Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 061947
AFDBUF

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

.SYNOPSIS...
SCATTERED SHOWERS AND A FEW THUNDERSTORMS...MAINLY ACROSS THE
SOUTHERN TIER AND THE FINGER LAKES...WILL DIMINISH AFTER SUNSET. A
WARM AND MUGGY AIRMASS WILL REMAIN IN PLACE TONIGHT AND TUESDAY WITH
SHOWERS AND THUNDERSTORMS BECOMING MORE WIDESPREAD TUESDAY AFTERNOON
AND EVENING. SOME OF THE THUNDERSTORMS TUESDAY AND TUESDAY EVENING
WILL HAVE THE POTENTIAL TO BECOME SEVERE WITH DAMAGING WINDS BEING
THE MAIN THREAT. A COLD FRONTAL PASSAGE TUESDAY NIGHT WILL USHER IN
COOLER AND DRIER WEATHER FOR WEDNESDAY INTO THURSDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
A LOOK AT REGIONAL WATER VAPOUR IMAGERY REVEALS THE TWO MAIN SYSTEMS
THAT WILL BE AFFECTING WESTERN AND NORTH-CENTRAL NEW YORK THROUGH
TOMORROW. THE FIRST IS A WEAKENING UPPER LEVEL LOW CENTERED OVER
EASTERN OHIO WITH A WEAK SURFACE REFLECTION OVER WEST VIRGINIA.
SOUTHERLY FLOW ON THE EASTERN SIDE OF THIS LOW IS PUMPING WARM MOIST
AIR ACROSS THE FORECAST AREA...RESULTING IN A MUGGY SUMMER-LIKE
READINGS IN THE UPPER 70S TO MID 80S. SHOWERS HAVE BEEN DEVELOPING
ACROSS THE SOUTHERN TIER AND WESTERN PA...CLOSER TO THE UPPER LOW
CENTER WHILE UPPER LEVEL RIDGING AND ASSOCIATED MID-LEVEL WARMTH IS
KEEPING A LID ON ANY CONVECTION FROM THE GENESEE VALLEY EAST. THIS
TREND SHOULD LARGELY HOLD THROUGH THE REST OF THE AFTERNOON AND INTO
THE EVENING HOURS...THOUGH A FEW SHOWERS MAY CREEP INTO THE LOWER
GENESEE VALLEY LATE THIS AFTERNOON AND EVENING AS THE UPPER LEVEL
RIDGE ERODES SLIGHTLY.

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 WARMEST AREAS BEING FOUND ALONG THE LAKE PLAINS. THE
AIRMASS WILL BECOME EVEN WARMER ON TUESDAY 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 BECOME MUCH MORE LIKELY ON TUESDAY AS THE WEAK UPPER
LEVEL RIDGING ENCOMPASSING MUCH OF THE AREA WILL BE REMOVED IN
FAVOUR OF THE SECOND SYSTEM OF NOTE IN THIS AFTERNOON`S WV
IMAGERY...A MUCH STRONGER UPPER LEVEL TROUGH CURRENTLY OVER 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-
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 /20Z MONDAY THROUGH SATURDAY/...
A WEAKENING UPPER LEVEL LOW OVER THE UPPER OHIO VALLEY WILL TRIGGER
SCATTERED SHOWERS ACROSS WNY WITH ISOLATED THUNDERSTORMS POSSIBLE
OVER THE SRN TIER/FINGER LAKES INTO THIS EVENING. ACTIVITY WILL BE
SCATTERED ENOUGH THAT PREVAILING VSBYS SHOULD REMAIN VFR THROUGH THE
EVENING HOURS. CONVECTION SHOULD QUICKLY DISSIPATE WITH THE LOSS
OF DAYTIME HEATING THIS EVENING AND VFR CONDITIONS WILL PREVAIL
THROUGH THE REST OF THE NIGHT.

CONVECTION WILL BE MORE WIDESPREAD AND STRONGER TUESDAY AFTERNOON
AHEAD OF AN APPROACHING COLD FRONT. AFTER A QUIET START TOT HE
DAY...EXPECT SHOWERS AND THUNDERSTORMS TO BREAK OUT ALONG LAKE
BREEZE BOUNDARIES AFTER 15Z. A FEW OF THESE THUNDERSTORMS MAY BECOME
SEVERE LATER IN THE AFTERNOON WITH LOCALIZED DAMAGING WINDS. ANOTHER
ROUND OF THUNDERSTORMS IS LIKELY TUESDAY EVENING...AROUND 00Z AS THE
COLD FRONT MOVES ACROSS THE FORECAST AREA. THERE IS A POTENTIAL FOR
A SQUALL LINE TO ACCOMPANY THIS FRONTAL PASSAGE...ONCE AGAIN
BRINGING A POTENTIAL FOR STRONG AND POSSIBLY DAMAGING WINDS.

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...WOOD
NEAR TERM...WOOD
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...WOOD
MARINE...WOOD



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