Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 300320
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1120 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/...
AN AMPLIFIED MID-LEVEL TROUGH IS FOUND ACROSS THE EASTERN CONUS LATE
THIS EVENING WITH SEVERAL SHORTWAVE DISTURBANCES MOVING THROUGH THE
FLOW ALOFT. TWO OF THE MORE PROMINENT DISTURBANCES HAVE TRIGGERED
THUNDERSTORMS ACROSS THE UPPER MISSISSIPPI RIVER VALLEY AND OHIO
RIVER VALLEY EARLIER TODAY. THIS SECOND DISTURBANCE IS CONTRIBUTING
TO DEVELOPMENT OF A SURFACE LOW OVER SOUTHWESTERN OHIO. THIS LOW AND
ITS ASSOCIATED WARM FROM WILL LIFT NORTH ACROSS LAKE ERIE TONIGHT
BRINGING WIDESPREAD SHOWERS AND POSSIBLE THUNDERSTORMS.

RADAR IMAGERY IS SHOWING THIS ACTIVITY HAS BEGUN TO MOVE OVER THE
SOUTHERN TIER AS OF 3Z WITH MESO MODELS AND RADAR EXTRAPOLATION
THEN SHIFTING THESE SHOWERS NORTH TO THE NIAGARA FRONTIER AND
GENESEE VALLEY NEAR 6Z. THE MORE WIDESPREAD ACTIVITY SHOULD HOLD
OFF UNTIL BETWEEN 8Z AND 12Z PER LATEST HRRR AND NAM RUNS. THERE
WILL ALSO BE A CHANCE FOR A FEW THUNDERSTORMS AS ABOUT 500-1000
J/KG OF ELEVATED MUCAPE WILL ACCOMPANY 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. NAM MUCAPE IS FORECAST TO RISE TO NEAR 1500
J/KG. 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. THE OHIO VALLEY LOW WILL DRIFT ACROSS
SOUTHERN ONTARIO AT THAT TIME...WITH A PRE FRONTAL TROUGH PASSING
THROUGH OUR REGION. THERE IS UNCERTAINTY AS TO THE AMOUNT OF BREAKS
IN CLOUD COVER THAT WE WILL EXPERIENCE IN THE WARM SECTOR AS WELL AS
TIMING OF A VORT MAX THAT LOOKS TO LIFT ACROSS WESTERN NEW YORK.
THESE TWO UNCERTAINTIES WILL PLAY A SIGNIFICANT ROLE IN THE AMOUNT
OF INSTABILITY AND FORCING AVAILABLE FOR THUNDERSTORM ACTIVITY.
TEMPERATURES ARE FORECAST TO RISE INTO THE 70S ACROSS WESTERN NEW
YORK WITH A FEW 80S POSSIBLE TOWARD THE FINGER LAKES WHICH MAY BRING
A HIGHER RISK FOR THUNDERSTORM ACTIVITY. SPC HAS A MARGINAL RISK FOR
SEVERE STORMS.

&&

.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 /03Z TUESDAY THROUGH SATURDAY/...
RADAR IS SHOWING SHOWERS LIFTING INTO THE SOUTHERN TIER LATE THIS
EVENING AHEAD OF A WARM FRONT AND SURFACE LOW LIFTING ACROSS THE
OHIO VALLEY. EXPECTING THESE SHOWERS AND A FEW THUNDERSTORMS TO
LIFT NORTH ACROSS THE FORECAST AREA AHEAD OF THE WARM FRONT WITH
THE MORE WIDESPREAD COVERAGE EXPECTED 8-12Z. 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 WITH ONLY A
SLIGHT CHANCE OF SHOWERS FOLLOWING THE IMMEDIATE PASSAGE OF THE WARM
FRONT. AS INSTABILITY INCREASES IN THE AFTERNOON...ADDITIONAL
CONVECTION IS LIKELY AS A DISTURBANCE SHIFT OVER WESTERN NEW YORK.

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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