Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 301741
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
141 PM EDT THU JUL 30 2015

.SYNOPSIS...
A DRIER AIRMASS WILL EXPAND ACROSS THE EASTERN GREAT
LAKES REGION THIS AFTERNOON AND THROUGH THE OVERNIGHT...PROVIDING
FOR MAINLY CLEAR SKIES AND MORE COMFORTABLE LEVELS OF HUMIDITY. AN
UPPER LEVEL TROUGH WILL SLIDE TOWARDS THE REGION BY FRIDAY EVENING
AND PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS THAT WILL REMAIN
POSSIBLE THROUGH THE WEEKEND...THOUGH MUCH OF THE TIME WILL BE
RAINFREE.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON FAIR WEATHER CUMULUS WILL FORM INLAND...AND ALONG
LAKE BREEZE BOUNDARIES. WITHIN THESE LAKE BREEZES SOUTHWEST WINDS
WILL GUST TO 20 TO 25 KNOTS...WHILE SOUTH OF LAKE ONTARIO NORTH
WINDS WILL GUST 15 TO 20 KNOTS. DAYTIME HIGHS WILL STILL MANAGE TO
REACH THE LOWER TO MID 80S IN MOST PLACES
...THOUGH CONDITIONS WILL TURN NOTICEABLY LESS HUMID AS DEWPOINTS
DROP INTO THE UPPER 50S AND LOWER 60S.

TONIGHT...EXPECT FAIR AND DRY WEATHER ALONG WITH DIMINISHING
WINDS AS HIGH PRESSURE OVER THE TENNESSEE AND OHIO VALLEYS
CONTINUES TO RIDGE NORTHEASTWARD INTO OUR REGION. WITH A SOMEWHAT
COOLER AND LESS HUMID AIRMASS IN PLACE...NIGHTTIME LOWS WILL RANGE
FROM THE UPPER 50S ACROSS INTERIOR SECTIONS OF THE SOUTHERN
TIER/NORTH COUNTRY TO THE LOWER TO MID 60S ACROSS THE REST OF THE
REGION...WITH THE WARMEST READINGS FOUND ALONG THE IMMEDIATE
LAKESHORES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
THE SUB TROPICAL RIDGE PREVIOUSLY CENTERED OVER TEXAS AND THE
LOWER MISSISSIPPI VALLEY WILL RETROGRADE TO NEW MEXICO AND THE
SOUTHERN ROCKIES DURING THIS PERIOD. MEANWHILE...A PHASED LONGWAVE
TROUGH WILL BE FOUND OVER THE LOWER GREAT LAKES AND EASTERN
CANADA. THIS WILL ESTABLISH A DEEP CYCLONIC FLOW OVER OUR FORECAST
AREA WITH MARGINALLY `COOLER` AIR EXPECTED. THE NEWSWORTHY HEAT
THAT HAS BEEN SO PREVALENT IN THE EAST WILL PUSH TO THE WESTERN
STATES.

WHILE DRY WEATHER WILL BE IN PLACE FOR OUR REGION FOR MUCH OF
THIS PERIOD...DIFFICULT TO TIME MID LEVEL DISTURBANCES CRUISING
SOUTHEAST INTO THE AFOREMENTIONED LONGWAVE TROUGH WILL GENERATE
SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS. WILL GENERALLY COVER
THIS ACTIVITY WITH CHC POPS AS THERE IS A FAIR AMOUNT OF
DISAGREEMENT EXPRESSED BETWEEN THE VARIOUS GUIDANCE PACKAGES.

A FAIRLY STRONG SHORTWAVE WILL CROSS THE UPPER GREAT LAKES DURING
THE DAY FRIDAY WHILE GENERAL SUBSIDENCE WILL BE FOUND ACROSS OUR
FORECAST AREA. THIS WILL SUPPORT DRY WEATHER FOR THE BULK OF THE
DAY...BUT AS WE GET DEEPER INTO THE AFTERNOON...A LINE OF
CONVECTION TRAILING SOUTH FROM THE MID LEVEL DISTURBANCE WILL
APPROACH THE IAG FRONTIER AND THOUSAND ISLANDS REGION.
TEMPERATURES FRIDAY WILL GENERALLY CLIMB INTO THE UPPER 70S TO
LOWER 80S.

