Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 190837
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
437 AM EDT SUN APR 19 2015

.SYNOPSIS...
HIGH PRESSURE OVER EASTERN CANADA WILL TOP OFF OUR WEEKEND STRETCH
OF NICE WEATHER TODAY...AS SUNSHINE WILL BE ACCOMPANIED BY FAIRLY
MILD TEMPERATURES. A COMPLEX STORM SYSTEM EVOLVING OVER THE MID WEST
WILL THEN PUSH A WARM FRONT NORTHWARDS ACROSS OUR REGION TONIGHT AND
EARLY MONDAY...AND THIS WILL RESULT IN ANOTHER SOAKING RAIN ALONG
WITH SOME GUSTY WINDS. AFTER A SIX HOUR BREAK IN THE UNSETTLED
WEATHER MONDAY AFTERNOON...A COLD FRONT WILL USHER MORE SHOWERS AND
POSSIBLE THUNDERSTORMS THROUGH THE AREA MONDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
IT WILL BE ANOTHER NICE DAY ACROSS WESTERN AND NORTH CENTRAL NEW
YORK TODAY...AS HIGH PRESSURE DRIFTING ACROSS QUEBEC WILL KEEP
MOSTLY SUNNY SKIES IN PLACE WHILE SUPPORTING AFTERNOON TEMPERATURES
IN THE 60S. THE SUNSHINE WILL FADE BEHIND THICKENING CIRRUS CLOUDS
OVER PORTIONS OF THE SRN TIER DURING THE AFTERNOON THOUGH...BUT THIS
WILL BE THE ONLY BLEMISH ON AN OTHERWISE NICE DAY TO BE OUTDOORS.

CONDITIONS WILL THEN DETERIORATE TONIGHT...AS THE FIRST IN A TRIO OF
MID LEVEL DISTURBANCES ROTATING THROUGH THE BASE OF A DIGGING
LONGWAVE TROUGH WILL PUSH A STRONG WARM FRONT INTO OUR REGION. THIS
WILL BE A VERY DYNAMIC SYSTEM WITH EXTRAORDINARY KINEMATIC
COMPONENTS. A HIGHLY ANOMALOUS SOUTHEASTERLY LOW LEVEL JET OF 70 TO
80 KTS CENTERED ARND H85 WILL NOT ONLY HELP TO TRANSPORT COPIOUS
AMOUNTS OF ATLANTIC MOISTURE ACROSS OUR REGION...BUT IT WILL SET THE
STAGE FOR STRONG WINDS ACROSS THE SOUTHERN TIER. MORE ON THIS IN A
MOMENT.

THE INFLUX OF RICH ATLANTIC MOISTURE WILL SEND PWAT VALUES SOARING
FROM UNDER A QUARTER INCH TODAY TO OVER AN INCH TONIGHT. AS THE
AFOREMENTIONED WARM FRONT LIFTS NORTH ACROSS LAKE ERIE AND THE
WESTERN COUNTIES TONIGHT...DEEP ISENTROPIC LIFT AND FORCING PROVIDED
BY THE UNUSUALLY STRONG LOW LEVEL JET IMPINGING ON THE FRONTAL
BOUNDARY WILL ACT UPON THE BURGEONING MOISTURE FIELD TO GENERATE A
SOAKING QUARTER TO A THIRD OF AN INCH OF RAIN OVER THE WESTERN
COUNTIES. LESSER AMOUNTS WILL FALL EAST OF LK ONTARIO DURING THE
OVERNIGHT...AS THE MAIN PERIOD OF RAIN WILL NOT REACH THAT AREA
UNTIL AFTER DAYBREAK.

THE MAIN CONCERN TONIGHT THOUGH WILL BE THE STRONG WINDS THAT WILL
BE PRODUCED ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER...AND
ESPECIALLY THE DOWNSLOPE WINDS ON THE LAKE PLAIN OF CHAUTAUQUA AND
SOUTHERN ERIE COUNTIES. LOCAL RESEARCH HAS SHOWN THAT A STRONG
SOUTHEASTERLY LOW LEVEL JET COMBINED WITH A FAIRLY STRONG LOW LEVEL
INVERSION NEAR THE TOP OF THE CHAUTAUQUA RIDGE AND A FAIRLY STABLE
LAYER TO THE SFC WILL OFTEN PRODUCE VERY STRONG SFC WINDS ALONG THE
NEW YORK THRUWAY ACROSS CHAUTAUQUA COUNTY AND SOUTHERN ERIE COUNTY.
THE MOST DRAMATIC DOWNSLOPE WINDS HAVE BEEN OBSERVED DURING RAINFREE
CONDITIONS...SO IT IS UNCERTAIN IF TONIGHTS RAINS WILL PLAY A ROLE
IN DAMPENING THIS RISK. WHAT IS KNOWN IS THAT EXCEPTIONALLY STRONG
H85 WINDS WITH A CLIMATOLOGICAL RETURN INTERVAL OF ONCE IN MORE THAN
A 30 YEAR PERIOD WILL BE IN PLACE...AND THIS WILL MOST CERTAINLY
PRODUCE STRONG WIND GUSTS IN EXCESS OF 30 KNOTS...IF NOT MORE THAN
40. HAVE THUS HOISTED A WIND ADVISORY FOR THE SOUTHERN TIER TO
COVER THE STRONG WINDS THAT SHOULD BE FOUND ALONG LAKE ERIE AND
ALSO ACROSS THE HIGHER TERRAIN. THIS THREAT SHOULD DIMINISH AS WE
APPROACH DAYBREAK.

