES WITH AN ATTENDANT
SURFACE LOW TRACKING IN THE VICINITY OF LAKE ONTARIO BEFORE LIFTING
INTO QUEBEC WEDNESDAY. SHOWERS AND THUNDERSTORMS WILL BE FAIRLY
WIDESPREAD IN THE EVENING WITH THE FOCUS SHIFTING TOWARDS THE
EASTERN HALF OF THE FORECAST AREA LATER TUESDAY NIGHT AS THE LEAD
SHORTWAVE LIFTS ACROSS THE AREA. GENERALLY WEAK INSTABILITY SHOULD
NEGATE THE SEVERE THREAT...AND GIVEN THE DYNAMIC NATURE OF THE
FORCING...STORMS SHOULD BE FAST-MOVING ENOUGH THAT FLOODING IS NOT
EXPECTED TO BE AN ISSUE EITHER.

THE FOCUS FOR CONVECTION WILL SHIFT TO EASTERN NEW YORK WEDNESDAY AS
THE SHORTWAVE ENERGY LIFTS OUT ACROSS THE SAINT LAWRENCE VALLEY AND
NEW ENGLAND WITH THE AFOREMENTIONED SURFACE LOW MOVING OFF INTO
QUEBEC. A TRAILING COLD FRONT WILL CROSS THE FORECAST AREA AND WILL
SERVE AS THE FOCUS FOR CONVECTION WITH THE EASTERN LAKE ONTARIO
ZONES SEEING THE BULK OF THE ACTIVITY OWING TO PROXIMITY TO DEEPER
MOISTURE AND UPSLOPE FLOW OFF LAKE ONTARIO. A SOMEWHAT DRIER AND
MORE STABLE AIRMASS WILL ALREADY BE IN PLACE ACROSS WESTERN NEW YORK
ON WEDNESDAY AND THIS SHOULD TAMP DOWN CONVECTION CONSIDERABLY. THAT
SAID...WESTERN NEW YORK WILL STILL BE UNDER THE INFLUENCE OF THE
LONGWAVE TROUGH AND AS SUCH CANNOT RULE OUT SOME SCATTERED
CONVECTION ACROSS THE AREA...PARTICULARLY IF THE FRONTAL PASSAGE IS
SLOWER THAN CURRENTLY EXPECTED.

CONVECTION SHOULD WANE QUICKLY WEDNESDAY NIGHT AS COOLER AND MUCH
DRIER AIR SURGES ACROSS THE LOWER GREAT LAKES IN THE WAKE OF THE
AFOREMENTIONED COLD FRONTAL PASSAGE. THIS REFRESHING AIRMASS WILL
SETTLE ACROSS THE REGION THROUGH THE REST OF PERIOD AS HIGH PRESSURE
MOVES ACROSS THE GREAT LAKES WITH SUNNY AND MILD DAYS WITH HIGHS IN
THE 70S AND EQUALLY MILD NIGHTS WITH LOWS IN THE 50S.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
IT WILL BE A QUIET END TO THE WEEK AS THE REGION WILL BE THE
BENEFICIARY OF A PROGRESSIVE UPPER LEVEL RIDGE THAT WILL BE CROSSING
THE LOWER GREAT LAKES INTO NEW ENGLAND. THE ASSOCIATED RISING
HEIGHTS WILL SIGNAL A RETURN TO MORE SUMMER-LIKE WARMTH IN TIME FOR
THE HOLIDAY WEEKEND. WHILE FRIDAY SHOULD ALMOST CERTAINLY BE
DRY...THIS MAY NOT HOLD TRUE FOR SATURDAY. THE FORECAST AREA WILL BE
CAUGHT IN BETWEEN TWO SYSTEMS...A SOUTHERN STREAM SHORTWAVE OVER THE
OHIO VALLEY AND A NORTHERN STREAM TROUGH OVER NORTHERN
ONTARIO/QUEBEC. OF THE MODELS...THE ECMWF IS MOST AGGRESSIVE IN
PHASING THESE TWO SYSTEMS...RESULTING IN FAIRLY WIDESPREAD
SHOWERS/THUNDERSTORMS FOR THE FOURTH OF JULY WHILE THE GFS KEEPS THE
SYSTEMS MORE SEPARATE...RESULTING IN WEAKER FORCING AND JUST A
CHANCE OF A LAKE BREEZE CONVECTION OR TWO IN THE AFTERNOON. FOR NOW
WILL HAVE TO KEEP A CHANCE OF SHOWERS/THUNDERSTORMS IN THE FORECAST
AS A COMPROMISE PENDING GREATER CLARITY FROM FUTURE RUNS.

