Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 030827
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
427 AM EDT MON AUG 3 2015

.SYNOPSIS...
A COLD FRONT OVER SOUTHERN ONTARIO WILL SLOWLY PUSH ACROSS OUR
FORECAST AREA TODAY WHILE PRODUCING SCATTERED SHOWERS AND
THUNDERSTORMS. SOME OF THESE STORMS COULD BECOME STRONG TO
SEVERE... ESPECIALLY EAST OF THE GENESEE VALLEY. A SECONDARY
COLD FRONT WILL TOUCH OFF A COUPLE MORE SHOWERS TUESDAY AND
TUESDAY NIGHT...OTHERWISE IT WILL BECOME COOLER AND MORE
COMFORTABLE FOR THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
IT WILL BE AN UNSETTLED DAY ACROSS OUR FORECAST AREA TODAY AS A
WAVY FRONTAL BOUNDARY OVER SOUTHERN ONTARIO WILL SLOWLY MAKE ITS
TO THE EAST...GENERATING SHOWERS AND THUNDERSTORMS IN THE PROCESS.
SOME OF THE CONVECTION WILL BECOME STRONG TO SEVERE DURING THE
MIDDAY AND AFTERNOON...WITH THE GREATEST RISK COMING SOUTH AND
EAST OF THE IAG FRONTIER.

A COUPLE WEAK WAVES HAVE ALREADY RIPPLED TO THE NORTHEAST ALONG
THE FRONTAL BOUNDARY...BUT A STRONGER WAVE IN THE VCNTY OF CHICAGO
AT 08Z IS PREVENTING THE FRONT FROM MAKING A STRONGER PUSH TO THE
EAST. THIS WAVE WILL RIDE ALONG THE FRONT AND CROSS THE LOWER
GREAT LAKES DURING THE MORNING HOURS...THUS ALLOWING THE FRONT TO
SURGE A BIT TO OUR WESTERN DOORSTEP BY MIDDAY...BUT GUIDANCE IS
SUGGESTING THAT ADDITIONAL WAVES WILL KEEP THE AFTERNOON
PROGRESSION TO A CRAWL.

DESPITE A FAIR AMOUNT OF MID AND HIGH LEVEL CLOUD COVER...THE
SLOW FRONTAL PASSAGE WILL ENCOURAGE MOST OF OUR FORECAST AREA TO
FURTHER DESTABILIZE. THIS WILL SET THE STAGE FOR STRONG TO SEVERE
CONVECTION LATER TODAY...PARTICULARLY OVER THE SOUTHERN TIER AND
FOR SITES EAST OF THE GENESEE VALLEY. SBCAPES FOR THESE AREAS ARE
FORECAST TO CLIMB TO AN AVERAGE OF 1500-2000 J/KG...WHILE BULK
SHEAR VALUES WILL RANGE FROM 40 TO AS MUCH AS 50 KNOTS. THIS WILL
CERTAINLY SUPPORT WELL ORGANIZED CONVECTION...WITH A GENERAL
UNIDIRECTIONAL FLOW FAVORING BOWING LINE SEGMENTS WITH DAMAGING
STRAIGHT LINE WINDS. ONE CONCERN IS ONE OF THE AFOREMENTIONED SFC
WAVES COULD PASS OVER THE REGION LATER THIS AFTERNOON AND BACK LOW
LEVEL WINDS ENOUGH TO GENERATE AN ISOLATED SUPERCELL OVER THE SRN
TIER OR FINGER LAKES. THIS RISK WOULD BE QUITE LOW...BUT WORTHY OF
KEEPING IN MIND. WILL USE LIKELY POPS TO THE EAST OF THE IAG
FRONTIER WHERE THE STRONGER...MORE WIDESPREAD CONVECTION IS
EXPECTED...WHILE HIGH CHC POPS WILL BE IN PLACE ELSEWHERE.

OTHERWISE IT WILL BE WARM AND HUMID ACROSS THE REGION
TODAY...WITH THE MOST UNCOMFORTABLE CONDITIONS BEING FOUND OVER
THE FINGER LAKES AND EASTERN LAKE ONTARIO REGION WHERE
TEMPERATURES COULD CLIMB INTO THE MID 80S.

