Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 070025
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
825 PM EDT MON JUL 6 2015

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS FAR WESTERN NEW YORK
EARLY THIS EVENING WILL DIMINISH AFTER SUNSET. A WARM AND MUGGY
AIRMASS WILL THEN REMAIN IN PLACE TONIGHT AND TUESDAY WITH SHOWERS
AND THUNDERSTORMS BECOMING MORE WIDESPREAD DURING THE COURSE OF
TUESDAY AFTERNOON AND EVENING...WITH SOME OF THE STORMS HAVING THE
POTENTIAL TO BECOME STRONG TO SEVERE WITH STRONG GUSTY WINDS BEING
THE MAIN THREAT. A COLD FRONTAL PASSAGE TUESDAY NIGHT WILL THEN
BRING THE SHOWERS AND STORMS TO AN END... WHILE USHERING IN COOLER
AND DRIER WEATHER FOR MIDWEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 820 PM...WIDELY SCATTERED TO SCATTERED CONVECTION CONTINUES
FROM THE GENESEE VALLEY WESTWARD...WITH A COUPLE STRONGER
REFLECTIVITY CORES STILL CAPABLE OF PRODUCING LIGHTNING NOTED OVER
ORLEANS COUNTY AND LAKE ONTARIO. THIS ACTIVITY WILL CONTINUE
THROUGH SUNSET...BEFORE SUBSEQUENTLY DIMINISHING WITH THE LOSS OF
HEATING. THIS SAID...WITH THE WEAK UPPER LOW OVER THE UPPER OHIO
VALLEY LIFTING NORTHEAST INTO OUR REGION IN THE PRESENCE OF A
MOIST AIRMASS OVERNIGHT...AN ADDITIONAL STRAY SHOWER OR TWO STILL
CANNOT BE COMPLETELY RULED OUT DURING THE LATE EVENING AND
OVERNIGHT HOURS...FOR WHICH SOME SLIGHT CHANCE TO LOW-END CHANCE
POPS WILL REMAIN IN PLAY. OTHERWISE...IT WILL BE A WARM AND SULTRY
NIGHT ACROSS THE REGION AS THE MOIST SOUTHERLY FLOW WILL BE
MAINTAINED WITH DEWPOINTS REMAINING WELL INTO THE 60S. AS
SUCH...LOOK FOR OVERNIGHT LOWS TO RANGE FROM THE MID TO UPPER
60S...WITH THE WARMEST AREAS BEING FOUND ALONG THE LAKE PLAINS.

ON TUESDAY...OUR AIRMASS WILL BECOME EVEN WARMER AS 850MB TEMPS
WILL BE RUNNING ABOUT A DEGREE WARMER THAN TODAY...AROUND
+17C...WHICH WILL TRANSLATE TO AFTERNOON HIGHS IN THE MID TO UPPER
80S...WITH THE GENESEE VALLEY CREEPING INTO THE LOWER 90S THANKS
TO A FRESHENING DOWNSLOPE SW WIND.

CONVECTION WILL ALSO BECOME MORE LIKELY WITH TIME TUESDAY
AFTERNOON AS THE WEAK UPPER LEVEL RIDGING ENCOMPASSING MUCH OF THE
AREA IS REMOVED IN FAVOR OF A MUCH STRONGER UPPER LEVEL TROUGH
PUSHING EASTWARD FROM THE UPPER GREAT LAKES. WITH SBCAPES CLIMBING
TOWARDS 1500 J/KG ACROSS WESTERN NEW YORK IN THE AFTERNOON...IT IS
QUITE LIKELY THAT WE WILL SEE CONVECTION INITIATE ALONG THE LAKE
BREEZE BOUNDARIES BY MID TO LATE AFTERNOON. WHILE SHEAR IN THE
AFTERNOON WILL NOT BE PARTICULARLY IMPRESSIVE...AROUND 25 KTS...A
SIGNIFICANT AMOUNT OF MID-LEVEL DRY AIR MAY ALLOW FOR THE
DEVELOPMENT OF DOWNBURSTS THAT MAY PRODUCE ISOLATED DAMAGING
WINDS. AS WE MOVE INTO THE EVENING HOURS...THE MAIN UPPER LEVEL
TROUGH AND ACCOMPANYING COLD FRONT WILL APPROACH THE
REGION...LIKELY RESULTING IN ANOTHER ROUND OF CONVECTION TUESDAY
EVENING.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
TUESDAY NIGHT A MID LEVEL TROUGH WILL SWING EAST ACROSS QUEBEC WITH
A TRAILING COLD FRONT CROSSING THE LOWER LAKES. MOST OF THE LARGE
SCALE FORCING FOR ASCENT WILL REMAIN WELL NORTH ACROSS CANADA...WITH
WEAK DPVA ON THE SOUTHERN EDGE OF THE TROUGH CROSSING OUR REGION.
MOST OF THE FORCING WILL COME FROM MESOSCALE FEATURES...INITIALLY
THE LAKE BREEZE CONVERGENCE BOUNDARIES LATE TUESDAY AFTERNOON AND
EVENING FOLLOWED BY CONVERGENCE ALONG THE COLD FRONT OR PRE-FRONTAL
TROUGH. MODERATE INSTABILITY WILL BE PRESENT UPSTREAM ACROSS OHIO
WHERE RICHER BOUNDARY LAYER MOISTURE EXISTS...WITH WEAKER
INSTABILITY EXTENDING INTO WESTERN NY.