WHILE UNCERTAINTY REIGNS THE FIRST HALF OF THE WEEKEND...SATURDAY
NIGHT AND SUNDAY SHOULD REMAIN DRY BY ALL ACCOUNTS AS THE
DISTURBANCES OF CONCERN WILL BE PAST THE FORECAST AREA WITH SOME
MEASURE OF UPPER LEVEL RIDGING MOVING ACROSS THE AREA. THIS SHOULD
HELP MAINTAIN THE SUMMER-LIKE WARMTH WITH HIGHS IN THE UPPER
70S/LOWER 80S.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
GENERALLY SCATTERED TO BROKEN CLOUDS 3-5K FT WILL REMAIN OVER THE
REGION FOR THE REST OF THE AFTERNOON WITH MID AND HIGH LEVEL
CLOUDS INCREASING AGAIN ACROSS THE WESTERN SOUTHERN TIER AND
NIAGARA FRONTIER. CONVECTION ALONG AND SOUTH OF THE NY-PA BORDER
SHOULD MOVE EASTWARD AND STAY MAINLY SOUTH OF THE BORDER LATE THIS
AFTERNOON. OTHER CONVECTION OVER SOUTHERN ONTARIO WILL REMAIN OVER
THE NIAGARA PENINSULA THROUGH EARLY EVENING.

THE SURFACE RIDGE WILL SLIDE OFF TO OUR EAST EARLY THIS EVENING AND
GIVE WAY TO ANOTHER AREA OF LOW PRESSURE LIFTING ACROSS THE OHIO
VALLEY. THIS WILL RESULT IN ADDITIONAL MID AND HIGH CLOUD COVER
SPREADING INTO THE AREA FROM THE SOUTHWEST LATER THIS AFTERNOON AND
EVENING...WITH INCREASING SHOWER CHANCES RETURNING TO THE VCNTY OF
KJHW BY 00Z TUESDAY...THEN SPREADING ACROSS THE REST OF THE REGION
THROUGH THE BALANCE OF THE TAF PERIOD. AFTER MIDNIGHT...CHANCES FOR
A FEW THUNDERSTORMS WILL ALSO SPREAD ACROSS AREAS SOUTH OF LAKE
ONTARIO IN A SIMILAR FASHION AS SOME WEAK TO MODEST ELEVATED
INSTABILITY DEVELOPS. WHILE CONDITIONS WILL GENERALLY REMAIN
VFR...IT IS POSSIBLE THAT ANY SUCH SHOWERS OR THUNDERSTORMS COULD
PRODUCE SOME BRIEF REDUCTIONS TO MVFR.

CONVECTION WILL MOVE EAST THROUGH THE FINGER LAKES AND EAST OF LAKE
ONTARIO IN THE MORNING AS THE WARM FRONT MOVES THROUGH THE REGION.
A BRIEF PERIOD OF RELATIVELY DRY WEATHER WILL FOLLOW THE PASSAGE OF
THE WARM FRONT...WITH ADDITIONAL CONVECTION LIKELY AFTER 17Z TUESDAY.

OUTLOOK...
TUESDAY NIGHT...MAINLY VFR...THOUGH WITH THE LIKELIHOOD OF A FEW
ROUNDS OF SHOWERS/THUNDERSTORMS AND ATTENDANT REDUCTIONS TO MVFR.
WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
THURSDAY AND FRIDAY...VFR.
SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES REGION TONIGHT
THROUGH WEDNESDAY. WHILE WINDS WILL FRESHEN A BIT IN ADVANCE OF
THIS SYSTEM TONIGHT AND TUESDAY...AT THIS POINT IT APPEARS THAT
CONDITIONS SHOULD REMAIN SAFELY BELOW ADVISORY LEVELS RIGHT
THROUGH THE UPCOMING WEEK. HIGH PRESSURE WILL BUILD OVER THE GREAT
LAKES THURSDAY AND FRIDAY.

&&

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

&&

$$

SYNOPSIS...FRANKLIN
NEAR TERM...FRANKLIN
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...FRANKLIN
MARINE...FRANKLIN



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