THE MID LEVEL DISTURBANCE WILL TRACK BY TO OUR NORTH FRIDAY NIGHT
WHILE AN ASSOCIATED WEAK SFC FRONTAL BOUNDARY WILL PUSH ACROSS OUR
FORECAST AREA. THIS MAY VERY WELL BE OUR HIGHEST CHANCE FOR PCPN
DURING THIS PERIOD...AS THERE SHOULD BE ENOUGH FORCING WITHIN A
FAIRLY UNSTABLE AIRMASS TO GENERATE SCATTERED SHOWERS AND
THUNDERSTORMS. WHILE OUR REGION HAS DRIED OUT CONSIDERABLY DURING
THE PAST WEEK OR TWO...UNFORTUNATELY THIS BOUNDARY IS NOT EXPECTED
TO PRODUCE MORE THAN A TENTH OF AN INCH OF RAIN FOR MOST AREAS.

THE NEXT SHORTWAVE WILL TAKE AIM ON OUR REGION ON SATURDAY.
AGAIN... WHILE SCATTERED SHOWERS AND THUNDERSTORMS ARE
ANTICIPATED...THE MAJORITY OF THE DAY SHOULD BE RAIN FREE. ANY
CONVECTION WILL HAVE TO BE CLOSELY WATCHED THOUGH...AS A WEST TO
NORTHWEST FLOW ALOFT (NOTORIOUS FOR SUPPORTING STRONG TO SEVERE
STORMS BECAUSE OF THE RESULTING GREATER SHEARED ENVIRONMENT) WILL
BE IN PLACE. SUBSIDENCE AND LOW LEVEL RIDGING IN THE WAKE OF THE
EXITING SHORTWAVE WILL PROMOTE FAIR WEATHER WITH CLEARING SKIES
SATURDAY NIGHT.

WEAK LOW LEVEL RIDGING SHOULD BE ABLE TO SUPPORT GENERALLY DRY
WEATHER ON SUNDAY...BUT GIVEN THE CYCLONIC FLOW AND UNCERTAINTY OF
THE TIMING OF ADDITIONAL SHORTWAVES...AN AFTERNOON SHOWER OR
THUNDERSTORM CANNOT BE RULED OUT. TEMPERATURES ON SUNDAY SHOULD
TOP OUT WITHIN A FEW DEGREES OF 80.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
THE GENERAL LONGWAVE PATTERN OF HAVING A RIDGE IN THE WEST AND A
TROUGH IN THE EAST WILL REMAIN IN PLACE THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK. THIS WILL KEEP TEMPERATURES CLOSE TO SEASONAL NORMALS
WITH HIGHS IN THE UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS RANGE
FROM THE LOWER 60S MONDAY NIGHT TO THE 50S FOR TUESDAY AND WEDNESDAY
NIGHTS. IN TERMS OF RAINFALL...MORE SUBTLE SHORTWAVES ROTATING
THROUGH THE BASE OF THE TROUGH WILL ENCOURAGE ALTERNATING PERIODS OF
SHOWERS AND THUNDERSTORMS...ALTHOUGH FAIR DRY WEATHER SHOULD
DOMINATE THE PERIOD.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT 18Z VFR FLIGHT
CONDITIONS WERE FOUND ACROSS THE REGION. FLIGHT RESTRICTIONS WILL BE
LIMITED THIS TAF PERIOD TO RIVER VALLEY FOG OVER THE SOUTHERN
TIER...WITH FOG POSSIBLY REACHING THE KJHW TERMINAL BETWEEN 08Z AND
13Z. SOUTHWEST WINDS OFF LAKE ERIE WILL GUST UP TO 25 KNOTS OVER
KIAG/KBUF AND KART. OTHERWISE LIGHT WINDS THROUGH THE TAF PERIOD.

OUTLOOK...FRIDAY THROUGH MONDAY...MAINLY VFR WITH ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS.
TUESDAY...MAINLY VFR.

&&

.MARINE...
FOLLOWING THE PASSAGE OF THE COLD FRONT...A BRISK
WESTERLY FLOW WILL SET UP ACROSS LAKE ERIE AND EASTERN PORTIONS OF
LAKE ONTARIO/ADJOINING PORTIONS OF THE SAINT LAWRENCE
RIVER...RESULTING IN ADVISORY-LEVEL CONDITIONS IN THESE AREAS. FOR
THIS REASON...SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT AS
OUTLINED.

FRIDAY AND INTO THE WEEKEND HIGH PRESSURE WILL SLIDE ACROSS THE OHIO
AND TENNESSEE VALLEYS. THIS WILL MAINTAIN A SOUTHWEST TO WESTERLY
FLOW OVER THE EASTERN GREAT LAKES WATERS...THAT MAY NEAR SMALL CRAFT
ADVISORY LEVEL ON LAKE ERIE FRIDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT FRIDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LOZ045.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         SLZ022.

&&

$$

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


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