Special Weather Statement, NWS Buffalo, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
358 AM EDT SUN SEP 4 2011

.SYNOPSIS...
A WARM AND MUGGY LATE SUMMER AIRMASS ACROSS THE REGION WILL FUEL
SHOWERS AND THUNDERSTORMS TODAY...WITH THE POTENTIAL FOR SOME OF
THESE STORMS TO BECOME SEVERE WITH DAMAGING WIND GUSTS AND HEAVY
RAIN. RAIN SHOWERS AND SCATTERED THUNDERSTORMS WILL CONTINUE
OVERNIGHT WITH LOCALIZED HEAVY DOWNPOURS LIKELY. THE UNSETTLED
PATTERN IS EXPECTED TO LINGER INTO LABOR DAY BEFORE HIGH PRESSURE
BUILDS INTO THE GREAT LAKES REGION LATER TUESDAY THROUGH MIDWEEK
WITH DRY AND COOLER WEATHER.

&&

.NEAR TERM /THROUGH TONIGHT/...
SEVERE THUNDERSTORM WATCH 831 IN EFFECT UNTIL 11 AM SUNDAY.

AT 07Z REGIONAL RADARS SHOW A CLUSTER OF SHOWERS AND POTENTIALLY
SEVERE THUNDERSTORMS ADVANCING NORTHEASTWARD ACROSS LAKE ERIE
FORMING ON THE LOW LEVEL CONVERGENCE ALONG A 25 KNOT JET NEAR 925
HPA. OPERATIONAL MODELS DO NOT HAVE A GOOD HANDLE ON THIS ACTIVITY
AND WILL INTERPOLATE THESE SHOWERS AND THUNDERSTORMS OUT...REACHING
THE WESTERN SOUTHERN TIER JUST PAST 7Z AND CROSSING WNY THROUGH THE
PREDAWN...AND DAWN HOURS. WILL START WITH CATEGORICAL POPS THIS
MORNING ACROSS THE SOUTHERN TIER...TAPERING OFF TO LIKELY AND CHC
FURTHER TO THE NORTH AS IR CLOUD TOPS ARE SHOWING A WARMING TREND.

ALOFT A DIGGING TROUGH OVER THE WESTERN GREAT LAKES IS DEEPENING A
SFC LOW JUST NORTH OF LAKE SUPERIOR THIS MORNING. OUR REGION WILL BE
FULLY WITHIN THE WARM SECTOR WITH A MILD SOUTHERLY FLOW TO START THE
DAY.

THROUGH THE DAY INSTABILITY WILL INCREASES WITH SUNSHINE BOOSTING SB
CAPES TO 1500 TO 2500 J/KG ACROSS THE REGION...ESPECIALLY ACROSS THE
GENESEE VALLEY AND INTO THE NORTHERN FINGER LAKES. THROUGH THE DAY
THE 0-6KM EFFECTIVE BULK SHEER WILL INCREASE TO 30 TO 35
KNOTS...WITH THE LARGER VALUES TO THE WEST CLOSER TO THE UPPER LEVEL
TROUGH. WITH A UNIDIRECTIONAL FLOW THROUGH 700 HPA EXPECT A SECOND
ROUND OF THUNDERSTORMS TODAY...LIKELY STARTING JUST PAST NOONTIME
WITH POSSIBLE DAMAGING WIND GUSTS.

TEMPERATURES SUNDAY WILL AGAIN BE ABOVE NORMAL WITH HIGHS CLIMBING
INTO THE MID 80S...WITH UPPER 80S ACROSS THE WARMER GENESEE VALLEY.