THE SOUTHEASTERLY FLOW WILL ALSO HELP TO HOLD TEMPERATURES UP
OVERNIGHT. MINS ARE ONLY FORECAST TO RANGE FROM THE UPPER 40S TO
NEAR 50 OVER THE FAR WESTERN COUNTIES TO THE LOWER 40S EAST OF LK
ONTARIO. THESE VALUES WILL BE SOME 10 DEG F ABOVE NORMAL.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
THIS PERIOD WILL OPEN WITH LOW PRESSURE LIFTING NORTHWARD FROM
LOWER MICHIGAN TO CENTRAL ONTARIO PROVINCE ON MONDAY. IN THE
PROCESS...THIS FEATURE WILL CONTINUE PUSHING ITS ASSOCIATED WARM
FRONT ACROSS THE AREA THROUGH THE EARLY AFTERNOON HOURS...WITH A
STINT IN THE WARM SECTOR THEN ENSUING BEFORE THE TRAILING COLD FRONT
APPROACHES FAR WESTERN NEW YORK LATE IN THE DAY. FAIRLY WIDESPREAD
SHOWERS ALONG AND OUT AHEAD OF THE WARM FRONT SHOULD QUICKLY
DIMINISH IN ITS WAKE AS A REGION OF SUBSIDENCE AND MUCH DRIER AIR
WORKS IN ALOFT...WITH LARGELY DRY CONDITIONS THEN EXPECTED TO
CONTINUE UNTIL THE COLD FRONT APPROACHES DURING THE LATE AFTERNOON
AND EARLY EVENING HOURS. AS THIS LATTER FEATURE NEARS...IT WILL
BRING INCREASING SHOWER CHANCES BACK TO FAR WESTERN NEW YORK BY LATE
IN THE DAY...ALONG WITH THE CHANCE OF A FEW THUNDERSTORMS SOUTH OF
LAKE ONTARIO OWING TO THE DEVELOPMENT OF SOME WEAK SURFACE-BASED
INSTABILITY.

THE DAY WILL ALSO START OUT ON THE BREEZY TO WINDY SIDE AS A STRONG
LOW LEVEL JET FINISHES PASSING THROUGH THE REGION ALOFT...WITH WINDS
THEN GENERALLY DIMINISHING FROM SOUTHWEST TO NORTHEAST FOLLOWING THE
PASSAGE OF THIS FEATURE. GIVEN THE TIMING OF THE STRONGEST WINDS
ALOFT AND THE GENERAL SOUTHEASTERLY TO SOUTHERLY FLOW REGIME...THE
STRONGEST WINDS SHOULD BE FOUND WITHIN THE TYPICALLY FAVORED REGIONS
OF DOWNSLOPE FLOW ALONG THE LAKE ERIE SHORELINE SOUTHWEST OF BUFFALO
EARLY IN THE DAY...AND ACROSS AREAS DOWNWIND OF THE TUG HILL THROUGH
THE MIDDAY/EARLY AFTERNOON HOURS. AT THIS POINT THE WINDS EAST OF
LAKE ONTARIO APPEAR AS IF THEY WILL REMAIN A BIT SHY OF ADVISORY
CRITERIA...SO HAVE HELD OFF ON ISSUING ANY WIND FLAGS FOR THAT
REGION...THOUGH THESE WILL BEAR CONTINUED WATCHING OVER THE NEXT
24-30 HOURS OR SO.

AS FOR TEMPERATURES...EXPECT A EAST-TO-WEST DICHOTOMY IN READINGS ON
MONDAY. AREAS EAST OF LAKE ONTARIO SHOULD SEE READINGS CONFINED TO
THE MID 50S TO LOWER 60S DUE TO MORE PERSISTENT SHOWER ACTIVITY AND
CLOUD COVER...WHILE THE LOWER ELEVATIONS WEST OF THE GENESEE VALLEY
SHOULD EXPERIENCE BALMIER HIGHS OF AROUND 70 DEGREES THANKS TO THE
COMBINATION OF A DOWNSLOPE SOUTHERLY FLOW...DRIER OVERALL
CONDITIONS...AND A GREATER POTENTIAL FOR SOME BREAKS OF SUNSHINE.