SUFFICIENT INSTABILITY AND FORCING LOOK TO BE PRESENT ALONG THE
ADVANCING FRONT TO JUSTIFY HIGH LIKELY POPS FOR TUESDAY EVENING.
DEEP LAYER SHEAR IS MARGINAL AT AROUND 30 KNOTS...BUT IF STORMS CAN
ORGANIZE INTO LINES SOME MAY PRODUCE GUSTY WINDS. SPC HAS CONTINUED
A MARGINAL RISK FOR A PORTION OF THE AREA...AND THIS LOOKS
REASONABLE GIVEN UNCERTAINTY ON CONVECTIVE EVOLUTION UPSTREAM. IF A
STRONGER LINE CAN DEVELOP UPSTREAM...THERE IS SOME RISK FOR DAMAGING
WINDS ACROSS WESTERN NY DURING THE EVENING. PWAT WILL REACH 2 INCHES
JUST AHEAD OF THE FRONT...AND THIS WILL BRING A RISK OF VERY HEAVY
DOWNPOURS WITH ANY STRONGER CONVECTION. IF TRAINING OR BACKBUILDING
OCCURS THIS MAY RESULT IN SOME ISOLATED FLOOD RISK.

LATER TUESDAY NIGHT THE FRONT WILL ADVANCE SOUTHEAST AND AWAY FROM
THE AREA. SHOWERS AND THUNDERSTORMS WILL TAPER OFF FROM NORTHWEST TO
SOUTHEAST WITH THE PASSAGE OF THE COLD FRONT OVERNIGHT.

ON WEDNESDAY THE FRONT WILL PUSH SOUTH INTO CENTRAL PA AND STALL...
WITH ONE OR TWO WEAK WAVES RIPPLING ALONG THE FRONT. LATEST 12Z
GUIDANCE CONTINUES TO KEEP THE FRONTAL ZONE FAR ENOUGH SOUTH TO KEEP
OUR ENTIRE REGION DRY WEDNESDAY. A COOLER AND LESS HUMID AIRMASS
WILL ARRIVE WITH HIGHS IN THE MID 70S ACROSS LOWER ELEVATIONS AND
AROUND 70 ON THE HILLS.

LATER WEDNESDAY NIGHT AND THURSDAY A CONVECTIVELY GENERATED MID
LEVEL WAVE WILL MOVE NORTHEAST ALONG THE FRONTAL ZONE ACROSS THE
OHIO VALLEY AND SPAWN ANOTHER WEAK WAVE OF LOW PRESSURE. THIS WAVE
IS FORECAST BY THE 12Z GFS/NAM/ECMWF SUITES TO BRING THE FRONTAL
ZONE BACK NORTHWARD INTO WESTERN AND CENTRAL NY. EVEN WITH THE MODEL
CONSISTENCY IN THE 12Z RUN...PREVIOUS MODEL RUNS HAVE SHOWN A GOOD
DEAL OF VARIABILITY WITH RESPECT TO THE TIMING AND PLACEMENT OF THIS
WAVE. COMBINE THAT WITH THE FACT THAT THE SYSTEM OF INTEREST IS
BEING GENERATED FROM SUBTLE MONSOONAL CONVECTION ACROSS THE FOUR
CORNERS REGION...AND CONFIDENCE IS STILL ONLY AVERAGE AT BEST FOR
THURSDAY. WITH THIS IN MIND WILL KEEP POPS IN THE CHANCE RANGE FOR
SHOWERS AND THUNDERSTORMS THURSDAY...WITH THE GREATER CHANCES FOR
SOUTHERN AREAS.