SUNDAY NIGHT AND INTO MONDAY THE PROSPECTS FOR MODERATE TO HEAVY
RAIN ACROSS THE REGION EXISTS. THE DIGGING TROUGH WILL BE ACROSS THE
CENTRAL GREAT LAKES WITH STRONG PVA...AND A STRENGTHENING 120 KNOT
250 HPA JET PROVIDING FOR DEEP UPWARD MOTION. WITH PWATS REMAINING
NEAR +1 TO +2 SD ABOVE NORMAL ACROSS THE REGION EXPECT SHOWERS TO
SPREAD NORTHWARD ACROSS THE CWA SUNDAY EVENING AND OVERNIGHT. WILL
FOCUS MORE ON HEAVY RAIN SHOWERS THAN THUNDERSTORMS IN THE GRIDS AS
INSTABILITY DECREASES OVERNIGHT THOUGH CONVERGENCE ALONG THE PASSAGE
OF THE COLD FRONT MAY STILL TRIGGER A FEW THUNDERSTORMS.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
OVERALL...THE FIRST HALF OF THE WEEK WILL BE AN ACTIVE PERIOD AS AN
UPPER LEVEL TROF SLOWLY CROSSES THE REGION. MONDAY WILL START WITH
AN UPPER LEVEL TROF ACROSS MICHIGAN AND A SURFACE TROF ACROSS NEW
YORK. BUFKIT FOR BOTH THE NAM/GFS SHOW THAT WITH COLD AIR IN THE
BOUNDARY LAYER...MOST OF THE LIFT IS ACTUALLY BEING GENERATED
ALOFT...WITH SINKING COLD AIR ADVECTION IN THE LOW-MID LEVELS. THIS
IS CONSISTENT WITH THE REGION BEING IN THE RIGHT REAR QUADRANT OF THE
JET...AND WITH THE UPPER TROF CROSSING. THIS SAID...WE WILL STILL
HAVE SOME TIE IN TO TROPICAL MOISTURE ALOFT AT LEAST. MODEL GUIDANCE
IS IN FAIRLY GOOD AGREEMENT ON THE SYNOPTIC SCENARIO FOR MONDAY.

WHILE THERE IS JUST ENOUGH ELEVATED INSTABILITY IN EASTERN SECTIONS
TO MAINTAIN A MENTION OF THUNDERSTORMS ON MONDAY MORNING...EXPECT
THE MAJORITY OF PRECIPITATION TO ONLY BE PSEUDO-CONVECTIVE ON
MONDAY...WITH PLAIN RAIN SHOWERS OR RAIN IN MOST LOCATIONS. STEADY
SHOWERS WILL TAPER FROM WEST TO EAST...BUT WITH THE TROF STILL
UPSTREAM MONDAY EVENING...WILL MAINTAIN AT LEAST CHANCE POPS
THROUGHOUT THE DAY. OTHERWISE...IT SHOULD BE A CLOUDY AND COOL
DAY...SHARPLY DIFFERENT FROM THE PAST FEW WARM AND MUGGY DAYS. HIGHS
WILL ONLY BE IN THE 60S ACROSS THE REGION.

MODEL GUIDANCE DIVERGES MONDAY NIGHT...WITH SIGNIFICANT DIFFERENCES
BETWEEN SOME VARIOUS MODEL RUNS. THE DIFFICULTY COMES IN HOW THE
MODELS HANDLE THE REMNANTS OF TROPICAL STORM LEE. THE NAM CAN BE
CONSIDERED A WORST CASE SCENARIO IN A LOT OF WAYS...IN THAT IT SPLITS
THE TROPICAL SYSTEM LIFTING A REMNANT LOW TO THE MID ATLANTIC...THEN
AGGRESSIVELY DEVELOPS THIS LOW. THE GGEM ALSO BRINGS A SIGNIFICANT
CHUNK OF MOISTURE ON MONDAY NIGHT...THOUGH IS MUCH LESS AGGRESSIVE.
FEEL THE NAM COASTAL LOW DEVELOPMENT IS UNLIKELY TO VERIFY...SO DO
NOT USE THE NAM FOR VIRTUALLY ANY GRIDS MONDAY NIGHT ONWARD. THE WET
GGEM DOES APPEAR FEASIBLE...THOUGH IT IS NOTEWORTHY THAT THE
GFS/UKMET ARE FAIRLY DRY MONDAY NIGHT IN KEEPING THE MAJORITY OF THE
TROPICAL REMNANTS WELL SOUTH. IN A LOW CONFIDENCE FORECAST...DEPICT
POPS/QPF TO SHOW SOME POSSIBILITY FOR A WAVE OF LOW PRESSURE RIDING
UP THE BAROCLINIC ZONE ACROSS NEW ENGLAND ON MONDAY NIGHT...BUT
REJECT THE VERY AGGRESSIVE NAM...AND TEMPER THE GGEM WITH THE
GFS/UKMET SOLUTIONS. TREND FROM CHANCE POPS IN BUFFALO...LIKELY IN
ROCHESTER...AND CATEGORICAL EAST OF LAKE ONTARIO. WESTERN NEW YORK
WILL SOLIDLY BE IN COOL AIR AT THE SURFACE...WITH PRECIPITATION
LIKELY TO BE SHOWERS...OR PERHAPS A PERIOD OF STEADY RAIN IF A
SIGNIFICANT IMPULSE DOES DEVELOP.