AS WE GET INTO MONDAY NIGHT...THE MAIN SURFACE LOW WILL LIFT FURTHER
NORTHWARD TO JAMES BAY...WHILE PIVOTING ITS COLD FRONT EASTWARD
ACROSS THE FORECAST AREA. DEEP MOISTURE AND PLENTIFUL LIFT ALONG
THE FRONT WILL GENERATE ANOTHER SWATH OF SHOWERS THAT WILL TRAVERSE
THE REGION FROM WEST TO EAST...WITH SOME LINGERING WEAK INSTABILITY
ALSO SUPPORTING A CONTINUED CHANCE OF THUNDER SOUTH OF LAKE ONTARIO
DURING THE EVENING HOURS. FOLLOWING THE COLD FRONTAL PASSAGE...THE
SHOWERS SHOULD BECOME MUCH MORE SCATTERED AS SIGNIFICANTLY COOLER
AND DRIER AIR ADVECTS INTO THE AREA...THOUGH AT LEAST LOW CHANCES OF
THESE WILL PROBABLY PERSIST THROUGH THE REST OF THE NIGHT AS
ADDITIONAL SHORTWAVE ENERGY ROTATES AROUND THE BASE OF DEEPENING
UPPER LEVEL TROUGHING ACROSS THE GREAT LAKES. OTHERWISE...THE
DEVELOPING COLD AIR ADVECTION REGIME WILL SEND TEMPERATURES
NOTICEABLY DOWNWARD...WITH READINGS LIKELY RANGING THROUGH THE 40S
AREAWIDE BY THE START OF TUESDAY MORNING.

ON TUESDAY...EXPECT A BREEZY AND COOLER DAY AS THE SLOWLY DIGGING
UPPER LEVEL TROUGH/CLOSED LOW OVER THE GREAT LAKES CONTINUES TO FEED
A BRISK WESTERLY FLOW OF COOLER AIR ACROSS OUR REGION. THE HIGH
TEMPERATURE FORECAST FOR TUESDAY REMAINS A BIT TRICKY AS THE 00Z
GUIDANCE SUITE CONTINUES TO DISAGREE ON THE EXACT EXTENT OF THE
COOLING ALOFT...SO AS A GUIDE HAVE CONTINUED TO LEAN MORE HEAVILY ON
A ROUGH BLEND OF THE MAIN MODEL PACKAGES RATHER THAN ANY ONE
PARTICULAR MODEL. USING THIS APPROACH AS A GUIDE...IT APPEARS THAT
HIGHS ON TUESDAY WILL LIKELY RANGE FROM THE UPPER 40S TO LOWER 50S
IMMEDIATELY DOWNWIND OF THE LAKES AND ACROSS THE HIGHEST TERRAIN...
TO THE MID AND UPPER 50S ACROSS THE LOWER ELEVATIONS OF THE GENESEE
VALLEY AND FINGER LAKES REGION.

WITH RESPECT TO PRECIPITATION CHANCES...A FAIRLY STRONG SHORTWAVE
ALSO LOOKS TO PASS ACROSS THE AREA RIGHT DURING PEAK DAYTIME HEATING
ON TUESDAY...WITH THE RESULTANT COMBINATION OF LIFT AND DIURNAL
INSTABILITY HELPING TO GENERATE SOME ADDITIONAL SCATTERED RAIN
SHOWERS...FOR WHICH SOME BROADBRUSH LOWER-END CHANCE POPS WILL
REMAIN IN PLAY. INCREASING SUBSIDENCE/DRYING IN THE WAKE OF THIS
WAVE AND THE LOSS OF DAYTIME HEATING SHOULD THEN LARGELY LEAD TO A
RETURN TO DRIER CONDITIONS FOR TUESDAY NIGHT...WHILE CONTINUED
COOLING OF OUR AIRMASS ALLOWS LOW TEMPERATURES TO DIP BACK INTO THE
MID AND UPPER 30S BY DAYBREAK ON WEDNESDAY.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE EXTENDED PORTION OF THE FORECAST STILL LOOKS TO BE DOMINATED BY
A LARGE UPPER LEVEL TROUGH/CLOSED LOW THAT WILL SLOWLY MEANDER ITS
WAY EASTWARD ACROSS EASTERN CANADA...WITH THE GREAT LAKES AND
NORTHEAST REMAINING FIRMLY ENTRENCHED WITHIN THE SOUTHERN HALF OF
ITS LARGE CYCLONIC CIRCULATION. SUCH A PATTERN WILL RESULT IN
PROGRESSIVELY COLDER CANADIAN AIR FEEDING SOUTHEASTWARD ACROSS THE
REGION THROUGH THE MIDDLE AND LATTER PORTIONS OF THIS WEEK...WHICH
WILL TRANSLATE TO A RETURN TO BELOW AVERAGE TEMPERATURES FOR THE
ENTIRE LONG TERM PERIOD...AND LIKELY BEYOND. MORE SPECIFICALLY...
EXPECT DAYTIME HIGHS TO BE MOSTLY CONFINED TO THE MID 40S TO LOWER
50S WEDNESDAY THROUGH SATURDAY...WHILE NIGHTTIME LOWS DROP BACK INTO
THE UPPER 20S AND LOWER 30S EACH NIGHT.