THURSDAY NIGHT THIS FRONTAL WAVE WILL EXIT INTO NEW ENGLAND WITH
RAIN CHANCES DIMINISHING FROM WEST TO EAST.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
FRIDAY AND SATURDAY A BUBBLE OF HIGH PRESSURE WILL STALL IN PLACE
OVER THE LOWER LAKES AND NEW ENGLAND WHILE A STALLED FRONTAL ZONE
REMAINS TO THE WEST ACROSS THE LOWER OHIO VALLEY AND WESTERN LAKES.
THIS SHOULD BRING DRY WEATHER BOTH DAYS WITH TEMPERATURES SLOWLY
WARMING BACK TO JUST ABOUT AVERAGE AFTER A FEW COOLER DAYS MIDWEEK.
THIS WILL TRANSLATE INTO HIGHS IN THE LOWER 80S ACROSS LOWER
ELEVATIONS.

SUNDAY INTO EARLY NEXT WEEK A MID LEVEL TROUGH WILL MOVE FROM THE
UPPER MIDWEST INTO THE WESTERN LAKES. THIS WILL FORCE INCREASING
MOISTURE AND INSTABILITY BACK INTO OUR REGION...WITH LARGE SCALE
FORCING INCREASING BY MONDAY AS THE MID LEVEL WAVE AND WEAK SURFACE
REFLECTION MOVE TOWARDS THE LOWER LAKES. THIS WILL BRING A CHANCE OF
SHOWERS AND STORMS AGAIN FROM LATER SUNDAY THROUGH MONDAY.
TEMPERATURES WILL REMAIN WARM SUNDAY AND MONDAY AS LONG AS SHOWERS
DONT BECOME TOO WIDESPREAD...WITH HIGHS IN THE LOWER 80S BOTH DAYS.
HUMIDITY WILL BE ON THE INCREASE AS WELL.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
WIDELY SCATTERED TO SCATTERED CONVECTION FROM THE GENESEE VALLEY
WESTWARD AS OF 00Z WILL TEND TO DIMINISH AFTER SUNSET WITH THE
LOSS OF HEATING...THOUGH AN ADDITIONAL STRAY SHOWER OR TWO WILL
STILL BE POSSIBLE DURING THE LATE EVENING AND OVERNIGHT HOURS AS A
WEAK UPPER LEVEL LOW LIFTS INTO OUR REGION FROM THE OHIO VALLEY.
ALL THIS STATED... EXPECT GENERAL VFR CONDITIONS TO LARGELY
PREVAIL THROUGH TONIGHT OUTSIDE OF ANY LINGERING EVENING
CONVECTION...WHICH WILL HAVE THE POTENTIAL TO PRODUCE BRIEF/
LOCALIZED REDUCTIONS IN CIG/VSBY.

GENERAL VFR CONDITIONS WILL THEN CONTINUE THROUGH TUESDAY
MORNING... BEFORE THE COMBINATION OF INCREASING DIURNAL
HEATING/INSTABILITY AND DEVELOPING LAKE BREEZE BOUNDARIES LEADS TO
AN INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS DURING TUESDAY
AFTERNOON...A FEW OF WHICH COULD BECOME STRONG TO SEVERE WITH
LOCALIZED STRONG WIND GUSTS. SHOWERS AND STORMS WILL THEN BECOME
MOST WIDESPREAD VERY LATE TUESDAY AFTERNOON AND EVENING WITH THE
APPROACH OF A COLD FRONT... WHICH COULD POTENTIALLY GENERATE A
SQUALL LINE WITH ACCOMPANYING STRONG WIND GUSTS. AS THE STORMS
DEVELOP TUESDAY AFTERNOON AND EVENING...EXPECT AN INCREASING
POTENTIAL FOR REDUCTIONS TO MVFR/IFR.

OUTLOOK...
TUESDAY NIGHT...AREAS OF MVFR AND BRIEF IFR/GUSTY WINDS WITH SHOWERS
AND THUNDERSTORMS LIKELY.
WEDNESDAY...VFR.
THURSDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
FRIDAY AND SATURDAY...VFR.

&&

.MARINE...
LIGHT WINDS WILL PERSIST THROUGH TONIGHT WITH TRANQUIL CONDITIONS ON
THE LAKES. SOUTHWESTERLY WINDS WILL FRESHEN TO AROUND 15KTS ON
TUESDAY AHEAD OF AN APPROACHING COLD FRONT...HOWEVER CONDITIONS
SHOULD REMAIN BELOW SMALL CRAFT LEVELS ON TUESDAY.

THE COLD FRONT WILL CROSS THE LAKES TUESDAY EVENING...POTENTIALLY
GENERATING A SQUALL LINE THAT MAY SWEEP ACROSS THE LAKES. WINDS WILL
QUICKLY SLACKEN BEHIND THE FRONT AS WEAK HIGH PRESSURE MOVES ACROSS
THE REGION AND LINGERS THROUGH THE REST OF THE WEEK.

&&

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

&&

$$

SYNOPSIS...JJR/WOOD
NEAR TERM...JJR/WOOD
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR/WOOD
MARINE...WOOD


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