AS IS...DO NOT SEE A SIGNIFICANT FLOODING THREAT AS A RESULT OF RAIN
MONDAY AND MONDAY NIGHT. HOWEVER...THERE STILL IS A WIDE SPREAD OF
POSSIBLY SOLUTIONS...WHERE IF THE WETTER SCENARIOS PLAY
OUT...FLOODING WOULD BE A POSSIBILITY EAST OF LAKE ONTARIO.

THE UPPER TROF WILL CONTINUE TO PUSH EASTWARD ON TUESDAY...WITH ANY
LINGERING SHOWERS ENDING FROM WEST TO EAST. ROCHESTER WEST SHOULD BE
DRY BUT COOL ON TUESDAY...WHILE EASTERN PORTIONS MAY HAVE A FEW
SHOWERS LINGER DURING THE MORNING HOURS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE WILL RIDGE IN FROM CANADA TUESDAY NIGHT INTO
WEDNESDAY. EXPECT FAIR BUT COOL CONDITIONS FOR TUESDAY NIGHT. ON
WEDNESDAY...THE REST OF WHATS LEFT OF TROPICAL STORM LEE WILL LIFT
ROUGHLY INTO THE TENNESSEE VALLEY...THOUGH MUCH UNCERTAINTY REMAINS
ON THE EXACT TIMING AND POSITION OF THIS. REMNANTS MAY REACH THE
SOUTHERN TIER LATE IN THE DAY WEDNESDAY.

THE CONFIDENCE IN THE FORECAST DURING THIS TIMEFRAME IS NOT THAT
HIGH DUE TO THE QUESTIONS ABOUT THE INTERACTION OF THE REMNANTS OF
LEE AND KATIA. MOST GUIDANCE IS LEANING TOWARD MOISTURE FROM THE
REMNANTS OF LEE MOVING NORTH ACROSS THE REGION IN THE WEDNESDAY NIGHT
THROUGH FRIDAY TIME FRAME RESULTING IN THE POTENTIAL FOR RAIN
HIGHEST ALONG OUR SOUTHERN BORDER. AT THIS POINT I AM NOT GOING TO
TRY TO SECOND GUESS THE ENSEMBLE OF GUIDANCE AND WILL KEEP A CHANCE
OF RAIN IN THE FORECAST THROUGH FRIDAY NIGHT. HOWEVER, I WOULD NOT
BE SURPRISED TO SEE CHANGES IN THE PRECIPITATION FORECAST AS WE GET
CLOSER TO THIS TIME FRAME. TEMPERATURES WILL BE SEASONABLE WITH
DAYTIME HIGHS IN THE 70S AND OVERNIGHT LOWS IN THE 50S.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
AT 06Z MVFR AND VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE
REGION...AND MVFR IS EXPECTED AT ALL LOCATIONS AT TIMES THROUGH THE
OVERNIGHT IN THIS WARM AND MUGGY AIRMASS. SHOWERS AND THUNDERSTORMS
ACROSS SOUTHERN LAKE ERIE AND OHIO AT THIS HOUR WILL CONTINUE TO
SPREAD NORTHEASTWARD. WILL INSERT -TSRA INTO THE KJHW TAF...WHILE
HOLDING ONTO -SHRA WITH A CB ACROSS THE NIAGARA FRONTIER AS ACTIVITY
MAY WEAKEN FURTHER INTO THE NIGHT.