PRECIPITATION-WISE...MULTIPLE SHORTWAVE DISTURBANCES ROTATING
THROUGH THE LARGE CYCLONIC GYRE ALOFT WILL ALSO MAINTAIN PERIODIC
CHANCES FOR RAIN SHOWERS THROUGH AT LEAST FRIDAY...BEFORE THE
ARRIVAL OF DRIER AIR POTENTIALLY LEADS TO A REDUCTION IN THESE FOR
THE START OF NEXT WEEKEND. WHILE THE BEST CHANCES FOR SHOWERS WILL
GENERALLY BE TIED TO THE PEAK OF THE DIURNAL HEATING CYCLE EACH
AFTERNOON...SOME ACTIVITY WILL ALSO REMAIN POSSIBLE EACH NIGHT...
AND ANY SUCH NOCTURNAL PRECIP COULD COME IN THE FORM OF A RAIN/SNOW
SHOWER MIX...OR EVEN PLAIN SNOW SHOWERS AS OUR AIRMASS GROWS
PROGRESSIVELY COLDER LATER ON IN THE WEEK.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE OVER EASTERN CANADA WILL KEEP FAIR VFR CONDITIONS IN
PLACE ACROSS ALL OF WESTERN AND NORTH CENTRAL NEW YORK TODAY.

CONDITIONS WILL DETERIORATE TONIGHT THOUGH AS A COMPLEX STORM SYSTEM
OVER THE MID WEST WILL ADVANCE TO THE UPPER GREAT LAKES. AN
ASSOCIATED WARM FRONT WILL PUSH NORTH ACROSS THE WESTERN COUNTIES IN
THE PROCESS...WITH LOWERING CIGS AND WIDESPREAD RAIN LEADING TO MVFR
CONDITIONS. IFR CONDITIONS WILL BE POSSIBLE ACROSS THE HIGHER
TERRAIN OF THE SRN TIER.

THE GREATEST CONCERN TONIGHT THOUGH WILL COME FROM A VERY STRONG LOW
LEVEL JET THAT WILL PRODUCE GUSTY WINDS ACROSS THE HIGHER TERRAIN OF
THE SOUTHERN TIER AND ALSO ALONG THE LAKE PLAIN OF CHAUTAUQUA AND
SOUTHERN ERIE COUNTIES. SFC WINDS AT KJHW AND KJHW MAY GUST TO 40
KNOTS WHILE WINDS AT 3K FT WILL RANGE FROM 60-80 KTS. WHILE THE CORE
OF THE HIGHLY ANOMALOUS LOW LEVEL JET MAY BE TOO HIGH TO PRODUCE
TRUE LOW LEVEL WIND SHEAR PROBLEMS...IT IS CERTAINLY WORTH
MENTIONING IN THIS DISCUSSION.

OUTLOOK...
TONIGHT AND MONDAY...AREAS OF MVFR WITH OCCASIONAL SHOWERS AND
STRONG GUSTY WINDS.
TUESDAY THROUGH THURSDAY...VFR/MVFR WITH SCATTERED SHOWERS.

&&

.MARINE...
HIGH PRESSURE OVER EASTERN CANADA THIS MORNING WILL DRIFT EAST AND
GIVE WAY TO A DEEPENING...COMPLEX STORM SYSTEM OVER THE MID WEST.
THIS WILL LEAD TO A TIGHTENING OF THE SFC PRESSURE GRADIENT OVER THE
LOWER GREAT LAKES THIS AFTERNOON AND TONIGHT...WITH FRESHENING
OFFSHORE WINDS OF 25 TO 30 KNOTS SUPPORTING SMALL CRAFT ADVISORIES
FOR ALL OF THE NEW YORK NEARSHORE WATERS THROUGH MONDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WIND ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT MONDAY FOR
     NYZ012-019>021-085.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON EDT MONDAY
         FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 AM EDT
         MONDAY FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM
         EDT MONDAY FOR LOZ042-043.
         SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 11 PM EDT
         MONDAY FOR LOZ044-045.

&&

$$

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






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