THE INITIAL COLD FRONT WILL LIMP TO OUR EAST TONIGHT...WHILE A
SECONDARY COLD FRONT WILL SETTLE ACROSS SOUTHERN ONTARIO TO OUR
DOORSTEP BY DAYBREAK. IT WILL BE THIS SECOND FRONT THAT WILL
ACTUALLY USHER IN A DIFFERENT AIRMASS...AS COOLER AND LESS HUMID
AIR WILL FOLLOW FOR THE REMAINDER OF THE WEEK. IN TERMS OF
PCPN...ANY LEFTOVER SHOWERS FROM THE FIRST FRONTAL BOUNDARY WILL
QUICKLY END DURING THE EVENING HOURS...BUT SHOWERS FROM THE
APPROACHING SECONDARY FRONT COULD BLOSSOM OVER AN INCREASINGLY
UNSTABLE AIRMASS OVER THE WARM WATERS OF LAKE ONTARIO BY DAYBREAK.
THIS IS A HINT OF THINGS TO COME.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
ON TUESDAY...THE AXIS OF THE MAIN UPPER LEVEL TROUGH WILL SETTLE
FROM THE WESTERN GREAT LAKES INTO SOUTHERN ONTARIO...ALONG WITH A
CORRESPONDING SURFACE TROUGH/SECONDARY COLD FRONT. WITH DIURNAL
HEATING OF THE COOLER AIRMASS THAT WILL BE IN PLACE ALOFT AND ONE
OR MORE SHORTWAVE IMPULSES SLIDING THROUGH THE BASE OF THE UPPER
LEVEL TROUGH AND ACROSS OUR REGION...EXPECT ANOTHER ROUND OF
SCATTERED SHOWERS AND THUNDERSTORMS TO AFFECT OUR REGION THROUGH
THE DAY ON TUESDAY. THE BEST POTENTIAL FOR THESE WILL MOST LIKELY
BE FOUND ACROSS THE NORTH COUNTRY AS THIS REGION SHOULD BE MORE
DIRECTLY IMPACTED BY THE PASSING MID AND UPPER LEVEL IMPULSES...
WITH PRECIP CHANCES LARGELY EXHIBITING A GRADUAL DECREASE WITH
INCREASING SOUTHWESTWARD EXTENT. OTHERWISE...THE CONTINUED GRADUAL
BUT STEADY COOL AIR ADVECTION REGIME WILL LEAD TO 850 MB TEMPS
FALLING TO THE +9C TO +12C RANGE BY AFTERNOON...WHICH SHOULD IN
TURN TRANSLATE INTO DAYTIME HIGHS REACHING THE LOWER TO MID 70S IN
MOST PLACES.

DURING TUESDAY NIGHT THE SECONDARY COLD FRONT WILL TRAVERSE OUR
REGION IN CONJUNCTION WITH THE MAIN UPPER LEVEL TROUGH AXIS. WHILE
LINGERING DIURNALLY-DRIVEN SHOWERS AND STORMS AT THE START OF THE
EVENING WILL PROBABLY BE FOLLOWED BY SOME ADDITIONAL SCATTERED
SHOWER ACTIVITY AS THESE FEATURES PASS...IN GENERAL THE LOSS OF
DAYTIME HEATING AND THE ARRIVAL OF DRIER AIR BEHIND THE SECONDARY
FRONT SHOULD LEAD TO PRECIP CHANCES DIMINISHING OVER TIME. THE ONE
EXCEPTION TO THIS WILL BE EAST OF LAKE ONTARIO... WHERE A WESTERLY
FLOW OF PROGRESSIVELY COOLER AIR CROSSING THE WARMER LAKE WATERS
WILL CONTINUE TO GENERATE SCATTERED SHOWERS RIGHT THROUGH THE
NIGHT VIA A COMBINATION OF OROGRAPHIC AND LAKE EFFECT
PROCESSES...AS 850 MB TEMPS WILL FALL TO BETWEEN +7C AND +8C. AS
FOR TEMPERATURES...EXPECT COMFORTABLE CONDITIONS FOR SLEEPING WITH
OVERNIGHT LOWS RANGING FROM THE LOWER TO MID 50S ACROSS INTERIOR
PORTIONS OF THE SOUTHERN TIER/NORTH COUNTRY TO RIGHT AROUND 60
ALONG THE IMMEDIATE LAKESHORES.