SUNDAY MORNING CONVECTION WILL WANE...TEMPORARILY BEFORE
ADDITIONAL SHOWERS AND THUNDERSTORMS CROSS THE REGION FROM WEST TO
EAST. EXPECT A LINE OF CONVECTION TO FORM AS INSTABILITY BUILDS
THROUGH THE DAY...STARTING EARLY AFTERNOON TOWARDS THE WEST AND THEN
ADVANCING EASTWARD. WILL HAVE A -TSRA IN ALL TAFS FOR THIS
ACTIVITY...WHILE TIMING MAY NEED TO BE FINE TUNED THROUGH THE DAY.

BEHIND THE CONVECTION THE UPPER LEVEL TROUGH WILL REMAIN OVER THE
REGION ALLOWING FOR RAIN SHOWERS FROM THE SOUTH TO ADVANCE
NORTHWARD. THIS RAIN WILL SPREAD ACROSS REGION...AND MAY LOWER VSBYS
INTO IFR...WITH MVFR CIGS.

OUTLOOK...
SUNDAY NIGHT AND MONDAY...AREAS OF IFR WITH RAIN AND EMBEDDED
THUNDERSTORMS.
TUESDAY AND WEDNESDAY...MAINLY VFR.
THURSDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
WINDS WILL INCREASE TODAY AHEAD OF A COLD FRONT THOUGH WINDS SHOULD
REMAIN BELOW SCA. EXPECT WINDS TO RAMP UP INTO THE 10 TO 20 KNOT
RANGE...WITH WATER BECOMING A LITTLE CHOPPY BUT REMAINING BELOW
SMALL CRAFT CRITERIA. NO SIGNIFICANT WINDS OR WAVES ARE EXPECTED
THROUGH MIDWEEK...ALTHOUGH THERE MAY BE A FEW PERIODS OF CHOPPY
WAVES AS WINDS BECOME MORE NORTH TO NORTHEAST MONDAY THROUGH
WEDNESDAY FOLLOWING THE PASSAGE OF THE SLOW MOVING COLD FRONT.

&&

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

&&

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...APFFEL
LONG TERM...APFFEL/TAN
AVIATION...THOMAS
MARINE...APFFEL/THOMAS

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
535 AM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0340 AM     MARINE TSTM WIND BARCELONA               42.34N  79.60W
09/04/2011  M56 MPH          CHAUTAUQUA         NY   C-MAN STATION

&&

EVENT NUMBER BUF1100254

APFFEL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
559 AM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0427 AM     TSTM WND DMG     1 NE LOCKPORT JUNCTION  43.17N  78.74W
09/04/2011                   NIAGARA            NY   911 CALL CENTER

            POWER LINES DOWN ON UPPER MOUNTAIN ROAD

&&

EVENT NUMBER BUF1100255

THOMAS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
603 AM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0431 AM     TSTM WND DMG     SOUTH LOCKPORT          43.15N  78.69W
09/04/2011                   NIAGARA            NY   911 CALL CENTER

            POWER LINES DOWN

&&

EVENT NUMBER BUF1100256

THOMAS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
605 AM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0427 AM     TSTM WND DMG     RIVERSIDE MANORS        43.19N  79.05W
09/04/2011                   NIAGARA            NY   911 CALL CENTER

            TREE DOWN ON LOWER RIVER ROAD

&&

EVENT NUMBER BUF1100257

THOMAS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
622 AM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0545 AM     MARINE TSTM WIND 20NM NE ROCHESTER       43.62N  77.41W
09/04/2011  M52 MPH          LOZ063             NY   BUOY

&&

EVENT NUMBER BUF1100258

APFFEL

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