Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 300031
AFDBUF

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

.SYNOPSIS...
A WARM FRONT WILL LIFT ACROSS WESTERN NEW YORK TONIGHT WITH LOW
PRESSURE CROSSING THE LOWER GREAT LAKES REGION TUESDAY. ANOTHER WEAK
LOW WILL LIFT NORTH ACROSS THE REGION AGAIN WEDNESDAY. EACH OF THESE
PERIODS WILL FEATURE CHANCES OF SHOWERS AND POSSIBLE THUNDERSTORMS.
HIGH PRESSURE WILL BUILD INTO THE GREAT LAKES AND NORTHEAST FOR
THURSDAY AND FRIDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
A CLUSTER OF DIURNAL SHOWERS IS DISSIPATING ACROSS THE INTERIOR
SOUTHERN TIER THIS EVENING WITH INCREASING CLOUD COVER OCCURRING
ACROSS THE FORECAST AREA AS CONVECTIVE DEBRIS FROM STORMS IN THE
OHIO VALLEY IS ADVECTED NORTH.

AN AMPLIFIED MID-LEVEL TROUGH IS FOUND ACROSS THE EASTERN CONUS THIS
EVENING WITH SEVERAL SHORTWAVE DISTURBANCES MOVING THROUGH THE FLOW
ALOFT. THE TWO MORE PROMINENT DISTURBANCES ARE TRIGGERING
THUNDERSTORMS ACROSS THE UPPER MISSISSIPPI RIVER VALLEY AND JUST
SOUTH OF THE OHIO RIVER. THIS SECOND DISTURBANCE IS CONTRIBUTING TO
DEVELOPMENT OF A SURFACE LOW OVER SOUTHERN OHIO. THIS LOW AND ITS
ASSOCIATED WARM FROM WILL LIFT NORTH ACROSS LAKE ERIE TONIGHT
BRINGING WIDESPREAD SHOWERS AND POSSIBLE THUNDERSTORMS. LATEST MESO
MODELS SHOW THIS WILL BEGIN TO MOVE OVER THE SOUTHERN TIER AROUND 3Z
THEN NORTH INTO WESTERN NEW YORK AROUND 6Z WITH THE MORE WIDESPREAD
ACTIVITY HOLDING OFF UNTIL BETWEEN 8Z AND 12Z. THERE WILL ALSO BE A
CHANCE FOR A FEW THUNDERSTORMS AS SOME WEAK TO MODEST ELEVATED
INSTABILITY DEVELOPS WITH THE WARM FRONT. TEMPERATURES WILL ONLY
SLIP BACK TO AROUND 60 OVERNIGHT WITH THE INCREASE CLOUDS AND WARM
ADVECTION ALOFT.

THE WARM FRONT WILL PUSH NORTH AND EAST ACROSS CENTRAL NEW YORK
DURING THE FIRST HALF OF TUESDAY...WITH SHOWERS AND THUNDERSTORMS.
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 /01Z TUESDAY THROUGH SATURDAY/...
MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO INCREASE ACROSS WESTERN
AND CENTRAL NEW YORK THIS EVENING AHEAD OF A WARM FRONT AND SURFACE
LOW DEVELOPING OVER THE OHIO VALLEY. LATER THIS EVENING...WITHIN A
FEW HOURS OF 6Z EXPECTING SHOWERS AND A FEW THUNDERSTORMS TO LIFT
NORTH ACROSS THE FORECAST AREA ALONG THE WARM FRONT. 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.
SOME MVFR CIGS LOOK POSSIBLE WITH/BEHIND THE WARM FRONT THEN A BRIEF
PERIOD OF RELATIVELY DRY WEATHER WILL FOLLOW THE PASSAGE OF THE WARM
FRONT...WITH ADDITIONAL CONVECTION LIKELY TUESDAY AFTERNOON AS THE
SURFACE LOW PASSES TO THE WEST.

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...
TWO WEAK AREAS OF LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES
REGION TONIGHT THROUGH WEDNESDAY EACH WITH SHOWERS AND POSSIBLE
THUNDERSTORMS. WHILE WINDS WILL FRESHEN A BIT IN ADVANCE OF A WARM
FRONT 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...JJR/SMITH
NEAR TERM...JJR/SMITH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...JJR/SMITH
MARINE...JJR/SMITH



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