ON WEDNESDAY...THE CORE OF THE UPPER LEVEL TROUGH WILL MEANDER
ITS WAY EAST ACROSS QUEBEC PROVINCE...WHILE SURFACE-BASED RIDGING
AND DRIER AIR DRAPED FROM THE WESTERN GREAT LAKES TO THE OHIO
VALLEY BUILDS EASTWARD INTO THE CENTRAL GREAT LAKES. WHILE THE
LATTER SHOULD RESULT IN A MAINLY DRY DAY FOR MOST AREAS SOUTH OF
LAKE ONTARIO...THE FAR NORTHEASTERN FINGER LAKES REGION AND NORTH
CENTRAL NEW YORK WILL BE SUBJECT TO SOME ADDITIONAL SCATTERED LAKE
AND OROGRAPHICALLY-DRIVEN SHOWERS EARLY WEDNESDAY...FOLLOWED BY
MORE GENERAL DIURNALLY-DRIVEN SHOWERS THE BALANCE OF THE DAY AS
ANOTHER SHORTWAVE SWINGS THROUGH THE BASE OF THE UPPER TROUGH IN
CONJUNCTION WITH RENEWED DAYTIME HEATING. ALL OF THIS SHOULD THEN
QUICKLY WIND DOWN WEDNESDAY NIGHT WITH THE LOSS OF HEATING AND AS
THE AFOREMENTIONED RIDGE BUILDS DIRECTLY OVERHEAD... RESULTING IN
A RETURN TO DRY WEATHER AREAWIDE TO CLOSE OUT THE SHORT TERM
PERIOD.

WITH RESPECT TO TEMPERATURES WEDNESDAY AND WEDNESDAY NIGHT...THESE
SHOULD REMAIN SOLIDLY BELOW NORMAL...AND SHOULD IN FACT BOTTOM OUT
FOR THE WEEK AS OUR AIRMASS REACHES ITS COOLEST OVERALL POINT OF
THE NEXT SEVEN DAYS. 850 MB TEMPS OF ROUGHLY +7C TO +10C SHOULD
TRANSLATE INTO HIGHS MOSTLY IN THE UPPER 60S TO LOWER 70S ON
WEDNESDAY...WITH THE COOLEST READINGS ACROSS THE HIGHER
TERRAIN...AND THE WARMEST OVERALL TEMPS FOUND IN THE GENESEE
VALLEY/WESTERN FINGER LAKES... WHERE A FEW SPOTS COULD STILL REACH
THE MID 70S. SUCH READINGS WILL THEN BE FOLLOWED BY LOWS RANGING
THROUGH THE 50S WEDNESDAY NIGHT... WHEN THE COOLEST INTERIOR
PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY COULD TICKLE THE
50 DEGREE MARK.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
IN THE LONGER TERM PORTION OF THE FORECAST...THE MID AND UPPER
LEVEL FLOW ACROSS OUR REGION WILL TEND TO GRADUALLY DEAMPLIFY
THROUGH THE LATTER PORTIONS OF THE WORK WEEK AND INTO THE FIRST
PART OF THE UPCOMING WEEKEND AS THE CORE OF THIS WEEK/S MAIN UPPER
TROUGH LIFTS OUT INTO THE NORTHERN ATLANTIC...AND MAY EVEN BRIEFLY
GO QUASI-ZONAL BEFORE A VERY MODEST MID-LEVEL TROUGH APPROACHES
OUR REGION IN TIME FOR SUNDAY. AS A RESULT...INITIALLY BELOW
NORMAL TEMPERATURES LATE IN THE WORK WEEK SHOULD TREND CLOSER TO
SEASONAL AVERAGES BY NEXT WEEKEND. MORE SPECIFICALLY...DAYTIME
HIGHS INITIALLY IN THE LOWER TO MID 70S ON THURSDAY SHOULD CLIMB
BACK INTO THE MID AND UPPER 70S FOR NEXT WEEKEND...WHILE NIGHTTIME
LOWS INITIALLY RANGING THROUGH THE 50S SHOULD SLOWLY MODERATE INTO
THE 55-60 RANGE.

AS FOR PRECIPITATION CHANCES...MAINLY DRY WEATHER SHOULD PREVAIL
THURSDAY THROUGH SATURDAY AS EXPANSIVE CANADIAN HIGH PRESSURE
DRAPED FROM ONTARIO PROVINCE TO THE UPPER OHIO VALLEY AT THE START
OF THE PERIOD SLOWLY DRIFTS EASTWARD INTO QUEBEC...AND KEEPS THE
MAIN SURFACE FRONTAL ZONE/ANY ATTENDANT WAVES OF LOW PRESSURE
SUPPRESSED TO OUR SOUTH. AFTER THAT...THE AFOREMENTIONED MID-LEVEL
TROUGH SHOULD PROVIDE ENOUGH OF AN INCREASE IN MOISTURE AND
SYNOPTIC- SCALE LIFT TO RESULT IN LIMITED CHANCES FOR
SHOWERS/THUNDERSTORMS RETURNING ON SUNDAY...WHICH AT THIS DISTANT
VANTAGE POINT WILL BE COVERED WITH SOME VERY LOW CHANCE POPS.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
STRONG THUNDERSTORMS HAVE PUSHED SOUTH ACROSS LAKE ERIE...BUT
ANOTHER ROUND OF STRONG TO SEVERE THUNDERSTORM ACTIVITY WILL BE
POSSIBLE LATER TODAY. THIS WILL ESPECIALLY BE THE CASE FOR SITES
SOUTH AND EAST OF THE IAG FRONTIER...POSSIBLY AFFECTING THE
KJHW... KROC AND KART TAF SITES.

OTHERWISE...VFR CONDITIONS IN PLACE AT 08Z WILL REMAIN IN PLACE
THROUGH AT LEAST MIDDAY. FOR THIS AFTERNOON...WHILE VFR CIGS ARE
ANTICIPATED...THERE MAY BE TIMES WHEN MVFR CONDITIONS WILL BE
FOUND IN AND NEAR CONVECTION.

TONIGHT...VFR CONDITIONS WILL BE FOUND ACROSS THE MAJORITY OF THE
REGION. THE EXCEPTION COULD BE ACROSS THE SOUTHERN TIER WHERE MVFR
CIGS COULD DEVELOP AFTER MIDNIGHT.

WINDS THROUGH EARLY THIS AFTERNOON WILL GUST TO 30 KNOTS AT TIMES
AT KBUF...KIAG AND KROC...WITH SOME LOW LEVEL WIND SHEAR ALSO
POSSIBLE AT KROC BEFORE DAYBREAK.

OUTLOOK...

TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
FRIDAY...CHANCE OF
THUNDERSTORMS OVER THE SOUTHERN TIER...OTHERWISE VFR.

&&

.MARINE...
A RELATIVELY TIGHT SFC PRESSURE GRADIENT WILL COMBINE WITH A
STRONG LOW LEVEL JET AHEAD OF A COLD FRONT TO PRODUCE GUSTY WINDS
ACROSS THE LOWER GREAT LAKES TODAY. A SMALL CRAFT ADVISORY IS
ALREADY IN PLACE FOR ALL OF THE NEW YORK NEARSHORE WATERS...AS
WELL AS BUF HARBOR...FOR WINDS THAT COULD GUST TO 30 KNOTS. THIS
WILL ESPECIALLY BE THE CASE ON LAKE ERIE. THE WINDS WILL DROP OFF
LATER THIS AFTERNOON AND EVENING IN THE WAKE OF A SLOW MOVING COLD
FRONT.

THE COLD FRONT WILL LIKELY GENERATE SOME SHOWERS AND
THUNDERSTORMS...ESPECIALLY OVER THE EASTERN HALF OF LAKE ONTARIO
WHERE THE STORMS COULD BECOME QUITE STRONG. MARINERS THROUGHOUT
THE LOWER GREAT LAKES SHOULD BE ALERT FOR POSSIBLE MARINE WARNINGS
THROUGHOUT THE DAY.

WINDS WILL DROP BELOW SMALL CRAFT ADVISORY LEVELS THIS EVENING
AND REMAIN RELATIVELY LIGHT DURING THE OVERNIGHT HOURS. THESE
WINDS WILL FRESHEN AGAIN ON TUESDAY AS ANOTHER FRONTAL BOUNDARY
WILL PUSH SOUTH ACROSS THE LOWER GREAT LAKES. THIS WILL ENCOURAGE
WAVES TO BUILD TO 3 TO 5 FEET...WITH ANOTHER ROUND OF SMALL CRAFT
ADVISORIES LIKELY FOR THE NEARSHORE WATERS OF LAKE ERIE AND
POSSIBLY FOR THE EASTERN END OF LAKE ONTARIO.

A FALL LIKE AIRMASS IN THE WAKE OF THIS SECOND COLD FRONT COULD
SET THE STAGE FOR WATERSPOUTS ON LAKE ONTARIO TUESDAY NIGHT AND
WEDNESDAY. WILL CARRY SLIGHT CHC FOR SPOUTS IN THE GRIDDED DATA
BASE FOR NOW. STAY TUNED.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LOZ042>045.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH



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